Phylogeography of an island endemic: the Puerto Rican freshwater crab, Epilobocera sinuatifrons.
Abstract: The endemic Puerto Rican crab, Epilobocera sinuatifrons
(Pseudothelphusidae), has a freshwater-dependant life-history strategy,
although the species has some capabilities for terrestrial movement as
adults. In contrast to all other freshwater decapods on the island
(e.g., caridean shrimp), E. sinuatifrons
does not undertake amphidromous migration, and is restricted to purely
freshwater habitats and adjacent riparian zones. As Puerto Rico has a
dynamic geologic history, we predicted that both the life history of E. sinuatifrons
and the geological history of the island would be important
determinants of phylogeographic structuring in the species. Using a
fragment of the cytochrome c oxidase subunit 1 mtDNA (mitochondrial
DNA) gene, we tested for deviations from panmixia among and within
rivers draining Puerto Rico and used statistical phylogeography to
explore processes that may explain extant patterns of genetic variation
in the species. While populations of E. sinuatifrons
were significantly differentiated among rivers, they were likely to be
recently derived because nested clade analysis (NCA) indicated
evolutionarily recent restricted gene flow with isolation by distance
(IBD) and contiguous range expansion at various spatial scales. Ongoing
drainage rearrangements associated with faulting and land slippage were
invoked as processes involved in sporadic gene flow among rivers
throughout the Pleistocene. Patterns of genetic differentiation
conformed to IBD and population demographic statistics were
nonsignificant, indicating that although recently derived, populations
from different rivers were in drift-mutation equilibrium. A shallow
(0.6 million years ago), paraphyletic split was observed in the
haplotype network, which NCA indicated arose via allopatric
fragmentation. This split coincides with an area of high relief in
central Puerto Rico that may have experienced relatively little
drainage rearrangements. Shallow but significant genetic isolation of
populations of E. sinuatifrons
among Puerto Rican rivers suggests phylogeographic patterns that are
intermediate to terrestrial habitat specialists (highly divergent
populations) and other freshwater biota, such as amphidromous species
and insects with aerial adult dispersal (highly connected populations).
Cook, B. D., C. M. Pringle, and J. M. Hughes. 2008. Phylogeography of an island endemic: the Puerto Rican freshwater crab, Epilobocera sinuatifrons. Journal of Heredity. xx: xx-xx.
Back to Literature Page
| Pringle's Home Page | University of Georgia | Odum School of Ecology |