A recent paper by Shaun Winterton, Hock Ping Guek, and Stephen Brooks describes a new species of lacewing (a type of insect in the order Neuroptera). There is nothing unusual in this– new species of animals, especially insects, are described all the time, and we have a few million more to go. What’s a bit unusual is how the species was recognized as new– a photograph of it was seen, more or less at random, by an entomologist while perusing Flickr.
After recognizing the species as new, Winterton had Guek obtain another specimen, which was sent to Winterton for study; this specimen became the holotype for the new species. A second specimen of the new species was found at the British Museum (Natural History) in London; this specimen is the paratype.
While quite a few new species are discovered during expeditions into the wild, many are also found in more prosaic circumstances, most often among sets of unidentified or misidentified specimens in museums (much like the paratype of the new lacewing). Many such undescribed species are already in museums. As a graduate student I recall seeing cabinets full of plaster-jacketed fossils in the basement of the Museum of Comparative Zoology, with labels like “Brazil 1936” (this was in the 80s), and I often wondered whether there might be any undescribed finds within. There’s a story I’ve heard, probably apocryphal, of a paleontologist who wrote a research grant proposing to fund an expedition to the basement of the British Museum, in order to examine the unsorted and unidentified specimens still awaiting study!
New species have also turned up in the pet trade. But my favorite example of a species discovered in an unusual place is the new species of lizard discovered by herpetologist Ngo Van Tri on his dinner plate (lizards- they’re not just for breakfast anymore); previous WEIT coverage here.
Winterton, S.L., H.P. Guek, and S.J. Brooks. 2012. A charismatic new species of green lacewing discovered in Malaysia (Neuroptera, Chrysopidae):the confluence of citizen scientist, online image database and cybertaxonomy. Zookeys 214:1-11. (pdf)
Since I first read about them when I was about 12 years old, I’ve been intrigued by the somewhat mysterious Vegas Valley leopard frogs. Known from a handful of springs, all in what is now more or less metropolitan Las Vegas, they had disappeared before the middle of the 20th century, and had been poorly known before apparently slipping out of existence. But now they’re back– sort of.
Evon Hekkala of Fordham University and her colleagues have a paper in press in Conservation Genetics in which, using DNA extracted from specimens of Vegas Valley frogs in the collection of the California Academy of Sciences, they find that Vegas frogs are closely related to the Chiricahua leopard frog of Arizona and nearby areas. In fact, the Vegas frogs are nested within the many samples of Chiricahua frogs they studied. From this they conclude that the Vegas frog is conspecific with the Chiricahua frog, and thus the Vegas Valley leopard frog is not extinct.
That the Vegas frogs (Rana fisheri) are conspecific with the Chiricahua frogs (Rana chiricahuensis) is a not unreasonable inference. North American leopard frogs, once thought to be a single widespread species, have proven to be a complex of several biological species, and although the situation is modestly clear in the eastern United States, there is much work yet to be done in the southwestern US and especially Mexico to figure out what’s going on. The Vegas frogs are not genetically identical to the Chiricahua frogs (contrary to some media reports), and, with only about 1200 base pairs examined at three loci, more differences are sure to be found.
So is the Vegas frog not extinct anymore? This isn’t just a biological species vs. amount-of-difference species concept question. One could accept, under various species concepts (and we know which one is right!), that the Vegas and Chiricahua frogs are conspecific, but still ask, is the Vegas Valley frog still extant because similar, but not identical, frogs continue to exist 100’s of kms away? I’m not sure. The US Endangered Species Act recognizes that population segments, even if they lack nomenclatural recognition or distinction, can be endangered, and be worthy of protection. And if a segment can be endangered, it can, of course, go extinct. So, while I’m glad we’ve learned who the Vegas Valley frogs’ closest relatives are, and that they’re quite similar, and that, due to the rules of nomenclature they will bear the name fisheri, I’m afraid the Vegas Valley frogs are still extinct.
The great herpetologists Albert & Anna Wright and Robert Stebbins summarized most of what will ever be known about the Vegas Valley frogs, and wrote, movingly yet scientifically, of their unsuccessful searches in the Vegas area in the 1940’s (they were last collected in January 1942, and last reported seen in the summer of ’42). The Wrights concluded:
Our R. fisheri may go with the old springs gone, the creek a mess.
Fisher, J., N. Simon, and J. Vincent. 1969. Wildlife in Danger. Viking, New York
Hekkala, E.R., R.A. Saumure, J.R. Jaeger, H.-W. Herrmann, M.J. Sredl, D.F. Bradford, D. Drabeck, and M.J. Blum. 2011. Resurrecting an extinct species: archival DNA, taxonomy, and conservation of the Vegas Valley leopard frog. Conservation Genetics in press. pdf
Moore, J.A. 1944. Geographic variation in Rana pipiens Schreber in eastern North America. Bulletin of the American Museum of Natural History 82:345-370. pdf
Pace, A.E. 1974. Systematic and biological studies of the leopard frogs (Rana pipiens complex) of the United States. Miscellaneous Publications, Museum of Zoology, University of Michigan 148, pp. 140. pdf
Stebbins, R.C. 1951. Amphibians of Western North America. University of California Press, Berkeley.
Wright, A.H. & A.A. Wright. 1949. Handbook of Frogs and Toads of the United Sates and Canada. Comstock, Ithaca, New York.
David Hillis of the University of Texas (who Jerry just mentioned) has done much of the work that has more recently both clarified, and pointed out the lacunae in, our understanding of leopard frogs. Many of his papers (on leopard frogs and many other subjects) are available here.
Update. David Hillis has kindly commented below, and quotes one of his papers (Hillis and Wilcox, 2005); here’s a link to the pdf of that paper.
At least since Socrates explored the meaning of the Greek maxim “Know thyself”, and Alexander Pope added that “the proper study of Mankind is Man”, we have been interested in knowledge about ourselves. But who are we? A paper in press in the Proceedings of the National Academy of Sciences by Ron Pinhasi and colleagues raises this issue with regard to Neanderthals, an issue which Jerry considered a while back: are they us?
In several senses, they obviously are us: fellow mammals, fellow primates, fellow hominids, and fellow members of the genus Homo, and thus men in the generic sense (in both the vernacular and technical senses of generic). But are they members of the same species as us, Homo sapiens? Or members of a distinct species, Homo neanderthalensis?
The question of whether they are a different species from us is the question of whether or not we could interbreed with each other. And not just mate– but successfully produce fertile offspring. For most of the time since the first reported Neanderthal in 1856, reproductive compatibility could only be inferred based on morphological data, and opinions varied as to whether Neanderthals were a subspecies of H. sapiens or a separate species. The great Finnish paleontologist Bjorn Kurten proposed in his novel, Dance of the Tiger, that Neanderthals and modern H. sapiens could mate and produce offspring, but that the offspring, while showing somatic luxuriance (they were really smart and strong), were completely sterile (a form of post-mating reproductive isolation). Published in 1980 before there was any genetic evidence, a novel, rather than a scientific paper, was probably the right venue for Kurten’s reasoned but entirely speculative proposal.
Early genetic data from mitochondrial DNA indicated that Neanderthal mitochondria were well outside the variability of modern populations, supporting the ideas of those (such as Kurten) who supposed that Neanderthals were a separate species. More recently obtained nuclear DNA sequences, however, showed that 1-4% of the genome of modern Eurasians was derived from Neanderthals (modern Africans lack this admixture of Neanderthal DNA). Thus there was enough successful interbreeding to leave a noticeable signature in modern genomes. Even more recently, a previously unknown fossil Asian population called Denisovans, related to but distinct from Neanderthals, has been shown to have contributed about 5% of the genome of modern Melanesians. Thus, measurable interbreeding occurred between anatomically modern humans and more archaic Eurasian populations as the former spread out of Africa across the remainder of the Old World.
The paper by Pinhasi et al. revises the dating of Neanderthal fossils from the Caucasus, finding them to be older than previously thought (about 40,000 years BP). The authors also suggest that other younger dates are unreliable, and that it is unlikely that anatomically modern humans and Neanderthals coexisted for any substantial length of time. If they are correct, then the Neanderthal (and Denisovan) contribution to modern genomes speaks even more strongly of conspecficity, as the gene flow had to occur over shorter periods of time. There are, regrettably, quite a few historical instances where two peoples (both of course undoubted anatomically modern H. sapiens) met, and one quickly disappeared, with relatively little measurable gene flow having occurred, so the rapid demise of Neanderthals in the face of anatomically modern humans is no bar to their having been the same species. I would interpret the genetic evidence so far as indicating that the Neanderthals, indeed, are us.
In addition to the references below, John Hawks of the University of Wisconsin, Madison, has a fine blog in which he often comments on Neanderthals and other paleoanthropological topics. His take on the Pinhasi et al. paper, which deals more with the dating issues, is here; his view on the species question is here. [JAC: I also discussed the species problem in Neanderthals, reaching the same conclusion as Hawks.]
Green, R.E. et al. 2010. A draft sequence of the Neandertal genome. Science 328:710-722.
Green, R.E., et al. 2008. A complete Neandertal mitochondrial genome sequence determined by high-throughput sequencing. Cell 134:416-426.
Kurten, B. 1980. Dance of the Tiger. Reissued by University of California Press, Berkeley, 1993.
Pinhasi, R., T.F.G. Highamb, L.V. Golovanovac, and V.B. Doronichev. 2011 Revised age of late Neanderthal occupation and the end of the Middle Paleolithic in the northern Caucasus. Proceedings of the National Academy of Sciences in press.
Reich, D., et al. 2010. Genetic history of an archaic hominin group from Denisova Cave in Siberia. Nature 468:1053-1060.
There are two issues here, both of which we’ve considered before here at WEIT. First is the species concept issue, which both Jerry and I mentioned recently (links to Jerry’s posts in mine). The second is a scientific nomenclature issue, one that arose in the infamous Darwinius case.
The species concept issue also comes in two parts. First, are the mainland clouded leopard (Neofelis nebulosa) and the insular clouded leopard (Neofelis diardi) distinct species? And, second, among the insular clouded leopards, are the Bornean and Sumatran populations distinct? The first issue was the focus of two papers in 2006 which raised the insular leopards to full species status. Normally, the raising of insular forms to full species status on the basis of being different from the mainland form raises a warning flag for me, but there is an additional consideration which I think in this case supports the raising to full species status. This is that the islands of Borneo and Sumatra are on the Sunda Shelf, and thus were connected to the mainland as recently as about 10,000 years ago (see Harold Voris’s superb series of paleo-bathymetric maps of the Sunda Shelf for details). So, the insular and mainland forms were in contact very recently, and one good explanation for why this contact would not have led to an erosion of the genetic differences between them is that they were reproductively isolated (i.e., different species). There are other possible interpretations, but the recent contact combined with observed differences certainly makes the 2-species taxonomy reasonable.
The new, unpublished, paper argues not for a new species, but for dividing the insular form into two subspecies, one from Borneo and one from Sumatra. (A subspecies is recognized when there is a particular pattern of geographic variation within a species, namely that there is a geographic segment of the species’ range within which individuals can be distinguished from individuals from other parts of the range. Basically, if you can tell where an individual is from by the way it looks, or, if you tell me where the individual is from, I can tell you what it looks like, then you can name a subspecies.) This seems perfectly reasonable to me.
The problem is that they describe a new subspecies in the paper (rather than reviving a previously described one), but they have also posted a pre-print online and allowed press coverage. Online posting does not constitute publication in the formal sense, and their paper will soon be published on paper. But by generating press coverage (the BBC has included the new name in its coverage) and posting online, they increase the chance that the name will be formally published before their paper appears in print, either accidentally, or on purpose by an unscrupulous individual wanting to steal credit for their work (it does happen). This was part of the problem with Darwinius: the name Darwinius was bandied about before the name was published.
The authors are actually compounding a problem they created for themselves earlier: they published the new name in 2007 (I have not seen this paper), but now consider their proposal at the time nomenclaturally defective, and the name not nomenclaturally available from that publication. (The technical term for what they now regard their 2007 effort is a nomen nudum: a nude name, i.e. a name without a proper description accompanying it, and thus not available for use as a scientific name). The nomenclature of this name could be confused. I hope their paper appears soon.
One thing highlighted by this paper that I want to unreservedly endorse is the use of camera traps for the study of elusive large mammals. These traps have helped with studies of a number of species, including several big cats: jaguars(including Arizona jaguars), Saharan cheetahs, Asiatic cheetahs, tigers, as well as clouded leopards. The BBC, NYT, and other media often highlight the results of these studies. Recently, camera traps revealed an unexpected high-altitude population of tigers in Bhutan, in a valley where three big cats– leopard, snow leopard, and tiger– all live together.
Buckley-Beason, V.A. et al. 2006. Molecular evidence for species-level distinctions in clouded leopards. Current Biology 16:2371-2376. (pdf)
Kitchener, A.C., M.A. Beaumont, and D. Richardson. 2006. Geographical variation in the clouded leopard, Neofelis nebulosa, reveals two species. Current Biology 16:2377-2383. (pdf)
Wilting, A., V.A. Buckley-Beason, H. Feldhaar, J. Gadau, S.J. O’Brien, and K.E. Linsenmair. 2007. Clouded leopard phylogeny revisited: support for species recognition and population division between Borneo and Sumatra. Front. Zool. 4:15. (not seen)
Wilting, A., P. Christiansen, A.C. Kitchener, Y.J.M. Kemp, L. Ambu, and J.Fickel. 2011. Geographical variation in and evolutionary history of the Sunda clouded leopard (Neofelis diardi) (Mammalia: Carnivora: Felidae) with the description of a new subspecies from Borneo. Molecular Phylogenetics and Evolution in press. (pdf)
Tuataras are very interesting animals: endemic to New Zealand, and the sole survivors of an ancient and once more widespread order of reptiles, the Sphenodontida, whose closest relatives are the squamates (lizards+snakes). I noted some of their distinctive traits in an earlier post. When a friend went to New Zealand for a visit during the holidays, I asked him to get a picture of a tuatara if one came his way, and he obliged.
Species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such group.
This definition, known as the biological species concept, is the one Jerry argued in favor of in his posts (and more extensively in Speciation, his book with Allan Orr). Through most of the 20th century, a single geographically variable species of tuatara, Sphenodon punctatus, was recognized. In 1990, on the basis of morphological and, primarily, allozyme differences, Charles Daugherty and colleagues argued that a second species, S. guntheri, occurring on islands in eastern Cook Strait (see map), should be recognized. (Allozymes are proteins which are different alleles at the same genetic locus, and which are usually distinguished by protein electrophoresis.)
At the time, this bothered me, as I saw it as an application of the old morphological species concept, extended to genetic data: if you can tell them apart, they are different species. This is also what Jerry argued against in the case of elephants: an arbitrary amount of morphological or genetic difference, or inferred time of separation based on the amount of genetic difference, is not a sound basis for a species concept.
Recently (2010), however , further studies of tuataras have been made, including study of their DNA, and the authors of this work conclude that, as had been held earlier, a single geographically varying extant species of tuatara should be recognized (the status of the extinct tuataras from the New Zealand mainland is still up in the air). So we’re back to S. punctatus as the sole surviving species in the Sphenodontida.
This turnaround in tuatara taxonomy is also a nice example of something Jerry considered in a previous post: scientists changing their mind in the light of new evidence, and not being shy about saying so (something which, of course, should not be rare). Two of the authors of the 1990 resurrection of S. guntheri, Charles Daugherty and Jennifer Hay, are also authors of its 2010 sinking.
Daugherty, C.H., A. Cree, J.M. Hay & M.B. Thompson. 1990. Neglected taxonomy and continuing extinctions of tuatara (Sphenodon). Nature 347:177-179. (abstract)
Hay, J.M., S. D. Sarre, D.M. Lambert, F.W. Allendorf & C.H. Daugherty. 2010. Genetic diversity and taxonomy: a reassessment of species designation in tuatara (Sphenodon: Reptilia). Conservation Genetics 11:1063-1081. (abstract)
That’s more or the less the question Ngo Van Tri, a Vietnamese herpetologist, must have asked himself after having a meal like that shown below, which surely rivals anything Jerry’s had in Colombia.
Tri contacted Lee Grismer of La Sierra University and his son Jesse Grismer, a graduate student at Villanova University, both herpetologists. They went to Vietnam and found that it was an undescribed species, which they named Leiolepis ngovantrii in Tri’s honor, in a paper (whose title oddly brings to mind the 2003 Red Sox) published this past spring in Zootaxa (abstract only).
All new species are interesting, but new ones are found all the time. What makes this one especially of note (besides being discovered on a dinner plate) is that it is a parthenogenetic species– consisting only of females, and reproducing asexually. This is a rather unusual mode of reproduction in vertebrates, but a fair number of lizards, including species in the families Teiidae, Lacertidae, Geckonidae, and (like Leiolepis) Agamidae, reproduce this way. Most parthenogenetic lizard species have arisen by hybridization between two sexual species. The Grismers, using mitochondrial DNA, have been able to identify the maternal parent species of L. ngovantrii, and also of the three other parthenogenetic species of Leiolepis, showing that parthenogenesis in this genus has arisen in the usual way for lizards. It’s also known to occur spontaneously in normally sexual species, such as the Komodo dragon, Varanus komodoensis.
The unusual method of discovery has attracted some media attention.
Grismer, J. and L.L. Grismer. 2010. Who’s your mommy? Identifying maternal ancestors of asexual species of Leiolepis Cuvier, 1829 and the description of a new endemic species of asexual Leiolepis Cuvier, 1829 from Southern Vietnam. Zootaxa 2433:47-61.
The photograph above is the best evidence we have for the existence of spotted lions. (The skin’s total length is 8 ft. 8 in., so it’s not a cub!). I’ve previously noted that photographs are not the best evidence for documenting the existence of a previously unknown species of animal, but in this case we have the benefit of the fact that the specimen in the photograph was examined by Reginald Pocock of the British Museum (Natural History) in the 1930s. Here is some of what Pocock, a world authority on cats, had to say, about the specimen loaned to him by Kenneth Gandar Dower (subscription required):
…it is a remarkable specimen owing to the distinctness of the spots in a beast of its size.
It is a male. … From it’s size I guessed it to be about three years old, a year or more short of full size.
…the peculiarity of the skin lies in the distinctness of its pattern of spots, consisting of large “jaguarine” rosettes arranged in obliquely vertical lines and extending over the flanks, shoulders and thighs up to the darker spinal area where they disappear.
As is well known, lion-cubs at birth generally, but not always, show a pattern of spots or stripes supposed, probably correctly, to be the remnants of an ancestral pattern transmitted from the time when lions were denizens of forests or jungles. In nearly all cases this juvenile pattern vanishes at three or four months on the body, but persists longer on the belly and legs and may sometimes be visible on those parts at maturity, especially apparently in sone lionesses from East Africa. Mr. Gandar Dower’s lion-skin is quite exceptional in this respect.
Pocock went on to indicate the absence of this pattern in a large series of adult specimens at the British Museum and the United States National Museum, but noted one account and one photograph that indicated at least an approach to being spotted. He also examined a skull provided by Gandar Dower, which may have come from this specimen, or from a female shot at the same time; the skulls were not kept when the animals were skinned, but one was retrieved later. Pocock concluded
…it is clear that no precise conclusion can be formed regarding this interesting beast until skins and skulls of adults have been collected.
As noted above, the skin was brought to Pocock by Kenneth Gandar Dower. Gandar Dower had read accounts of the spotted lion and mounted an expedition to East Africa to try to find one, but was unsuccessful, save for the skin and skull which he obtained from Michael Trent, a farmer in the Aberdare Mountains of Kenya, who had shot a pair of spotted lions a few years earlier. Gandar Dower recounted his expedition in a book, The Spotted Lion. Bernard Heuvelmans summarized Gandar Dower’s investigations, and recounted later stories of the spotted lion in his On the Track of Unknown Animals.
So what is the spotted lion? There are several possibilities. First, it might represent a distinct population that lives in the Aberdare Mountains of Kenya. In this case, it might be a species distinct from other lions, or it could be a geographical race or subspecies of the familiar lion. Second, it could just be a rare individual variation, in the same way that populations of house cats have spotted, striped, particolored, solid, etc. patterns occurring in individuals that are part of the same breeding population (and, indeed, part of the same litter). Finally, it could be a hybrid, perhaps between a lion and a leopard. Pocock, however, was well familiar with interspecific hybrids in large cats, and did not mention this possibility; also, interspecific hybridization in large cats is known (almost?) exclusively among captive animals. So, a hybrid origin does not seem likely to me.
If the first possibility is true, then there would indeed be something we can rightfully call the spotted lion. If the second is true, while there would then be known to exist lions with spots, there would not be a distinct natural population. And if the third is true, then there aren’t spotted lions at all– only lion-leopard hybrids that have spots. Further study of the skin or supposed skull, especially using modern techniques, might have allowed at least some of the possibilities to be eliminated, but unfortunately, Pocock apparently did not retain them at the British Museum, and I am unaware of their current whereabouts. (I had thought they were at the British Museum until reading Pocock’s full account, in which he notes the specimens were left for him to examine, but makes no mention of them being donated to the collection.) To solve this problem, we thus must, as Pocock did over 70 years ago, await the collection of more specimens.
Gandar Dower, K. 1937. The Spotted Lion. Little Brown, Boston.
Heuvelmans, B. 1959. On the Track of Unknown Animals. Hill and Wang, New York.
Pocock, R.I. 1937. Note on the spotted lion of the Aberdares. pp. 317-321 in Gandar Dower, 1937.
No, it’s not a reptilian hors d’oeuvre. It’s pictures of a Galapagos land iguana, Conolophus subcristatus, to whet your appetites for those Jerry will have when he gets back. I toured the Galapagos 20 years ago, and took loads of pictures, but they’re Kodachromes (which I haven’t scanned), so the pictures of our saurian friend below are from my colleague and fellow evolutionary biologist Joe Balsano, who visisted in 2007, and then kindly regaled my Darwin class with tales and pictures of his adventure. (More Galapagos reptile photos, at the Galapagos Conservancy, here.)
The Galapagos land iguana, Conolophus subcristatus (Joe Balsano).
The first link above for the Galapagos land iguana, from the Galapagos Conservation Trust (the UK companion to the US-based Galapagos Conservancy) is slightly out of date when it says there are two species of Galapagos land iguana: there are three. The common, or just Galapagos, land iguana, Conolophus subcristatus, is shown above. The Barrington land iguana, C. pallidus, occurs only on the island of Santa Fe (also known as Barrington). The two species differ fairly subtly in color and scalation (pallidus being less colorful, with a more distinctive crest of spines; see the original description by Edmund Heller here [go to Proceedings of the Washington Academy of Sciences in the left sidebar], and the classic paper by van Denburgh and Slevin on Galapagos iguanid lizards from the California Academy Expedition here [go to Proceedings-California Academy of Sciences 4th series in the left sidebar]). These subtle differences are the sort of differences between allopatric populations (i.e., populations inhabiting distinct, nonoverlapping, geographic areas) that can lead to long and inconclusive arguments as to whether the populations should be recognized as species, or subspecies, or not named at all. These arguments are a common, and not at all unexpected, issue when dealing with organisms living on islands. (The evolutionary process issues involved, although not the taxonomic issues, are dealt with comprehensively in Jerry’s and Allen Orr’s Speciation.) But the newly discovered species the pink land iguana of Volcan Wolf on Isla Isabela (Albemarle), Conolophus marthae, is not one of these wishy-washy, is-it or is-it-not-a-species, cases: it’s a new species, alright.
The pink land iguana, Conolophus marthae. From Gentile, G., et al. 2009. An overlooked pink species of land iguana in the Galápagos. Proceedings of the National Academy of Sciences 106:507-511.
It is amply distinct, both morphologically and genetically, from the other two species, including in coloration and form of the nuchal crest, as you can see from the pictures above. But, more importantly, it is also sympatric (i.e., living together in the same place) with the common land iguana. This is important because the truest test of species status is the test of sympatry: whether two forms interbreed when they co-occur in nature. In this case, the two species live together side by side, and reproductive isolating barriers, such as differences in male behavior (see the original species description by Gabriele Gentile and Howard Snell), keep them genetically isolated from one another. (Gentile and colleagues did find a single individual which showed evidence of some genetic mixing, but it is evidently insufficient to breakdown the genetic isolation of the forms.) This is a really remarkable and exciting discovery, given how many scientists, park rangers, and even just tourists, have traversed these islands. (I have been to Isabela, not far, at least as the crow flies, from where the new species was discovered.)
Although I think it’s fair to say that interested scientists have been delighted by the discovery of the pink land iguana, a number have been disturbed by what Gentile and Snell did, or rather didn’t do, in naming the species: they did not collect a specimen to document the species, but relied upon blood samples and photos. Usually, when a new species of animal is described, a particular specimen is designated the holotype, and preserved and deposited in the collection of a museum that will make the specimen available for study by other scientists. The specific identity of the holotype fixes the application of the name, and study of the holotype helps resolve any questions or confusions concerning the status or identity of the species, as well as contributing to further knowledge of the species’ biology. But if there is no holotypic specimen, then other scientists are unable to check the describer’s claims, or test their conclusions, or advance the study of the species in any way. Gentile and Snell were aware that what they were doing was problematic, and addressed the question in their paper. They even designated a particular iguana as the holotype, but left it in the wild, hoping that at some later time it might be retrieved using a radio tag they put in it. They did not collect it out of concern that loss of even a single individual might drive the species extinct.
Alain Dubois of the Museum nationale d’Histoire naturelle and Andre Nemesio of the Universidade Federal de Minas Gerais, Brazil, have led the criticism of Gentile and Snell, while acknowledging that there may be times when it is not wise to collect a specimen. See papers by them here, here, and here; Thomas Donegan of Fundacion Proaves supports what Gentile and Snell did. In the bad old days of systematic zoology, species were often named without holotypes, and this led to much confusion. Lately, there have been several species named for which holotypes have not been collected, for the same reasons advanced by Gentile and Snell, and this has led to much controversy; many of the key papers are cited in the woks of Dubois, Nemesio, and Donegan, or in works cited therein.
Some people might ask, what’s wrong with a photo? Well, I think it should be evident that there are many things you can’t determine from a photo, but perhaps a mention of the most famous species named on the basis of a photograph will make some of the problems clear: that species is the Loch Ness monster, Nessiteras rhombopteryx (abstract only without subscription). To put it only a bit too simply, specimens are what separate zoology from cryptozoology, science from pseudoscience. More on this in a later post.
Until Jerry settles back in there’ll be a bit of overlap in our posting, so I’m providing this Caturday’s felid. Actually it’s two felids: the lion and the tiger (both of these links come from a wonderful page maintained by Virginia Hayssen of Smith College), both photographed today at the Racine Zoo in Wisconsin.
The tiger, unfortunately, sat back out of useful range of the camera I had with me, so I had to settle for this.
In captivity hybrids between lions and tigers, called ligers (male lion X tigress) and tigons (male tiger X lioness), can be produced, which are healthy and vigorous. As Jerry explains in chapter 7 of WEIT, species are defined by their reproductive relationships: members of the same species will interbreed with one another, while members of different species are kept from successfully reproducing by one or more reproductive isolating barriers. Why, then, do we consider lions and tigers different species?
Tigers were widespread in Asia, from the Caucasus to Siberia in the north and Java and Bali in the south. Until man began to decimate them, lions and tigers broadly overlapped in southern Asia, but remained distinct, without interbreeding. Thus, in nature, lions and tigers did not interbreed. And the full definition of a species, given by Ernst Mayr in 1940, is that species are groups of actually or potentially interbreeding populations in nature, reproductively isolated from other such groups.