Coral reefs are the most biologically diverse of shallow water marine ecosystems but are being degraded worldwide by human activities and climate warming. Analyses of the geographic ranges of 3235 species of reef fish, corals, snails, and lobsters revealed that between 7.2% and 53.6% of each taxon have highly restricted ranges, rendering them vulnerable to extinction. Restricted-range species are clustered into centers of endemism, like those described for terrestrial taxa. The 10 richest centers of endemism cover 15.8% of the world's coral reefs (0.012% of the oceans) but include between 44.8 and 54.2% of the restricted-range species. Many occur in regions where reefs are being severely affected by people, potentially leading to numerous extinctions. Threatened centers of endemism are major biodiversity hotspots, and conservation efforts targeted toward them could help avert the loss of tropical reef biodiversity.

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Recent studies suggest that freshwater turtle populations are becoming increasingly male-biased. A hypothesized cause is a greater vulnerability of female turtles to road mortality. We evaluated this hypothesis by comparing sex ratios from published and unpublished population surveys of turtles conducted on-versus offroads. Among 38 166 turtles from 157 studies reporting sex ratios, we found a consistently larger female fraction in samples from on-roads (61%) than off-roads (41%). We conclude that female turtles are indeed more likely to cross roadways than are males, which may explain recently reported skewed sex ratios near roadways and signify eventual population declines as females are differentially eliminated.

Abstract. Although studies of population genetic structure are very common, whether genetic structure is stable over time has been assessed for very few taxa. The question of stability over time is particularly interesting for frogs because it is not clear to what extent frogs exist in dynamic metapopulations with frequent extinction and recolonization, or in stable patches at equilibrium between drift and gene flow. In this study we collected tissue samples from the same five populations of leopard frogs, Rana pipiens, over a 22-30 year time interval (11-15 generations). Genetic structure among the populations was very stable, suggesting that these populations were not undergoing frequent extinction and colonization. We also estimated the effective size of each population from the change in allele frequencies over time. There exist few estimates of effective size for frog populations, but the data available suggest that ranid frogs may have much larger ratios of effective size (N e ) to census size (N c ) than toads (bufonidae). Our results indicate that R. pipiens populations have effective sizes on the order of hundreds to at most a few thousand frogs, and N e /N c ratios in the range of 0.1-1.0. These estimates of N e /N c are consistent with those estimated for other Rana species. Finally, we compared the results of three temporal methods for estimating N e . Moment and pseudolikelihood methods that assume a closed population gave the most similar point estimates, although the moment estimates were consistently two to four times larger. Wang and Whitlock's new method that jointly estimates N e and the rate of immigration into a population (m) gave much smaller estimates of N e and implausibly large estimates of m. This method requires knowing allele frequencies in the source of immigrants, but was thought to be insensitive to inexact estimates. In our case the method may have failed because we did not know the true source of immigrants for each population. The method may be more sensitive to choice of source frequencies than was previously appreciated, and so should be used with caution if the most likely source of immigrants cannot be identified clearly.Key words. Anuran, genetic structure, microsatellite, Rana pipiens, temporal stability, temporal variation, variance effective size. A fundamental goal of population genetics is to understand the relative importance of microevolutionary forces in determining the existing patterns of genetic variation within a species. Consequently, using molecular markers to estimate parameters such as the effective sizes of, and migration rates among, natural populations has become a major focus in the field of evolutionary biology. However, elucidation of past processes and the prediction of future patterns from molecular data requires that a state of equilibrium have developed between genetic drift and gene flow in the populations of interest. Demographic instability can disrupt that equilibrium (Whitlock 1992), rendering single ''snapshot'' estimates of population struc...

Lack of historical data against which to measure population trends greatly hampers understanding the status of amphibians. In 2001-2002 we resurveyed a hitherto unexamined baseline of monitoring data established in 1973-1980 at some 300 sites in western, central, and northern New York State, USA, and contrasted population transitions with environmental conditions to identify correlates of population change in American toads (Bufo americanus), northern spring peepers (Pseudacris crucifer), western chorus frogs (Pseudacris triseriata), leopard frogs (Rana pipiens), and wood frogs (Rana sylvatica). At the regional level, loss of habitats along roadsides has been substantial (minimally 7-12% of sites), yet within remaining wetlands, populations of most anurans have not declined. At the local level, population disappearance was associated with elevated levels of acid deposition (in American toad, spring peeper, western chorus frog, and leopard frog), urban development (American toad and spring peeper), increased forest cover (western chorus frog), and high-intensity agriculture (spring peeper); whereas population persistence was associated with increased deciduous forest cover (American toad, spring peeper, and wood frog) and low-intensity agriculture (American toad and western chorus frog). Habitat configurations at surprisingly large spatial scales (5-10 km from surveyed populations) were most closely associated with transitions in local anuran populations, implying that largescale extinction-recolonization dynamics influence population transitions, a result land managers should consider in conservation planning.