IngentaConnect Combined molecular and morphological approaches to documenting re...

Abstract:

Guralnick, R. P. (2005). Combined molecular and morphological approaches to documenting regional biodiversity and ecological patterns in problematic taxa: a case study in the bivalve group Cyclocalyx from western North America. —Zoologica Scripta, 34, 469 –482.

Genetic and morphological data were used to examine regional biodiversity in a taxonomically poorly known group of freshwater bivalves, Cyclocalyx. Cyclocalyx 16S rRNA genes were sampled from multiple habitats across western North America, focusing on an elevation gradient from sea level up to 3400 m. From this sampling and previous reference datasets, a phylogenetic hypothesis was constructed and lineages delineated, leading to an estimate of regional biodiversity. Morphometric analyses of shell outlines were used to test whether lineages from the gene tree were significantly different in shape from one another, and whether shell shape can be used to predict lineage affiliation. Finally, broad habitat variables were plotted onto the trees and examined in an evolutionary context. The results uncovered many unnamed, genetically and morphologically distinct lineages, remarkable range extensions, and an unexpected lack of abundance of some lineages. The results also show patterns with basal lineages restricted to high-elevation lakes and more nested lineages at lower elevations or with very wide tolerances. This work challenges almost all previous concepts of regional biodiversity of this lineage, while providing a foundation for future hypothesis testing about the ecology and evolution of the group. It also documents an approach to documenting regional biodiversity that can be applied to other taxa.

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Combined molecular and morphological approaches to documenting regional biodiversity and ecological patterns in problematic taxa: a case study in the bivalve group Cyclocalyx (Sphaeriidae, Bivalvia) from western North America