Apalone spinifera

Abstract: Reptiles display a wide diversity of sex-determining mechanisms ranging from temperature-dependent sex determination (TSD) to genotypic sex determination (GSD) with either male (XY) or female (ZW) heterogamety. Despite this astounding variability, the origin, structure, and evolution of sex chromosomes remain poorly understood. In turtles, TSD is purportedly ancestral while GSD arose multiple times independently. Here we test whether independent (XY or ZW) or morphologically divergent heterogametic sex chromosome systems evolved in tryonichids (Cryptodira) using the GSD spiny softshell turtle, Apalone spinifera, a species with previously unidentified sex chromosomes. A female-specific signal from comparative genomic hybridization (CGH) was detected in a Giemsa/4′,6-diamidino-2-phenylindole faint portion of a microchromosome, indicating the presence of a ZZ/ZW system in A. spinifera. In situ hybridization of a fluorescently labeled 18S rRNA probe identified a large nucleolar organizer region block in the female-specific region of the W (co-localizing with the female-specific CGH signal) and a smaller block on the Z. The heteromorphic ZZ/ZW micro-sex chromosome system detected here is identical to that found in another tryonichid, the Chinese softshell turtle Pelodiscus sinensis, from which A. spinifera diverged ∼95 million years ago. These results reveal a striking sex chromosome conservation in tryonichids, compared to the divergent sex chromosome morphology observed among younger XX/XY systems in pleurodiran turtles. Our findings highlight the need to understand the drivers behind sex chromosome lability and conservation in different lineages and contribute to our knowledge of sex chromosome evolution in reptiles and vertebrates.

Abstract: Several studies have shown that wetland loss and habitat fragmentation can alter diversity and abundance of herpetofauna, but taxonomic attention has been skewed towards amphibians. We assessed responses of aquatic turtles to features at multiple spatial scales in an intensively farmed region of the Midwestern United States. Spatially hierarchical sampling was conducted from 2001 to 2003 in 35 randomly selected 23-km2 cells throughout the upper Wabash River basin in Indiana. Hoop nets were used at wetlands to capture common snapping turtles (Chelydra serpentina serpentina) (n=258), midland painted turtles (Chrysemys picta marginata) (151), eastern spiny softshells (Apalone spinifera spinifera) (70), red-eared sliders (Trachemys scripta elegans) (59), northern map turtles (Graptemys geographica) (27), false map turtles (Graptemys pseudogeographica pseudogeographica) (6), Blanding’s turtles (Emydoidea blandingii) (3), and stinkpot turtles (Sternotherus odoratus) (3). We examined the degree to which these aquatic species were nonrandomly distributed in 14 landscapes. Assemblages of turtles generally were random and the extent of nestedness was influenced by the diversity of landcover, the proportion of grassland, and the total length of roads in each landscape. The occurrence and abundance of several species also were modeled to test hypotheses regarding the importance of site, patch, and landscape-level variables. Red-eared sliders appeared to be most sensitive to habitat fragmentation, whereas painted turtles, snapping turtles, map turtles, and spiny softshells were less affected. Factors at multiple spatial scales affect turtle distributions, suggesting differential responses to landscape fragmentation.

Abstract: The pet-turtle market has grown in recent years and become an important pathway for the introduction of alien species in Europe. The import of Trachemys scripta elegans has been banned by European Commission Regulation due to its species’ expanding territory and negative impact on native species. Since the demand from hobby breeders persists, however, blocking imports of this popular subspecies opens up the possibility for the introduction of other potentially invasive turtles. We determined those turtle species most common in the pet trade within the Czech Republic, which is the most important producer, importer and exporter of ornamental aquatic animals in the EU. The determination of establishment risk for the EU as a whole was then individually evaluated for turtle species based on known establishment models. Chelydra serpentina , Apalone spinifera , Apalone mutica , and Sternotherus odoratus were considered most problematic, because these species have serious establishment risk and are imported to the EU in substantial numbers. Also localities in the EU were identified where probability is highest for establishment of non-native turtles.

Abstract: Leeches are one of the most commonly observed parasites of freshwater turtles. We used baited hoop traps to capture 433 turtles belonging to five species (Apalone spinifera, Chelydra serpentina, Chrysemys picta, Sternotherus odoratus, and Trachemys scripta) to determine the host (species, microclimate use, sex, reproductive stage, and body size) and environmental characteristics (month of capture, turtle abundance, vegetation, turbidity, pond size, and availability of basking structures) that affected leech parasitism in Illinois ponds. Leech prevalence on turtles varied significantly among turtle species, was highest on bottom-walkers and adults, and varied throughout the year. Leech intensity was highest on larger turtles and in turbid ponds. The results from this study display the importance of utilizing turtle assemblages for examining overall trends in host–parasite dynamics, demonstrate the influence of environmental characteristics on leech parasitism, and provide baseline data for future ...