Phylogenetic relationships in the iguanid lizard genus Liolaemus: multiple origins of viviparous reproduction and evidence for recurring Andean vicariance and dispersal

Phylogenetic relationships within the iguanid lizard genus Liolaemus are investigated using 1710 aligned base positions (785 phylogenetically informative) of mitochondrial DNA sequences, representing coding regions for eight tRNAs, ND2, and portions of ND1 and COL Sixty new sequences ranging in length from 1736 to 1754 bases are compared with four previously reported sequences. Liolaemus species form two well-supported monophyletic groups of subgeneric status, Liolaemus and Eulaemus. These subgenera appear to have separated at least 12.6 million years ago based on the amount of molecular evolutionary divergence between them. Hypotheses that species occurring in the Andes, west of the Andes, and east of the Andes, each comprise distinct monophyletic groups are independently rejected statistically. The shortest estimate of phylogeny suggests mat Liolaemus originated either in the Andes or the eastern lowlands. Numerous evolutionary shifts have occurred between the Andes, and the eastern and western lowlands, suggesting recurring vicariance and dispersal. Species occurring at high elevations or high latitudes usually have viviparous reproduction. Depending on whether parity mode is considered reversible in Liolaemus , the most parsimonious reconstruction supports at least six independent origins of viviparity or at least three gains followed by three losses of viviparity among die 60 Liolaemus lineages examined.     

Microhabitat shifts of lizards under different contexts of sympatry: a case study with South American Liolaemus

Summary The Iguanid lizard Liolaemus tenuis is shown to be a rock and trunk dweller (apparently preferring perches between 0–30 cm height) in a central Chilean locality where it coexists with a single ground-dwelling congener. In its southern distributional ranges L. tenuis is sympatric with another tree-dweller, L. pictus. Habitat shift is demonstrated in this latter case by L. tenuis concentrating on tree trunks, and at modal heights 30–60 cm. Liolaemus pictus occupies lower (apparently more favorable) perches, actively interferring with its congener.     

Seri Indian traditional knowledge and molecular biology agree: no express train for island‐hopping spiny‐tailed iguanas in the Sea of Cortés

Aim The role of human activities in species biogeography can be difficult to identify, but in some cases molecular techniques can be used to test hypotheses of human‐mediated dispersal. A currently accepted hypothesis states that humans mediated the divergence of two species of spiny‐tailed iguanas in the Ctenosaura hemilopha species complex, namely C. conspicuosa and C. nolascensis, which occupy islands in the Sea of Cortés between the peninsula of Baja California and mainland Mexico. We test an alternative hypothesis that follows the traditional knowledge of the Seri Indians and states that the divergence of these species was not mediated by humans. Location Mexico, including Baja California, Sonoran and Sinaloan coastal regions, and Isla San Esteban and Isla San Pedro Nolasco in the Sea of Cortés. Methods We analysed mitochondrial (cytochrome b and cytochrome c oxidase subunit III) DNA sequences from four species in the C. hemilopha species complex. Maximum parsimony and Bayesian inference were used to infer matriarchal genealogical relationships between the species and several outgroup taxa. Bayesian methods were used to estimate divergence times for the major nodes on the trees based on previously published, fossil‐calibrated priors. Results Our analysis indicated that lineages within the C. hemilopha species complex diverged long before human colonization of the Americas. The divergence of C. nolascensis and C. conspicuosa could not be attributed to Seri translocations. The matriarchal genealogy of the species complex currently defies a simple biogeographical interpretation. Main conclusions We conclude that humans did not mediate the divergence of C. nolascensis and C. conspicuosa. This conclusion is consistent with the traditional knowledge of the Seri people. These results demonstrate the utility of molecular techniques in investigating potential cases of human‐mediated dispersal of plants and animals, and reinforce the importance of considering traditional knowledge in the formation of scientific hypotheses and the interpretation of results.     

The relationship between morphology, escape behaviour and microhabitat occupation in the lizard clade Liolaemus (Iguanidae: Tropidurinae: Liolaemini)

Phenotypic differences among species are known to have functional consequences that in turn allow species to use different habitats. However, the role of behaviour in this ecomorphological paradigm is not well defined. We investigated the relationship between morphology, ecology and escape behaviour among 25 species of the lizard clade Liolaemus in a phylogenetic framework. We demonstrate that the relationship between morphology and characteristics of habitat structure shows little or no association, consistent with a previous study on this group. However, a significant relationship was found between morphology and escape behaviour with the distance a lizard moved from a potential predator correlated with body width, axilla-groin length, and pelvis width. A significant relationship between escape behaviour and habitat structure occupation was found; lizards that occupied tree trunks and open ground ran longer distances from predators and were found greater distances from shelter. Behavioural strategies used by these lizards in open habitats appear to have made unnecessary the evolution of limb morphology that has occurred in other lizards from other clades that are found in open settings. Understanding differences in patterns of ecomorphological relationships among clades is an important component for studying adaptive diversification.     

Ecology and signal evolution in lizards

Current models of signal evolution explain diversity by invoking a variety of social, perceptual and environmental factors. Social systems and spacing patterns determine the active space of signals and their function. Receiver sensory systems and habitat characteristics interact to constrain signal design. These factors are traditionally implicated in promoting directional evolutionary change, leading to increases or decreases in signal complexity. We examine macro-evolutionary trends in signal design, as reflected by display modifier repertoire size, for 124 species of iguanian lizards to identify the importance of ecological factors in display evolution. Possessing a small home range, being arboreal and feeding on moving prey are all correlated with the evolution of large repertoires. However, living in closed habitats is associated with increased evolutionary change in repertoire size, producing greater signal diversity. Ecological factors can thus act either directionally or to promote evolutionary lability.   © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 127–148.     

Defining spatial and temporal patterns of phylogeographic structure in Madagascar's iguanid lizards (genus Oplurus)

Understanding the remarkably high species diversity and levels of endemism found among Madagascar’s flora and fauna has been the focus of many studies. One hypothesis that has received much attention proposes that Quaternary climate fluctuations spurred diversification. While spatial patterns of distribution and phylogenetic relationships can provide support for biogeographic predictions, temporal estimates of divergence are required to determine the fit of these geospatial patterns to climatic or biogeographic mechanisms. We use multilocus DNA sequence data to test whether divergence times among Malagasy iguanid lizards of the subfamily Oplurinae are compatible with a hypotheses of Pliocene–Pleistocene diversification. We estimate the oplurine species tree and associated divergence times under a relaxed‐clock model. In addition, we examine the phylogeographic structure and population divergence times within two sister species of Oplurus primarily distributed in the north‐west and south‐west of Madagascar (Oplurus cuvieri and Oplurus cyclurus, respectively). We find that divergence events among oplurine lineages occurred in the Oligocene and Miocene and are thus far older and incompatible with the hypothesis that recent climate fluctuations are related to current species diversity. However, the timing of intraspecific divergences and spatial patterns of population genetic structure within O. cuvieri and O. cyclurus suggest a role for both intrinsic barriers and recent climate fluctuations at population‐level divergences. Integrating information across spatial and temporal scales allows us to identify and better understand the mechanisms generating patterns diversity.     

Molecular tests of phylogenetic taxonomies: a general procedure and example using four subfamilies of the lizard family Iguanidae

A general procedure is described for examining when results of molecular phylogenetic analyses warrant formal revision of taxonomies constructed using morphological characters. We illustrate this procedure with tests of monophyly for four subfamilies in the lizard family Iguanidae using 1561 aligned base positions (838 phylogenetically informative) of mitochondrial DNA sequences, representing coding regions for eight tRNAs, ND2, and portions of ND1 and COI. Ten new sequences ranging in length from 1732 to 1751 bases are compared with 12 previously reported sequences and 67 morphological characters (54 phylogenetically informative) from the literature. New morphological character states are provided for Sator. Phylogenies derived from the molecular and combined data are in agreement but both conflict with phylogenetic inferences from the morphological data alone. Strong support is found for the monophyly of the subfamilies Crotaphytinae and Phrynosomatinae. Monophyly of the Iguaninae is weakly supported in each analysis. All analyses suggest that the Tropidurinae is not monophyletic but the hypothesis of monophyly cannot be rejected. A phylogenetic taxonomy is proposed in which the Tropidurinae* is maintained as a metataxon (denoted with an asterisk), for which monophyly has not been demonstrated. Within the Phrynosomatinae, the close relationship of Sator and Sceloporus is questioned and an alternative hypothesis in which Sator is the sister taxon to a clade comprising Petrosaurus, Sceloporus, and Urosaurus is presented. Statistical tests of monophyly provide a powerful way to evaluate support for taxonomic groupings. Use of the metataxon prevents premature taxonomic rearrangements where support is lacking.