ADVERTISEMENT
  About the SA Blog Network













Tetrapod Zoology

Tetrapod Zoology


Amphibians, reptiles, birds and mammals - living and extinct
Tetrapod Zoology Home

Leiosaurus: big heads, bold patterns


Email   PrintPrint



Leiosaurus bellii: a short tail, broad, well-muscled head and distinctive 'shark tooth' dorsal pattern. Photo by Oliver Rauhut, used with permission. CC BY.

I like iguanian lizards – who doesn’t? Among the enormous number of taxa that you hardly ever hear anything about is the endemic Argentinean taxon Leiosaurus, type species of Leiosauridae. I did a quick check online and was surprised to find that there’s hardly any information out there on these neat little South American lizards, most sources saying that little is known about them. Well, ain’t that helpful.

All Leiosaurus species are stout-bodied, insectivorous, terrestrial iguanians, easily identifiable due to their proportionally big, wide, well-muscled heads, a tail that is slightly longer than the body, relatively smooth-looking skin (hence the name: it means ‘smooth lizard’) and a unique dorsal pigmentation pattern that involves large spots or blotch on or on either side of the vertebral midline. These blotches form so-called ‘shark tooth’ or ‘fleur-de-lis’ patterns in some species. They are lizards of arid and semi-arid places.

Another view of the same Leiosaurus bellii shown above. Photo by Oliver Rauhut, used with permission. CC BY.

Four Leiosaurus species are currently recognised (L. bellii, L. caramarcensis, L. jaguaris, and L. paronae). L. jaguaris is the newest, having been named in 2007 (Laspiur et al. 2007a). Its name reflects the superficial similarity between its bold dorsal patterning and that of its namesake, the big cat Panthera onca. Several additional species once included within Leiosaurus seem to be part of a closely related taxon, Diplolaemus. Some phylogenies indicate that Diplolaemus is closer to Pristidactylus than to Leiosaurus (Frost et al. 2001) though these authors recovered some topologies where Leiosaurus was paraphyletic with respect to the Diplolaemus + Pristidactylus clade. Abdala et al. (2009) incorporated a lot more data, however, and supported the monophyly of Leiosaurus. Good support for the monophyly of Leiosaurus comes from its complicated gular musculature (Abdala et al. 2009). The name Aperopristis Peracca, 1897 is available for the L. caramarcensis + L. paronae clade, should anyone want to use it (at the moment, they don’t). Leiosaurus and its relatives are closely related to the enyaliines, a group I’ll ignore for now.

Incidentally, an alleged fossil species of Leiosaurus (L. marellii Rusconi, 1937), based on vertebrae from the Pleistocene of San Isidro in Argentina, is not a leiosaurid at all but a misidentified member of Amphisbaena (Torres & Montero 1998).

Palmar view of a Leiosaurus manus, from Abdala et al. (2009). Note the big sesamoid.

These lizards possess a large sesamoid on the palm of the hand, embedded in the tendinous sheet associated with the flexor tendons (funny how you don’t ever hear much about sesamoids in lizards). In Leiosaurus, the palmar sesamoid is especially large, perhaps because the terrestrial, arid-land lifestyle of these lizards has encouraged the evolution of features that enhance the rigidity of the hand. Climbing leiosaurid species have smaller palmar sesamoids, presumably because this permits an enhanced ability to flex the fingers (Abdala et al. 2009).

Another neat (and poorly known) thing about these lizards is that they vocalise, making distinct warning noises and combat noises. The warning vocalisations are associated with postural behaviour: an animal jerks backwards and erects its tail while making these sounds (Laspiur et al. 2007b). Leiosaurus is not unique among iguanians in making noises of this sort, since Pristidactylus species do as well. Vocalisations have not been much reported across Iguania but there are indications that they’re more widespread than currently thought.

The whole ‘Iguanidae Thing’, again

The section of the Pyron et al. (2013) squamate mega-phylogeny that shows leiosaurids and their close relatives. Oplurids are the endemic Madagascan iguanian. Yeah, we'll cover that some other time. Reminder: Pyron et al. (2013) is OPEN ACCESS.

Where and how these lizards are classified varies depending on which source you consult. Tradition has it that pleurodont iguanians (that is, those iguanians that are outside of Acrodonta, the acrodont-toothed clade that includes chameleons and agamas) are included within a super-inclusive Iguanidae, carved up into numerous ‘subfamilies’. Leiosaurus used to be included in Polychrotinae, a group imagined (prior to the late 1980s) to include an array of arboreal, chameleon-like and anole-like iguanians – sometimes termed para-anoles – as well as the terrestrial, shorter-bodied, cryptically coloured leiosaurines. The Leiosaurus species were sometimes called either ‘leiosaur polychrotids’ back in those days, or ‘pristidactylines’ due to the (probably correct) idea that Leiosaurus forms a clade with Pristidactylus and also Diplolaemus.

Nowadays, Leiosaurus and a few close relatives are generally classified within a group variously termed Leiosaurinae or Leiosauridae and taken to include both pristidactylines and enyaliines (Frost et al. 2001, Abdala et al. 2009, Pyron et al. 2013). Some authors argue that we should emphasise monophyly and stick with a conservative taxonomy where possible: according to this view, it’s wise to maintain a super-inclusive Iguanidae that contains a Leiosaurinae and numerous other subfamily-level divisions. Other authors argue that maintaining a super-inclusive Iguanidae is misleading, since it downplays the diversity and disparity of these lizards (some authors have also wanted to avoid using ‘Iguanidae’ in the grand, inclusive sense since there were concerns that it referred to a paraphyletic grade. That no longer seems to be the case though, since modern phylogenies find pleurodont iguanians to be a clade).

A tiny selection of pleurodont iguanians. From top to bottom: Basiliscus, a corytophanid; Leiosaurus, a leiosaurid, and Oplurus, an oplurid. Images by Tina Whitlock, Oliver Rauhut, and Mary Blanchard. CC BY.

I think that the decision to avoid the old, super-inclusive version of ‘Iguanidae’ is desirable, since including all of these many lineages within one ‘family’ is inappropriate when we compare their diversity with that of mammals and birds (where just about every distinct taxon is considered special enough to get its own higher-level taxonomic entity). Of course, invertebrate workers usually make witty retorts at this stage, saying that all of tetrapod diversity could hypothetically be included within a single nematode genus or whatever. Well, screw that: we’re not talking about making tetrapod taxonomy consistent with that of midges or snails, but consistent with that of other tetrapods. Some say that this stuff doesn’t matter as long as we know which taxa we’re talking about. I can agree with that, but I also think that it does matter since we’re still lumbered with a wholly anachronistic and inaccurate view of biodiversity whereby people think that living amphibians and non-avian reptiles are substantially less diverse than mammals and birds.

One last thing. Why did I write this article? Because my colleague Oliver Rauhut happened to share some nice photo of Leiosaurus on facebook. Thank you, Oliver. I love writing about obscure squamate taxa, so – dear readers – please keep me in mind if you have good photos that you’re prepared to let me use.

For previous Tet Zoo articles on iguanians, see…

Refs – -

Abdala, V., Manzano, A. S. & Nieto, L. 2009. Comparative myology of Leiosauridae (Squamata) and its bearing on their phylogenetic relationships. Belgian Journal of Zoology 139, 109-123.

Frost, D. R., Etheridge, R., Janies, D. & Titus, T. A. 2001. Total evidence, sequence alignment, evolution of polychrotid lizards, and a reclassification of the Iguania (Squamata: Iguania). American Museum Novitates 3343, 1-38.

Laspiur, A., Carlos Acosta, J. & Abdala, C. S. 2007a. A new species of Leiosaurus (Iguania: Leiosauridae) from central-western Argentina. Zootaxa 1470, 47-57.

- ., Sanabria, E. & Carlos Acosta, J. 2007b. Primeros datos sobre vocalización en Leiosaurus catamarcensis (Koslowsky, 1898) y Pristidactylus scapulatus Burmeister, 1861, (Iguania, Leiosauridae) de San Juan, Argentina. Revista Peruana Biologie 14, 2.

Pyron, R. A., Burbrink, F. T. & Wiens, J. J. 2013. A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC Evolutionary Biology 2013, 13:93 doi:10.1186/1471-2148-13-93

Torres, S. E. & Montero, R. 1998. Leiosaurus marellii Rusconi 1937, is a South American amphisbaenid. Journal of Herpetology 32, 602-604.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com!

Nature Blog Network

Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





Rights & Permissions

Comments 49 Comments

Add Comment
  1. 1. Cai Yuan 5:42 am 10/7/2013

    There are roughly 10000 extant squamate vs. ~5500 extant mammal species. End of story. That’s the fact to be telling people. The people who think extant reptiles are “less diverse” than extant mammals don’t care if there are 5 or 500 reptile “families”, and to try to make the system work otherwise is to go down a fruitless rabbit hole. Should we then split Muridae into 30 families so that people aren’t confused about its diversity? Where does it end? Education about species richness and lineage age is worth more than worrying about shuffling labels to conform to what we think should be true.

    Link to this
  2. 2. naishd 5:53 am 10/7/2013

    Thanks for the comment, Cai. I kind of agree with your sentiment.. and I kind of don’t. I “kind of don’t” because I’ve seen people say things like “we’ve never lost a single bird family, thus birds aren’t going extinct”, without there being the realisation that family-level classification is arbitrary, subjective as – as per the case discussed above – misleading.

    Darren

    Link to this
  3. 3. naishd 5:58 am 10/7/2013

    By the way, I think that the paraphrased thing about the extinction of ‘families’ comes from Bjørn Lomborg’s book. It also reminds me of those studies on extinction rates that measure ‘families’, ‘orders’ and so on (cf various of Michael Benton’s papers) … as if they mean something.

    Darren

    Link to this
  4. 4. Cai Yuan 6:31 am 10/7/2013

    That’s definitely a problem, but is the time spent renaming, arguing in the literature over the names, and making an active push to enforce the new nomenclature in general biology texts, field guides, etc. worth it? It just seems like trying to correct that inherent misconception is the better use of time, rather than fighting historical inertia (especially because this is a case where tradition isn’t “wrong” per se).
    Like for those “family-count” papers you’re talking about. They had their place in the ’70s when that was the only data available, but with modern species-level databases there’s no excuse. Should you waste time making families more amenable for someone like Benton to count, or try to stop that altogether? I can’t get behind the argument that “people are going to do it this way anyway, so we should try and make their results as not-skewed as possible”.

    Link to this
  5. 5. naishd 6:48 am 10/7/2013

    Again, that seems fair enough and I don’t wholly disagree with you. My get-out clause here is that I’m not personally wasting any research time on this (since I don’t publish technical research on iguanians), merely discussing the issue here on a blog because… I think it needs to be discussed.

    Having said all that, I’ve always said that taxonomy should work on the basis of whatever the consensus is. As you note, it isn’t what’s right or wrong, it’s what’s deemed most useful for the purposes of communication. Today, recent literature indicates that the consensus prefers the view of a multi-’family’ version of the pleurodont clade (cf Pyron et al. 2013). And I think that this consensus needs to become better known, hence the coverage it receives here.

    Darren

    Link to this
  6. 6. David Marjanović 7:10 am 10/7/2013

    Of course, invertebrate workers usually make witty retorts at this stage, saying that all of tetrapod diversity could hypothetically be included within a single nematode genus or whatever. Well, screw that:

    *splitter fistbump*
    :-)

    with modern species-level databases there’s no excuse

    Such databases exist for fewer taxa than you seem to imagine; and species are arbitrary, too, perhaps especially in the fossil record.

    Link to this
  7. 7. Cai Yuan 8:30 am 10/7/2013

    “Today, recent literature indicates that the consensus prefers the view of a multi-’family’ version of the pleurodont clade (cf Pyron et al. 2013). And I think that this consensus needs to become better known, hence the coverage it receives here.”

    Fair enough, and sorry for derailing conversation into philosophy, when it should be about how awesome leiosaurids are! In Argentina they are one of several similar lizards called “matuasto” (the others are liolaemids). Apparently it is believed to have all sorts of evil powers locally, and features in some were-animal legends:
    http://patagoniamonsters.blogspot.de/2010/11/matuasto-monstrous-midget-lizard.html

    Link to this
  8. 8. Dartian 10:29 am 10/7/2013

    Cai:
    is the time spent renaming, arguing in the literature over the names, and making an active push to enforce the new nomenclature in general biology texts, field guides, etc. worth it?

    Well, some of us consider that kind of activity not only interesting but also important. But to each his own, I suppose.

    As a battle-scarred veteran of Tet Zoo’s Nomenclature Wars, I’d like to point out here, for the record, that taxonomic ranks don’t need be (totally) arbitrary; they can be made to correspond to (for example) geological divergence dates.

    I have argued here on Tet Zoo for such a divergence-date-based classification scheme several times, and I’d prefer not to repeat myself. But, in short: Experience has shown that when sensibly applied, within Mammalia at least such a system actually works pretty well in practice, and results in surprisingly few radical departures from ‘traditional’ classification schemes. (Unfortunately, AFAIK this method has thus far not been seriously applied to virtually any other higher-level taxa, so we don’t really know yet what kind of taxonomical upheavals it might or might not lead to in them. But such practical difficulties with implementation would not, of course, make the principle itself theoretically unsound.)

    Link to this
  9. 9. vdinets 11:13 am 10/7/2013

    Dartian: But wouldn’t such a system be forever haunted by shadow lineages? And what about groups with poor fossil record? You can’t use molecular clock for them, either, because you can’t calibrate it…

    Link to this
  10. 10. Dartian 11:34 am 10/7/2013

    what about groups with poor fossil record?

    Mammals, as a whole, relatively speaking have an excellent fossil record – that’s why that system works so well for them.

    Link to this
  11. 11. vdinets 12:50 pm 10/7/2013

    Dartian: That’s good to know. Finally we can use strict criteria to develop a better bat classification ;-)

    Link to this
  12. 12. Heteromeles 11:04 pm 10/7/2013

    On the conservation end, we routinely get into questions like: is it worth saving all orchid species (there are butt-loads of them) or that single relict solenodon that some might find butt-ugly (although I think they’re cute). One could argue that the solenodon, dangling out in its own clade, is infinitely more important than any number of ephemeral orchid species, but thousands of orchids aficionados would beg to differ.

    So yes, these questions matter. It’s not necessarily that we need to hammer out a hard-and-fast answer. However, learning to argue these things effectively with people of all backgrounds is pretty damn important. Otherwise, how can you make a case for saving a rare Leiosaurus in front of a rural council who think the little buggers are all evil shapeshifters?

    Link to this
  13. 13. HaroldBakker 5:25 am 10/8/2013

    I visited the Galapagos this year and there were loads of tetrapods.
    Feel free to use any of my pictures, they’re CC licenced. Check the description for where each photo was taken. Of particular interest may be the pics of a lava lizard on a sea lion (they eat the flies that annoy sea lions when they are basking in the sun) and finches with marine iguanas (they eat parasites and dead skin). I tried to provide accurate scientific names, although I’m not a biologist but merely a librarian so I didn’t try to determine the various finch or lava lizard subspecies.

    http://www.flickr.com/photos/haroldbakker/sets/72157634953740157/

    Link to this
  14. 14. David Marjanović 10:41 am 10/8/2013

    Mammals, as a whole, relatively speaking have an excellent fossil record – that’s why that system works so well for them.

    How does it work for the fossil record itself? Or are you just talking about neontology, and the paleontologists live in their own little world as usual?

    Link to this
  15. 15. Dartian 12:44 pm 10/8/2013

    David:
    How does it work for the fossil record itself? Or are you just talking about neontology, and the paleontologists live in their own little world as usual?

    I am admittedly neontologically biased. For wholly extinct species, applying a divergence-date-based taxonomic scheme gets more tricky. But even there I think it can work pretty well, at least in some groups.

    Mammals are, again, perhaps the best example (by virtue of their better-than-average fossil record). If we, for the sake of argument, decide that any mammalian lineage that originated between 35 and 45 MYA (I’m pulling these figures out of my butt, but I hope that my general point does get across) represents a ‘family’, then not only would we recover almost all currently recognised extant carnivoran families* but also such extinct carnivoran taxa as amphicyonids and barbourofelids would (at least IIRC) retain their traditional ‘family’ status (that these two taxa went subsequently extinct is of no consequence here).

    * Some, such as the pinnipeds, might have to be re-ranked in this hypothetical example.

    However, with organisms such as, for example, Mesozoic dinosaurs my own thinking regarding this question has evolved over the last few years to the point that I no longer think that a one-size-fits-all solution is necessary or even desirable. Perhaps the simplest and most sensible solution is indeed to abandon ranks altogether when classifying pre-Cenozoic organisms? (Except at the very highest levels: phyla, etc.)

    Link to this
  16. 16. Tayo Bethel 10:06 pm 10/8/2013

    How common is vocal behavior among squamates? One sometimes gets the impression that geckos are unique in being highly vocal among squamates.

    Link to this
  17. 17. David Marjanović 6:34 am 10/9/2013

    If we, for the sake of argument, decide that any mammalian lineage that originated between 35 and 45 MYA [...] represents a ‘family’, then

    …every species that lived during that time becomes its own family, and every species that’s older than that becomes a monotypic taxon of even higher rank, right?

    Link to this
  18. 18. Dartian 11:48 am 10/9/2013

    David:
    every species that lived during that time becomes its own family, and every species that’s older than that becomes a monotypic taxon of even higher rank, right?

    No; I should have written “any extant mammalian lineage that originated between 35 and 45 MYA”. Wholly extinct clades can really only be allocated to their own respective ranks when these are seen relative to the extant ones. (E.g., if we assume that felids and barbourofelids are sister groups – as they probably are – then every individual fossil species that’s more closely related to, say, Barbourofelis fricki than to crown Felidae goes into Barbourofelidae.)

    For the record, I have nothing against phylogenetic definitions of extant taxa. To the contrary, I think that such definitions could and should be used in combination with a divergence-date-based classification system. What I’m less convinced about is that their specifiers should (must?) be crown-group taxa. That’s impractical (in the sense of significantly upsetting traditional taxonomic usage) for groups with few living members but a rich fossil record; groups such as, for example, elephants, rhinos, horses, and camelids.

    Link to this
  19. 19. naishd 4:18 am 10/10/2013

    Thanks for all the comments, great discussion. Tayo Bethel (comment # 16) asked about the distribution of a vocalising habit in squamates. While, yes, vocalisation is ‘normal’ and widespread in Gekkota, its distribution elsewhere seems to be patchy, and much of what’s been written is more semi-anecdotal than would be ideal. Elsewhere in iguanians, iguanines and chameleons are also reported to make definite vocalisations, as are certain skinks and lacertids. There are also reports of anguids and colubroids making definite noises. In short, the ability to vocalise seems scattered about Squamata at the moment – is this because vocalising really has evolved independently 7 or so times, or is vocalisation more widespread and just under-reported or chronically understudied? Or both?

    Darren

    Link to this
  20. 20. David Marjanović 6:20 am 10/10/2013

    What I’m less convinced about is that their specifiers should (must?) be crown-group taxa. That’s impractical (in the sense of significantly upsetting traditional taxonomic usage) for groups with few living members but a rich fossil record; groups such as, for example, elephants, rhinos, horses, and camelids.

    I think you’re in full agreement with Recommendation 10G (very bottom of the page).

    Link to this
  21. 21. ectodysplasin 4:32 pm 10/11/2013

    The problem with constraining yourself to absolute dates is that higher taxonomic levels like “families” generally indicate important radiations, often facilitated by the evolution of key characteristics. For example, when we talk about the Cichlidae, we’re talking about a fish radiation that was facilitated in large part by novel morphology of the pharyngeal apparatus, or if we talk about the Mormyridae, we’re talking about a radiation that was facilitated by novel features of the electrogenerative and electroreceptive organs of that specific fish clade. And so on and so forth. The age at which these radiations occurred is not really relevant. What matters is that there are novel characteristics or suites of characteristics that have facilitated a diversification of this group, sometimes uniquely and sometimes at the expense of other groups.

    Link to this
  22. 22. vdinets 10:30 pm 10/11/2013

    ectodysplasin: and that approach, too, has a lot of inherent problems. First, it is highly subjective, and second, it immediately means that our species should be considered a separate order, if not a class.

    Link to this
  23. 23. naishd 6:53 am 10/12/2013

    vdinets: what you say is obviously not true when we account for fossil taxa, right?

    Darren

    Link to this
  24. 24. Dartian 9:04 am 10/12/2013

    ectodysplasin:
    higher taxonomic levels like “families” generally indicate important radiations, often facilitated by the evolution of key characteristics

    With that statement, you reveal that you do not really understand what this discussion is about. You are talking about diagnoses of taxa. This discussion is about definitions of taxa. Specifically, the definitions of monophyletic clades*. And such definitions only make evolutionary sense if they are based on the phylogeny – the evolutionary history – of organisms. Which is where all this talk about lineage divergences and crown clades comes in.

    * Tautology intended.

    The age at which these radiations occurred is not really relevant.

    See above; that sentence is a non sequitur. Either educate yourself on the very basic concepts behind this subject, or stay out of it.

    And the same goes for

    Vlad:
    it is highly subjective

    Lineage divergence dates are the closest thing we currently have to objective taxonomic rank assignment criteria. By using modern phylogenetic research methods such dates are also, at least in principle, relatively easy to determine with a sufficiently high degree of confidence.

    Seriously, we have had discussions on this subject countless times here on Tet Zoo over the years. The relevant issues have been explained especially by David Marjanović but also by others in excruciating detail. You have read these discussions (or at least you have frequently participated in the comments threads). Have you really learned nothing of significance about this subject during all this time?!?

    Link to this
  25. 25. David Marjanović 10:06 am 10/12/2013

    higher taxonomic levels like “families” generally indicate important radiations

    Plainly untrue – at least when you try to be the least bit objective about it.

    With that statement, you reveal that you do not really understand what this discussion is about. You are talking about diagnoses of taxa. This discussion is about definitions of taxa.

    What – no. What you talk about in comments 8, 15 and 18 is rank assignment, which is independent of both the diagnosis of taxa and the definition of their names*.

    * Clades exist in nature. Names only exist inside our skulls; they can be defined, clades cannot.

    Vlad:
    “it is highly subjective”

    That was a reply to ectodysplasin’s claim that “higher taxonomic levels like ‘families’ generally indicate important radiations”, which was an argument against your position.

    Link to this
  26. 26. Jerzy v. 3.0. 10:13 am 10/12/2013

    A solution may be a list of morphologically defined groups which correspond to what a zoological practicioner might consider a group, but may or may not be clades.

    Clades could be described only by branch species but never by common names. So no confusion between pair-hoofed mammals and ‘Sus-Bos clade’ containing whales.

    Otherwise the cladistic guys are going forever to confuse the world by replacing traditional meaning of words describing groups of organisms by clades which contain some completely different organisms.

    Examples: ‘turtles are not reptiles’ ‘sparrow is a dinosaur’ or ‘people are highly derived bacterial colonies’.

    Link to this
  27. 27. Dartian 8:11 am 10/13/2013

    David:
    What you talk about in comments 8, 15 and 18 is rank assignment, which is independent of both the diagnosis of taxa and the definition of their names

    Actually, not quite. Rank assignment is in principle independent of both the diagnosing and defining taxa, yes, but in practise these subjects do go almost always hand in hand (at least in internet discussions). I was referring there to the whole wider history of the discussion about ‘phylogenetic nomenclature vs. Linnaean nomenclature’ and clade definitions that you, I, and several others have intermittently had on Tet Zoo (in its various incarnations) since the year 2008 at least. That’s why I said in comment #8 that I’d “prefer not to repeat myself”.

    Admittedly my comment #24 was a bit on the trigger-happy side, for which I apologise. But I do feel that there are certain subjects that come up here so frequently that it’s reasonable to expect anyone who’s been following this blog for more than twenty minutes to have at least some level of detailed understanding of them (or else have the good sense to stay out of the discussion).

    That was a reply to ectodysplasin’s claim that “higher taxonomic levels like ‘families’ generally indicate important radiations”, which was an argument against your position.

    What I had more in mind when I wrote that was his earlier comment about bats (which, from the context, I presumed was meant as a cheap shot against my position) – and it was not a valid counter-argument. You can apply the divergence-date-based classification system just as well to bats as you can to almost any other crown mammal group. Bats don’t have a particularly good fossil record (by mammalian standards), but they have a fossil record that’s good enough. Their ‘family’-level divergence dates can therefore be reconstructed too. See, for example:

    Jones, K.E., Bininda-Emonds, O.R. & Gittleman, J.L. 2005. Bats, clocks, and rocks: diversification patterns in Chiroptera. Evolution 59, 2243-2255.

    Link to this
  28. 28. vdinets 9:15 am 10/13/2013

    Darren: why? There is a long chain of important fossil taxa leading to H. sapiens, each with spectacular modifications. Bipedality, use of fire, symbyosis with countless plants and animals, etc., etc. As long as you don’t have time- or monophyly- based criteria, there’s no reason not to split us into a class separate from other mammals.

    David: my comment was referring to the comment by ectodysplasin, so it looks like you read it in a way exactly opposite to what I intended :-)

    Link to this
  29. 29. David Marjanović 12:01 pm 10/13/2013

    Examples: ‘turtles are not reptiles’

    what

    As long as you don’t have time- or monophyly- based criteria, there’s no reason not to split us into a class separate from other mammals.

    At the same time, there’s no reason not to do what Linnaeus intended and lump all primates known to him into the same genus.

    Rank assignment is in principle independent of both the diagnosing and defining taxa, yes, but in practise these subjects do go almost always hand in hand (at least in internet discussions).

    Yes, so stop contributing to this confusion at last! :-) The sooner it gets unravelled, the better!

    Link to this
  30. 30. ectodysplasin 4:30 pm 10/13/2013

    @vdinets:

    ectodysplasin: and that approach, too, has a lot of inherent problems. First, it is highly subjective, and second, it immediately means that our species should be considered a separate order, if not a class.

    I agree that it’s subjective. All taxonomy is.

    What I’m saying, however, is that “family” is a stand-in for something real, which is to say adaptive radiation. That’s not to say that it is a perfectly objective measure of adaptive radiation, nor that adaptive radiations and families have a 1-to-1 correspondence in our current understanding of biodiversity, because neither is the case. I’m just saying that what we’re identifying when we identify “families” are diversifications that are the end-result of real biological processes, rather than taxonomic artifacts.

    Link to this
  31. 31. ectodysplasin 5:10 pm 10/13/2013

    @Dartian:

    With that statement, you reveal that you do not really understand what this discussion is about. You are talking about diagnoses of taxa. This discussion is about definitions of taxa. Specifically, the definitions of monophyletic clades*. And such definitions only make evolutionary sense if they are based on the phylogeny – the evolutionary history – of organisms. Which is where all this talk about lineage divergences and crown clades comes in.

    Let’s establish a few things.

    1. Higher taxa are not objective things. This includes everything from Genus on up. These are all holdovers from Linnean taxonomy, which is based on typologies and an understanding of the origin of species and of diversity that is starkly in contrast with how we currently understand the origin of biodiversity. There is, for example, a reason why biodiversity in the Linnean system was originally organized by pentads (five kingdoms of life, five classes of vertebrates, etc).

    2. “Species” is not an objective thing either. The Mayr definition falls apart pretty quickly because it turns out that horizontal gene transfer is the name of the game even up to the family level, and that hybrid zones are often persistent things, even when main populations have diverged significantly.

    3. Phylogeny is not known. It can only be inferred. This is especially the case when we look at fossil taxa, but it also applies to many modern taxa. Squamate phylogeny is notoriously unstable, for example. So is bird phylogeny. So, when we name clades based on phylogeny, these names are hypotheses that must be tested with further studies.

    4. Divergence dates are not known. As divergence dates are inferred based on phylogenetic inferences as well as various other assumptions (clocklike evolution, certain identification of often-fragmentary fossil remains, etc), those divergence dates are themselves hypotheses that require rigorous testing.

    So while I recognize your desire for a stable and objective taxonomic system, I don’t think this is likely to ever exist. Phylogenetic systematics has moved away from higher taxa entirely….we keep genera because they’re required by the ICZN in order to make the name valid, but we don’t really care too much about where those lines are drawn, unless a genus is obviously not monophyletic or unless a worker is shamelessly splitting otherwise stable genera in order to name snakes after his friends, family, and childhood dog. Typically, what we do nowadays is name higher taxa in ways that are not governed by ICZN protocols and simply specify a phylogenetic definition that is itself falsifiable.

    Families are still used in biodiversity estimates in deep time because family count does estimate the relationships between phylogeny and niche occupation, but this is a usage that does not take phylogeny into direct account, and in many cases these analyses will use families that are known or suspected to be paraphyletic.

    So yes, I agree. “Family,” as the concept is used today, is not stable and objective. However, I disagree that this means that we need an overhaul of the concept of “family.” We just need to recognize that “family” has one set of uses and phylogeny has another.

    Link to this
  32. 32. ectodysplasin 6:15 pm 10/13/2013

    @Dartian,

    Actually, not quite. Rank assignment is in principle independent of both the diagnosing and defining taxa, yes, but in practise these subjects do go almost always hand in hand (at least in internet discussions). I was referring there to the whole wider history of the discussion about ‘phylogenetic nomenclature vs. Linnaean nomenclature’ and clade definitions that you, I, and several others have intermittently had on Tet Zoo (in its various incarnations) since the year 2008 at least. That’s why I said in comment #8 that I’d “prefer not to repeat myself”.

    Ranks do not exist in nature. In fact, the existence of species as discrete units (rather than condensations of reproductive activity) is quite questionable as well.

    Higher taxon nomenclature, then, does not need to serve the purpose of naming “real objective things.” What it needs to do is serve the purposes of those people who use those names as a reasonable proxy for other things. I don’t see how a divergence time will offer that, whereas the current approach, while not objective, seems to do the trick quite nicely.

    Link to this
  33. 33. Jerzy v. 3.0. 6:17 pm 10/13/2013

    I wonder if there were any serious attempts to improve or change higher ranks in taxonomy? Other than removing ranks in cladistics, that is.

    Link to this
  34. 34. ectodysplasin 10:45 am 10/14/2013

    @Jerzy,

    I wonder if there were any serious attempts to improve or change higher ranks in taxonomy? Other than removing ranks in cladistics, that is.

    There’s been a push to make sure that named ranks are monophyletic. Beyond that, there have been attempts by individuals to propose changes, but none have really caught on because there’s no real need for it.

    Link to this
  35. 35. Dartian 11:56 am 10/14/2013

    ectodysplasin:
    The Mayr definition

    But his Biological Species Concept is far from the only species concept in active use. Under the Phylogenetic Species Concept, for example, naturally occurring hybridisation dos not necessarily mean that two populations should be classified as belonging to the same species.

    Phylogeny is not known.
    and
    Divergence dates are not known.

    Strictly speaking, little or nothing can ever be really “known” in science. But that’s no reason not to take the best ideas we have at any given moment, and use them as our best-guess working hypotheses (until some better hypotheses come along). Otherwise no science could ever get done.

    I recognize your desire for a stable and objective taxonomic system

    What? No! I have never desired taxonomy to be “stable” (as in being never-changing and immutable) and I can’t recall ever having said anything that could reasonably be interpreted to that effect. To the contrary, I have always been of the opinion that any biological classification system must be amenable to change should the situation so require.

    I don’t see how a divergence time will offer that

    Divergence dates have the advantage of being, at least in principle, testable and repeatable. Two researchers, given the same data to analyse, ought to be able to reach approximately the same conclusion about when any two given two lineages diverged. I can’t see how different researchers independently trying to somehow quantify, say, morphological ‘disparity’ would ever have a hope to reach any comparable level of non-subjectivity in their assessments.

    Link to this
  36. 36. David Marjanović 12:06 pm 10/14/2013

    divergence dates are inferred based on phylogenetic inferences as well as various other assumptions (clocklike evolution

    Clocklike evolution hasn’t been assumed by programs for molecular divergence date estimation in more than 10 years. There’s much that’s problematic with many published dates – I’ve gotten two papers out of that fact; in particular, calibration is hard –, but this isn’t one of those problems.

    a phylogenetic definition that is itself falsifiable

    What? Phylogenetic definitions are definitions. They’re correct by definition – they’re not falsifiable!

    …Oh. Do you mean it’s testable (against parsimony) whether a particular clade fits a particular definition and therefore gets to bear the name that’s tied to that definition? Because that is true.

    Families are still used in biodiversity estimates in deep time because family count does estimate the relationships between phylogeny and niche occupation

    No. They estimate the relationships between phylogeny and somebody’s vague, unquantified ideas about some combination of niche occupation, morphological disparity, availability of empty slots in the rank hierarchy, and who knows what else!

    However, I disagree that this means that we need an overhaul of the concept of “family.” We just need to

    ditch the term altogether, recognizing there never was a concept behind it. :-)

    In fact, the existence of species as discrete units (rather than condensations of reproductive activity) is quite questionable as well.

    Different species concept describe different entities, many of which exist in nature. They just don’t have much in common with each other, apart from the fact that they’re all called “species”.

    Depending on the species concept, there are from 101 to 249 endemic bird species in Mexico.
    Agapow, P.-M., Bininda-Emonds, O. R. P., Crandall, K. A., Gittleman, J. L., Mace, G. M., Marshall, J. C., & Purvis, A. (2004). The impact of species concept [sic] on biodiversity studies. The Quarterly Review of Biology 79(2): 161–179.
    Peterson, A. T. & Navarro-Sigüenza, A. G. (1999). Alternate species concepts as bases for determining priority conservation areas. Conservation Biology 13(2): 427–431.

    Link to this
  37. 37. ectodysplasin 12:32 pm 10/15/2013

    @Dartian:

    But his Biological Species Concept is far from the only species concept in active use. Under the Phylogenetic Species Concept, for example, naturally occurring hybridisation dos not necessarily mean that two populations should be classified as belonging to the same species.

    Phylogenetic species concept has its own problems. The biggest problem is that it assumes that cladogenesis is the only real process going on in the history of all life, which is not the case. The existence of stable hybrid zones, the formation of new species via hybridization, and other such things seem to be more commonplace than we’ve ever imagined, and all of these violate the most basic assumptions of the phylogenetic species concept.

    The other problem with the phylogenetic species concept is that there is no stability of taxonomic inclusion within a species. This is especially the case where you have a large source population that is relatively stable that throws off small rapidly-diverging populations that rapidly become isolated and specialized. According to the phylogenetic species concept, the large stable source population “speciates” every time one of these small isolated populations is established, despite there being no substantial change in the source population.

    Some aspects of the phylogenetic species concept are also problematic because they are based entirely on methodological constraints of traditional cladistic analyses i.e. the inability to infer ancestor-descendant relationships in the fossil record. We should expect to find some number of ancestors in the fossil record, and both mathematical models and empirical tests that explicitly consider anagenesis rather than solely cladogenesis actually do recover ancestors at roughly the same rate as the models suggest. Anagenic transformation within a single lineage would thus negate the idea that these are separate species, despite the fact they exhibit distinct and obvious differences, ofentimes in ways that are extremely useful for systematists, stratigraphers, etc (this is especially the case in marine inverts and conodonts).

    Strictly speaking, little or nothing can ever be really “known” in science. But that’s no reason not to take the best ideas we have at any given moment, and use them as our best-guess working hypotheses (until some better hypotheses come along). Otherwise no science could ever get done.

    There’s a difference between saying “these things are inferences that generally lack stability” and saying “we can’t really know anything ever.” I’m saying the former. Given that higher taxa are category names, we want those names to sustain some sort of stability of the objects (in this case, OTUs) included within that category. To me, it makes sense to say “well, we established this category based on phylogeny but this thing that has traditionally been included in that category clearly doesn’t belong because it evolved separately.” It does not make sense to say “well, this clade seems to have diverged earlier than 50 Ma, therefore species X, Y, and Z actually belong in a different category” especially considering that different analyses may recover different taxa as falling out at the base of a clade, and may stick different taxa within or outside of that 50 Ma mark.

    What? No! I have never desired taxonomy to be “stable” (as in being never-changing and immutable) and I can’t recall ever having said anything that could reasonably be interpreted to that effect. To the contrary, I have always been of the opinion that any biological classification system must be amenable to change should the situation so require.

    By stable and objective taxonomic system I meant objective thresholds for assigning names higher taxa. Sorry if that wasn’t clear.

    Link to this
  38. 38. ectodysplasin 12:59 pm 10/15/2013

    @David,

    Clocklike evolution hasn’t been assumed by programs for molecular divergence date estimation in more than 10 years. There’s much that’s problematic with many published dates – I’ve gotten two papers out of that fact; in particular, calibration is hard –, but this isn’t one of those problems.

    BEAST infers a distributed rate parameter and dates based on observed character data and a series of first occurrences of lineages. Although it does not impose a single rate parameter on an ultrametric tree the way the original methods used to, you’re still estimating a mean rate parameter with some dispersion. So while not strictly clocklike in that 1 bp change does not directly correspond to some number of millions of years, some of the methodological constraints still exist. It’s hard to handle coalescence issues as well as character saturation issues, even with the bayesian methods, not to mention biases such as clade-specific changes in generation time and other things like blatant A-T bias in some clades.

    …Oh. Do you mean it’s testable (against parsimony) whether a particular clade fits a particular definition and therefore gets to bear the name that’s tied to that definition? Because that is true.

    Whether the clade definition that is associated with a specific name is supported by phylogenetic analyses. For example, the clade “Haemothermia” was defined to include birds and mammals to the exclusion of all other extant tetrapods. We see no support for this clade in modern analyses. The hypothesis H(clade Haemothermia exists) is pretty convincingly falsified.

    No. They estimate the relationships between phylogeny and somebody’s vague, unquantified ideas about some combination of niche occupation, morphological disparity, availability of empty slots in the rank hierarchy, and who knows what else!

    Yes. I cannot pick two families out of a hat and assume they are directly comparable, because they probably are not. However, when we compare dozens to hundreds of families, we do find some properties of families that are comparable at that gross level, and which can tell us things about community structure etc. And while the results may not be as high-resolution as you’d get by working at the species level, you can avoid some of the worker bias issues that are involved in splitting/lumping and worker attention in some groups, which will artificially inflate or deflate species count in certain taxa and intervals.

    So, not perfect, but sometimes useful.

    ditch the term altogether, recognizing there never was a concept behind it. :-)

    I agree it’s no use for phylogeneics work. But I do think there are places where it’s useful.

    Different species concept describe different entities, many of which exist in nature. They just don’t have much in common with each other, apart from the fact that they’re all called “species”.

    What I’d argue is that these species concepts describe end-members of variation in gene flow. BSC describes the end-member of gene flow blockage, where there is zero gene flow for an extended period of time. PSC describes a situation where gene flow is repeatedly blocked without recommencing of flow. MSC describes situations where blockage of gene flow at some amount or another allows different populations to evolve distinct and non-overlapping morphology. But these are all end-members of gene flow and divergence.

    Link to this
  39. 39. ectodysplasin 7:17 pm 10/15/2013

    @Dartian,

    Divergence dates have the advantage of being, at least in principle, testable and repeatable.

    And the disadvantage of being utterly useless.

    I can’t see how different researchers independently trying to somehow quantify, say, morphological ‘disparity’ would ever have a hope to reach any comparable level of non-subjectivity in their assessments.

    There a numerous multivariate approaches that have been used to estimate disparity, nichespace occupation, morphospace occupation, etc, including in a phylogenetic context. I suppose you could criticize landmark selection or measurement choice or whatever as “arbitrary” but I’m not sure that’s really legitimate either.

    Link to this
  40. 40. Dartian 1:35 am 10/16/2013

    And the disadvantage of being utterly useless.

    That statement is just… wrong.

    For the record, I’ll state my case again (for the N:th time):

    Traditional taxonomic ranks are arbitrary; this was never in dispute. But these ranks could be made significantly less arbitrary by ‘standardising’ them*. And a satisfactorily objective way to do this is to use lineage divergence date as the rank assignment criterion. That has been my POV for the last five years or more. (This idea isn’t really ‘mine’, of course; it was originally conceived by Willi Hennig, and subsequently developed by John Avise, Morris Goodman, Colin Groves, and others.)

    In other words, within the parameters of this argument, divergence dates are eminently useful. Which makes your above statement logically wrong and/or nonsensical in the current context.

    * That, of course, is assuming that we should preserve taxonomic ranks in the first place. Some people are of the opinion that we should not. I am of the opinion that they can be of practical utility, provided that they are made less subjective (as per above).

    I suppose you could criticize landmark selection or measurement choice or whatever as “arbitrary”

    It’s a bit hard to criticise unknown sources. Give me the references and I’ll look into them.

    Link to this
  41. 41. ectodysplasin 9:32 am 10/16/2013

    @Dartian,

    In other words, within the parameters of this argument, divergence dates are eminently useful. Which makes your above statement logically wrong and/or nonsensical in the current context.

    So the divergence dates are useful because they can be used to assign an arbitrary higher taxonomic rank, and the arbitrary higher taxonomic rank is useful because it indicates divergence date…

    The point of keeping the current family concept intact is that “family” actually means something now, even if assignment of taxa to the family level adheres to subjective rather than objective criteria. To use a salient iguanian example, terms like Agamidae, Chamaeleonidae, Iguanidae, Polychrotidae, Phrynosomatidae, Tropiduridae, Crotophytidae, and Corytophanidae all indicate diversifications that are associated with specific morphologies…for instance, if we talk about Agamidae, we’re talking about a diversification of iguanians that all exhibit an acrodont dentition, among other things. If we talk about Crotophytidae, we’re talking about medium-sized omnivorous desert-dwelling lizards.

    So while these categories are arbitrary, they carry some amount of actual meaning about what sort of animals are contained and are not contained in that category. This is useful. Let’s say we have stomach contents of a lizard and want to know what it’s been eating. Good luck identifying that material to species, but maybe it’s assignable to family (or order) and that can tell you something, still, about the lizard’s diet. Furthermore, even if you can assign them to species, some taxa are so diverse that each species may not be abundant enough to do any sort of useful statistics on, but in aggregate they might be. Family then becomes a way of usefully aggregating these individual occurrences in an ecologically useful manner.

    It’s a bit hard to criticise unknown sources. Give me the references and I’ll look into them.

    Pierce, S. E., Angielczyk, K. D., & Rayfield, E. J. (2008). Patterns of morphospace occupation and mechanical performance in extant crocodilian skulls: a combined geometric morphometric and finite element modeling approach. Journal of morphology, 269(7), 840-864.

    Stayton, C. T. (2005). Morphological evolution of the lizard skull: a geometric morphometrics survey. Journal of Morphology, 263(1), 47-59.

    Stayton, C. T., & Ruta, M. (2006). Geometric morphometrics of the skull roof of stereospondyls (Amphibia: Temnospondyli). Palaeontology, 49(2), 307-337.

    For example. Honestly the literature is vast and it would be difficult to provide a thorough bibliography.

    Link to this
  42. 42. David Marjanović 11:32 am 10/16/2013

    According to the phylogenetic species concept, the large stable source population “speciates” every time one of these small isolated populations is established, despite there being no substantial change in the source population.

    I think you’ve conflated the phylogenetic species concept with Hennig’s species concept. Hennig is the one who used “speciation” as just another word for cladogenesis and “species” as just another word for internode.

    In a stunning victory for terminology, even the cladistic species concept (whatever it actually is) isn’t the same as Hennig’s!

    For example, the clade “Haemothermia” was defined to include birds and mammals to the exclusion of all other extant tetrapods. We see no support for this clade in modern analyses. The hypothesis H(clade Haemothermia exists) is pretty convincingly falsified.

    Ah, OK, but few definitions are potentially self-destructive.

    To me, it makes sense to say “well, we established this category based on phylogeny but this thing that has traditionally been included in that category clearly doesn’t belong because it evolved separately.” It does not make sense to say “well, this clade seems to have diverged earlier than 50 Ma, therefore species X, Y, and Z actually belong in a different category”

    Here you confuse rank assignment with name assignment.

    However, when we compare dozens to hundreds of families, we do find some properties of families that are comparable at that gross level, and which can tell us things about community structure etc.

    Show me.

    (Or, better yet, get a publication out of it. You could aim very high when choosing a journal! This is not sarcasm.)

    This idea isn’t really ‘mine’, of course; it was originally conceived by Willi Hennig

    Hennig himself later abandoned it, though.

    The point of keeping the current family concept intact

    There is no family concept.

    There are some 150 species concepts. There’s 1 genus concept that almost nobody has ever tried to use. There are 0 family, order, class, whatever concepts.

    “family” actually means something now

    Yeah, it shows us something about the esthetic preferences of certain taxonomists. That’s all. That’s literally all.

    To use a salient iguanian example, terms like Agamidae, Chamaeleonidae, Iguanidae, Polychrotidae, Phrynosomatidae, Tropiduridae, Crot[a]phytidae, and Corytophanidae all indicate diversifications that are associated with specific morphologies…

    That’s because they’re clade names, not because they have been assigned the rank of family (following recent splitting in most of these cases, before which most of these names held subfamily rank but designated the exact same clades).

    Let’s say we have stomach contents of a lizard and want to know what it’s been eating. Good luck identifying that material to species, but maybe it’s assignable to family (or order)

    Maybe it’s assignable to a specific clade – no matter what rank you assign to its name.

    Link to this
  43. 43. Dartian 2:38 am 10/17/2013

    ectodysplasin: Thanks for the references. They are certainly interesting (especially the one about crocodylians), but I’m afraid that they are all rather beside the point because they do not actually deal with the issue of applying standards to rank assignment at all.

    All of those authors have taken a pre-existing, family-level classification as their starting point! That’s putting the cart before the horse! Nowhere do these authors even seriously consider the question that it might be necessary to revise those family assignments – still less do they suggest any criteria or guidelines for doing so.

    What these authors do in those papers is that they compare the (dis)similarity between members of those various ‘families’ in morphospace. In their analyses, members of the respective ‘families’ tend to cluster together – but that should come as no surprise if these ‘families’ really represent actual clades (if the species have a shared ancestry, they will surely also uniquely share certain characteristics; look hard enough, and you’ll find them). That just means that the phylogenies these authors used were probably pretty close to being correct.

    That’s all fine and well, but that’s also really not what this whole discussion that we’re having is about. This is not just about identifying clades and assigning ranks to them; it is about trying to make those ranks as uniform and consistent as is reasonably possible, ideally across the entire kingdom Animalia* (for better or for worse, plants and bacteria currently still have their own nomenclatural systems, so we may as well leave them out of this discussion for now).

    Incidentally, it is also notable that none of those authors seriously discuss, or even cite, certain key publications. There is hardly any of mention of, for example, papers by Jacques Gauthier and Kevin de Queiroz dealing explicitly on the issue of phylogenetic nomenclature (and arguing for the total abandonment of ranks). Support them or oppose them, their PhyloCode project has been a game-changer and must be taken into account by anyone who’s seriously going to deal with the question of preserving the taxonomic rank concept in biology.

    * As a practical matter, the methods described in those three papers you cited obviously can’t be applied to the vast majority of living animals. Invertebrates don’t have any cranial characters that one could compare morphometrically. (Invertebrate clades do, however, represent evolutionary lineages that diverged at some specific point in geological time, and it is possible at least in principle to establish those dates.)

    Link to this
  44. 44. Dartian 2:47 am 10/17/2013

    David:
    Hennig himself later abandoned it

    Even the greatest make mistakes sometimes, don’t they? ;)

    Link to this
  45. 45. David Marjanović 6:39 am 10/17/2013

    ectodysplasin: Thanks for the references. They are certainly interesting (especially the one about crocodylians), but I’m afraid that they are all rather beside the point because they do not actually deal with the issue of applying standards to rank assignment at all.

    I thought the point was just that they show morphospace can be quantified, and that this fact could be (but hasn’t yet been) used to develop some oddly half-phenetic family concept for the purpose of rank assignment.

    Link to this
  46. 46. Dartian 8:41 am 10/17/2013

    David:
    I thought the point was just that they show morphospace can be quantified, and that this fact could be (but hasn’t yet been) used to develop some oddly half-phenetic family concept for the purpose of rank assignment.

    While I was hoping for references showing how the morphospace approach can be used to assign ranks in actual practise, I was even more than that hoping for a paper laying out the theoretical framework behind this idea. Morphological disparity can be quantified (heck, almost anything can be quantified!), but it doesn’t matter what you quantify if you don’t do it sensibly. Those papers didn’t test any morphospace-based family concept. I’m still hoping for references where they do explicitly that.

    Link to this
  47. 47. David Marjanović 7:55 pm 10/17/2013

    I’m still hoping for references where they do explicitly that.

    No such papers exist.

    Link to this
  48. 48. Dartian 1:32 am 10/18/2013

    No such papers exist.

    In that case, there isn’t much to discuss either, is there? :(

    Link to this
  49. 49. David Marjanović 11:21 am 10/18/2013

    Not as far as I can tell.

    Link to this

Add a Comment
You must sign in or register as a ScientificAmerican.com member to submit a comment.

More from Scientific American

Scientific American MIND iPad

Give a Gift & Get a Gift - Free!

Give a 1 year subscription as low as $14.99

Subscribe Now >>

X

Email this Article

X