RESUMEN
Wild pigs (Sus scrofa) alter ecosystems, affect the economy, and carry diseases that can be transmitted to livestock, humans, and wildlife. Understanding wild pig movements and population structure data, including natural population boundaries and dispersal, may potentially increase the efficiency and effectiveness of management actions. We trapped, conducted aerial shootings, and hunted wild pigs from 2005 to 2009 in southern Texas. We used microsatellites to assist large-scale applied management. We quantify broad-scale population structure among 24 sites across southern Texas by computing an overall Fst value, and a Bayesian clustering algorithm both with and without considering the spatial location of samples. At a broad geographic scale, pig populations displayed a moderate degree of genetic structure (Fst = 0.11). The best partition for number of populations, based on 2nd order rate of change of the likelihood distribution, was K = 10 genetic clusters. The spatially explicit Bayesian clustering algorithm produced similar results, with minor differences in designation of admixed sites. We found evidence of past (and possibly ongoing) translocations; many populations were admixed. Our original goal was to identify landscape features, such as barriers or dispersal corridors, that could be used to aid management. Unfortunately, the extensive admixture among clusters made this impossible. This research shows that large-scale management of wild pigs may be necessary to achieve control and ameliorate damages. Reduction or cessation of translocations is necessary to prevent human-mediated dispersion of wild pigs.
RESUMEN
Trace element composition in plant biomass could be used as an indicator of environmental stress, management practices and restoration success. A longitudinal study was conducted to compare Pb, Cd, and Cu content in seagrass Syringodium filiforme collected at a former bombing range in Puerto Rico with those of a Biosphere Reserve under similar geoclimatic conditions. Trace elements were measured by atomic absorption after dry-ashing of samples and extraction with acid. In general, levels of Pb, Cd, and Cu varied during 2001, 2003, 2005-2006, and 2013-2016. Results showed that bioaccumulated concentration of these trace elements were consistently higher, but not significant, at the bombing range site. As expected in polluted areas, greater variability in Pb and Cd content were observed in the military impacted site with levels up to 14 and 17 times higher than seagrass from the reference site, respectively. Although a decrease in Pb was observed after cessation of all military activities in 2003, the concentration in plant biomass was still above levels of ecological concern, indicating that natural attenuation is insufficient for cleanup of the site.
RESUMEN
Amphibian populations have been declining worldwide and the exact mechanisms underlying these changes are not well understood. We examined environmentally induced phenotypic changes that may reflect ongoing stresses on individuals and therefore their ability to persist in increasingly changing landscapes. Specifically, we evaluated the contribution of habitat loss on the size, allometry, and levels of fluctuating asymmetry of Eleutherodactylus antillensis and E. coqui, 2 common species that are endemic to Puerto Rico. We x-rayed frogs collected at 9 sites that differed in the amount of forest cover and measured their snout-vent, radio-ulna, femur, and tibio-fibula lengths. E. antillensis and E. coqui were smaller in the highly disturbed (< or =20% forest cover) than in the intermediately (20-70% forest cover) and little-disturbed (> or =70% forest cover) landscapes. In E. antillensis but not in E. coqui, the slope and intercept of the curves relating snout-vent length with the length of the 3 bones differed with degree of forest cover, suggesting an effect of habitat loss on body shape. In E. antillensis and E. coqui, differences between right and left sides corresponded to true fluctuating asymmetry; however, only the radio-ulna length of E. coqui showed a trend toward an increase in fluctuating asymmetry with habitat loss. Because body size scales with a variety of physiological, life history, and ecological traits, conservation programs aimed at monitoring morphological changes in amphibians may help in understanding the mechanisms that contribute to their persistence in changing environments.