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The ‘ghosts’ of extinct birds in modern ecosystems

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


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Three moa species (Pachyornis elephantopus, Dinornis giganteus and Anomalopteryx didiformis) with the divaricating plant Myrsine divaricata in the background. Did browsing pressure from moa result in the evolution of divarication? Image by Darren Naish, CC BY.

It needs to be better appreciated that the vast majority of modern ecosystems and communities are ‘broken’ or, at least, very much incomplete compared to the situation present within very recent geological history: they lack an often significant number of key component species including some, many or all of the so-called keystone species. Why? As is well known, human hunting, climatic change and a combination of the two has eradicated a diverse assemblage of big-bodied mammals, birds, crocodylians, tortoises and other taxa across the Americas, Australasia, the Pacific and elsewhere. Small-bodied taxa have been removed as well, across the board.

Cover of Barlow (2000), a key volume on the incompleteness of modern ecosystems.

The animals I have in mind were generally ubiquitous throughout the Pleistocene, persisted into the early parts of the Holocene (that is, the last 11,700 years or so) and, in cases, survived into truly ‘modern’ times. Gigantic herbivorous birds, like moa on New Zealand and elephant birds on Madagascar, for example, were still alive as recently as 1000 years ago (at least). Even in places where the megafauna has persisted (many of the Eurasian and east African taxa are still extant, for example), they are substantially reduced in population and range, typically being extinct across huge tracts of their historical range. The end (read: modern) result of this wave of extinctions is a set of depauperate communities where whole setups, entire ecosystems, are missing some, many or all of the parts they co-evolved with (Johnson 2009). Plants produce specialised seeds and fruits for animals that are no longer around to exploit and transport them, and prey species exhibit defences for predators that no longer hunt them, or are super-abundant and have caused partial or total ecosystem collapse due to a knock-on effect that has initiated a so-called trophic cascade (Eisenberg 2010).

This idea – that the ‘ghosts’ of lost species can be detected in extant ecosystems – essentially arose in the 1970s as ecologists began to consider the impact that giant, recently extinct herbivores (specifically, moa on New Zealand) must have had on local floras. The idea became increasingly popular to the extent that people began to report ‘ghosts’ everywhere. On the one hand, it might be true that co-evolution with mostly lost megaherbivores is common and perhaps ubiquitous, given the state the world is in. On the other hand, it can be all too easy to jump to conclusions about perceptions of co-evolution and we often need to consider other possibilities: plants may grow tall, may grow weird or giant fruit, or may exhibit ‘defensive’ adaptations for reasons unrelated to the presence of their predators, for example, since plants have complex evolutionary interactions all their own. Indeed, some classic alleged examples of co-evolution that supposedly involve lost partners are now thought to be erroneous (see the section below on Dodos and Tambalacoque trees).

You're interested in the prehistory of New Zealand? Your opinions are irrelevant unless you own Worthy & Holdaway (2002). If you know the book, what's wrong with the cover image shown here?

In the remainder of this article, I want to talk specifically about pieces of evidence that – so it’s been suggested – represent the incomplete leftovers of co-evolutionary relationships that specifically involve birds. Don’t get me wrong – there are ‘incomplete’ modern relationships that involved now extinct tortoises, mammals and other animals too (see Barlow (2000) and Johnson (2009) for reviews) – but I’ll have to cover them some other time (yeah yeah, sure).

And we’ll start with New Zealand, since it’s the plants and animals here that – together with tropical American fruits that look suited for absent proboscideans (Janzen & Martin 1982) – really kick-started the idea of these ‘biological ghosts’.

Anti-moa browsing adaptations…. or not

Many plants endemic to New Zealand are spiny, appear morphologically similar to toxic species, resemble dead twigs, have purplish-black or dark bronze ‘camouflaged’ juveniles, or possess a so-called divaricating morphology where the branches are tough and wire-like, diverge at high angles, and form a ‘cage’ around the small, widely spaced leaves (Atkinson & Greenwood 1989, Worthy & Holdaway 2002). Greenwood & Atkinson (1977) and other authors interpreted these features as anti-browsing adaptations that co-evolved with moa.

However, the hypothesis that divarication is explained by co-evolution with moa is controversial since it’s been argued that divarication can also represent adaptation to both low air temperatures and to the minimisation of damage caused by either frost or bright sunlight (Howell et al. 2002). Furthermore, moa gizzard contents show that moa clipped twigs from divaricating species and weren’t demonstrably interested in consuming the ‘protected’ foliage anyway (Burrows 1980). Other objections have been raised as well (Worthy & Holdaway 2002). Ergo, it remains controversial as to whether the floral peculiarities seen on New Zealand really do represent anti-moa adaptations or not… maybe they don’t.

Burrs for elephant birds, flowers for hummingbirds

Madagascan Uncarina burr: the product of co-evolution with elephant birds? Image by Didier Descouens, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

A set of branch and foliage characteristics are present in over 20 plant lineages endemic to Madagascar: these features make them wiry and springy and have often been interpreted as anti-browsing adaptations (Bond & Silander 2007). The large prickly fruits of the Madagascan sesame plant Uncarina have been suggested to be trample burrs that were distributed across open habitats by large, terrestrial herbivores (Midgley & Illing 2009) [adjacent image by Didier Descouens]. These floral characteristics almost certainly represent co-evolution with the browsing habits of elephant birds or aepyornithids: we can imagine these giant birds clipping foliage from shrubs and trees (and hence exerting continual pressure on these plants), but also moving across the landscape with great spiky Uncarina burrs stuck to their plumage or skin (ouch). Thorns on Hawaiian lobelias have also been suggested as an anti-browsing adaptation, in this case as a possible defence against the recently extinct moa-nalos (James & Burney 1997), a group of large, flightless waterfowl.

Does evidence for co-evolution between (now extinct) hummingbirds and flowering plants still surround us today? This is a Purple-throated carib (Eulampis jugularis). Photo by Charlesjsharp, file is licensed under Creative Commons Attribution 3.0 Unported license.

Another, more surprising possible case of bird-plant co-evolution was suggested by Mayr (2005) following the discovery of the stem-hummingbird Eurotrochilus in the Lower Oligocene of Germany. So-called ornithophilous plants in the New World possess features that make them especially attractive to hummingbirds; curiously, several African and Asian plants (including Agapetes, Canarina eminii and Impatiens sakeriana) also look ornithophilous. More specifically, they look suited for co-evolution with hovering avian pollinators, not simply with any old nectarivorous groups, like the sunbirds that pollinate them today (Bartoš et al. 2012). Mayr (2005) suggested that these plants are relicts of co-evolution with extinct Old World hummingbirds [Adjacent hummingbird photo by Charlesjsharp]. If this suggestion is valid, it indicates that Old World hummingbirds fed by sustained hovering in the same manner as extant New World taxa. I would like to know what botanists think of Mayr’s idea – is hummingbird-induced pressure the only likely cause of the ornithophilous morphology?

The sorry case of the Dodo and the Tambalacoque tree

Illustration I once produced (for an article by Karl Shuker!) showing Raphus and Sideroxylon. CC BY.

Of all the cases discussed in this article, without doubt the most popular and well known concerns that giant flightless pigeon, the Dodo Raphus cucullatus. The Dodo became extinct some time round about 1690 (give or take a decade or two on either side). During the 1970s, it seemed that an endemic Mauritian tree – the Tambalacoque tree Sideroxylon grandiflorum (formerly Calvaria major) – was down to just its last few specimens, all of which were ailing, centuries-old individuals.

In two much-read articles (both published in Science, no less), Stanley Temple (1977, 1979) explained how modern Tambalacoque seeds never germinated and that the general form of the Tambalacoque’s thick-shelled seeds look suited for co-evolution with a large herbivore. He made the intriguing suggestion that Sideroxylon had evolved a mutualistic relationship with the Dodo, the extinction of the latter now meaning that Sideroxylon was doomed since it relied on the bird for successful germination. This idea is mentioned in Gerald Durrell’s books Golden Bats and Pink Pigeons and I’ve met various people who remember Durrell’s (1977) discussion of it. What they don’t remember is Durrell highly perceptive comment “It’s a lovely story… but I’m afraid it’s got more holes in it than a colander” (Durrell 1977).

Indeed, Temple’s hypothesis of obligate mutualism between the two species has been known not to be true ever since botanists went looking for live Tambalacoque trees and found them, at all growth stages, and with no anachronistic dodos around (Witmer & Cheke 1991). Some Mascarene specialists have referred to Temple’s hypothesis as “notorious” and even as a “myth” (Cheke & Hume 2008).

The ghosts of predators past?

Did the extinct New Zealand giant eagle Harpagornis (or Hieraaetus moorei) exert significant selection pressure on the appearance and lifestyle of the bird species it preyed on? Image by John Megahan, licensed under Creative Commons Attribution 2.5 Generic license.

Behavioural and morphological traits present in various extant animals have also been suggested to represent co-evolution with now extinct birds. The cryptic colouration and nocturnal habits of various New Zealand birds, for example, plausibly represent the results of predation pressure previously exerted by extinct raptors (Holdaway 1989, Diamond 1990). The giant New Zealand eagle Hieraeetus moorei (or Harpagornis moorei) appears to have been a formidable predator of other birds and may well have exerted considerable pressure on other species; the large, accipiter-like harrier Circus eylesi was also almost certainly a bird-killer.

However, again we should be sceptical of the idea that extinct raptors are wholly responsible for the possible adaptive responses we have in mind here, since less exotic predators (like skuas and even kea) might also have driven the evolution of the birds concerned.

The extinct Madagascan eagle Stephanoaetus mahery successfully attacks a ruffed lemur. Image by Julian P. Hume.

Meanwhile, the strong fear response that Madagascar’s lemurs have of airborne raptors has also been suggested to represent predation pressure from extinct taxa, most notably the gigantic Stephanoaetus mahery (Goodman et al. 1993, Goodman 1994), a relative of the living Crowned eagle S. coronatus of the African mainland. Again, we can be sceptical of the latter idea, since it seems to assume that S. mahery is the only raptor that might represent a possible lemur predator. In fact, we now know that extant Madagascan raptors – including Henst’s goshawk Accipiter henstii and Madagascar Harrierhhawk Polyboroides radiatus – are significant predators of lemurs, even of big species like avahis and ruffed lemurs. Nevertheless, raptors almost certainly exerted far more predation pressure on lemurs in the recent past than they do today: S. mahery was presumably hunting Madagascan primates on a regular basis.

As should be clear from this brief review, there are reasonable indications that the ecological ‘ghosts’ of extinct birds do indeed exist in some modern ecosystems, and doubtless there are other possible examples out there. As should also be clear, we need to be careful not to jump to conclusions when confronted with what look like co-evolutionary features – it’s very easy to see weird floral adaptations and immediately conclude that they owe their form to co-evolution with megafauna. I’m concerned that this has already happened to a degree, and for that reason the zoologists and palaeontologists who look at these floral adaptations really need to talk a lot with botanists, climatologists and ecologists.

Finally, as a Mesozoic-flavoured palaeozoologist I simply have to mention the idea that there might be entire legions of co-evolutionary floral adaptations that remain unknown or unappreciated: did the browsing behaviour of such megaherbivores of the past as sauropods, duckbilled dinosaurs and giant kangaroos result in weird and wonderful plant forms, some of which persist today? It’s something to think about… [image below from here on Antediluvian Salad]

I leave you with this speculative illustration, from Antediluvian Salad.

For more on various of the topics mentioned here, see…

Refs – -

Atkinson, I. A. E. & Greenwood, R. M. 1989. Relationships between moas and plants. New Zealand Journal of Ecology 12, 67-96.

Barlow, C. C. 2000. The Ghosts of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms. Basic Books, New York.

Bartoš, M., Janeček, Š., Padyšáková, E., Patácová, E., Altman, J., Pešata, M., Kantorová, J. & Tropek, R. 2012. Nectar properties of the sunbird-pollinated plant Impatiens sakeriana: a comparison with six other co-flowering species. South African Journal of Botany 78, 63-74.

Bond, W. J. & Silander, J. A. 2007. Springs and wire plants: anachronistic defences against Madagascar’s extinct elephant birds. Proceedings of the Royal Society B 274, 1985-1992.

Burrows, C. J. 1980. Some empirical information concerning the diet of moas. New Zealand Journal of Ecology 3, 125-130.

Cheke, A. & Hume, J. 2008. Lost Land of the Dodo. Yale University Press, New Haven and London.

Diamond, J. M. 1990. Biological effects of ghosts. Nature 345, 769-770.

Durrell, G. 1977. Golden Bats and Pink Pigeons. Collins, London.

Eisenberg, C. 2010. The Wolf’s Tooth: Keystone Predators, Trophic Cascades and Biodiversity. Island Press, Washington.

Goodman, S. M. 1994. Description of a new species of subfossil eagle from Madagascar: Stephanoaetus (Aves: Falconiformes) from the deposits of Ampasambazimba. Proceedings of the Biological Society of Washington 107, 421-428.

Goodman, S. M., O’Connor, S. & Langrand, O. 1993. A review of predation on lemurs: implications for the evolution of social behaviour in small, nocturnal primates. In Lemur Social Systems and their Ecological Basis: 51-66. Kappeler, P. M. & Ganzhorn, J. U. (Eds). New York: Plenum Press.

Greenwood, R. M. & Atkinson, I. A. E. 1977. Evolution of the divaricating plants in New Zealand in relation to moa browsing. Proc. New Zeal. Ecol. Soc. 24, 21-33.

Holdaway, R. N. 1989. New Zealand’s pre-human avifauna and its vulnearability. New Zealand Journal of Ecology 12 (Supplement), 11–25.

Howell, C. J., Kelly, D. & Turnbull, M. T. H. 2002. Moa ghosts exorcised? New Zealand’s divaricate shrubs avoid photoinhibition. Functional Ecology 16, 232-240.

James, H. F. & Burney, D. A. 1997. The diet and ecology of Hawaii’s extinct flightless waterfowl: evidence from coprolites. Biological Journal of the Linnean Society 62, 279-297.

Janzen, D. H. & Martin, P. S. 1982. Neotropical anachronisms: the fruits the gomphotheres ate. Science 215, 19-27.

Johnson, C. N. 2009. Ecological consequences of Late Quaternary extinctions of megafauna. Proceedings of the Royal Society B 276, 2509-2519.

Mayr, G. 2005. Fossil hummingbirds in the Old World. Biologist 52, 12-16.

Midgley, J. J. & Illing, N. 2009. Were Malagasy Uncarina fruits dispersed by the extinct elephant bird? South African Journal of Science 105, 467-469.

Temple, S. A. 1977. Plant-animal mutualism: coevolution with dodo leads to near extinction of plant. Science 197, 885-886.

- . 1979. The dodo and the tambalacoque tree. Science 203, 1364.

Witmer, M. C. & A. S. Cheke. 1991. The dodo and the tambalacoque tree: an obligate mutualism reconsidered. Oikos 61, 133-137.

Worthy, T.H. & Holdaway, R.N. 2002. The Lost World of the Moa. Bloomington: Indiana University Press.

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. barndad 6:21 am 12/13/2013

    I’ve done field work with Richard!
    My guess for cover wrongness is that the skull on right is Harpagornis (only found on South Island, weirdly), but skull on left is North Island moa of some stripe?

    Link to this
  2. 2. Jerzy v. 3.0. 6:24 am 12/13/2013

    Nice story, time to look for adaptations of Atlantic fish to predation of Great Auks. Or for adaptations of European plants to browsing straight-tusked elephants, merck’s rhinos etc.!

    However, if we go much further back (to possible Miocene hummingbirds or Mesozoic dinosaurs) evolution had more than enough time to lose these adaptations. But I wonder if there are fossils of divaricating Mesozoic plants, or Mesozoic trees with tough, herbivore-adapted leaves at the bottom and unprotected leaves on the top?

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  3. 3. Richard Hing 6:25 am 12/13/2013

    I read in ‘Feral’ by George Monbiot that European trees are supposed to be over-engineered for surviving browsing pressure by deer, so it was suggested they might be adapted to survive elephant attacks. Thought it was a neat idea, but don’t know how well supported it is:

    http://www.monbiot.com/2013/05/27/a-manifesto-for-rewilding-the-world/

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  4. 4. Gigantala 6:42 am 12/13/2013

    Poor sauropod looks very unhappy.

    Anyways, the beauty of an ecosystem is that adptational ghosts are almost impossible to correcly access.

    The only ghost I can think off that seems unambiguously valid is pronghorn cursoriality (and even then did the american “cheetahs” actually survive that recently? I was under the impression they disappeared before the rest of the more iconic late Pleistocene megafauna did).

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  5. 5. ekocak 8:57 am 12/13/2013

    Re: Sauropod ghosts…I wonder how recently evolved the giant coniferous trees in the pacific northwest of the U.S. are.

    Yeah, I have no idea. But it’s kinda fun imagining.

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  6. 6. naishd 9:43 am 12/13/2013

    I deliberately didn’t mention the idea that sauropods may have driven the evolution of size in trees (have you seen McLoughlin’s Archosauria?). It was a popular idea for a while but was mildly smacked down in the 1990s.

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  7. 7. SciaticPain 10:17 am 12/13/2013

    I think it might prove useful to distinguish between diffuse coevolution- in which an organism(s) may adapt to a number of different species, for example a prey species that develops speed to thwart a variety of predators i.e. horses- and more intensive specific coevolution involving two species in a tight coevolutionary handshake over time, for example the mutualistic coevolution of yucca and yucca moths.

    For large herbivores and plants I find diffuse evolution predominates. A number of large herbivores enacting selective pressure on plants over time. Often times the herbivores going extinct or being replaced by other herbivores and the plant persisting with or without the herbivores.

    Overall I thing the biggest missing piece from modern ecosystems due to lack of large herbivores is large dung piles and the transfer of nutrients via big piles of crap throughout the landscape. Also large piles of dung serve as nurseries for plants/fungi and refugia/habitat for small fauna, esp amphibians.

    Campos-Arceiz, Ahimsa. Shit Happens (to be useful)! Use of Elephant Dung as Habitat for Amphibians. Biotropica 2009

    Regarding Mesozoic flora and dinosaurs: I have for a while been intrigued by several genera of osmundacean ferns (Osmunda and Osmundastrum). These ferns develop their spores on colorful, flower like stalks that rise above the main body of the fern. Since ferns of this family were around in the Mesozoic this habit begs the question, for me at least, were they trying to attract herbivores to eat their spores and spread them in herbivore dung? Granted I am not positive that ferns of said pseudo flowering habit were alive then just the family itself… and evidence of fern spore passing through herbivore guts and surviving is lacking as far as I have found. But then again ferns are not commonly consumed by large mammalian herbivores…

    Thanks for including my pic Darren, should give my site a lot of hits!!

    Duane Nash
    antediluvian salad

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  8. 8. naishd 10:36 am 12/13/2013

    Thanks, Duane – a useful insight. Regarding the Campos-Arceiz paper, err… check this out.

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  9. 9. Heteromeles 10:58 am 12/13/2013

    It’s also worth throwing bears into the mix, if we’re talking about ghost herbivores. In California (where the iconic grizzly bear was eliminated in the early 20th Century), there are quite a few chaparral species that have berries with tough seeds. The best-known is manzanita (Arctostaphylos), where the berries have one (rarely two) thick-coated seeds that germinate after either being burned or soaking in acid for a day. Manzanitas are now considered fire-followers, but their fruits are eaten by black bears where the later exist. One wonders whether, in the not-so-distant past, manzanitas and similar plants were distributed by grizzly bears. California Indian lore also suggests that chaparral (where manzanitas were common) was grizzly bear habitat.

    I’ve amused myself with the idea of feeding manzanita berries to captive grizzlies, just to see if the seeds germinate better from grizzly poop. If anyone has the connections, I’d be happy to talk.

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  10. 10. SciaticPain 11:13 am 12/13/2013

    @ Heteromeles I have found a lot of coyote scat while hiking in California, in areas with no black bears, with manzanita seeds in it. The book Bear in Mind: The California Grizzly is a great book to check out and yes dry, shrubby chaparral/oak savanna were their preferred haunts and not the redwood belt or high sierra.

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  11. 11. Andreas Johansson 12:45 pm 12/13/2013

    Is there a linguistic connection betweeen “moa” and “moa-nalo”? Both Maori and Hawaiian being Polynesian, it seems offhand plausible.

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  12. 12. Yodelling Cyclist 1:32 pm 12/13/2013

    Thanks for making the time to do this Darren, these articles are really helping with some thorny thesis writing.

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  13. 13. Sebastian Marquez 3:52 pm 12/13/2013

    @Andreas

    Moa Nalo is a term coined by Olsen & James meaning lost fowl. We don’t know what Hawaiians originally called the birds. The word Moa is the Hawaiian word for chicken though.

    Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part I. Non-Passeriformes”. Ornithological Monographs 45: 38–42.

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  14. 14. Heteromeles 5:26 pm 12/13/2013

    Thanks SP, I’ll have to check that book out. I know that coyotes have taken over the frugivore duties, but I still think it would be an excellent study to compare the relative efficacy of grizzlies, coyotes, and whatever else at getting manzanita seeds to break dormancy.

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  15. 15. John Harshman 5:37 pm 12/13/2013

    We don’t know what Hawaiians originally called the birds.

    …but they apparently didn’t call them late for dinner.

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  16. 16. Metridia 6:06 pm 12/13/2013

    Of course, the extent of coevolution with extinct species is debatable, but certainly there are ecological ghosts of recently extinct megaherbivores.

    As far as the dense foliage of the bushes deterring moa- well, African acacias still get eaten by giraffes, no? Does that mean the spines have no deterrence effect? It’s possible that they still reduce impact of browsing while not completely eliminating it!

    > weren’t demonstrably interested in consuming the ‘protected’ foliage anyway

    I assume they used double-blind taste tests with the moas to determine this…

    If your only point is to say it’s controversial, well ok, but you don’t give much info on why!

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  17. 17. Heteromeles 6:48 pm 12/13/2013

    I was trying to be gentle about this, but it’s worth noting a few things, namely:

    Plant structures often serve more than one purpose (such as the divaricating branches), so it’s hard to say that some structure is evolved for precisely one purpose.

    Also (with respect to the idea of European hummingbirds), there’s been a lot of doubt cast on the idea of pollination syndromes. What can be said is that a flower shape doesn’t make a species go extinct, not (in most cases) that it suggests that a species is or used to be present. Darwin’s hawk moth prediction is the exception, not the rule, AFAIK.

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  18. 18. Christopher Taylor 7:35 pm 12/13/2013

    I couldn’t say what botanists would think of Mayr’s hummingbird-ghost suggestion, but I could tell you what entomologists would think of it: it’s unnecessary. Europe has living hover-pollinators already: the hawk moths.

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  19. 19. naishd 7:37 pm 12/13/2013

    Thanks for great comments, everyone.

    Metridia (comment # 16): regarding moa apparently not being “demonstrably interested in consuming the ‘protected’ foliage”, the argument goes that, since moa gizzard contents show that the birds were (apparently preferentially) clipping the twigs of these divaricating plants – that is, they were not eating the foliage that the divaricating branches were supposedly protecting – they were not exerting the browsing pressure supposed to have resulted in the divaricating morphology in the first place.

    An alternative explanation might be, ha ha, that the divaricating morphology was ‘doing its job’ and preventing the browsing moa from reaching the leaves…

    Regarding comment # 17 (and some other comments here), I feel pretty sceptical about most or all of the suggested co-evolutionary scenarios discussed here – I was hoping that this was properly conveyed throughout the text.

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  20. 20. Yodelling Cyclist 8:17 pm 12/13/2013

    Removing the main grazing pressure must have had some significant effect on the flora of New Zealand. Are there no archaic pollen records which might show a distinct change broadly co-incident with human arrival (and presumably moa extinction), or am I just hoping for too much? I also recall a podcast mention of eDNA evidence for oodles of moa, is it not possible to obtain floral eDNA?

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  21. 21. vdinets 11:30 pm 12/13/2013

    Gigantala (#4) We’ve had a discussion of the cheetah-pronghorn theory here a while ago. I was in the minority that was highly skeptical of this theory. (Don’t remember for sure, but perhaps that minority is just me.) People generally assume that if you run just a little bit faster than wolves, you are safe from them. But the geometry of attacks by pack-hunting predators is such that the prey needs all speed advantage it can get. Mongolian gazelles run much faster than wolves (they can outrun a car making 75-80 kph, that’s faster than a greyhound), but they still get caught by wolves regularly. No matter how fast you run, there is still selective pressure towards running even faster.

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  22. 22. Jenny Islander 12:15 am 12/14/2013

    Another potential ecological ghost: Did Columbian mammoths dig waterholes in the parts of North America that were always relatively arid and warm? We know that desert populations of African elephants do this. Have we lost a number of oases, and therefore migratory routes for other species of animals, because we no longer have proboscideans around to keep them open?

    And another: It has been argued that the known population of Steller’s sea cow was living in an inhospitable portion of its prehistoric range. I’ve seen speculative maps (based, IIRC, on bones and current offshore vegetation) that put the species habitat in a large arc from northern Japan to California. What might the near-shore kelp meadows and estuaries of this area look like with these big beasts grazing in them?

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  23. 23. Andreas Johansson 4:12 am 12/14/2013

    Sebastian Marquez wrote:
    Moa Nalo is a term coined by Olsen & James meaning lost fowl. We don’t know what Hawaiians originally called the birds. The word Moa is the Hawaiian word for chicken though.

    Thanks. Would this Hawaiian word for chicken be cognate with Maori “moa”?

    Link to this
  24. 24. Jerzy v. 3.0. 7:20 am 12/14/2013

    @7
    Another overlooked effect of herbivores is providing carrion. Currently, even if herbivores exist, carcasses are collected by hunters or farmers.

    Interesting studies are in Netherlands in the reserve called Oostvaardersplassen, where a population of red deer, primitive cattle and horses is living completely unmanaged, that is not supplementary fed in winter and not collected. As you said, dung attracted an interesting fauna of coprophilous beetles. But carrion resulted also in unusual density of wintering birds of prey, including nationally rare species.

    One can imagine that in ancient eosystems, carrion in winter was important for survival of carnivores and raptors, especially young animals. For Golden Eagles, White-tailed Eagles and many other predators, biggest mortality is in first winter of life, and due to starvation.

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  25. 25. Jerzy v. 3.0. 7:22 am 12/14/2013

    @23
    Apparently ‘moa’ is word for ‘fowl’ or ‘bird’ in many Polynesian languages.

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  26. 26. Jerzy v. 3.0. 7:24 am 12/14/2013

    @20
    Some New Zealand plants have non-divaricating ecotypes on small offshore islands, where selection pressure from sunlight etc. is the same, but where there was presumably no moa.

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  27. 27. vdinets 7:57 am 12/14/2013

    Jenny Islander: Russian biologists working at Commander Islands have suggested that the extinction of the sea cow is the cause of boom-and-bust cycles involving kelp, sea urchins and sea otters. I don’t know if this idea ever got published – I only heard it in private conversations.

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  28. 28. naishd 8:03 am 12/14/2013

    Great comments – lots to think about here. ‘Boom and bust’ cycle involving Steller’s sea cow, kelp, urchins, sea otters and other organisms in the community has indeed been discussed in the literature – check out my brief coverage of it in the Tet Zoo article that reviews Eisenberg’s The Wolf’s Tooth. Also…

    Anderson, P. 1995. Competition, predation and the evolution and extinction of Steller’s sea cow, Hydrodamalis gigas. Marine Mammal Science 11, 391-394.

    Turvey, S. & Risley, C. 2006. Modelling the extinction of Steller’s sea cow. Biology Letters 2, 94-97.

    Link to this
  29. 29. llewelly 10:59 am 12/14/2013

    vdinets: “Gigantala (#4) We’ve had a discussion of the cheetah-pronghorn theory here a while ago. I was in the minority that was highly skeptical of this theory.”

    Is that still the minority view?

    Articles like this: http://phenomena.nationalgeographic.com/2013/01/08/did-false-cheetahs-give-pronghorn-a-need-for-speed/ by Brian Switek have left me with the impression that more and more scientists are skeptical of the “American cheetah” made pronghorn super-fast theory.

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  30. 30. Heteromeles 6:06 pm 12/14/2013

    @vdinets: Here in California we have issues with urchins, kelp, and sea otters–and I don’t think we’ve had sea cows any time recently if at all. What’s so special about Alaska?

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  31. 31. David Marjanović 7:11 pm 12/14/2013

    the Tambalacoque tree Sideroxylon grandiflorum (formerly Calvaria major)

    Does anyone know what happened there nomenclatorily?

    Meanwhile, the strong fear response that Madagascar’s lemurs have of airborne raptors has also been suggested to represent predation pressure from extinct taxa, most notably the gigantic Stephanoaetus maharey (Goodman et al. 1993, Goodman 1994), a relative of the living Crowned eagle S. coronatus of the African mainland.

    It’s S. mahery. Looks like you remembered the pronunciation but switched to an English spelling…!

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  32. 32. Heteromeles 7:30 pm 12/14/2013

    As for Calvaria major to Sideroxylon grandiflorum…

    I can’t tell when it happened, because Calvaria is a bone in the skull, and those (expletive deleted) biomedical researchers have cluttered the search engines with irrelevancies, as has everyone harshing on Temple’s Dodo story.

    That said, it’s Sideroxylon grandiflorum A DC. That A DC is a giveaway, because Alphonse de Candolle was a major early botanist. According to Kew, de Candolle named a specimen Sideroxylon grandiflorum back in 1844. It was renamed Calvaria grandiflora by Dubard in 1912, then conflated with what at the time was Calvaria major (now Sideroxylon majus, which is a species on Reunion island.

    I don’t know who did it or when (I’m guessing recently and with DNA), but it appears that subsequent research unwound both the connection with the Reunion species, and Calvaria was (re)submerged back into Sideroxylon, and given back its original name. Calvaria is not considered a valid genus at the moment.

    Looks like part of the eternal lumper/splitter debate.

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  33. 33. David Marjanović 10:08 am 12/15/2013

    Thanks!

    Link to this
  34. 34. vdinets 1:10 am 12/16/2013

    llewelly (#29) and Heteromeles (#30): sorry, I don’t know. I haven’t followed the pronghorn-cheetah debate lately, and never studied the sea cow-kelp-urchins-sea otters issue in any detail.

    Link to this
  35. 35. David Marjanović 10:10 am 12/16/2013

    Oh, I forgot: the extreme running endurance of rheas has been blamed on phorusrhacids racing after them.

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  36. 36. zzoom 11:05 pm 12/16/2013

    Many Polynesian peoples called chickens Moa. On Easter Island today you can buy a Moa burger. As New Zealand historian James Bellich has observed, it must have tickled the imagination of the first arrivals in the vast (by Polynesian standards) new land of New Zealand/ Aotearoa to call those giant birds chickens. A measure of what a treasure trove they had discovered.

    Another example is the flightless Kakapo, often mischaracterised as having evolved to be slow and flightless due to lack of predation pressure. In fact as the article notes New Zealand was awash with several now-extinct avian predators that hunted by sight. The Kakapo’s tree hugging freeze-when-threatened behaviour combined with superb camouflage served it very well, but proved disastrous against recently arrived mammalian predators hunting by smell.

    Here is a photo of a Kakapo from about 1 meter away. It is in the middle and fills about one-third of the photo.
    http://cyclingdutchgirl.files.wordpress.com/2012/04/well-camouflaged.jpg?w=675&h=506

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  37. 37. CFowler 1:43 pm 12/17/2013

    Jenny Islander (#22) – If there are lost oases, I wonder if human activity compensates. We maintain reservoirs in some pretty arid places, and migratory birds in my area don’t hesitate to use man made water features year round.

    Jerzy (#24) – “Currently, even if herbivores exist, carcasses are collected by hunters or farmers.” I think you could reasonably argue there might be less biomass, but I’m mystified by your statement. There are deer in my suburban area, but no hunters and no farmers, and certainly no one I know goes out and collects dead deer. Where do farmers/hunters collect dead animals to the degree that scavengers can’t scavenge?

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  38. 38. Metridia 1:48 am 12/18/2013

    @Darren- I still don’t think you’ve made a strong case here overall, not just with the twigs…Again, defenses don’t have to be 100% effective to have a worthwhile effect, obviously. Predators can increase standing biomass of vegetation simply by decreasing loiter time of herbivore prey. Likewise, if the moa clip twigs from the divaricating bush, perhaps they don’t clip as much because they don’t get the return on feeding-time investment that they want, and thus the plant defense has succeeded. And as Jerzy notes, the same plants on possibly moa-free offshore islands apparently lack divarication.

    Here’s a recent ref on moa browsing, suggesting a generalist approach at least for one species:

    Wood JR, Wilmshurst JM, Wagstaff SJ, Worthy TH, Rawlence NJ, et al. (2012) High-Resolution Coproecology: Using Coprolites to Reconstruct the Habits and Habitats of New Zealand’s Extinct Upland Moa (Megalapteryx didinus). PLoS ONE 7(6): e40025. doi:10.1371/journal.pone.0040025

    Generalist to me suggests they could be affected by deterrence.
    Another one, suggesting extensive coevolution of moa and their browse:
    http://extinct-website.com/pdf/NZJEcol12_s_57.pdf

    From what I recall, there are also trees with distinct sapling morphs, like kauri, that have been suggested to be due to herbivore grazing pressure.

    Again, not really convinced by the discussion you presented above…seems like there was a lot left unmentioned.

    Link to this
  39. 39. LeeB 1 3:43 am 12/18/2013

    The podocarp tree the Matai Prumnopitys taxifolia starts as a divaricating shrub then after a few years changes to an upright tree; shedding its divaricating branches as it does so.
    Other podocarp trees such as the Monoao Halocarpus kirkii have distinctly different juvenile and adult foliage.
    Among the angiosperms the Lancewoods Pseudopanax crassifolius and P. ferox have long leathery leaves and an unbranched erect trunk at first; when they are several metres tall they switch to broader fleshy leaves and the trees start to branch.
    A related Pseudopanax species from the Chatham Islands (where Moa did not occur) does not change the form of it’s foliage like this.

    But it is not only in New Zealand that plants seem to show adaptation to extinct browsers.

    North America has the Osage Orange tree whose fruit seem to be adapted to dispersal by large browsers and there was once a very funny article on the internet about a person trying to prune an Osage Orange to control it’s height; this backfired spectacularly as the reaction of the tree was to immediately produce strong vertical branches covered with extra long thorns.
    Further attempts to prune these led to the production of even more spiny vertical branches.
    The writer of the article concluded that the tree was attempting to outgrow browsers by gaining height rapidly while producing extra long thorns to attempt to discourage the browser.

    LeeB.

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  40. 40. naishd 6:49 am 12/18/2013

    Metridia (comment # 38): the article here is meant to be a review – the section on alleged coevolution between moa and flora is brief and not intended to provide detailed, in-depth coverage. My idea is that, should you want to read such, you should look at the literature I cited – Worthy & Holdaway (2002) for starters. So, yes, I left a lot unmentioned, sorry about that.

    As for ‘not making a strong case’, well, I can’t see that I’ve made (or tried to make) any case of any sort – I basically say what’s been suggested, then say that it’s been doubted, and, personally, I don’t have strong feelings either way on this particular subject. In other words, there’s a controversy here, with different people favouring different interpretations of the data. I think I get the point that I didn’t write the article you thought I should have. Sorry about that.

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  41. 41. Hydrarchos 2:32 pm 12/18/2013

    I had no idea that the Tambalacocque thing had been debunked (or indeed that younger specimens of the tree had been found). Wasn’t there some attempt to force-feed the seeds to chickens (or turkeys?) to attempt to replicate the effect of a dodo’s digestive system on them?

    In general I often wonder what species well-adapted to living in human-managed environments (e.g. most common bird species in western Europe) did before the human population explosion. How different an avifauna must England have had when what is now farmland, heath and moorland was nearly all broadleaf woodland?

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  42. 42. David Marjanović 2:43 pm 12/19/2013

    The moorland was moorland, and so was some of the farmland.

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  43. 43. Jerzy v. 3.0. 3:47 pm 12/19/2013

    @37
    In most of Europe, or wherever the hunting goes on.

    Also, hunters in Europe tend to supplementary feed deer and boar in snowy winters. They do it “to help animals” and of course, to protect their quarry. But this also means that other animals – carnivores – cannot get carrion.

    @41
    There are interesting observations from Poland, from Bialowieza forest. This closed forest lacks many birds which are most common in Europe, like tree sparrow, goldfinch, linnet, greenfinch, grey partridge… Open country species must have been much rarer in pre-farming Europe.

    Link to this
  44. 44. vdinets 11:01 pm 12/20/2013

    Jerzy: isn’t it possible that the forests were much more open and fragmented when the megafauna was still around?

    Link to this
  45. 45. Jerzy v. 3.0. 11:59 am 12/21/2013

    @Vlad
    Yes, it is more than likely. It seems that during Eemian, the previous interglacial, Western Europe had many open habitats created by extinct megafauna (straight-tusked elephants, rhinos, aurochs, bison etc). In any case, lots of plants and animals which are obligate open habitat specialists occured in Eemian Central and Western Europe. These include many species which need large treeless habitats and are not happy with just treefall gaps, forest burned-up areas, patches of inundated grassland etc. See eg. sousliks, European hamster etc.

    In the current interglacial the megafauna is either extinct or rare. Natural succession produced large-scale closed forests where many open country plants and animals cannot live. Low intensity farming replaced megafauna in creating open habitats. In 20. and 21. century, the agriculture changed to high-intensity one. Thying to keep low-intensity agriculture especially for nature is prohibitively expensive. There are attempts to maintain open marshland, meadows, thermophilic grassland etc. in natural reserves by grazing of herds of primitive cattle, horses, reintroduced wisent etc.

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  46. 46. llewelly 5:21 pm 12/21/2013

    If there were “ghosts” from the Mesozoic, would it not be best to examine relationships between birds and conifers?

    After all, both birds and conifers evolved during the Mesozoic. Perhaps they co-evolved some behaviors which persist to this day.

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  47. 47. Heteromeles 6:55 pm 12/21/2013

    @llewelly: After 60 million years of evolution from both birds and conifers? Unlikely. This is where island evolution plays a pretty critical role. If you look at how fast things evolve in the absence of predators or competitors, it gives you a pretty good estimate of how much evidence of ghosts of relationships past will remain. Personally, I doubt either conifers or birds show much of their Mesozoic relationships, not the least because the most common conifers today (Pinaceae) depend on an ectomycorrhizal relationship that probably evolved in the late Mesozoic, but did not become widespread until well into the Paleogene. Since ectomycorrhizae short-circuit nutrient recycling, this is a non-trivial change in the way coniferous forests work.

    Link to this

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