A multi-taxonomic framework for assessing relative petrochemical vulnerability of marine biodiversity in the Gulf of Mexico.

A fundamental understanding of the impact of petrochemicals and other stressors on marine biodiversity is critical for effective management, restoration, recovery, and mitigation initiatives. As species-specific information on levels of petrochemical exposure and toxicological response are lacking for the majority of marine species, a trait-based assessment to rank species vulnerabilities to petrochemical activities in the Gulf of Mexico can provide a more comprehensive and effective means to prioritize species, habitats, and ecosystems for improved management, restoration and recovery. To initiate and standardize this process, we developed a trait-based framework, applicable to a wide range of vertebrate and invertebrate species, that can be used to rank relative population vulnerabilities of species to petrochemical activities in the Gulf of Mexico. Through expert consultation, 18 traits related to likelihood of exposure, individual sensitivity, and population resilience were identified and defined. The resulting multi-taxonomic petrochemical vulnerability framework can be adapted and applied to a wide variety of species groups and geographic regions. Additional recommendations and guidance on the application of the framework to rank species vulnerabilities under specific petrochemical exposure scenarios, management needs or data limitations are also discussed.

Hybridization in large-bodied New World primates.

Well-documented cases of natural hybridization among primates are not common. In New World primates, natural hybridization has been reported only for small-bodied species, but no genotypic data have ever been gathered that confirm these reports. Here we present genetic evidence of hybridization of two large-bodied species of neotropical primates that diverged approximately 3 MYA. We used species-diagnostic mitochondrial and microsatellite loci and the Y chromosome Sry gene to determine the hybrid status of 36 individuals collected from an area of sympatry in Tabasco, Mexico. Thirteen individuals were hybrids. We show that hybridization and subsequent backcrosses are directionally biased and that the only likely cross between parental species produces fertile hybrid females, but fails to produce viable or fertile males. This system can be used as a model to study gene interchange between primate species that have not achieved complete reproductive isolation.

Species-level phylogeography and evolutionary history of the hyperdiverse marine gastropod genus Conus.

Phylogenetic and paleontological analyses are combined to reveal patterns of species origination and divergence and to define the significance of potential and actual barriers to dispersal in Conus, a species-rich genus of predatory gastropods distributed throughout the world's tropical oceans. Species-level phylogenetic hypotheses are based on nucleotide sequences from the nuclear calmodulin and mitochondrial 16S rRNA genes of 138 Conus species from the Indo-Pacific, eastern Pacific, and Atlantic Ocean regions. Results indicate that extant species descend from two major lineages that diverged at least 33 mya. Their geographic distributions suggest that one clade originated in the Indo-Pacific and the other in the eastern Pacific + western Atlantic. Impediments to dispersal between the western Atlantic and Indian Oceans and the central and eastern Pacific Ocean may have promoted this early separation of Indo-Pacific and eastern Pacific + western Atlantic lineages of Conus. However, because both clades contain both Indo-Pacific and eastern Pacific + western Atlantic species, migrations must have occurred between these regions; at least four migration events took place between regions at different times. In at least three cases, incursions between regions appear to have crossed the East Pacific Barrier. The paleontological record illustrates that distinct sets of Conus species inhabited the Indo-Pacific, eastern Pacific + western Atlantic, and eastern Atlantic + former Tethys Realm in the Tertiary, as is the case today. The ranges of <1% of fossil species (N=841) spanned more than one of these regions throughout the evolutionary history of this group.

Gene expression and feeding ecology: evolution of piscivory in the venomous gastropod genus Conus.

Differential expression of gene-family members is typically associated with the specific development of certain tissues and organs, but its importance in the ecological adaptation of organisms has rarely been investigated. Several specialized feeding modes have evolved within the predatory marine gastropod genus Conus, including molluscivory and piscivory. Based on phylogenetic investigations of Conus species, it has been concluded that piscivory arose at least twice in this genus. Moreover, molecular analyses of conotoxin mRNA transcripts reveal that piscivores from independent evolutionary lineages express the same subset of four-loop conotoxins, contrary to phylogenetic expectations. These results demonstrate that differential expression of gene-family members can play a key role in adaptive evolution, particularly during shifts to new ecological niches.

Roles of diversifying selection and coordinated evolution in the evolution of amphibian antimicrobial peptides.

Antimicrobial peptides are expressed in the skin of amphibians and are used to prevent infection by microorganisms. Frog species store distinct collections of antimicrobial peptides that show variation in size, charge, conformation, and bactericidal activity, and so the evolution of antimicrobial peptide gene families may reflect the adaptive diversification of these loci. We examined the molecular evolution of antimicrobial peptide transcripts from hylid and ranid frog species. Our results show that after the gene family arose in the common ancestor of the Hylidae and Ranidae, before the divergence of these families in the Mesozoic, it subsequently diversified within these groups with numerous duplication events and divergence of loci. Moreover, we provide evidence that suggests that members of the antimicrobial peptide gene family have been subject to diversifying selection within both propiece and mature domains of hylids and solely within the mature domain of ranids. Finally, our results suggest that coordinated and compensatory amino acid replacements have occurred within the acidic propiece and cationic mature domain of hylid antimicrobial peptide precursors, as has been observed for mammalian defensin genes, but not among those of ranid precursors.