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Elpidio A Remigio

Publications and source records attributed to Elpidio A Remigio.

3 recordsLinked to original sources
PubMed2006

Probing the relationships of the branchiopod crustaceans.

The Branchiopoda display extraordinary variation in body form, even within the morphologically diverse crustaceans. To fully understand the origin and evolution of these morphological reconfigurations, a robust phylogeny of the group is essential. To infer the affinities among branchiopods, we employed two approaches to taxon and gene sampling, presented new sequence data from three genes, incorporated previously published sequence data from three additional genes, and utilized comprehensive techniques of phylogeny reconstruction. The results provided support for a number of longstanding hypotheses concerning the relationships among the orders. For example, we obtained support for the Cladoceromorpha and Gymnomera, and favoured a unique arrangement of the cladoceran orders. A few affinities remain to be resolved, particularly at the base of the Phyllopoda and within the Anomopoda. However, the results suggest that increased gene sampling is recommended for future investigations of branchiopod systematics.

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PubMed2002

Accelerated molecular evolution in halophilic crustaceans.

In contrast to the stable ionic composition of the oceans, inland waters show striking diversity, possessing salt concentrations varying from I mM to 5 M. Although species diversity is highest in fresh water, some lineages have colonized hypersaline environments where they encounter elevated levels of both ultraviolet (UV) radiation and osmotic stress. This study compares rates of evolution in halophilic and freshwater taxa for two groups of microcrustaceans, anostracans and daphniids, from Australia and North America. The results establish that halophilic species show consistent rate acceleration, involving elevated levels of both insertion/deletion events and of nucleotide substitutions. The elevated pace of molecular evolution does not appear to be linked to selection or to other agents that are known to influence the supply rate of mutations, such as UV exposure, generation length, or shifts in metabolic rate. However, variance in ionic strength, which is known to have potent effects on DNA-protein interactions as well as on the structural properties of DNA and proteins, might account for the lowered fidelity of DNA replication in life from hypersaline settings. Regardless of its cause, the consistent rate acceleration in halophiles suggests that past efforts to employ sequence divergences to date events, such as the age of asexual lineages in Artemia, have resulted in serious overestimates. More generally, the results indicate that coordinated shifts in rates of molecular evolution may occur in lineages exposed to extreme environmental conditions.

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