Anole Annals

With the 2013 Herp Meetings in Albuquerque coming to a close, there have been some great anole posters presented over the 3 poster sessions. I spoke with some of the presenters about their exciting results.

Kristin Winchell presenting her award-winning poster at the Friday ASIH poster session.

SSAR Student Poster Winner Kristin Winchell of the Revell Lab studied differences in morphology in urban and natural Anolis cristatellus populations in Puerto Rico. Kristin found that urban populations had longer limbs, more subdigital lamellae and higher body temperatures than natural populations of lizards. She believes these morphological features are adaptations for clinging to the broad, smooth surfaces of an urban landscape. She will continue this work by using a common-garden setup to rule out phenotypic plasticity as the cause of these differences. This is an interesting study that will hopefully inspire more research on how reptiles will adapt to an increasingly urban world. You can read more about Kristin’s research on her website. Congratulations Kristin!

Ian Latella’s poster on changes in anole habitat use in All-American Park in Miami, FL.

Continuing with the theme of anoles in human-mediated environments, Ian Latella of the Poe lab presented his poster on changes in a small, introduced Anolis community. An assemblage of six introduced species reside in All-America Park in Miami: A. distichus, A. equestris, A. garmani, A. porcatus, A. sagrei, and A. cristatellus. This provides a natural experiment for investigating invasion dynamics and short-term community assembly. Ian compared data on habitat use from 2002 and 2012 to identify changes across time. The preliminary results are interesting: after a 10 year period, A. sagrei utilized higher perches, while A. porcatus switched to lower perch heights.

Aja King of Steven Poe’s lab presenting her poster on island differences in A. allisoni.

Aja King, also from the Poe lab, was interested in comparing A. allisoni populations in Cuba and the Bay Islands. She constructed a molecular phylogeny containing specimens from Cuban and Bay Island populations. Her phylogeny showed that the Bay Island populations nested within an Eastern Cuba clade, suggesting the possibility of an invasion of the Bay Islands from Cuba. Aja also performed a discriminant function analysis to look for differences in continuous morphological characters. She was excited that the Bay Island and Cuban populations were significantly different with respect to morphology: she could correctly identify the island of origin based on specimen morphology every time!

Poster from Steven Poe describing their in-progress computerized key.

Steven Poe, New Mexico’s local anole expert, presented his poster on Sunday publicizing the lab’s efforts to develop a computerized Anolis key. The key would include all 381 species of Anolis. Rather than a dichotomous key-style approach, the user would check a series of boxes representing character states. The key would then search through the species matching the set of inputted characters. This project would lead to an app-style user interface that researchers could use on the go. This will be a great resource for professional and hobbyist herpetologists alike.

Kirsten Nicholson’s poster on South-North expansion of Norops capito.

Kirsten Nicholson, professor at Central Michigan University, presented some of the results of her phylogeographic study on Norops capito, a mainland species. Previous hypotheses suggested that members of the Norops group originated in the Caribbean after the separation of North and South America and the break-up of Caribbean islands, dispersing overwater to Mexico and then moving southward. Kirsten’s molecular phylogeny of N. capito shows a contrasting pattern. Panamanian individuals form an outgroup, with Costa Rican, Nicaraguan, and Honduran individuals nested within. This suggests a South->North dispersal pattern. Along with N. limifrons, this is the second species to show this pattern. Kirsten plans to estimate divergence times from her data to further elucidate the picture of anole dispersal.

The 2013 Herp Meetings have showcased an assortment of great ongoing anole projects. What a great venue for drawing the anole community together! Check back soon for more on the conference.

Slide from Anthony Geneva’s talk, showing the placement of the A. d. ravitergum and A. d. ignigularis crosses on the scale of reproductive isolation.

The Joint Meeting of Ichthyologists and Herpetologists kicked off this week in Albuquerque, NM. Anoles are well represented, with 7 posters and 5 talks. During the conference, I will report on some of the exciting work being presented.

Anthony Geneva, Ph.D. student in Rich Glor’s lab at the University of Rochester, gave a proper introduction to the meetings with his talk Friday morning. Anthony’s study investigates the degree of reproductive isolation in the parapatric subspecies pair A. disticus ravitergum and A. d. ignigularis. Each subspecies is genetically and morphologically distinct, though not completely isolated. Along the pair’s contact zone, there is a clinal gradient from a pure red (ignigularis) to a pure white (ravitergum) dewlap. Evidence for introgression in mtDNA haplotypes also follows this clinal pattern, with hybrids existing in the middle of the range. This provides an excellent model system for studying the process of speciation.

Anthony used a classic genetic cross to search for evidence for intrinsic isolating mechanisms in the subspecies pair. The product of these crosses was a whopping 1702 eggs and 857 babies. One convincing result was that hybrid crosses produced a greater proportion of slug (unfertilized eggs) than pure crosses! These results suggest that the barrier preventing coalescence is post-mating, prezygotic isolation. He was able to quantify the degree of intrinsic isolation on the index above, with 0 representing no isolation and 1 representing complete isolation. On this index, the focal Anolis disticus subspecies pair is placed in between the classic speciation model systems of Ficedula flycatchers and Rhagoletis apple maggots.

The presence of post-mating pre-zygotic isolating mechanisms suggests that cryptic female choice and sexual selection play a role in separating the two subspecies. Anthony plans to continue this work by backcrossing hybrid individuals to pure individuals, and hopes to use genetic cline analysis to identify the genomic regions underlying intrinsic isolation.

Over the next few days, I will also post about some of the other Anolis talks and posters here at the JMIH. Check back soon!

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

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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.