A new species of dactyloid anole (Iguanidae, Polychrotinae, Anolis) from the southeastern slopes of the Andes of Ecuador

We describe a new species of Anolis from the southeastern slopes of the Andes of Ecuador, province of Zamora-Chinchipe, Parque Nacional Podocarpus. It belongs to (1) the aequatorialis species-group by being of moderate to large size with narrow toe lamellae, and (2) the eulaemus sub-group by having a typical Anolis digit, in which the distal lamellae of phalanx II distinctly overlap the proximal scales of phalanx I. The new species is most similar morphologically to Anolis fitchi but differs from it mainly by having a dewlap with longitudinal rows of 2-5 granular, minute scales separated by naked skin (longitudinal rows of one or two keeled, large scales separated by naked skin in Anolis fitchi) and a vertically shorter dewlap (longer dewlap in Anolis fitchi).     

Ten polymorphic tetranucleotide microsatellite markers isolated from the Anolis roquet series of Caribbean lizards

The Anolis roquet series of Caribbean lizards provides natural replicates with which to examine the role of historical contingency and ecological determinism in shaping evolutionary patterns. Here, we describe 10 polymorphic tetranucleotide microsatellites to facilitate studies on population differentiation and gene flow. All loci successfully amplified in several species from this series. Genotyping 96 individuals from two A. roquet populations demonstrated the markers’ suitability as population genetic markers: genetic diversity was high (9–22 alleles per locus); there were no instances of linkage disequilibrium; and, with one exception, all genotypic frequencies conformed to Hardy–Weinberg equilibrium expectations.     

Evaporative Water Loss in Insular Populations of the Anolis cristatellus Group (Reptilia: Sauria) in the British Virgin Islands II: The Effects of Drought1

Previous work has shown that water loss in some populations of Anolis cristatellus from the British Virgin Islands is closely tied to the conditions available on the islands they inhabit. This manifested itself in a strong correlation between habitat aridity and several water loss rate parameters. Here we report on a similar study conducted in the same locations in 1994, a year of extreme drought. We hypothesized that lizards caught at the height of the drought will experience lower rates of water loss than those measured during a normal year. Our findings show that in 1994, as in 1993, habitat aridity and water loss parameters were strongly correlated. Also as before, the Guana Island population of A. cristatellus displayed higher resistance to water loss than expected by the island's aridity. However, a striking change occurred within populations. All were at least as good at retaining water (measured as integumentary resistance to water loss, R) as in 1993, and some were over 3.5 times better. Existing evidence is insufficient to determine whether these changes were the result of phenotypic plasticity or attributable to differential mortality of nonresistant individuals.     

Experimentally replicated disruptive selection on performance traits in a Caribbean lizard

A central theme underlying studies of adaptive radiation is that ecologically mediated selection drives diversification. However, demonstrating the ecological basis of natural selection and linking this process to patterns of morphological diversity represents a formidable challenge. This is because selection experiments that test correlations between an organism's phenotype and its ecology are difficult to perform in the wild. Previous studies of Anolis lizards have shown that divergent morphologies are correlated with habitat use and have evolved repeatedly on islands throughout the Greater Antilles. Here, we show that the forms of selection acting within a species support an ecological mechanism for diversification. In natural populations, performance-related traits such as limb length are subject to correlational and disruptive selection driven by differences in habitat use. Experimental manipulations in the wild verify the same pattern of selection and indicate that both the targets and forms of selection are consistent through time. Elsewhere, we have demonstrated that these traits are heritable and should therefore evolve in response to selection. Our results provide evidence for the short-term repeatability of selection and its potency in the diversification of anoles.     

Mainland colonization by island lizards

Aim We investigate biogeographic relationships within the lizard genus Anolis Daudin, 1802 to test the hypothesis that the mainland (Central and South American) Norops‐clade species descended from a West Indian Anolis ancestor. Previous hypotheses have suggested that close island relatives of mainland Norops species (the Cuban Anolis sagrei and Jamaican A. grahami series) represent over‐water dispersal from a mainland ancestor. These previous hypotheses predict that the A. sagrei and A. grahami series should be phylogenetically nested within a Norops clade whose ancestral geography traces to the mainland. If Norops is West Indian in origin, then West Indian species should span the deepest phylogenetic divergences within the Norops clade. Location Central and South America and West Indian islands. Methods The phylogenetic relationships of Anolis lizards are reconstructed from aligned DNA sequences using both parsimony and Bayesian approaches. Hypotheses are tested in two ways: (1) by reconstructing the ancestral geographic location for the Norops clade using Pagel & Lutzoni's (2002) Bayesian approach, and (2) by testing alternative topological arrangements via Wilcoxon Signed‐Ranks tests ( Templeton, 1983 ) and Shimodaira–Hasegawa tests ( Shimodaira & Hasegawa, 1999 ). Results Our evidence supports an origin of mainland Norops anoles from a West Indian ancestor. A West Indian ancestor to the Norops clade is statistically supported, and alternatives to the biogeographic pattern [Cuban (Jamaican, Mainland)] are statistically rejected by Shimodaira–Hasegawa tests, although not by Wilcoxon Signed‐Ranks tests. Main conclusions Our data support the hypothesis of a West Indian origin for mainland Norops. This result contradicts previous hypotheses and suggests that island forms may be an important source for mainland biodiversity.     

Does ecological specialization transcend scale? Habitat partitioning among individuals and species of Anolis lizards

Ecological specialization is common across all levels of biological organization, raising the question of whether the evolution of specialization at one scale in a taxon is linked to specialization at other scales. Anolis lizards have diversified repeatedly along axes of habitat use, but it remains unknown if this diversification into habitat use specialists is underlain by individual specialization. From repeated observations of individuals in a population of Anolis sagrei in Florida, we show that the extent of habitat use specialization among individuals is comparable to the extent of specialization in the same traits among ten sympatric Anolis habitat specialist species in Cuba. However, the adaptive correlations between habitat use and morphology commonly seen across species of Anolis were not observed across individuals in the sampled population. Our results therefore suggest that while patterns of ecological specialization can transcend scale, these parallels are the consequence of distinct ecological processes acting at microevolutionary and macroevolutionary scales.     

The roles of allopatric divergence and natural selection in quantitative trait variation across a secondary contact zone in the lizard Anolis roquet

Populations of the Caribbean lizard, Anolis roquet, are thought to have experienced long periods of allopatry before recent secondary contact. To elucidate the effects of past allopatry on population divergence in A. roquet, we surveyed parallel transects across a secondary contact zone in northeastern Martinique. We used diagnostic molecular mitochondrial DNA markers to test fine‐scale association of mitochondrial DNA lineage and geological region, multivariate statistical techniques to explore quantitative trait pattern, and cline fitting techniques to model trait variation across the zone of secondary contact. We found that lineages were strongly associated with geological regions along both transects, but quantitative trait patterns were remarkably different. Patterns of morphological and mitochondrial DNA variation were consistent with a strong barrier to gene flow on the coast, whereas there were no indications of barriers to gene flow in the transitional forest. Hence, the coastal populations behaved as would be predicted by an allopatric model of divergence in this complex, while those in the transitional forest did not, despite the close proximity of the transects and their shared geological history. Patterns of geographical variation in this species complex, together with environmental data, suggest that on balance, selection regimes on either side of the secondary contact zone in the transitional forest may be more convergent, while those either side of the secondary contact zone on the coast are more divergent. Hence, the evolutionary consequences of allopatry may be strongly influenced by local natural selection regimes.     

Introduced species as moving targets: changes in body sizes of introduced lizards following experimental introductions and historical invasions

Introduced species usually fail to establish, but when they succeed, may undergo character release and rapid evolutionary divergence in novel environments. We collected brown anoles (Anolis sagrei: Lacertilia: Iguanidae) from a single Florida population and released them onto two ecologically different dredge-spoil islands in central Florida (forested and non-forested) and measured differences in population growth, individual growth, body size, and condition over four years. The population on the non-forested island expanded twice as fast as the forested island population and reached a density of ca. 12,000 lizards ha^–1 and a biomass of ca. 43.3 kg ha^–1, among the largest values recorded for non-aggregated terrestrial vertebrates. First-year progeny grew larger than their surviving parents on both islands, indicating character release occurred in early stages of both invasions. However, in subsequent years, lizards became larger on the forested island, but smaller on the non-forested island. Body condition declined over time on both islands, but the effect was most dramatic on the non-forested island. Lizards on the forested island had the lowest survival rates and highest tail autotomy frequencies. These results were attributed to differences in abiotic and biotic conditions on the two islands. Brown anoles are generally larger on islands where they have been introduced than on their native Caribbean islands, and are much larger on mainlands than on islands, indicating character release occurred at larger geographic scales as well. Habitat influences the morphology of introduced species possessing the ability to rapidly adapt to local conditions, presenting invasive species managers with moving targets.     

Physiological evolution during adaptive radiation: A test of the island effect in Anolis lizards

Phenotypic evolution is often exceptionally rapid on islands, resulting in numerous, ecologically diverse species. Although adaptive radiation proceeds along various phenotypic axes, the island effect of faster evolution has been mostly tested with regard to morphology. Here, we leveraged the physiological diversity and species richness of Anolis lizards to examine the evolutionary dynamics of three key traits: heat tolerance, body temperature, and cold tolerance. Contrary to expectation, we discovered slower heat tolerance evolution on islands. Additionally, island species evolve toward higher optimal body temperatures than mainland species. Higher optima and slower evolution in upper physiological limits are consistent with the Bogert effect, or evolutionary inertia due to thermoregulation. Correspondingly, body temperature is higher and more stable on islands than on the American mainland, despite similarity in thermal environments. Greater thermoregulation on islands may occur due to ecological release from competitors and predators compared to mainland environments. By reducing the costs of thermoregulation, ecological opportunity on islands may actually stymie, rather than hasten, physiological evolution. Our results emphasize that physiological diversity is an important axis of ecological differentiation in the adaptive radiation of anoles, and that behavior can impart distinct macroevolutionary footprints on physiological diversity on islands and continents.