Incubation temperature influences locomotor performance in young wood ducks (Aix sponsa).

Incubation temperature is an important maternal effect in birds that can influence numerous offspring traits. For example, ducklings from eggs incubated at lower temperatures have lower growth rates, protein content, and are in poorer body condition than ducklings from eggs incubated at higher temperatures. Based on these observations, we predicted that incubation temperature would indirectly influence performance through its direct effects on body size. Wood duck (Aix sponsa) eggs were incubated at three ecologically relevant temperatures (35, 35.9, 37°C). After hatching, all ducklings were housed under identical conditions and were subjected to aquatic and terrestrial racing trials at 15 and 20 days posthatch (dph). Contrary to our prediction, incubation temperature did not influence most duckling body size parameters at 15 or 20 dph. However, incubation temperature did have a strong influence on locomotor performance independent of body size and body condition. Ducklings hatched from eggs incubated at the lowest temperature had significantly reduced maximum aquatic swim velocity than ducklings from higher temperatures. Maximum terrestrial sprint velocity followed a similar pattern, but did not differ statistically among incubation treatments. To our knowledge, this is the first study to demonstrate that slight changes in incubation temperature can directly affect locomotor performance in avian offspring and thus provide a significant source of phenotypic variation in natural wood duck populations.

Reproduction, embryonic development, and maternal transfer of contaminants in the amphibian Gastrophryne carolinensis.

Although many amphibian populations around the world are declining at alarming rates, the cause of most declines remains unknown. Environmental contamination is one of several factors implicated in declines and may have particularly important effects on sensitive developmental stages. Despite the severe effects of maternal transfer of contaminants on early development in other vertebrate lineages, no studies have examined the effects of maternal transfer of contaminants on reproduction or development in amphibians. We examined maternal transfer of contaminants in eastern narrow-mouth toads (Gastrophryne carolinensis) collected from a reference site and near a coal-burning power plant. Adult toads inhabiting the industrial area transferred significant quantities of selenium and strontium to their eggs, but Se concentrations were most notable (up to 100 microg/g dry mass). Compared with the reference site, hatching success was reduced by 11% in clutches from the contaminated site. In surviving larvae, the frequency of developmental abnormalities and abnormal swimming was 55-58% higher in the contaminated site relative to the reference site. Craniofacial abnormalities were nearly an order of magnitude more prevalent in hatchlings from the contaminated site. When all developmental criteria were considered collectively, offspring from the contaminated site experienced 19% lower viability. Although there was no statistical relationship between the concentration of Se or Sr transferred to eggs and any measure of offspring viability, our study demonstrates that maternal transfer may be an important route of contaminant exposure in amphibians that has been overlooked.