A Contemporary,Sex‐Limited Change in Body Size of an Estuarine Turtle in Response to Commercial Fishing

Abstract: Juvenile growth rate and adult body size are important components of life‐history strategies because of their direct impact on fitness. The diamondback terrapin (Malaclemys terrapin) is a sexually dimorphic, long‐lived turtle inhabiting brackish waters throughout the Atlantic and Gulf coasts of the United States. In parts of its range, terrapins face anthropogenically imposed mortality: juveniles of both sexes inadvertently enter commercial crab traps and drown. For adult females, the carapace eventually grows large enough that they cannot enter traps, whereas males almost never reach that critical size. We compared age structure, carapace dimensions, growth curves, and indices of sexual dimorphism for a Chesapeake Bay population of terrapins (where mortality of turtles is high due to crab traps) with contemporary terrapins from Long Island Sound and museum specimens from Chesapeake Bay (neither group subject to commercial crab traps). We also calculated the allochronic and synchronic rates of evolutionary change (haldanes) for males and females to measure the rate of trait change in a population or between populations, respectively. We found a dramatic shift to a younger male age structure, a decrease in the length of time to terminal female carapace size, a 15% increase in female carapace width, and an increase in sexual dimorphism in Chesapeake Bay. In a new twist, our results implicate a fishery in the selective increase in size of a reptilian bycatch species. These sex‐specific changes in life history and demography have implications for population viability that need to be considered when addressing conservation of this threatened turtle.     

Estimating the extent and structure of trade in horticultural orchids via social media

The wildlife trade is a lucrative industry involving thousands of animal and plant species. The increasing use of the internet for both legal and illegal wildlife trade is well documented, but there is evidence that trade may be emerging on new online technologies such as social media. Using the orchid trade as a case study, we conducted the first systematic survey of wildlife trade on an international social‐media website. We focused on themed forums (groups), where people with similar interests can interact by uploading images or text (posts) that are visible to other group members. We used social‐network analysis to examine the ties between 150 of these orchid‐themed groups to determine the structure of the network. We found 4 communities of closely linked groups based around shared language. Most trade occurred in a community that consisted of English‐speaking and Southeast Asian groups. In addition to the network analysis, we randomly sampled 30 groups from the whole network to assess the prevalence of trade in cultivated and wild plants. Of 55,805 posts recorded over 12 weeks, 8.9% contained plants for sale, and 22–46% of these posts pertained to wild‐collected orchids. Although total numbers of posts about trade were relatively small, the large proportion of posts advertising wild orchids for sale supports calls for better monitoring of social media for trade in wild‐collected plants.     

Evolutionary Distinctiveness,Threat Status,and Ecological Oddity in Primates

Abstract: The EDGE (evolutionarily distinct and globally endangered) conservation program ( http://www.edgeofexistence.org ) uses a composite measure of threat and phylogenetic isolation to rank species for conservation attention. Using primates as a test case, we examined how species that rank highly with this metric represent the collective from which they are drawn. We considered the ecological and morphological traits, including body mass, diet, terrestriality, and home range size, of all 233 species of primates. Overall, EDGE score and the level of deviance from the mean of 20 different ecological, reproductive, and morphological variables were correlated (mean correlation r =0.14, combined p =1.7 × 10^?14). Although primates with a high EDGE score had characteristics that made them seem odd, they did not seem to express more ancestral characteristics than expected. Sets of primate species with high EDGE scores will, therefore, collectively capture a broader than expected range of the biology of the clade. If similar patterns hold in other groups, the EDGE metric may be useful for prioritizing biodiversity for conservation.     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Hunting Effects on Favourable Conservation Status of Highly Inbred Swedish Wolves

The wolf (Canis lupus) is classified as endangered in Sweden by the Swedish Species Information Centre, which is the official authority for threat classification. The present population, which was founded in the early 1980s, descends from 5 individuals. It is isolated and highly inbred, and on average individuals are more related than siblings. Hunts have been used by Swedish authorities during 2010 and 2011 to reduce the population size to its upper tolerable level of 210 wolves. European Union (EU) biodiversity legislation requires all member states to promote a concept called “favourable conservation status” (FCS) for a series of species including the wolf. Swedish national policy stipulates maintenance of viable populations with sufficient levels of genetic variation of all naturally occurring species. Hunting to reduce wolf numbers in Sweden is currently not in line with national and EU policy agreements and will make genetically based FCS criteria less achievable for this species. We suggest that to reach FCS for the wolf in Sweden the following criteria need to be met: (1) a well‐connected, large, subdivided wolf population over Scandinavia, Finland, and the Russian Karelia‐Kola region should be reestablished, (2) genetically effective size (N_e) of this population is in the minimum range of N_e = 500–1000, (3) Sweden harbors a part of this total population that substantially contributes to the total N_e and that is large enough to not be classified as threatened genetically or according to IUCN criteria, and (4) average inbreeding levels in the Swedish population are <0.1. Efectos de la Cacería sobre el Estatus de Conservación Favorable de Lobos Suecos con Endogamia Alta     

Genetic Bottlenecks Driven by Population Disconnection

Abstract: Connectivity among populations plays a crucial role in maintaining genetic variation at a local scale, especially in small populations affected strongly by genetic drift. The negative consequences of population disconnection on allelic richness and gene diversity (heterozygosity) are well recognized and empirically established. It is not well recognized, however, that a sudden drop in local effective population size induced by such disconnection produces a temporary disequilibrium in allelic frequency distributions that is akin to the genetic signature of a demographic bottleneck. To document this effect, we used individual‐based simulations and empirical data on allelic richness and gene diversity in six pairs of isolated versus well‐connected (core) populations of European tree frogs. In our simulations, population disconnection depressed allelic richness more than heterozygosity and thus resulted in a temporary excess in gene diversity relative to mutation drift equilibrium (i.e., signature of a genetic bottleneck). We observed a similar excess in gene diversity in isolated populations of tree frogs. Our results show that population disconnection can create a genetic bottleneck in the absence of demographic collapse.     

Combining Measures of Dispersal to Identify Conservation Strategies in Fragmented Landscapes

Abstract: Understanding the way in which habitat fragmentation disrupts animal dispersal is key to identifying effective and efficient conservation strategies. To differentiate the potential effectiveness of 2 frequently used strategies for increasing the connectivity of populations in fragmented landscapes—corridors and stepping stones—we combined 3 complimentary methods: behavioral studies at habitat edges, mark‐recapture, and genetic analyses. Each of these methods addresses different steps in the dispersal process that a single intensive study could not address. We applied the 3 methods to the case study of Atrytonopsis new species 1, a rare butterfly endemic to a partially urbanized stretch of barrier islands in North Carolina (U.S.A.). Results of behavioral analyses showed the butterfly flew into urban and forested areas, but not over open beach; mark‐recapture showed that the butterfly dispersed successfully through short stretches of urban areas (<500 m); and genetic studies showed that longer stretches of forest (>5 km) were a dispersal barrier, but shorter stretches of urban areas (≤5 km) were not. Although results from all 3 methods indicated natural features in the landscape, not urbanization, were barriers to dispersal, when we combined the results we could determine where barriers might arise: forests restricted dispersal for the butterfly only when there were long stretches with no habitat. Therefore, urban areas have the potential to become a dispersal barrier if their extent increases, a finding that may have gone unnoticed if we had used a single approach. Protection of stepping stones should be sufficient to maintain connectivity for Atrytonopsis new species 1 at current levels of urbanization. Our research highlights how the use of complementary approaches for studying animal dispersal in fragmented landscapes can help identify conservation strategies.     

Genotoxicity of chromium in vitro on yeast: Interaction with DNA†

The genotoxicity of chromium chloride was investigated in cells of D₇ strain of Saccharomyces cerevisiae harvested either from logarithmic or stationary growth phase.

A weak induction of mifotic gene conversion and point reverse mutation was obtained when the incubations were performed using phosphate buffer. No genetic effect was observed when the incubations were performed using Tris‐HCl buffer.

The experiments with ⁵¹Cr radiotracer demonstrated that Cr³⁺ ion enters the yeast cells and binds to DNA even if the incubation mixture was performed with Tris HCl buffer. This behaviour could be due to the highest concentration of CrCl₃ that cause some damages to cytoplasmatic membrane.     

Effects of Dam‐Induced Landscape Fragmentation on Amazonian Ant–Plant Mutualistic Networks

Mutualistic networks are critical to biological diversity maintenance; however, their structures and functionality may be threatened by a swiftly changing world. In the Amazon, the increasing number of dams poses a large threat to biological diversity because they greatly alter and fragment the surrounding landscape. Tight coevolutionary interactions typical of tropical forests, such as the ant–myrmecophyte mutualism, where the myrmecophyte plants provide domatia nesting space to their symbiotic ants, may be jeopardized by the landscape changes caused by dams. We analyzed 31 ant–myrmecophyte mutualistic networks in undisturbed and disturbed sites surrounding Balbina, the largest Central Amazonian dam. We tested how ant–myrmecophyte networks differ among dam‐induced islands, lake edges, and undisturbed forests in terms of species richness, composition, structure, and robustness (number of species remaining in the network after partner extinctions). We also tested how landscape configuration in terms of area, isolation, shape, and neighborhood alters the structure of the ant–myrmecophyte networks on islands. Ant–myrmecophytic networks were highly compartmentalized in undisturbed forests, and the compartments had few strongly connected mutualistic partners. In contrast, networks at lake edges and on islands were not compartmentalized and were negatively affected by island area and isolation in terms of species richness, density, and composition. Habitat loss and fragmentation led to coextinction cascades that contributed to the elimination of entire ant–plant compartments. Furthermore, many myrmecophytic plants in disturbed sites lost their mutualistic ant partners or were colonized by opportunistic, nonspecialized ants. Robustness of ant–myrmecophyte networks on islands was lower than robustness near lake edges and in undisturbed forest and was particularly susceptible to the extinction of plants. Beyond the immediate habitat loss caused by the building of large dams in Amazonia, persistent edge effects and habitat fragmentation associated with dams had large negative effects on animal–plant mutualistic networks. Efectos de la Fragmentación del Paisaje Inducida por Presas sobre Redes Mutualistas Hormiga‐Planta Amazónicas