M. Jowers

The islands of Trinidad and Tobago form a southern extension of the Lesser Antilles. Unlike the continental island of Trinidad, the more northerly Tobago formed as an older oceanic island volcanic arc. Their reptile biodiversity reflects colonization events from the South American mainland through land bridge connections at times of glacial maxima. Most of Tobago's herpetofauna has colonized through stepping-stone

A toad in the Rhinella granulosa group has been recognized as present on Trinidad since 1933. In 1965, the Trini-dadian population was described as a subspecies of Bufo granulosus, B. g. beebei. It has its type locality on the island and was eventually raised to species status as B. beebei (Beebe's toad). Recently Beebe's toad was synonymized with Rhinella humboldti, a species with a type locality in the Magdalena Valley of western Colombia. The Magdalena Valley is separated from the Orinoco Basin by the Eastern and Merida Cordilleras. These ranges have peaks that exceed 5,000 m and an almost continuous altitude at about 3,000 m. Here we examine the morphology, advertisement calls, and mtDNA from several populations of these lowland toads to test whether the western Colombian R. humboldti and the Orinoco-Trinidad R. beebei are conspecific and form a single taxon that occurs on both sides of the Andes. The morphological, molecular, and advertisement call analyses suggest that R. humboldti and R. beebei are distinct taxa composed of independent evolving lineages. Rhinella beebei is therefore resurrected from the synonymy of R. humboldti for the Trinidad and some of the adjacent mainland Orinoco populations in both Venezuela and Colombia. This increases the number of described species in the clade to fourteen. Rhinella humboldti and its sister R. centralis (Panama) are the only members of the R. granulosa group to occur west of the Andes, and our molecular results suggest the TMRCA for R. beebei and R. humboldti at about 9 Mya, a time when the Eastern Cordillera was much lower in altitude than it is today and the Merida Cordillera was in its early stages of formation.

Dispersal has consequences not only for individual fitness, but also for population dynamics, population genetics and species distribution. Social Hymenoptera show two contrasting colony reproductive strategies, dependent and independent colony foundation modes, and these are often associated to the population structures derived from inter and intra-population gene flow processes conditioned by alternative dispersal strategies. Here we employ microsatellite and mitochondrial markers to investigate the population and social genetic structure and dispersal patterns in the ant Cataglyphis emmae at both, local and regional scales. We find that C. emmae is monogynous and polyandrous. Lack of detection of any population viscosity and population structure with nuclear markers at the local scale suggests efficient dispersal, in agreement with a lack of inbreeding. Contrasting demographic differences before and during the mating seasons suggest that C. emmae workers raise sexuals in peripheric nest chambers to reduce intracolonial conflicts. The high genetic differentiation recovered from the mtDNA haplotypes, together with the significant correlation of such to geographic distance, and presence of new nuclear alleles between areas (valleys) suggest long-term historical isolation between these regions, indicative of limited dispersal at the regional scale. Our findings on the ecological, social and population structure of this species increases our understanding of the patterns and processes involved under independent colony foundation.