Year: 2013 Page 16 of 37

Eminent herpetologist Laurie Vitt, recently retired from the University of Oklahoma (but active as ever), gave the Distinguished Herpetologist’s Lecture at the 2012 Annual Meeting of the Herpetologists League, which was part of The World Congress of Herpetology 7. The talk, the basis of a just-published paper in Herpetologica, was a paean to the fundamental importance of natural history to modern science, using vignettes from Laurie’s career as excellent examples.

The article starts in a thought-provoking way:

“Darwin’s studies provide a prime example of the importance of natural-history studies to conceptual biology… [On his voyage on the Beagle], Darwin collected a massive amount of data on geology, zoology, and botany while on land; and after returning, publishing some classic monographs, and mulling over his observations, he assembled his classic volume “On the Origin of Species,” in which a massive amount of natural-history data combined with experimental studies on selective breeding were used to support his theory of evolution by natural selection.”

And the key take-home:

“At least five key elements contributed to Darwin’s ability to put together his compelling theory, which continues to be the unifying theme of modern biology: (1) five continuous years in the field collecting natural-history data, (2) funding with no apparent restrictions on what he could do, (3) no electronic distractions, (4) time to write and think after returning, and (5) much help, including funding for the classic Zoology series, edited by Darwin but published by various authors.”

Though not extensively autobiographical at a personal level, there are some vignettes:

This wasn’t mentioned in the article.

“I grew up with an interest in natural history, subjecting my parents to loose bats and garter snakes in the house, as well as rattlesnakes and later, Old World vipers including puff adders, Gaboon Vipers (Bitis gabonica), and Russell’s Vipers (Daboia russelii) in terraria in my bedroom (which in retrospect suggests that I was either ignorant of the potential effects of snakebite, or downright stupid!).”

And it concludes with an important, little appreciated message

Read More

A pretty Dactyloa, Anolis chloris. Photo from the Reptile Database.

Two years ago, Castañeda and de Queiroz published a phylogeny of Dactyloa clade anoles based on molecular data for 40 species, approximately half of the clade. It was far and away the best phylogenetic work published on the clade and brought sense to a previously not well understood part of the anole world. The study revealed the existence of six geographically coherent clades and had important implications for our understanding of morphological evolution in this clade, which contains the mainland giants.

Name that Dactyloa. Photo from Pbertner’s photostream. See end of this post for a hint.

Recently, Castañeda and de Queiroz have published a follow up study in which they add morphological data for 60 species (the original 40 plus 20 more). The paper is published in the Bulletin of the Museum of Comparative Zoology and, like all MCZ publications, is freely available for download (click on Breviora or BMCZ on the left hand of the page). We’ve already previously discussed one aspect of the paper, a note added in press critiquing the Nicholson et al. proposal to split Anolis into eight genera.

The main focus of the paper, however, is to ask whether adding morphology increases the resolution or changes the story of the phylogeny based on molecular data. And the answer is: no, it doesn’t. As found in previous studies, morphology on its own does not provide a coherent picture of anole relationships, nor does it seem to substantially change the results derived from the much more informative molecular data. However, morphology certainly has one advantage–it allows us to add in taxa for which no molecular data are available.

The paper’s abstract gives much more detail and, of course, you should check out the paper itself.

ABSTRACT. We present a phylogenetic analysis of the Dactyloa clade of Anolis lizards, based on morphological (66 characters of external morphology and osteology) and molecular (4,700 bases of mitochondrial and nuclear DNA) data. Our set of morphological characters includes some that exhibit continuous variation and others that exhibit polymorphism within species; we explored different coding methods for these classes of characters. We performed parsimony and Bayesian analyses on morphology-only and combined data sets. Additionally, we explicitly tested hypotheses of monophyly of: 1) Dactyloa including Phenacosaurus, 2) Dactyloa excluding Phenacosaurus (as traditionally circumscribed), 3) taxa previously ranked as series or species groups described based on morphological characters, and 4) clades inferred from molecular data. The morphological data alone did not yield Dactyloa or any of the previously recognized series described based on morphological characters; only the Phenacosaurus clade (as delimited based on molecular data) was inferred with the morphological data, and only in the parsimony analysis. In contrast, Dactyloa was inferred as monophyletic with the combined data set, although topology tests failed to reject the hypothesis of non-monophyly. Additionally, five clades inferred based on molecular data (eastern, latifrons, Phenacosaurus, roquet, and western) were inferred with the combined data sets with variable support and including additional species for which molecular data were not available and which have geographic distributions that conform to those of the clades in which they were included. Of the previously recognized taxa based on morphological characters, only the roquet series, which corresponds in species composition to the roquet clade, was inferred with the combined data. Topology tests with the combined data set rejected the monophyly of the aequatorialis, latifrons (as traditionally circumscribed), and punctatus series but not that of the tigrinus series and Phenacosaurus (as traditionally circumscribed). Our phylogenetic analyses and topology tests indicate that a new taxonomy for Dactyloa is warranted; we therefore present a revised taxonomy based on the results our phylogenetic analyses and employing phylogenetic definitions of taxon names.

Anolis carolinensis from Miami. Photo by J. Losos.

Think quick: how many states does A. carolinensis occur in naturally? And can you name them?

Read More