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Grassland earless dragons

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Captive Grassland earless dragon climbing in tussock; image by Tony Gamble, used with permission.

Today: LIZARDS. Even better: obscure Australian agamids, or dragon lizards, or dragons, if you prefer. I’ve written about agamids a few times on Tet Zoo but have never gotten to say much (if anything) about the Australian radiation, grouped together into the clade Amphibolurinae.

In this article, I won’t – I’m very sorry to say – be providing a grand tour of this remarkable and fascinating radiation but, instead, will merely talk about but one of the many species: the endangered and poorly known Grassland earless dragon Tympanocryptis pinguicolla, long misinterpreted as a subspecies of a supposedly well-known, widely distributed species but now rightfully recognised as a taxonomically distinct grassland specialist associated with arthropod burrows. Or… is that – a complex of species of distinct grassland specialists associated with arthropod burrows?

T. pinguicolla was originally named as a subspecies of the White-streaked earless dragon T. lineata back in 1948 (Mitchell 1948). This is the widespread, longitudinally striped dragon that’s supposed to occur throughout the Australian interior. However, a study of morphological and allozyme variation across earless dragons found pinguicolla to be consistently distinct from the rest of T. lineata as well as from other earless dragon taxa: it is not part of T. lineata but warrants distinction as a separate species (Smith et al. 1999).

Temperate-grassland, arthropod-burrow-dwelling specialist

All of the eight or so Tympanocryptis dragons are predominantly terrestrial. As you might guess from the generic name, their tympanic region is obscured by scaly skin. Does this mean that they’re completely deaf? I don’t know. Other obvious anatomical features include raised, spiny dorsal scales and a shortened fifth toe formed from three phalanges as opposed to four (Cogger 2000).

Captive Grassland earless dragon. Image by Tony Gamble, used with permission.

Grassland earless dragons inhabit fragile temperate grasslands in south-eastern Australia. They are highly cryptic, taking refuge in grass tussocks but also in burrows made by wolf spiders and crickets (these lizards are small: less than 15 cm in total, and just 7-9 cm SVL). In fact, individuals have sometimes been found sharing active burrows with Lycosa spiders – I don’t know if the nature of this relationship has been studied, but it would be fascinating to know more about it. Do the spiders simply tolerate the lizards, is there a mutualistic relationship of some sort, or is aggression and mortal danger involved? Very little is known about reproductive behaviour in this lizard – apparently only two egg clutches have ever been found. One was deposited under stones and soil in a shallow scrape; the second one was disturbed before the nest form was observed; the eggs were later incubated in a laboratory (DoE 2014).

Grassland loss, degradation and fragmentation seem to be the main threats to this lizard: something like 95% of its habitat has been lost in recent decades and there are concerns that loss of key vegetation to rabbits and the destruction of arthropod burrows due to soil disturbance are major continuing threats to the integrity of its populations (DoE 2014). It seems to be one of Australia’s most endangered lizards.

Captive Grassland earless dragon. Image by Tony Gamble, used with permission.

Are we really dealing with one species here? Err…

Molecular phylogeny for earless dragons from Melville et al. (2007): note the positions of the different populations conventionally thought to be part of T. pinguicolla.

Three distinct modern populations are known: the two Canberra and Cooma populations in eastern New South Wales and the Darling Downs population of south-eastern Queenland, discovered in 2001. Grassland earless dragons certainly occurred in Victoria as well until recently – five sightings were reported there between 1988 and 1990 – but they haven’t been seen since and are now thought locally extinct.

And here where things are made more complicated, since phylogenetic studies done on these populations don’t find them to group together. The Canberra and Cooma populations are highly divergent in genetic terms, their 5% genetic divergence apparently being ancient and pre-dating habitat fragmentation caused since European settlement (Scott & Keogh 2000). These differences are significant enough that some authors imply that they should eventually warrant recognition as distinct species. A museum specimen of one of the Victorian lizards indicates that this (probably) extinct population was close to, but outside, the clade that includes the Canberra and Cooma populations (Melville et al. 2007)… so, should this be recognised as a species as well?

Captive Long-tailed earless dragon. Image by Joachim Frische, licensed under Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license.

As for the Darling Downs population, it doesn’t group together with any of the others, instead being genetically closest to another earless dragon species: the Long-tailed earless dragon T. tetraporophora (Melville et al. 2007) [adjacent photo by Joachim Frische]. When it comes to morphology, Darling Downs animals have larger spiny scales than other Grassland earless dragons, proportionally longer hindlimbs, spines along the sides of the body that are lacking in the other populations, and they also differ in head shape and in labial scale counts. In short, a strong case can be made for the idea that the Darling Downs dragons are not conspecific with the other Grassland earless dragon populations: Melville et al. (2007) suggested that the Darling Downs animals have been distinct from the others for at least 5.5 million years, and – pending further work – they suggested that this population be referred to as T. cf. tetraporophora for now, the possibility existing that it’s part of the Long-tailed earless dragon, not a new species. If the Darling Downs dragons are a new species, then an urgent reassessment of their conservation status is needed. If they’re actually conspecific with the Long-tailed earless dragon, things aren’t so urgent, since this species is not regarded as being of conservation concern.

So – what was thought to be a single species (and, pre-1999, a single subspecies of a far more widespread species) now seems to be a complex of perhaps three distinct earless dragon taxa that have been separate since – or before – the Pliocene. I need not remind you that major climatic and palaeoenvironment changes occurred across south-eastern Australia during the Pliocene in particular – it being precisely the time when grassland-dwelling species could get broken up, isolated, and forced to speciate.

Australia has suffered numerous small mammal extinctions within recent centuries. Here are a few of the species concerned. Clockwise from top left: Pseudomys gouldii, Macrotis leucura, Conilurus albipes and Lagorchestes leporides. Images by John Gould (except the Macrotis) and in the public domain.

If we are looking at a species complex that involves a patchwork of long-distinct, locally distributed, specialised populations – some of which are extinct – a new picture emerges. It used to be thought that Australia’s small mammals – its marsupials and rodents – had not fared too badly in the face of human-caused changed. Alas, this proved woefully naïve: in recent decades it’s been shown that numerous species have been severely affected by human hunting and habitat change, with over 20 extinctions now on record. The story for now is that reptiles have not experienced any extinctions since European settlement but.. are we sure about that? Well, whatever, the persisting Grassland earless dragon populations definitely need our help if they are survive into the future.

Finally, this whole article was made possible by Tony Gamble of the University of Minnesota, who kindly shared the photos you see here. Thanks indeed, Tony. More agamids to come – it all depends on getting the images. For previous Tet Zoo articles on agamids and other iguanian lizards, see…

Refs – -

Cogger, H. G. 2000. Reptiles and Amphibians of Australia. Reed New Holland, Sydney.

Department of the Environment. 2014. Tympanocryptis pinguicolla in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Sat, 4 Jan 2014 06:56:47 +1100.

Melville, J., Goebel, S., Starr, C., Keogh, J. S. & Austin, J. J. 2007. Conservation genetics and species status of an endangered Australian dragon, Tympanocryptis pinguicolla (Reptilia: Agamidae). Conservation Genetics 8, 185-195.

Mitchell, F. J. 1948. A revision of the lacertilian genus TympanocryptisRecords of the South Australian Museum 9, 57-86.

Scott, I. A. W. & Keogh, J. S. 2000. Conservation genetics of the endangered grassland earless dragon Tympanocryptis pinguicolla (Reptilia: Agamidae) in Southeastern Australia. Conservation Genetics 1, 357-363.

Smith, W. J. S., Osborne, W. S., Donnellan, S. C. & Cooper, P. D. 1999. The systematic status of earless dragon lizards Tympanocryptis (Reptilia: Agamidae) in south-eastern Australia. Australian Journal of Zoology 47, 551-564.

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! Follow on Twitter @TetZoo.

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





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  1. 1. Sordes 10:16 am 01/4/2014

    Given the fact that cats can be highly potent predators of small reptiles, especially ground-dwelling species, there´s really some risk that some only locally distributed species, for example flap-footed lizards, could have become extinct without any notice.

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  2. 2. naishd 10:54 am 01/4/2014

    Yes, I agree. Worldwide, there are numerous populations of small animals conventionally assumed to be part of a more widespread species – but which later turn out not to be when studied properly. Has this happened in the temperate grasslands of Australia? I don’t know, but it’s the question I’m asking.

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  3. 3. BilBy 12:23 pm 01/4/2014

    @Sordes – I’ve seen the stomach contents of some feral cats shot in SW Australia – I was surprised to see how little chewing was involved in ingesting lizards and frogs. One cat had about a dozen reptiles in its stomach, including Lialis burtonis.

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  4. 4. naishd 12:27 pm 01/4/2014

    Seeing as Lialis just got mentioned, there are eyewitness reports (from New Guinea, not Australia) of an unrecognised form, as yet unknown to science (Mark O’Shea, pers. comm.). May as well mention it here.

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  5. 5. BilBy 1:33 pm 01/4/2014

    @naishd – a different Lialis to the already described NG species? Cool

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  6. 6. Heteromeles 1:54 pm 01/4/2014

    Gee, reading up about Lialis burtonis on Wikipedia, it sounds like it’s ripe for some DNA work, to see how many cryptic species, if any, there are within this “common, widespread species.”

    BTW, if you make your career out of finding cryptic but critical genetic variation that’s hidden within morphological variation of notionally widespread animal species, does that make you a cryptozoologist? Just curious.

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  7. 7. Yodelling Cyclist 2:48 pm 01/4/2014

    Could someone explain for a non biologist what the magical number for genetic difference is? Popular literature bandies around numbers like 2,5,10% genetic difference, yet there seems to be rather subtle morphological variations which might previously be declared variation between populations. I know that the species concept is hazy, but essentially I’m asking what, when a paper gets reviewed, is classed as crucial degree of difference (if we leave the old “can they breed” concept).

    Is it that, for some “species” (I hope using this term will not be confusing) we have significant variations between populations, but we also have bridging populations, whereas for others we see two extrema having lost the bridge?

    Nope, that question was poorly phrased; I shall resort to a hypothetical question. Imagine two mountains and a plain between them. A species of lizard, exhibiting a certain degree of intraspecies genetic variation inhibits all of these environments, with (for some reason) very slow genetic transmission from one mountain to the other. This environment is examined in the 19th century and herpetologists declare there to be one species. If we now flood the valley, and unleash 21st century biologists, confronted by morphologically all but identical populations, but apparently genetically distinct groups, could they then declare two species?

    Is there a critical number of generations of separation required?

    Finally, if (say) Caucasians, Australian aborgines and everyone else were eliminated, would one then decide that the San, Congo pygmies and Native Americans were distinct (but closely related) species? (Or is it the case in humans that group outside the San represents a subset of San genetic diversity?)

    Sorry for the rambling.
    Yod

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  8. 8. Heteromeles 4:00 pm 01/4/2014

    @Yod: The answer is, it depends. Chimps and humans are genetically more similar than strains of E. coli, yet there’s no question we’re separate species. A bigger factor is whether genetically distinct individuals can interbreed and produce fertile offspring. With humans and chimps, we can’t, because we have separate numbers of chromosomes. Even assuming a humanzee was biologically viable, it would almost certainly be sterile, because we have different numbers of chromosomes. It’s not just a matter of having the same information, it’s a matter of having it organized in the same way on the same number of chromosomes. Swap it around (as has happened with us and chimps), and we can’t interbreed.

    That’s for animals. For plants, it gets a lot more complicated. The wheat tribe, basis for our civilization that it is, is notorious for rampant hybridization. Bread wheat (Triticum aestivum), for example, is a hexaploid from three different species, two of which are goatgrasses (Aegilops speltoides and Aegilops tauschi), one of which was wheat (Triticum uratu). Note that this was a sequential process, although it’s not entirely clear which of the intermediates resulted in the modern wheats. The Triticeae (wheat tribe) is one place where organismal cladistics breaks down: people know which genes and bits of genome came from which diploid ancestor, but they’ve intermixed so much that a species-level cladogram, made mostly of polyploids, looks like a spiderweb. Oaks do something similar, as do manzanitas and ceanothus in California, tarplants in Hawaii, and others, so it’s not exactly uncommon. It’s just best studied in the wheatgrasses. In grad school, we once had a week-long discussion of what a plant species was, and came to no firm, single conclusion.

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  9. 9. Yodelling Cyclist 4:27 pm 01/4/2014

    @Heteromeles: Plants are just…too damn complicated. On your discussion about whether or not two populations can breed: well, is Oxyura leucocephala synonymous with Oxyura jamaicensis then? What on earth to make of the Congolese Spotted Lion? Finally (for this post, I know the fertile hybrid list is a text book in itself) coral species allegedly hybridise rampantly.

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  10. 10. BilBy 4:47 pm 01/4/2014

    @Heteromeles – Lialis is odd all right. I have seen two Lialis in two adjacent pitfall traps with very different appearances: one slate grey, the other more or less chequered. There are gold and yellow ones too.

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  11. 11. Heteromeles 4:53 pm 01/4/2014

    @Yod: it’s useful to remember that, even in plants, a large majority of species (not biomass, species) follow the biological species concept with reproductive isolation pretty nicely. This is also true (AFAIK) for animals. Then there are the exceptions. If they were small, weird populations in odd places, no one would care. Unfortunately, they include some of our major crop plants (probably not an accident) as well as some species (oaks, manzanitas, ceanothus, corals) that dominate their local landscapes. The challenge isn’t to the taxonomists (who are mostly right when they designate species based on simple morphology or a few gene sequences), but to the theorists who expound on the advantages of reproductive isolation and species boundaries. The exceptions don’t just exist, they can dominate.

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  12. 12. Yodelling Cyclist 5:03 pm 01/4/2014

    @Heteromeles: That’s probably true, but my question was (despite bad phrasing) directed to the specific case of recent literature announcements of distinct species: the authors did not mount an aggressive attempt to hybridise/breed their lizards. The recent tapir species was not declared so after a few years of trying to mate them/IVF cross them with other tapirs, but if (once upon a time) this had been tried with quite a range of (say) waterfowl then we would have far fewer species. Probably fewer genera too.

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  13. 13. Heteromeles 5:42 pm 01/4/2014

    Based on past evidence, I’d suggest that the new species are real with an 80-90% probability. As for waterfowl, I remember one of the professors at the Museum of Vertebrate Zoology pulling out the one Mallard X Pintail in their collection at the time, and they have quite a few specimens of both species. Hybridization isn’t common in most groups, even if they can do it.

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  14. 14. ayates 6:30 pm 01/4/2014

    Really interesting article. Since moving back to Oz I’ve rekindled my interest in Australian squamates. It is interesting to note that T. pinguicola isn’t the only temperate grassland specialist lizard that it is in trouble, the pygopodid Delma impar and the dwarf bluetongue that doesn’t have a blue tongue, Tiliqua adelaidensis are two further examples.
    As for extinct Australian reptile species, there is one that is now reduced to a single surviving individual, so has joined the ranks of the living dead. This is Emoia nativitatis, a forest skink from Christmas Island (so its not continental Australia but is still an Australian Territory). What is disturbing is how rapid its collapse was. It was still described as abundant right up to the mid 1990′s.
    BTW Darren, if you’d like Aussie agamid pictures I can provide pictures of species that are wild around Alice Springs.

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  15. 15. Dr_AnnaM 11:11 pm 01/4/2014

    Nice to see you turn your attention to the GED Darren! Interesting timing for your article because colleagues of mine are working on captive breeding of this species and this has been in the news over here just this week: http://www.abc.net.au/news/2014-01-03/canberra-breeding-program-bolsters-tiny-endangered-dragons/5183140
    Sadly their habitat in Canberra is highly fragmented and overlaps with desirable urban areas – this fragmentation and the effects of a severe drought a few years ago are thought to have caused the large declines in numbers at some localities.

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  16. 16. vdinets 1:17 am 01/5/2014

    Yod: we had a lengthy discussion of species concepts, frivolous splitting and human systematics here about, I think, a year ago. I don’t remember in which post the thread was, but perhaps Darren does.

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  17. 17. Dartian 6:40 am 01/5/2014

    Heteromeles:
    Hybridization isn’t common in most groups, even if they can do it.

    True. In some animal groups, for example primates, it does happen at a non-trivial frequency though. There may not be any humanzee on record, but there is at least the mandrill – which is a hybrid between a man and a drill (or so I’ve been told). ;)

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  18. 18. Tayo Bethel 7:11 am 01/5/2014

    Looking forwardto articleson the Australian agamid radiation. Australia’s small reptile and mammalian faunas seem underrepresented at least in the online literature. For instance,informationon the Sminthopsis radiation of marsupials is hard to find andwhat there is is frequently paywalled.

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  19. 19. naishd 7:48 am 01/5/2014

    Thanks for comments, everyone. Pleased to hear about the baby Grassland earless dragons recently raised in captivity! (see comment # 15).

    Bilby (comment # 5): yes, a third Lialis. I’ll ask Mark whether he plans to ever share the info. They might, however, have been a weird morph of the New Guinean species L. jicari.

    ayates (comment # 14): if you have good photos you’re prepared to share, I’m definitely interested, thanks.

    As for the whole species concept thing… I deliberately avoided discussing of that issue in the article, since I knew it would come up in the comments. If those genetically distinct earless dragon populations are as distinct as are other units widely accepted as ‘species’, my take is that they should indeed be regarded as ‘species’, this decision being made in the knowledge that the concept of ‘species’ is subjective and variable according to which group of organisms you’re looking at.

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  20. 20. naishd 7:54 am 01/5/2014

    Incidentally, for those wanting to hear more about Lialis and other flap-footed lizards, aka pygopodids, check out the series of articles at Tet Zoo ver 2…

    Meet the pygopodids (gekkotans part IX)
    The pygopodid radiation: diverse diets and the ‘pygopodids got there first’ hypothesis (gekkotans part X)
    Blindsnake mimics, scaly-foots and javelin lizards (gekkotans part XI)
    How gekkotans evolved into predatory ‘snakes’ (gekkotans part XII)

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  21. 21. David Marjanović 9:06 am 01/5/2014

    Does this mean that they’re completely deaf?

    Would surprise me; they’re probably bad at hearing high frequencies, though.

    Could someone explain for a non biologist what the magical number for genetic difference is? Popular literature bandies around numbers like 2,5,10% genetic difference, yet there seems to be rather subtle morphological variations which might previously be declared variation between populations. I know that the species concept is hazy, but essentially I’m asking what, when a paper gets reviewed, is classed as crucial degree of difference (if we leave the old “can they breed” concept).

    There is no magic number (though 30 % difference is often used for bacteria).

    There isn’t even a single species concept, however hazy. There’s easily 150 of them (it’s a species if it’s different enough; no, it’s only a species if the differences are innovations; no, it’s a species if it has its own ecological niche; no, it’s a species if it evolves independently of other species; no, it’s a species if it doesn’t interbreed with others too much; no, let’s take take every internode on a phylogenetic tree and call it a species… and then there are concepts that combine any of the above criteria and more…), and they yield different results: depending on the species concept, there are from 101 to 249 endemic bird species in Mexico, and the region with the greatest diversity of such species moves all over the country.

    What’s really going on is that binominal nomenclature requires us to pretend that there’s a single species concept: if you don’t refer an organism to a species, you can’t give it a name – you can hardly talk about it. In reality, many species concepts describe interesting entities that really exist in nature; they just don’t have anything in common other than the word “species”, so they overlap widely and chaotically.

    And no, the codes of nomenclature do not require authors to mention which species concept they’re having in mind. (Many may not even have any particular one in mind, I’m sure.) They don’t even mention the issue. It’s part of taxonomic freedom.

    So, the answers to all your general and hypothetical questions depend on the species concept one chooses.

    Oh, and, the “Biological Species Concept” is actually two concepts: fertile hybrids being possible, and fertile hybrids actually occurring in the wild. Naturally, plenty of species according to the second concept are not species according to the first. I forgot which one Ernst Mayr proposed (I think the second); he did specify.

    With humans and chimps, we can’t [produce fertile offspring], because we have separate numbers of chromosomes.

    No. As I’ve learned here on Tet Zoo, individuals with different numbers of chromosomes frequently occur in the same population of wild boars. As long as the fused and the split chromosomes stay similar enough to line up during meiosis, there is no problem; this is how differences in chromosome numbers are able to evolve in the first place (or anyway why they’re not extremely rare).

    Even assuming a humanzee was biologically viable

    As I’ve also learned here on Tet Zoo, the experiment necessary to test this assumption seems to have never been done, despite rumors of a proposal to do it in the early Soviet Union. We don’t actually know if a humanzee is possible.

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  22. 22. Dartian 11:04 am 01/5/2014

    David:
    if you don’t refer an organism to a species, you can’t give it a name – you can hardly talk about it

    I don’t really disagree with what you say – but I can’t resist mentioning a counter-example. To this day, the fossil Denisova hominin (discovered in 2008, published in 2010) still hasn’t been named – but that hasn’t stopped people from discussing it, studying it, and publishing papers on it.

    As I’ve learned here on Tet Zoo, individuals with different numbers of chromosomes frequently occur in the same population of wild boars.

    Yes; this was discussed in the comments thread of part IV in the mammalian “Pouches, pockets and sacks”-series back in 2010.

    the experiment necessary to test this assumption seems to have never been done, despite rumors of a proposal to do it in the early Soviet Union

    As a matter of fact, they were more than just proposals. The Russian biologist Ilya Ivanov (1870-1932) sought, and got, permission and funding from the Soviet Academy of Sciences to perform hybidisation experiments between humans and great apes in the 1920ies. (Apparently, at least some of the members of the Soviet Academy of Sciences hoped that a successful human-ape hybridisation experiment would be a devastating blow to people’s religious beliefs; in the 1920ies, the anti-religion campaign in the USSR was running high.)

    Ivanov was, however, unable to perform his experiments in the USSR due to the fact that there were no live apes available there for this purpose. Thus, he had no choice but to humbly cooperate with representatives of the ‘Western imperialist’ powers; they, after all, were the ones who were in possession of colonies in the regions of the world where wild apes lived. Eventually, Ivanov ended up in French Guinea (modern-day independent Guinea), at the research station of Kindia.

    There he actually did try to artificially inseminate at least two female chimpanzees in 1926-1927. After these experiments failed (unsurprisingly, considering the crude methods that were used), he planned to inseminate a local woman – without her knowledge! – with chimpanzee sperm. Fortunately, the French colonial authorities, upon learning about Ivanov’s plans, stopped him (less because of moral scruples and more because they feared riots and uprisings among the natives if these were to hear about Ivanov’s experiments).

    Back home in the USSR, the members of the Soviet Academy of Sciences were also most unhappy to learn about Ivanov’s unethical experimental plans. The Soviets wanted to come across as the champions of liberty and equality for the oppressed people of colour in the colonies. Having a white Russian scientist trying to inseminate black African women with ape sperm was bad, bad PR. Thus, Ivanov’s funding was cut and he was ordered to return back home.

    He was allowed, however, to bring live chimpanzees with him and continue his experiments in the USSR. This Ivanov did, and once back home he planned to inseminate Russian women with chimpanzee sperm. Incredibly, at least one volunteer came forward. However, before the experiments could start all of Ivanov’s chimpanzees died of illness. New animals (both chimpanzees and orangutans) were ordered, but before they arrived the political landscape changed. Stalin* came to power in the late twenties, and that put an end to the relative political and ideological liberalism that had characterised the Soviet twenties. In advance of the great purges later in the thirties, there was an early ideological shakeup of the entire Soviet state, including the scientific establishment. Ideologically suspicious individuals were sacked – or worse – and replaced by those more willing to follow the Party line (it was, incidentally, at these times that Lysenko’s rise to power begun). Ivanov was among those who lost his position. He was sentenced to hard labour for ‘contrarevolutionary activities’ in 1930, and sent to the gulag in Kazakhstan. (He was pardoned in 1932 but by then his health had so deteriorated that he died of a heart attack a day before his release.)

    * When the subject of Ivanov’s ape-human hybridisation experiments are brought up, one sometimes hears claims that he performed them on Stalin’s orders. That’s utter nonsense. Stalin had never anything to do with them (and possibly was not even aware of them).

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  23. 23. Jerzy v. 3.0. 12:08 pm 01/5/2014

    Coming to species concept, Homo sapiens, neanderthalensis and denisovensis should be sunk as sub-species, because most living people are hybrids at least between the two. This holds across a number of common species definitions, for slightly different reasons.

    BTW, I met some African biologists joking why the older book Walker’s Mammals of The World included humans, but the recent Handbook of the Mammals of the World did not. The reason is that many lemurs and monkeys which differ in color and shape of fur tufts are split into species. Therefore, a question would be asked why humans are not split into several species, too (with the hybrid zones and populations of uncertain status, as these lemurs and monkeys). That would be extremely bad PR, of course.

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  24. 24. Heteromeles 12:32 pm 01/5/2014

    @David: according to the omniscient Wikipedia, Humans have chromosome 2, which is a fusion at the telomeres of chimpanzee (and other ape) chromosomes 2A and 2B. That means there are vestigial telomere and centromere bits in human chromosome 2. That’s not the only difference, though: there are also chromosomal segment inversions between chromosomes 1, 4, 5, 9, 12, 15, 16, 17, and 18. I’m not enough of a geneticist to know what this would all do to mitotic pairing, but I suspect it would be a bit of a mess. For whatever reason, plants can pull of this kind of craziness more easily than animals can.

    One could theoretically make a case that scientists could learn something useful about meiosis by trying to create humanzee embryos and studying their cell divisions or failure thereof. Given that pigs have different chromosome numbers and are not so laden with political and ethical burdens, it would be easier to do the experiments with pig embryos.

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  25. 25. Heteromeles 12:37 pm 01/5/2014

    @Jerzy: While I understand the jokes about skin color in African humans, it would be bad biology: when you look at total morphological variation found on the African continent (including, but not limited to, that tremendous range of skin color subsumed under the white/brown/black categories), it’s quite obvious that almost all the features thought to be unique to races elsewhere (possibly except for blue eyes and red hair) are naturally found in Africa. Therefore, the only proper thing to do is to subsume all the human races under the label African. We’re all black, really.

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  26. 26. Yodelling Cyclist 1:12 pm 01/5/2014

    @Heteromeles: If you’re not a sufficient geneticist to grapple with this, then I have no hope, but I would point out that fertile mules have occurred – and there’s a mismatch in the number of chromosomes there.

    The possibility of a humanzee is not ridiculous – just horrifying. I’m just surprised that in this big, wide crazy world full of highly dubious humans this hasn’t been tried.

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  27. 27. vdinets 1:25 pm 01/5/2014

    In the afterword to Next novel by late Michael Crichton, it is said that humanzees are impossible because of “differences in uterine environment”. The book doesn’t have a references list, but I guess he got it somewhere in scientific literature.

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  28. 28. Heteromeles 1:40 pm 01/5/2014

    Getting back to grassland earless dragons, one thing I’d like to know more about is how one goes about conserving or preserving things like the Australian grasslands. I’m grappling with the same problem where I live in California, trying to figure out how to save small patches of things like vernal pools and coastal chaparral in largely urbanized areas. It’s an analogous case, because researchers are finding that there’s more cryptic diversity than they expected. Additionally, I’ve got to deal with the impacts from hundreds of mountain bikers, dozens of dog walkers, feral cats, and so forth.

    Any thoughts or good strategies? “Fence and forget” (e.g. set it aside as a reserve with lots of no trespassing signs) is worse than useless (think of it as a sign for “pot growers are safer here”), but getting mountain bikers to even see things like coastal horned lizards is extremely difficult too.

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  29. 29. Jerzy v. 3.0. 3:56 pm 01/5/2014

    @Heteromeles
    Unfortunately lemurs and monkeys (as well as ungulates, birds etc) are also split without much thinking about the full range of variation, importance of characters etc.

    Link to this
  30. 30. Jerzy v. 3.0. 4:04 pm 01/5/2014

    @Heteromeles (conservation)
    Lots of small reserves worldwide cope with variants of this problem.

    There are different solutions dependent on how educated is public, how much you can rely on law enforcement, do these habitat patches maintain themselves or need management eg. burning or grazing.

    Link to this
  31. 31. Andreas Johansson 5:44 am 01/6/2014

    @Heteromeles: I don’t know how true it is, but blue eyes are said to be common among Berbers.

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  32. 32. Yodelling Cyclist 7:11 am 01/6/2014

    @Heteromeles: Have you considered the benefits of landmines ;-)

    http://en.wikipedia.org/wiki/Korean_DMZ#Nature_reserve

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  33. 33. David Marjanović 11:03 am 01/6/2014

    I don’t really disagree with what you say – but I can’t resist mentioning a counter-example. To this day, the fossil Denisova hominin (discovered in 2008, published in 2010) still hasn’t been named – but that hasn’t stopped people from discussing it, studying it, and publishing papers on it.

    Good point. There are more such exceptions that prove the rule – it works as long as there are few enough of them. The Late Jurassic crocodylomorph Fruitachampsa showed up in phylogenetic analyses as “Fruita form” for something like 10 years before its description and name were published.

    That’s not the only difference, though: there are also chromosomal segment inversions between chromosomes 1, 4, 5, 9, 12, 15, 16, 17, and 18. I’m not enough of a geneticist to know what this would all do to mitotic pairing, but I suspect it would be a bit of a mess.

    The more there are, the more difficult it gets, and the more improbable a fertile hybrid becomes. I have no idea about actual numbers for these probabilities.

    In the afterword to Next novel by late Michael Crichton, it is said that humanzees are impossible because of “differences in uterine environment”. The book doesn’t have a references list, but I guess he got it somewhere in scientific literature.

    Or he talked to somebody who wasn’t an expert but was willing to offer a speculation. Or he made it up. Crichton’s approach to science left a lot to be desired.

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  34. 34. David Marjanović 11:05 am 01/6/2014

    I have no idea about actual numbers for these probabilities.

    I’m sure they depend on the sizes and positions of those inversions, too. Anyway, the point (supported by the few fertile mules) is that the ability to interbreed is gradual.

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  35. 35. Heteromeles 11:12 am 01/6/2014

    @David: agreed. The problem for Yod and the others is that the chromosomes line up gene by gene before cell division. If the genes are in inverted sequenced and/or scattered among other chromosomes, mitotic and meiotic lineups become difficult, and cell division goes awry. How much chaos is too much is something probably even the geneticists don’t know for sure.

    @Andreas: thanks, I’d forgotten about the blue-eyed Berbers, although to be fair, they may be old European migrants IIRC.

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  36. 36. Heteromeles 1:59 pm 01/6/2014

    @Yod: The issue is structural: preserves for endangered species were put created next to developments. There’s little or no buffer, and landmines won’t help. It’s a huge problem in coastal California, and I’m sure it’s a similar issue in areas such as SE and SW Australia, the Cape of Good Hope, and so forth.

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  37. 37. ectodysplasin 8:46 pm 01/6/2014

    @David:

    Good point. There are more such exceptions that prove the rule – it works as long as there are few enough of them. The Late Jurassic crocodylomorph Fruitachampsa showed up in phylogenetic analyses as “Fruita form” for something like 10 years before its description and name were published.

    In a lot of cases, what happens is that a specimen is described either as a member of one big lumped taxon or as an exemplary specimen of a specimen with poorly preserved type material, but then is later identified as something unique and worth talking about in and of itself. However, the taxonomic effort that’s involved in revising a species can be extensive and daunting and sometimes outside of the scope of someone’s interest, so the differences are remarked upon, all relevant taxa are coded into matrices, etc., but names aren’t given.

    This relates directly to the diversity within Tympanocristus. Whether or not all of these populations make up a single ‘species’ is not really the important question. What is important is whether each of these identified genetically distinct populations is worthy of scientific discussion in and of themselves. The answer seems to me to be an obvious “yes.”

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  38. 38. Heteromeles 1:33 am 01/7/2014

    The other issue with species is that, along with subspecies and variety but unlike other taxonomic or cladistic terms, they have legal meaning with regards to things like endangered species acts, CITES, and conservation plans.

    If you’re concerned about “whether each of these identified genetically distinct populations is worthy of scientific discussion,” AND you want to keep them around long enough to have the discussion about living organisms, rather than museum specimens, it behooves you to name each separate population using some combination of species and subspecies, and to make the case for why they each matter to society at large and conservation agencies in particular.

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  39. 39. Jerzy v. 3.0. 12:00 pm 01/7/2014

    @Heteromeles
    What about eg. marking favorite trails for mountain bikers, block the other ones by fence or barriers, and discussing with the local police to check these areas?

    I know one reserve where stff actually lots of effort digging bumps and holes on and around public paths, to discourage people and bikers from wandering away from trails.

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  40. 40. Heteromeles 4:26 pm 01/7/2014

    @Jerzy: That’s what we’re doing right now. The problem is that some of the bikers rip down the fences and signs, there’s not enough police presence to deter them, and all the bikers benefit from the open fences. There’s a whole series of self-justifying stories running around about why ripping down the fences is a good thing, too, and they benefit from the silence of the authorities on the matter. “You’re supposed to do what we tell you,” is about as far as they’ve said anything on the matter.

    The part I’m trying to get the authorities to do is a major education program. Most of the cyclists are ignorant, but willing to do the right thing (most of the time) if they know what the right thing is. Then there’s a few vandals and creeps. Trying to inform the good bikers and stop the vandals is a bigger challenge than you might expect.

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  41. 41. ectodysplasin 5:42 pm 01/7/2014

    Gonna point out that outdoor recreationists are not the primary problem, and most outdoor recreationists actually care quite deeply about conservation issues. The central problem is that wilderness areas in many parts of the country are so completely restricted that any use of wilderness area is going to have an impact on the population.

    Trying to restrict outdoor recreationists like mountain bikers, climbers, etc. will sometimes be met with hostility not because those people hate conservation, but rather that they perceive some conservation efforts as unfairly targeting their sports and restricting their ability to practice their sport while ignoring high-impact commercial development right down the road. In these cases, it can feel like conservation groups are going after easy wins against people who’d otherwise be allied with the conservation movement, rather than going after the worst offenders.

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  42. 42. ectodysplasin 5:45 pm 01/7/2014

    @Heteromeles

    The other issue with species is that, along with subspecies and variety but unlike other taxonomic or cladistic terms, they have legal meaning with regards to things like endangered species acts, CITES, and conservation plans.

    If you’re concerned about “whether each of these identified genetically distinct populations is worthy of scientific discussion,” AND you want to keep them around long enough to have the discussion about living organisms, rather than museum specimens, it behooves you to name each separate population using some combination of species and subspecies, and to make the case for why they each matter to society at large and conservation agencies in particular.

    This is correct, to a point. If you oversplit everything, however, you lose credibility with government oversight agencies, and can actually undermine legitimate conservation efforts.

    Link to this
  43. 43. Heteromeles 7:35 pm 01/7/2014

    @ectodysplasin (re: outdoor recreation)….and that’s story number one. Really, I’m not being cynical. I’ve heard that from cyclists who attack me for pointing out that they’re riding in a closed area.

    The problem is (as I’ve documented for the park I work at), many sensitive species are so small (horned lizards, annual plants that grow in the road, and so forth), that conscientious cyclists can ride over them without noticing. I had a long talk with a man who did notice when he’d run over a coast horned lizard, and wanted to know what to do about it. He was distraught, and even more unhappy when he learned that the no trespassing signs he’d ridden past was put there to keep him from doing what he’d just done.

    Please note that a lot of mountain bikers do get it and do stay out, ride clean, and act as good environmental citizens. I applaud them for it. The problem is that, when vandals remove signs and spread false stories about why the government is evil/stupid/wrong to restrict access to an area, a lot of cyclists come in and cause damage knowingly or unknowingly. I’m looking for good ways to stem this problem, which is causing almost all the damage I see.

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  44. 44. vdinets 12:43 pm 01/8/2014

    Heteromeles: Have you tried to make “No trespassing” signs more informative? Put up a lizard photo with a little explanation, perhaps?

    If that doesn’t work, go to Google Shopping and enter “caltrop” ;-)

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  45. 45. Heteromeles 1:05 pm 01/8/2014

    @vdinets: Yes, the somewhat more informative no trespassing signs (in metal) went up last year. I just unfolded one yesterday, and one got stolen Christmas day. Hopefully sometime this year I can launch a major environmental education campaign.

    As for the caltrops, thanks. I needed that LOL.

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  46. 46. ectodysplasin 7:40 pm 01/9/2014

    @Heteromeles,

    Once again, I recognize that a cyclist (or hiker or whatever) can kill these endangered species without noticing. What I’m hesitant to accept is that these people are the primary threat to the ongoing survival of these endangered species. Outdoor recreationists are few and their impact is generally very minimal, and restricted to a small number of trails. I agree, any impact can be a threat to a highly endangered species, but I think it’s important to keep a sense of the scale of impact in mind when confronting involved parties.

    I’m definitely not the kind of person who’d enter a closed area, but I definitely think some recreational closures have little actual conservation impact and serve more as a means for certain conservation groups to achieve a small victory of any sort by targeting people who are inherently allies of the conservation movement, and that’s something that alienates me and generally dissuades me from donating to conservation organizations. Restricting already limited sporting access while not fighting against development, road expansions, and so on strikes me as a spiteful and ineffective approach to conservation.

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  47. 47. Heteromeles 11:57 pm 01/9/2014

    @46: That’s what I would have thought too. Thing is, they had wildlife cameras out this summer, and there were over 1500 visits per month in this closed area as recorded on the cameras. While I’m not sure how many people this is, since people have taken to doing multiple laps, but the original plan called for much less than 100 visits per month.

    Note that I’ve seen 27 cyclists in one train going through here, although the norm is one or two together. Last weekend I saw eight men together.

    Link to this

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