In addition to a number of Anole posters yesterday, the Joint Meeting of Icthyologists and Herpetologists featured a talk by Rich Glor entitled “Phylogenetics and Diversification of Anolis Lizards.” In his 12 minutes Rich covered a lot of material. He described: the key components in diagnosing an adaptive radiation (speciation, adaptation and the more controversial extraordinary diversification), how the properties of adaptive radiations result in problems resolving their phylogenies (particularly when diversification rates are extraordinary), leveraging the anole genome project to generate and analyze new, informative loci for anole phylogenetics, the impact of incomplete data matrices on the ability to accurately infer phylogenies, and closed with a presentation of the latest, greatest genus-wide phylogeny of Anoles.
Category: New Research Page 61 of 66
Today’s JMIH poster session was an anole lover’s paradise! Five posters featured molecular phylogenetic work on anoles, including studies of A. humilis (John Phillips from Central Michigan University), A. limifrons (Jenny Gubler from CMU), the pentaprion group (Julian Davis from the University of New Mexico), the distichus group (Anthony Geneva from the University of Rochester), and the ricordii group (Shea Lambert from the U of R).
The recent literature has been full of doom and gloom regarding the prospects for lizard survival in the face of global climate change (e.g., Sinervo et al. 2010). A talk by Alex Gunderson from Manuel Leal’s lab at Duke University provided some important new insights on how our favorite lizards are likely to weather this storm. Gunderson investigated thermal ecology of Anolis cristatellus at nine localities, including four mesic and five xeric locales. His data included thousands of field collected temperature records from live animals and copper models as well as data on preferred body temperature and sprint speed performance across a range of temperatures. Temperature data from live animals and co-distributed copper models showed that the xeric, but not the mesic, populations are behavioral thermoregulators that tend to be found in cooler spots than the randomly placed copper models. Even with the benefit of behavioral thermoregulation, the xeric forest lizards were consistently active at temperatures that exceeded their preferred body temperature. When Gunderson integrated these findings with data on sprint speed performance and climate change, he found that the xeric forest animals are likely to suffer significant reductions in performance associated with climate change. Gunderson ended with a teaser by showing that he has accumulated comparable data on performance across a range of temperatures for all the other Puerto Rican anoles. Next year’s talk should be a blockbuster!
Lots of anole action at the herp meetings starting on Wednesday in Minneapolis. Listed below are the talks and posters found by searching for “anol” in the online program abstract. If you know of others, please let us know. And…if you’re going to attend the meetings, how about posting on the talks and posters, so those of us not in the northlands can stay up to speed? Abstracts can be found by going here (I just read through them–some great stuff!).
Talks (NOTE: Gunderson’s talk on thermal ecology of A. cristatellus was originally scheduled for Saturday, but has just been rescheduled for Friday at 2:30 in Conrad B & C)
Friday, 2:30 pm: Alex Gunderson. Geographic Variation in the Thermal Ecology and Physiology of Anolis cristatellus and its Implications in a Changing World
Saturday, 2 pm: Rich Glor. Phylogenetics and Diversification of Anolis Lizards
Sunday, 8:45 am: A. Reedy. Maternal Nest-site Choice in the Lizard Anolis sagrei: A Unique Research-based Educational Model for Youth at an Urban High School
Sunday, 2:45 pm: J. Deitloff. Hemipenes vs. Dewlaps: Which Morphological Characters Can be Used to Delineate Species in Anoles?
Sunday, 2:45 pm: H. Waddle. Brown Anole Presence Reduces Occupancy of Green Anoles in Southern Florida Natural Areas
Posters:
Saturday, Poster 14: J. Phillips. Evolutionary and Biogeographic Relationships Among Species of the Anolis humilis Complex
Saturday, Poster 15: J. Davis. A phylogenetic analysis of the Anolis pentaprion Species Group
Saturday, Poster 16: J. Gubler. Investigation of the Evolutionary Relationships Among Species of the Anolis limifrons Complex
Saturday, Poster 75: A. Geneva. A Multi-locus Molecular Phylogeny of Distichoid Anoles
Saturday, Poster 76. S. Lambert. Molecular Systematics of Hispaniolan Crown-giant Anoles
Sunday, Poster 21: M. Moody. Egg Environments have Large Effects on Embryonic Development, but have Minimal Consequences for Fitness-Related Phenotypes in a Lizard (Anolis sagrei)
Sunday, Poster 35: M. Zhuang. Comparative Gliding Performance of Anolis carolinensis and Anolis sagrei
Sunday, Poster 44: P. Cupp. Responses of ground skinks, Scincella lateralis, and Green anoles, Anolis carolinensis, to Chemical Deposits of Eastern Milk Snakes, Lampropeltis triangulum
After receiving three generally positive reviews in the first round, the revised version of the manuscript reporting the genome sequencing of A. carolinensis has just been submitted. Hopefully, it won’t be long now! Stay tuned.
Joel McGlothlin received the 2011 Dobzhansky Prize, given to an outstanding young scientist in the field of evolutionary biology. Successfully fending off technical AV difficulties, Joel gave a fascinating talk in which he examined the idea that evolution should occur along lines of least genetic resistance, which are determined by the genetic correlations among traits. This hypothesis predicts that as traits diverge, they should diverge in ways that mirror the trait genetic correlations. Moreover, one would expect that this effect would attenuate over time, so that more distantly related species would show less evidence of diverging along these lines.
Luke Mahler received this year’s Fisher Award, given by the Society for the Study of Evolution for the best paper emanating from a Ph.D. thesis published in Evolution in the preceding year. Mahler asked “what is the trigger for adaptive radiation?” and answered, “ecological opportunity”: a wealth of evolutionarily accessible resources (from Schluter). This leads to the prediction that the pace of adaptive radiation is regulated by competition, and is thus diversity-dependent. This hypothesis has been tested greatly in recent years by seeing if the rate of species diversification decreases through time as a clade radiates. But, Mahler argued, counting species is not enough—rather, we need to focus on patterns of diversification in adaptive traits.
Focusing on Greater Antillean anoles, Mahler asked whether rates of ecomorphological diversification decline as the number of species on an island increases. Testing this hypothesis requires estimating historical ecological opportunity (EO) by inferring ancestral species richness on an island and estimating rates of morphological evolution at ancestral nodes and how they changed as a function EO. To do this, Mahler and co-author Liam Revell developed at maximum likelihood approach to infer ancestral states incorporating uncertainty on the reconstruction of ancestral biogeographic locations.
The result is strong support for the ecological opportunity model. Rates of ecomorphological evolution are high early in anole radiation, but decline with increasing species richness.
Anolis sagrei from near one of Dan Warner's field sites. Photo by Aaron Reedy.
American Society of Naturalists’ Young Investigator Award winner Dan Warner presented a marvelous synthesis of studies of how external influences affect phenotype and survival in eggs and offspring of lizards and turtles. Among other things, he has demonstrated
that some types of plasticity are adaptive: in temperature sensitive sex determining lizards, males are produced at temperatures at which the fitness of male offspring is greater than that of females, and vice-versa.
In a fascinating talk, Chad Watkins reported the discovery of a surprising frequency of homeotic mutations along the anterior-posterior axis and implicated the high rate of transposons in the Hox D cluster as a possible cause. Watkins reported that 27% of DNA in the HoxD cluster is comprised of transposons, much higher than in other vertebrates. Moreover, Hox D gene expression is shifted posteriorly. For example, Hox D10 normally should express at anterior boundary of hip, but in A. carolinensis it is all the way down at the tip of the tail. Further, in later stage embryo, ectopic expression of D13 occurs in the hand and feet, which is novel in vertebrates. Could this be related to ecomorph differentiation in limb elements?
Yoel Stuart reported on studies of sympatric anoles on small, man-made islands in Mosquito Lagoon in the Intra-Coastal Waterway in Florida. These dredge spoil islands were naturally colonized by A. carolinensis and more recently—sometimes by the hand of man—by A. sagrei. Surveying a dozen or so islands, Yoel asked whether the green anoles differ in the habitat use and morphology depending on whether they occur with brown anoles. Because we know that brown anoles are recent arrivals, any differences would be recent in origin.
Sure enough, in the presence of browns, green anoles perch higher and have larger toepads. Assuming that the change is genetic, the rate of change would be among the fastest ever recorded. But that’s a big assumption, and as Yoel notes, laboratory studies are needed to investigate whether differences truly are genetically based. Given that the number of lamellae is a trait thought to be fixed at birth, environmentally driven phenotypic plasticity seems unlikely, but this needs to be examined directly. In addition, Yoel plans to measure vegetation structure on the islands to investigate whether, by chance, differences exist between islands with and without brown anoles.