Integrative zoology最新文献

We found that embryonic behavioral thermoregulation could not enhance the thermoregulatory capacity of turtle hatchlings. Our study is not only the first to provide experimental evidence regarding the impact of embryonic behavioral thermoregulation on offspring thermoregulation but also falsifies the play behavior hypothesis that suggests thermotaxis by embryos allows them to practice thermoregulatory tactics at later life stages.

Rising global temperatures have a wide range of effects at organismal, population, and ecosystem levels. Increased winter temperatures are expected to alter the energetics of species that are dormant during this time. Hatchling painted turtles (Chrysemys picta) spend their first ∼8 months in shallow nests on land, where they putatively rely on residual yolk reserves to fuel energetic demands during this period of inactivity before they emerge in the spring. We performed a laboratory experiment to characterize changes in residual yolk quantity in hatchling C. picta and experimentally tested the effect of temperature on residual yolk, hatchling size, and survival over the winter brumation period. We manipulated winter nest temperature by simulating two natural thermal regimes ("low" vs "high" treatments) and one regime that approximates warmer temperatures expected by 2100 ("future" treatment). Because high temperature increases metabolism, we predicted that the future temperature treatment would decrease the amount of residual yolk remaining by the end of winter and reduce hatchling mass and survival. Residual yolk over winter did not differ from that before winter, and the temperature had no effect on the quantity of residual yolk or hatchling survival by the following spring. However, hatchlings that experienced future temperatures lost more mass over winter than those from the other treatments. These results correspond with previous work indicating that residual yolk does not fuel the energetic needs of hatchlings during winter. The effect of future warming temperatures on body mass may have negative consequences during energetically demanding activities during spring emergence and dispersal.

Pavlovian fear conditioning serves as a valuable method for investigating species-specific defensive reactions (SSDRs) such as freezing and flight responses. The present study examines the role of white noise under different experimental conditions. Given that white noise has been shown to elicit both conditional (associative) and unconditional (nonassociative) defensive responses, we compared the response to noise following three separate training conditions: shock-only, white noise paired with shock, and context-only. Results showed that baseline freezing level significantly changed across groups: Both the shock-only group and the white noise paired with shock group froze more than the context-only group on the test day. White noise evoked differential freezing between groups on day 2: The shock-only group froze more than the context-only group although both groups were never exposed to white noise during training. Further, an activity burst triggered by white noise was similar for the shock-only and white noise paired with shock groups during testing, although shock-only group was never exposed to white noise stimuli during training. This aligned with c-fos data, indicating similar c-fos activity levels across different periaqueductal gray (PAG) regions for both shock-only and white noise paired with shock groups. However, the driving force behind c-fos activation-whether freezing, activity burst, or a combination of both-remains uncertain, warranting further analysis to explore specific correlations between SSDRs and c-fos activity within the PAG and related brain areas.