Characterization of microsatellite DNA markers for the alligator snapping turtle,Macrochelys temminckii

Two trinucleotide and seven tetranucleotide microsatellite loci were isolated from an alligator snapping turtle Macrochelys temminckii. To assess the degree of variability in these nine microsatellite loci, we genotyped 174 individuals collected from eight river drainage basins in the southeastern USA. These markers revealed a moderate degree of allelic diversity (six to 16 alleles per locus) and observed heterozygosity (0.166–0.686). These polymorphic microsatellite loci provide powerful tools for population genetic studies for a species that is afforded some level of conservation protection in every state in which it occurs.     

Extremely long-distance seed dispersal by an overfished Amazonian frugivore

Throughout Amazonia, overfishing has decimated populations of fruit-eating fishes, especially the large-bodied characid, Colossoma macropomum. During lengthy annual floods, frugivorous fishes enter vast Amazonian floodplains, consume massive quantities of fallen fruits and egest viable seeds. Many tree and liana species are clearly specialized for icthyochory, and seed dispersal by fish may be crucial for the maintenance of Amazonian wetland forests. Unlike frugivorous mammals and birds, little is known about seed dispersal effectiveness of fishes. Extensive mobility of frugivorous fish could result in extremely effective, multi-directional, long-distance seed dispersal. Over three annual flood seasons, we tracked fine-scale movement patterns and habitat use of wild Colossoma, and seed retention in the digestive tracts of captive individuals. Our mechanistic model predicts that Colossoma disperses seeds extremely long distances to favourable habitats. Modelled mean dispersal distances of 337-552 m and maximum of 5495 m are among the longest ever reported. At least 5 per cent of seeds are predicted to disperse 1700-2110 m, farther than dispersal by almost all other frugivores reported in the literature. Additionally, seed dispersal distances increased with fish size, but overfishing has biased Colossoma populations to smaller individuals. Thus, overexploitation probably disrupts an ancient coevolutionary relationship between Colossoma and Amazonian plants.     

Frugivores and seed dispersal: mechanisms and consequences for biodiversity of a key ecological interaction

The 5th Symposium on Frugivores and Seed Dispersal, held in Montpellier (France), 13-18 June 2010, brought together more than 220 researchers exemplifying a wide diversity of approaches to the study of frugivory and dispersal of seeds. Following Ted Fleming and Alejandro Estrada's initiative in 1985, this event was a celebration of the 25th anniversary of the first meeting in Veracruz, Mexico. Frugivory and seed dispersal are active research areas that have diversified in multiple directions since 1985 to include evolution (e.g. phylogenetic diversity and dispersal adaptations), physiology (e.g. sensory cues and digestion), landscape ecology (movement patterns), molecular ecology (e.g. gene flow, genetic diversity and structure), community ecology (e.g. mutualistic interaction networks) and conservation biology (effects of hunting, fragmentation, invasion and extinction), among others. This meeting provided an opportunity to assess conceptual and methodological progress, to present ever more sophisticated insights into frugivory in animals and dispersal patterns in plants, and to report the advances made in examining the mechanisms and consequences of seed dispersal for plants and frugivores.     

Predicted distributions and abundances of the sea turtle ‘lost years’ in the western North Atlantic Ocean

Oceanic dispersal characterizes the early juvenile life-stages of numerous marine species of conservation concern. This early stage may be a ‘critical period’ for many species, playing an overriding role in population dynamics. Often, relatively little information is available on their distribution during this period, limiting the effectiveness of efforts to understand environmental and anthropogenic impacts on these species. Here we present a simple model to predict annual variation in the distribution and abundance of oceanic-stage juvenile sea turtles based on species’ reproductive output, movement and mortality. We simulated dispersal of 25 cohorts (1993–2017) of oceanic-stage juveniles by tracking the movements of virtual hatchling sea turtles released in a hindcast ocean circulation model. We then used estimates of annual hatchling production from Kemp's ridley Lepidochelys kempii (n = 3), green Chelonia mydas (n = 8) and loggerhead Caretta caretta (n = 5) nesting areas in the northwestern Atlantic (inclusive of the Gulf of Mexico, Caribbean Sea and eastern seaboard of the U.S.) and their stage-specific mortality rates to weight dispersal predictions. The model's predictions indicate spatial heterogeneity in turtle distribution across their marine range, identify locations of increasing turtle abundance (notably along the U.S. coast), and provide valuable context for temporal variation in the stranding of young sea turtles across the Gulf of Mexico. Further effort to collect demographic, distribution and behavioral data that refine, complement and extend the utility of this modeling approach for sea turtles and other dispersive marine taxa is warranted. Finally, generating these spatially-explicit predictions of turtle abundance required extensive international collaboration among scientists; our findings indicate that continued conservation of these sea turtle populations and the management of the numerous anthropogenic activities that operate in the northwestern Atlantic Ocean will require similar international coordination.     

Birds introduced in new areas show rest disorders

All colonizing individuals have to settle in a novel, conspecific-free environment. The introduction process should be poorly compatible with a good rest. We compared the resting behaviour of radio-tagged house sparrows (Passer domesticus) experimentally translocated into new, conspecific-free areas (introduced individuals, n = 10), with that of translocated sparrows that settled in naturally established populations (controls, n = 5). Resting habits of introduced sparrows markedly differed from those of control birds: they did not vocalize before going to roost, they changed their roosting habitat and they roosted 24 ± 7 min later and departed 13 ± 4 min earlier from the roost, resulting in a 5% rest debt. Because colonizing a new environment is expected to require heightened cognitive and physical activities, which in turn are constrained by the quality and duration of rest, we hypothesize that rest disorders and resulting cognitive impairments of newly released individuals could functionally contribute to the low post-release survival observed in (re)introduction attempts.     

Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic

We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199–397 864) green (Chelonia mydas), loggerhead (Caretta caretta) and Kemp''s ridley (Lepidochelys kempii) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp''s ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp''s ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9–76.3%) of turtles came from Mexico, 14.8% (11–18%) from Costa Rica, 5.9% (4.8–7.9%) from countries in northern South America, 3.4% (2.4–3.5%) from the United States and 1.6% (0.6–2.0%) from West African countries. Thus, the spill''s impacts may extend far beyond the current focus on the northern Gulf of Mexico.     

A genetic survey of heavily exploited, endangered turtles: caveats on the conservation value of trade animals

Asian turtles face an extinction crisis, and so it is imperative that systematists accurately determine species diversity in order to guide conservation strategies effectively. We surveyed mitochondrial and nuclear DNA (mtDNA and nuDNA) variation of the heavily exploited Mauremys mutica complex, a clade of Asian turtles that contains the endangered M. mutica from Japan, Taiwan, China and Vietnam, and the critically endangered Mauremys annamensis from central Vietnam. We discovered extensive mtDNA and nuDNA variation among samples that did not correspond to the currently recognized taxonomy. Both nuDNA and mtDNA data suggest that M. mutica is paraphyletic with respect to M. annamensis . Surprisingly, M. annamensis exhibits a previously unknown mtDNA structure in the form of two clades that are paraphyletic to M. mutica . These data reveal that the currently recognized taxonomy of the mutica complex does not reflect the genetic diversity of our samples. Unfortunately, many conservation-oriented captive-breeding efforts for turtles are also based on trade samples such as the ones studied here. These efforts include plans to breed trade-rescued individuals and release their progeny into the wild. Because our genetic survey reveals that the taxonomic identity of these samples does not reflect genetic diversity, we raise serious questions about the efficacy of these programs. In order to address conservation issues and provide more accurate estimates of evolutionary lineages within Mauremys , we recommend continued surveys for wild populations of the mutica complex to provide new genetic material and additional distributional data, attempts to extract DNA from historic museum specimens and a shift in conservation focus to in situ preservation of wild populations and associated habitat.     

On a collision course: competition and dispersal differences create no-analogue communities and cause extinctions during climate change

Most climate change predictions omit species interactions and interspecific variation in dispersal. Here, we develop a model of multiple competing species along a warming climatic gradient that includes temperature-dependent competition, differences in niche breadth and interspecific differences in dispersal ability. Competition and dispersal differences decreased diversity and produced so-called 'no-analogue' communities, defined as a novel combination of species that does not currently co-occur. Climate change altered community richness the most when species had narrow niches, when mean community-wide dispersal rates were low and when species differed in dispersal abilities. With high interspecific dispersal variance, the best dispersers tracked climate change, out-competed slower dispersers and caused their extinction. Overall, competition slowed the advance of colonists into newly suitable habitats, creating lags in climate tracking. We predict that climate change will most threaten communities of species that have narrow niches (e.g. tropics), vary in dispersal (most communities) and compete strongly. Current forecasts probably underestimate climate change impacts on biodiversity by neglecting competition and dispersal differences.