The multi-peak adaptive landscape of crocodylomorph body size evolution

Background: Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller ( Results: Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent an essentially continual decline since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions. Conclusions: Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution on large phylogenetic and temporal scales, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.</p

GENETIC STRUCTURE AND PHENOTYPIC VARIATION IN WILD POPULATIONS OF THE MEDICINAL TETRAPLOID SPECIES BROMELIA ANTIACANTHA (BROMELIACEAE)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Premise of the study : The patterns of genetic structure in plant populations are mainly related to the species life history and breeding system, and knowledge of these patterns is necessary for the management, use, and conservation of biological diversity. Polyploidy is considered an important mode of evolution in plants, but few studies have evaluated genetic structure of polyploid populations. We studied the patterns of genetic structure and morphological variation of Bromelia antiacantha (Bromeliaceae) populations, a polyploid terrestrial species. Methods : Microsatellite markers and morphological analyses were used to explore patterns of genetic and morphological diversity in wild populations of B. antiacantha. Key results : The results of our simple-sequence repeat analyses supported that B. antiacantha is a polyploid species. The inbreeding coefficients were high and significant in all populations (F(IS) = 0.431), indicating homozygote excess. Bromelia antiacantha showed high levels of genetic differentiation among populations (F(ST) = 0.224) and therefore was highly structured. High morphological variation was observed in fruit phenotypic traits in the populations studied. Conclusions : The levels of genetic diversity and the pattern of the population's structure may be related to the low recruitment of seeds, clonal reproduction, and the population's colonization history. The genetic and morphological variability displayed in this study are important issues in planning the conservation and exploitation of this resource in a sustainable way.98915111519Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)PPGBM (Programa de Pos Graduacao em Genetica e Biologia Molecular-UFRGS)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Microsatellite loci for an endemic stingless bee Melipona seminigra merrillae (Apidae, Meliponini) from Amazon

Melipona seminigra merrillae is one of the main pollinators of Central Amazon native flora. These stingless bees are reared as economic alternative and for forest conservation purposes. Nine polymorphic microsatellite markers were characterized in 44 genotypes of M. seminigra merrillae from the Meliponary of the Instituto Nacional de Pesquisas da Amazonia, INPA (3° 05.838′S 059° 59.103′W), Manaus, Brazil. The number of alleles observed for each locus ranged from 3 to 8, with an average of 3.7 alleles per locus. The polymorphism information content (PIC) varied between 0.21 and 0.81 (average 0.50) and the discriminating power (D) ranged from 0.59 to 0.98 (average 0.77). The observed heterozygosity (H o) and the expected heterozygosity (H e) were 0.04-0.68 and 0.19-0.84, respectively. A cross-amplification test in three Melipona species suggested potential transferability of these microsatellites. These microsatellite markers should be useful for characterizing natural populations and specie conservation. © Springer Science+Business Media B.V. 2009