Calabash (Belize) and A. palmata from Puerto Morelos (Mexico) showed some genetic differentiation from the rest of the MBRS populations, and (3) A. palmata from MBRS, Panama, Puerto Rico and Venezuela were grouped into four subregions that could be considered as management units. A more spatially detailed sampling program and the inclusion of recruits will be necessary to get a comprehensive understanding of coral population structure and current gene flow patterns in these two species.
Patterns of dispersal and connectivity of the Caribbean gorgonian Antillogorgia elisabethae in The Bahamas were assessed in both adults and recently settled recruits from 13 sites using microsatellite loci. Adult populations along the Little Bahama Bank (LBB) exhibited a clear pattern of isolation by distance (IBD) which described 86% of the variance in pairwise genetic distances. Estimates of dispersal based on the IBD model suggested dispersal distances along the LBB on the order of 100 m. Increasing the spatial scale to include sites separated by open ocean generated an apparent IBD signal but the relationship had a greater slope and explained less of the variance. This relationship with distance reflected both stepping stone based IBD and regional differentiation probably created by ocean currents and barriers to dispersal that are correlated with geographic distance. Analysis of recruits from 4 sites on the LBB from up to 6 years did not detect differences between years nor differences with adult populations. The result suggests that neither selection on recruits nor inter-annual variation in dispersal affected adult population structure. Assignment tests of recruits indicated the most likely sources of the recruits were the local or adjacent populations. Most of the patterning in population structure in the northern Bahamas can be explained by geographic distance and oceanographic connectivity. Recognition of these complex patterns is important in developing management plans for A. elisabethae and in understanding the effects of disturbance to adult populations of A. elisabethae and similar species with limited dispersal.
Lampsilis bracteata (Gould), the Texas Fatmucket, is a regional endemic species in the central Texas biogeographic province which is a candidate to be listed as threatened or endangered under the Endangered Species Act of 1973. Lampsilis bracteata is morphologically similar to the common species L. hydiana (Lea). Here, we examine the molecular taxonomic identification of L. bracteata, and compare its historical range with its current geographic distribution. Tests of genetic affinities based on two mitochondrial genes typically used for DNA barcoding (cytochrome oxidase subunit 1, COI and NADH dehydrogenase subunit 1, ND1) support recognition of L. bracteata as a full species. An unexpected spin-off result was that ND1 sequences of L. satura (Lea), a threatened species in Texas, formed a highly supported cluster within putative L. cardium Rafinesque. As an endemic species, the distribution of L. bracteata has been historically restricted; however, poor land and water management practices have further reduced its distribution from eighteen to just eight streams in the Colorado River drainage and to one stream in the Guadalupe River drainage. For L. bracteata, as for many other imperiled freshwater mussel species, effective conservation measures rely on correct species identification, definition of its geographic range and assessment of its changes in the recent past.
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