Photo by James Stroud
At JMIH 2016, I chatted with Johanna Wegener, a graduate student at the University of Rhode Island in Jason Kolbe’s lab, about her poster detailing her work identifying hybridization between Anolis carolinensis and A. porcatus in southern Florida.
Interspecific hybridization in anoles is thought to be fairly rare, with the best-known example being hybridization between Anolis carolinensis (native to the southeastern U.S.) and A. porcatus (native to Cuba) in southern Florida. I was surprised to learn how little we know about this rumored hybrid zone.
A. porcatus was likely introduced into Florida within the last few decades, but the striking morphological similarities between A. carolinesis and A. porcatus make anecdotal reports of hybridization hard to confirm. Wegener conducted the first genetic analyses of hybridization between A. carolinesis and A. porcatus. She genotyped 18 nuclear microsatellites from green anoles in Florida (Palm Beach and South Miami) and western Cuba and conducted a STRUCTURE analysis and found support for three genetic clusters consisting of Cuban A. porcatus, and two Floridian groups (one from Palm Beach and one from South Miami). With the addition of the mitochondrial ND2 marker, she found that the South Miami population had both A. carolinensis and A. porcatus haplotypes. Interestingly, there appeared to be very few recent hybrids; instead, the hybrid group appeared distinct from either parent group, suggesting that hybridization has been occurring for several generations.
In addition, Wegener looked at the variation in A. porcatus and A. carolinensis markers in each hybrid individual and found examples of some parent markers being retained at high proportions in the hybrids, possibly suggesting the retention of beneficial parent alleles in the hybrids.
Given that this study was only conducted at two sites in Florida, the exciting next step of this study is to better quantify the genetic makeup of hybrids across southern Florida and map out the hybrid zone.
- Evolution 2019: How Many Species of Anolis distichus? - June 23, 2019
- SICB 2019: Anole Setal Morphological Diversity - January 7, 2019
- SICB 2019: Sexual Differences in Relative Lengths of Toes - January 5, 2019
Skip Lazell
Hello to Johanna! Nifty stuff! We have 5+ acres on Middle Torch Key, Monroe Co., and summer in Jamestown, RI. We are both URI Ph.Ds. Maybe meet someday? Dr. Kolbe has met us…. I wrote Wildlife of the Florida Keys too many years ago: only A. car. there then.
Skip
Hanna Wegener
Hi Skip,
thanks. Sure, lets meet. I’ll be in RI for most of the summer. I’d love to hear about the book.
Hanna
George Gorman
Nearly 50 years ago, stimulated in part by the observations of and conversations with Skip Lazell over beers in Cambridge, MA., we began to publish a moderately extensive analysis of interspecific hybridization between two species of Anolis on Trinidad….trinitatis and aeneus.. These species differ in karyotype, and hybrids have a problem in meiosis. Males have reduced testis size and there is greatly reduced fecundity of the hybrid females. There seem to be weak pre-zygotic isolating mechanisms and strong post-zygotic isolating mechanisms. Both species were presumably introduced to Trinidad by accidental human intervention…they are otherwise endemic to two neighboring Lesser Antillean Island banks. They appear to be “good species” in a classical Ernst Mayr sense.
See for example
Gorman GC, Atkins L, 1968. Natural hybridization between two sibling species of Anolis lizards: chromosome cytology. Science, 159:1358-1360.
Gorman GC, Licht P, 1975. Differences between the reproductive cycles of sympatric Anolis lizards on Trinidad. Copeia, 1975:332-337.
Gorman GC, Licht P, Dessauer HC, Boos JO, 1971. Reproductive failure among the hybridizing Anolis lizards on Trinidad. Systematic Zoology, 20:1-18.
Gorman GC, Yang SY, 1975. A low level of backcrossing between the hybridizing Anolis lizards of Trinidad. Herpetologica, 31:196-198.
Is there any observational or experimental evidence that Cuban porcatus and North American carolinensis behave as “good species”. Are there any behavioral, physiological, or genetic attributes to suggest that the two populations will not freely exchange genes via hybridization? That is, are these long isolated and diverging populations of what still might be considered a single species?
Skip Lazell
Thanks George! Excellent question. Indeed, are the anoles of the Lower Keys intermediate naturally? Good to hear from you! Best, Skip
Archie S.
I have lived in South Florida all my life, and while I am not a biologist, it seems obvious to me that recent green anole population explosion (at least in the Miami suburbs) is a different animal than the green anoles of my youth. They are larger and their behavior is different.
I watched the population of green anoles dwindle as the brown anoles took over, and was originally excited about the resurgence of green anoles, but it seems that these may be just another invader. Miami is full of them.
That said, if they are not actually their own species, I suppose I can take some comfort in that. I don’t understand the modern scientific definition of a species, and given the arguments over the Florida scrub jay, it seems that scientists don’t agree either!
I wish you all well on your scientific work, and if it hasn’t been done already, it seems there is probably much that can be studied regarding Anolis carolinensis vs. Anolis porcatus. From my point of view, the new greens are much prettier than the brown, and therefore welcome, even if they aren’t the cuties of my youth.
George C Gorman
I don’t know whether biologists will ever agree completely on the definition of “species”… but it’s widely known that populations that are isolated from one another for some amount of time or generations, may differentiate morphologically in ways that are easy for us to see (color, size) ; this could occur because of natural selection; or random genetic drift. There could be substantial genetic divergence between the populations….it doesn’t mean thy represent different species. Look at humans.
Some Floridian lizard lover/graduate student with access to greenhouses or other sorts of large walk-in cages could seed the enclosures with various combinations of porcatus and carolinensis (both species/both sexes together; male of one female of the other; conspecific pairs only, as control etc.) and observe the behavioral interactions, raise the offspring if any etc.
One could get a handle on whether there are any behavioral pre-zygotic isolating mechanisms, or whether they exhibit little or no populational mate choice favoritism; Do the hybrids show the expected reproductive potential?
If there’s little or no interbreeding, or the f-1’s are sterile or clearly of reduced reproductive fitness they would seem to be “good species”. If the opposite is the case, they would seem to be geographic races of the same species.
Folks shouldn’t minimize using information from captive breeding and introduced populations to gain insights into evolution. Darwin probably got more evolutionary understanding from his domestic pigeons than his Galapagos finches (his “The Variability of Plants and Animals under Domestication” takes up two thick volumes; double the Origin of Species!)