Lourdes Rodríguez Schettino

Genetic variation increases during biological invasion by a Cuban lizard

A genetic paradox exists in invasion biology: how do introduced populations, whose genetic variation has probably been depleted by population bottlenecks, persist and adapt to new conditions? Lessons from conservation genetics show that reduced genetic variation due to genetic drift and founder effects limits the ability of a population to adapt, and small population size increases the risk of extinction. Nonetheless, many introduced species experiencing these same conditions during initial introductions persist, expand their ranges, evolve rapidly and become invasive. To address this issue, we studied the brown anole, a worldwide invasive lizard. Genetic analyses indicate that at least eight introductions have occurred in Florida from across this lizards native range, blending genetic variation from different geographic source populations and producing populations that contain substantially more, not less, genetic variation than native populations. Moreover, recently introduced brown anole populations around the world originate from Florida, and some have maintained these elevated levels of genetic variation. Here we show that one key to invasion success may be the occurrence of multiple introductions that transform among-population variation in native ranges to within-population variation in introduced areas. Furthermore, these genetically variable populations may be particularly potent sources for introductions elsewhere. The growing problem of invasive species introductions brings considerable economic and biological costs. If these costs are to be mitigated, a greater understanding of the causes, progression and consequences of biological invasions is needed.

Niche lability in the evolution of a Caribbean lizard community

Niche conservatism—the tendency for closely related species to be ecologically similar—is widespread. However, most studies compare closely related taxa that occur in allopatry; in sympatry, the stabilizing forces that promote niche conservatism, and thus inhibit niche shifts, may be countered by natural selection favouring ecological divergence to minimize the intensity of interspecific interactions. Consequently, the relative importance of niche conservatism versus niche divergence in determining community structure has received little attention. Here, we examine a tropical lizard community in which species have a long evolutionary history of ecological interaction. We find that evolutionary divergence overcomes niche conservatism: closely related species are no more ecologically similar than expected by random divergence and some distantly related species are ecologically similar, leading to a community in which the relationship between ecological similarity and phylogenetic relatedness is very weak. Despite this lack of niche conservatism, the ecological structuring of the community has a phylogenetic component: niche complementarity only occurs among distantly related species, which suggests that the strength of ecological interactions among species may be related to phylogeny, but it is not necessarily the most closely related species that interact most strongly.

Partial island submergence and speciation in an adaptive radiation: a multilocus analysis of the Cuban green anoles

Sympatric speciation is often proposed to account for species–rich adaptive radiations within lakes or islands, where barriers to gene flow or dispersal may be lacking. However, allopatric speciation may also occur in such situations, especially when ranges are fragmented by fluctuating water levels. We test the hypothesis that Miocene fragmentation of Cuba into three palaeo–archipelagos accompanied species–level divergence in the adaptive radiation of West Indian Anolis lizards. Analysis of morphology, mitochondrial DNA (mt DNA) and nuclear DNA in the Cuban green anoles (carolinensis subgroup) strongly supports three pre dictions made by this hypothesis. First, three geographical sets of populations, whose ranges correspond with palaeo–archipelago boundaries, are distinct and warrant recognition as independent evolutionary lineages or species. Coalescence of nuclear sequence fragments sampled from these species and the large divergences observed between their mtDNA haplotypes suggest separation prior to the subsequent unification of Cuba ca. 5 Myr ago. Second, molecular phylogenetic relationships among these species reflect historical geographical relationships rather than morphological similarity. Third, all three species remain distinct despite extensive geographical contact subsequent to island unification, occasional hybridization and introgression of mtDNA haplotypes. Allopatric speciation initiated during partial island submergence may play an important role in speciation during the adaptive radiation of Anolis lizards.

A phylogenetic perspective on foraging mode evolution and habitat use in West Indian Anolis lizards

Although many descriptive studies of foraging mode have been performed, the factors that underlie the evolution of foraging mode remain poorly understood. To test the hypothesis that foraging mode evolution is affected by habitat use, we analysed two data sets including 31 species of West Indian Anolis lizards. In this genus, the same suite of habitat specialists (or ecomorphs) has evolved on four islands, providing the replication necessary to evaluate the generality of the relationship between foraging mode and habitat use. Using habitat and behavioural data, we conducted phylogenetic comparative analyses to determine whether species of the same ecomorph have evolved similar foraging behaviour and whether differences in foraging mode are associated with differences in habitat use. We found that Anolis species show substantial variation in foraging behaviour, including differences in movement and eating rates. Furthermore, variation among ecomorphs indicates that foraging behaviour is related to habitat use, although the specific environmental factors driving foraging divergence are unclear. Our results show that foraging mode is an evolutionarily labile trait that is influenced by evolution of habitat use.

The Anoles of Soroa: Aspects of Their Ecological Relationships

Abstract Most lizard communities are characterized by having one or two dominant species and a handful of other species that occur at relatively low densities. However, Soroa, a site in the Sierra del Rosario of western Cuba, is home to 11 sympatric species of Anolis, of which nine are found in high abundance. In this study, we evaluate how interspecific differences in structural niche, thermal niche, body size, and behavior might allow the extraordinarily high anole species diversity at this site. We found that all pairs of species differ in at least one of the following niche axes: vegetation types occupied, substrates used, perch height, irradiance at occupied perch sites, and body temperature. Interspecific differences across these axes might serve to reduce competition, allowing the 11 species to live sympatrically within a relatively small geographic area.