Effect of glyphosate (Roundup Active®) on liver of tadpoles of the colombian endemic frog Dendropsophus molitor (amphibia: Anura).

Glyphosate-based herbicide (GBH) using is increasing on a global scale. Few studies have investigated the sub-lethal effects of GBH in endemic amphibian species. The present work tested the GBH Roundup Active® on the tadpoles of Dendropsophus molitor. The exposure was in a range of plausible environmental concentrations (0-0.75 µg a.e./L) during a month. D. molitor is an endemic tropical frog of South America. The exposure from 325 µg a.e./L caused histological alterations in the liver. The high-resolution optical microscopy (HROM) detected sinusoidal dilatation and cytoplasmic vacuolization. The transmission electron microscopy (TEM) showed disorganization of the endoplasmic reticulum. Since the liver is essential for detoxification, these results suggest choric effects. Exposure to another GBH has caused histological alterations in liver tadpoles liver in a previous study, but, this study tested another endemic South-American frog for only 96h. The present work applied HROM to observe lipid alterations since it does not use organic solvents; and TEM for the ultrastructural observation of hepatocytes. Environmental risk of GBH can improve by including sub-lethal effects in endemic species.

Molecular phylogenetics and biogeography of the Neotropical skink genus Mabuya Fitzinger (Squamata: Scincidae) with emphasis on Colombian populations.

Understanding the phylogenetic and geographical history of Neotropical lineages requires having adequate geographic and taxonomic sampling across the region. However, Colombia has remained a geographical gap in many studies of Neotropical diversity. Here we present a study of Neotropical skinks of the genus Mabuya, reptiles that are difficult to identify or delimit due to their conservative morphology. The goal of the present study is to propose phylogenetic and biogeographic hypotheses of Mabuya including samples from the previously under-studied territory of Colombia, and address relevant biogeographic and taxonomic issues. We combined molecular and morphological data sampled densely by us within Colombia with published data representing broad sampling across the Neotropical realm, including DNA sequence data from two mitochondrial (12S rRNA and cytochrome b) and three nuclear genes (Rag2, NGFB and R35). To evaluate species boundaries we employed a general mixed Yule-coalescent (GMYC) model applied to the mitochondrial data set. Our results suggest that the diversity of Mabuya within Colombia is higher than previously recognized, and includes lineages from Central America and from eastern and southern South America. The genus appears to have originated in eastern South America in the Early Miocene, with subsequent expansions into Central America and the Caribbean in the Late Miocene, including at least six oceanic dispersal events to Caribbean Islands. We identified at least four new candidate species for Colombia and two species that were not previously reported in Colombia. The populations of northeastern Colombia can be assigned to M. zuliae, while specimens from Orinoquia and the eastern foothills of the Cordillera Oriental of Colombia correspond to M. altamazonica. The validity of seven species of Mabuya sensu lato was not supported due to a combination of three factors: (1) non-monophyly, (2) <75% likelihood bootstrap support and <0.95 Bayesian posterior probability, and (3) GMYC analysis collapsing named species. Finally, we suggest that Mabuya sensu stricto may be regarded as a diverse monophyletic genus, widely distributed throughout the Neotropics.

Using historical biogeography to test for community saturation.

Saturation is the idea that a community is effectively filled with species, such that no more can be added without extinctions. This concept has important implications for many areas of ecology, such as species richness, community assembly, invasive species and climate change. Here, we illustrate how biogeography can be used to test for community saturation, when combined with data on local species richness, phylogeny and climate. We focus on a clade of frogs (Terrarana) and the impact of the Great American Biotic Interchange on patterns of local richness in Lower Middle America and adjacent regions. We analyse data on species richness at 83 sites and a time-calibrated phylogeny for 363 species. We find no evidence for saturation, and show instead that biotic interchange dramatically increased local richness in the region. We suggest that historical biogeography offers thousands of similar long-term natural experiments that can be used to test for saturation.

The Great American Biotic Interchange in frogs: multiple and early colonization of Central America by the South American genus Pristimantis (Anura: Craugastoridae).

The completion of the land bridge between North and South America approximately 3.5-3.1 million years ago (Ma) initiated a tremendous biogeographic event called the Great American Biotic Interchange (GABI), described principally from the mammalian fossil record. The history of biotic interchange between continents for taxonomic groups with poor fossil records, however, is not well understood. Molecular and fossil data suggest that a number of plant and animal lineages crossed the Isthmus of Panama well before 3.5 Ma, leading biologists to speculate about trans-oceanic dispersal mechanisms. Here we present a molecular phylogenetic analysis of the frog genus Pristimantis based on 189 individuals of 137 species, including 71 individuals of 31 species from Panama and Colombia. DNA sequence data were obtained from three mitochondrial (COI, 12S, 16S) and two nuclear (RAG-1 and Tyr) genes, for a total of 4074 base pairs. The resulting phylogenetic hypothesis showed statistically significant conflict with most recognized taxonomic groups within Pristimantis, supporting only the rubicundus Species Series, and the Pristimantis myersi and Pristimantis pardalis Species Groups as monophyletic. Inference of ancestral areas based on a likelihood model of geographic range evolution via dispersal, local extinction, and cladogenesis (DEC) suggested that the colonization of Central America by South American Pristimantis involved at least 11 independent events. Relaxed-clock analyses of divergence times suggested that at least eight of these invasions into Central America took place prior to 4 Ma, mainly in the Miocene. These findings contribute to a growing list of molecular-based biogeographic studies presenting apparent temporal conflicts with the traditional GABI model.