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The temperate South American lizard genus Liolaemus is the one of the most widely distributed and species-rich genera of lizards on earth. The genus is divided into two subgenera, Liolaemus sensu stricto (the 'Chilean group') and Eulaemus (the 'Argentino group'), a division that is supported by recent molecular and morphological data. Owing to a lack of reliable fossil data, previous studies have been forced to use either global molecular clocks, a standardized mutation rate adopted from previous studies, or the use of geological events as calibration points. However, simulations indicate that these types of assumptions may result in less accurate estimates of divergence times when clock-like models or mutation rates are violated. We used a multilocus data set combined with a newly described fossil to provide the first calibrated phylogeny for the crown groups of the clade Eulaemus, and derive new fossil-calibrated substitution rates (with error) of both nuclear and mtDNA gene regions for Eulaemus specifically. Divergence date estimates for each of the crown groups and appropriate rate estimates will provide the foundation for understanding rates of speciation, historical biogeography, and phylogeographical history for various clades in one of the most diverse lizard genera in the poorly studied Patagonian region.

The evolutionary history of leeches is employed as a general framework for understanding more than merely the systematics of this charismatic group of annelid worms, and serves as a basis for understanding blood-feeding related correlates ranging from the specifics of gut-associated bacterial symbionts to salivary anticoagulant peptides. A variety of medicinal leech families were examined for intraluminal crop bacterial symbionts. Species of Aeromonas and Bacteroidetes were characterized with DNA gyrase B and 16S rDNA. Bacteroidetes isolates were found to be much more phylogenetically diverse and suggested stronger evidence of phylogenetic correlation than the gammaproteobacteria. Patterns that look like co-speciation with limited taxon sampling do not in the full context of phylogeny. Bioactive compounds that are expressed as gene products, like those in leech salivary glands, have 'passed the test' of evolutionary selection. We produced and bioinformatically mined salivary gland EST libraries across medicinal leech lineages to experimentally and statistically evaluate whether evolutionary selection on peptides can identify structure-function activities of known therapeutically relevant bioactive compounds like antithrombin, hirudin and antistasin. The combined information content of a well corroborated leech phylogeny and broad taxonomic coverage of expressed proteins leads to a rich understanding of evolution and function in leech history.

Historical climate changes and orogenesis are two important factors that have shaped intraspecific biodiversity patterns worldwide. Although southern South America has experienced such complex events, there is a paucity of studies examining the effects on intraspecific diversification in this part of the world. Liolaemus pictus is the southernmost distributed lizard in the Chilean temperate forest, whose genetic structure has likely been influenced by Pleistocene glaciations. We conducted a phylogeographic study of L. pictus in Chile and Argentina based on one mitochondrial and two nuclear genes recovering two strongly divergent groups, Northern and Southern clades. The first group is distributed from the northernmost limit of the species to the Araucanía region while the second group is distributed throughout the Andes and the Chiloé archipelago in Southern Chile. Our results suggest that L. pictus originated 751 Kya, with divergence between the two clades occurring in the late Pleistocene. Demographic reconstructions for the Northern and Southern clades indicate a decrease in effective population sizes likely associated with Pleistocene glaciations. Surprisingly, patterns of genetic variation, clades age and historical gene flow in populations distributed within the limits of the Last Glacial Maximum (LGM) are not explained by recent colonization. We propose an “intra-Andean multiple refuge” hypothesis, along with the classical refuge hypothesis previously proposed for the biota of the Chilean Coastal range and Eastern Andean Cordillera. Our hypothesis is supported by niche modelling analysis suggesting the persistence of fragments of suitable habitat for the species within the limits of the LGM ice shield. This type of refuge hypothesis is proposed for the first time for an ectothermic species.

This study examines the phylogeographic structure within the Patagonian lizard Liolaemus petrophilus and tests for patterns of between-clade morphological divergence and sexual dimorphism, as well as demographic and niche changes associated with Pleistocene climate changes. We inferred intraspecific relationships, tested hypotheses for historical patterns of population expansion, and incorporated ecological niche modeling (ENM) with standard morphological and geometric morphometric analyses to examine between-clade divergence as indirect evidence for adaptation to different niches. The two inferred haploclades diverged during the early Pleistocene with the Southern clade depicting the genetic signature of a recent population increase associated with expanding niche envelope, whereas the Northern clade shows stable populations in a shrinking niche envelope. The combination of molecular evidence for postisolation demographic change and ENM, suggest that the two haploclades have responded differently to Pleistocene climatic events.