Category: All Posts Page 39 of 149
The brown (a.k.a. “festive”) anole, A. sagrei, is slowly making its way around the world. Latest report: Panama City, Panama!
Anoles throughout the Caribbean are found in urban environments and differ in the extent to which they utilize anthropogenic habitats. There is strong phylogenetic signal in urban tolerance but is not correlated with ecomorphology of anole species. Previous work by Dr. Kristin Winchell (currently a postdoctoral researcher at Washington University in St. Louis with Dr. Jonathan Losos) and collaborators showed that Anolis cristatellus commonly uses anthropogenic perches (e.g.- buildings and fences) in urban habitats, and that A. cristatellus has repeatedly adapted to urban environments. Urban A. cristatellus have longer limbs and greater numbers of lamellae when compared to their more rural counterparts, a pattern that is repeated island-wide.
With the prediction that species within the same ecomorph class would adapt to urban environments similarly, sampling has begun with four species from the Greater Antilles. Three species belong to the trunk-ground ecomorph (Anolis cybotes, Anolis lineatopus, and Anolis sagrei) and one trunk-crown species (Anolis grahami). In the Bahamas, examining Anolis sagrei she found significant shifts in relative limb length but in the opposite direction as seen in A. cristatellus. Meaning that urban A. sagrei have relatively shorter limbs, but it is worth noting that they have longer absolute limb length along with larger body sizes. Preliminary analyses of Anolis cybotes (Dominican Republic) and Anolis grahami (Jamaica), suggest shifts in relative and absolute limb lengths consistent with the morphological differences found in urban A. cristatellus. In Anolis lineatopus, the suggested shifts in relative and absolute limb length are consistent with those shifts seen in A. sagrei.
Additionally, Kristin had all of us at the conference beat when it came to attire. Her Anolis lineatopus dress that she designed the art work for was spectacular. If you are interested in her Anolis and urban stickers and art– check out her work on RedBubble— all proceeds from her art goes to printing more stickers for outreach purposes in the communities she does her field research in.
Excellent job Kristin and we are all looking forward to learning more about this work!
The origin and maintenance of reproductive isolation between species is a central question to evolutionary biologists. Divergent sex chromosomes can play an important role in this process, and are generally assumed to have outsized importance in the establishment of reproductive barriers. Studying the origin and evolution of sex chromosomes – and their respective fusions and fissions – may therefore provide key insights into their role in these processes.
Anole are known to vary in sex chromosome size and content, although all anoles are male heterogametic. In a poster at Evolution, de Mello et al. investigate the neo-sex chromosomes of Anolis distichus, one of the “model anoles” of speciation research. Starting from a newly assembled genome, these researchers used differences in coverage, k-mer comparisons, and synteny mapping to the Anolis carolinensis genome, to identify the sex-linked genomic regions of A. distichus.
From these results, de Mello et al. were able to identify deep conservation of the X chromosome between A. distichus and A. carolinensis – implying an ancient origin of a shared anole X chromosome. They also identified explicitly Y-linked scaffolds for the first time in any Anolis species, which will prove useful for future work on the evolution of these sex chromosomes. However, perhaps most excitingly, de Mello et al. identified a chromosome fusion of the Anolis carolinensis microchromosomes 11 and 12 to the A. distichus X chromosome. In other words, the A. distichus X chromosome has expanded through the fusion of these two microchromosomes.
de Mello et al.’s result that the A. distichus sex chromosomes are simultaneously ancient and newly expanding provides a fascinating look at the dynamic lives of these sex chromosomes. Future investigations into the evolution of Anolis sex chromosomes will surely prove fruitful to understanding their role in the diversification of the Anolis lineages.
Anolis distichus is a highly variable species from Hispaniola. It’s especially variable in its dewlap color, ranging from white, to orange, to red. In the past, A. distichus has been broken up into 16 subspecies based on its dewlap variation! Previous work by Rich Glor and his students used genetic data to identify six candidate species, although these six candidate species didn’t correspond well with the 16 dewlap-based subspecies. In order to get a better handle on how justified these candidate species are, undergraduate Tanner Myers, working with Pietro Longo Hollanda de Mello and Rich Glor, from the University of Kansas, presented a poster titled Identifying species when boundaries are blurred.
Myers collected morphological data from populations of A. distichus from across Hispaniola. The authors expected their morphological data to also partition along with the previously identified genetic candidate species. They found this to not be the case! When the authors looked at their morphological data (linear body, limb, and head measurements), to see if these 6 candidate species had any morphological divergence, they found no strong pattern. All of the candidate species clustered together to support one morphological group. In the end, the authors suggest that Anolis distichus may represent a highly variable group in in the early stages of speciation, but at this point, they do not support any taxonomic revisions of the species.
Tanner Myers will be starting graduate school with Jamie Oaks at Auburn University in the fall.
Anolis sagrei now established on the Pacific coast of Mexico.
Anolis sagrei, the brown or festive anole, continues its march through Central America (see previous posts on the species elsewhere in Mexico and in Costa Rica, not to mention South America). New reports reveal populations on the Pacific coast of Mexico (figures above and below) and in Panama City. Where next?
Periodically here on Anole Annals, we have posts about three-legged lizards. The most recent such post was last year from Miami. Here’s another lizard, with a twist: it’s got four legs, sort of. Looking at the floppy left hindleg of this lizard, caught in the Bahamas two years ago. An x-ray confirms that this is odd–there’s no bone in most of that limb! I’ve never seen anything like it, and wonder how it happened.
Despite this seeming impediment, the lizard looked quite healthy, and as the video shows, could run quite adeptly up a note pad.
And here she is when we released her back at the place where we caught her. Pretty nimble!
Video courtesy Buddy and Cindy Pinder.
It seems hard to believe almost a year has passed since the last Evolution meeting. Last year we brought you coverage of the anole talks and posters in Montpelier, France. This year, we’re coming to you live from Providence, Rhode Island from June 22nd – 25th! This year there are eight talks and eight posters scheduled *(searching the schedule for keywords “anole” and “Anolis“). There’s some pretty fascinating topics on the schedule – here’s what you have to look forward to each day:
Saturday:
- Habitat use, competition, and phylogenetic history shape the evolution of claw morphology in Lesser Antillean anoles (Yuan, Jung, Wake, Wang)
- Estimating premating isolation among allopatric Anolis sagrei populations (Poster board #152) (D’Agostino, Geneva, Donihue, Losos)
- Morphological assessment reveals candidate species of Anolis lizards to be truly cryptic (Poster board #175) (Meyers, de Mello, Glor)
Sunday:
- Mountaintop endemics and climate change: is warming always a problem? (Farallo, Muñoz)
- Sexual signal diversity and population genetic structure in Amazonian anole lizards (Prates, D’Angiolella, Melo-Sampaio, Rodrigues, de Quieroz, Bell)
- The effects of volcanic activity on the phylogeographic history of the Plymouth Anole, Anolis lividus, on Montserrat (Poster board #72) (Jung, Yuan, Wang, Frederick)
- Identification and assembly of an anole sex-chromosome: Rapid degeneration since autosomal fusion? (Poster board #160) (de Mello, Hime, Glor)
- Effects of urbanization on toe pad shape and lamellae size in Anolis cristatellus (Poster board #174) (Howell, Hagey, Winchell)
Monday:
- Using archival DNA to elucidate anole phylogeny (Mayer, Gamble)
- Comparative landscape genetics and epigenetics of two trunk-ground anoles (Wang, Wogan, Yuan, Mahler)
- Ancient hybridization in the adaptive radiation of Anolis lizards on Puerto Rico (Wogan, Yuan, Wang)
- Urban adaptation in anole lizards of the Greater Antilles (Poster board #7) (Winchell)
- Cities in the Spotlight: Does Tolerance of Artificial Light at Night Promote Urban Invasions? (Poster board #97) (Thawley, Kolbe)
- Sex-specific mortality and senescence in a wild population of brown anole lizards (Poster board #102) (Reedy, Kahrl, Seears, Wittman, Bhave, Cox, Schwartz)
- Adaptive radiation in the multidimensional phenotype (Bodensteiner, Muñoz)
- Patterns of morphological diversity in Draconura clade anole lizards (Huie, Prates, Bell, de Quieroz)
Did we miss any? If so, let us know in the comments so we can be sure to add it to our schedules! We will be live blogging the meeting as usual, so check back starting June 22nd to hear about the latest in anole evolutionary research. And if you are attending the meeting, consider blogging a talk or poster for us (new contributors welcome!). Just send me an email and I will fill you in on all you need to know.
Anolis (Phenoacosaurus) heterodermus, a mainland anole that co-occurs with few or no other anole species
One of the most important questions in ecology and evolution is about the role of biotic interactions in driving phenotypic and behavioral changes across species. The insular Anolis species are a good model to address this kind of question due to their high abundance and pervasive ecological interactions across islands. Some insular species, however, live in isolation on small islands across the Pacific and Caribbean islands (21 species). These species have evolved similar morphologies across islands. For instance, Poe et al (1) found that body size evolved by exaptation (remember the classic Gould and Vrba 1982 paper) to colonize these small (and depauperate) islands successfully. By contrast, Poe et al. (1) showed that sexual size dimorphism (SSD) evolved by adaptation likely after island colonization to minimize intraspecific competition.
In brief, these solitary insular anoles evolved phenotypic (body size and SSD) traits by two different processes. Cool! But, what happens in mainland areas? Much work has been devoted to Caribbean species, but the mainland offers many more species and very little research has been conducted there to understand ecological and evolutionary processes. So, we decided to establish whether solitary ecology can be extended to mainland species or whether it is an island ecological phenomena.
The first problem that we had to resolve was trying to establish whether mainland species tend to live in geographical/ecological isolation as insular species. We adopted a novel concept in macroecology (the diversity field concept) developed by Mexican macroecologists (Hector Arita and Fabricio Villalobos see 2, 3) implemented here using extensive distributional information for almost all known Anolis species (377 spp), which I generated during my Ph.D. thesis (see 4 for an example using these maps). The diversity field concept allows us to establish how many species co-occur with a given species across its geographic range.
We calculated how many congeners can co-occur within the distributional area of each Anolis species using the range maps (see figure below). We divided mainland species into two groups: those co-occurring with few congeners (i.e., “solitary-like”, I had to say that his term did not like to reviewers, so we used a “species-poor” forms in the paper). Then, we test whether these “solitary-like” mainland species are different from other mainland species using a randomization approach. Our results revealed that “solitary-like” mainland species exhibit different traits from random mainland assemblages. These unique traits (i.e., uniform body size and greater SSD) suggest that solitary ecology from insular anoles can be extended to mainland settings.
Figure. Diversity fields for some Anolis species. Note that the diversity field is the set of richness values of co-occurring anoles inside each distributional area.
The next question was focused to establish whether similar (ecological and evolutionary) processes affected body size and SSD patterns in a similar way. We found that the phylogenetic position of body size and SSD shifts did not coincide and also with the evolutionary transitions to solitariness (i.e., reduced level of sympatry). We suggested that both traits are decoupled across the entire Anolis radiation and likely that both traits evolved exaptatively. In other words, it is possible to think that “solitary-like” species retained body size and SSD from their most recent common ancestors to facilitates the lonely life.
The paper is very short (less than 2500 words) and was published in the May number of Biology Letters(5).