Biology

Changes in reproductive state or the environment may affect the sensitivity of the hypothalamicpituitary-andrenal (HPA) axis. However, little is
known about the dynamics of the resulting corticosteroid stress response, in particular in tropical mammals. In this study, we address the modulation of
corticosterone release in response to different reproductive conditions and seasonality in 326 free-living
common fruit-eating bats (Artibeus jamaicensis) on
Barro Colorado Island in Panama during dry and wet
seasons. We present strong evidence that stress sensitivity is primarily modulated by reproductive condition. In reproductively active females, corticosterone
increases were more rapid and reached higher levels,
but also decreased significantly faster than in inactive
females. The corticosterone response was weaker in
reproducing males than in females and delayed compared to non-reproductive males. Testes volume in
reproductively active males was negatively correlated
with corticosterone concentrations. Our findings suggest differentiated dynamics in the corticosterone stress
response between sexes, potentially reflecting conflicting ecological demands. In females, a strong acute
corticosterone response may represent high stress- and
risk-sensitivity that facilitates escape and thus helps to
protect reproduction. In males, suppression during
reproductive activity could reflect lowered stress sensitivity to avoid chronically elevated corticosterone
levels in times of frequent aggressive and therefore
costly inter-male encounters.

Approved: ______________________________________________________ Giovanna Rosenlicht Social behavior such as play, affiliation, and some vocalizations of captive animals can be indicators of good welfare. Cheetahs (Acinonyx jubatus) at the Cheetah Conservation Fund (CCF) near Otjiwarongo, Namibia are often housed in social groups with various backgrounds. Observations of social and active behaviors were recorded for a group of four hand-raised (HR) cheetahs and of five wild-caught (WC) cheetahs (≥ 5 months old

In alpine Australia, Orthoptera are abundant, dominant herbivores, important prey species, and hosts for parasites and parasitoids. Despite the central role of orthopterans in alpine ecosystems, the impact of parasites on orthopteran populations is under-explored. In this study we describe the relationship between parasite prevalence and host sex, body size and year of collection. We accessed an existing, preserved collection of 640 Kosciuscola tristis collected from across its range between 2007 and 2011. Upon dissection we collected juvenile parasites and used molecular tools to identify them to three families (Nematoda; Mermithidae, and Arthropoda: Diptera: Tachinidae and Sarcophagidae). The prevalence of nematodes ranged from 3.5% to 25.0% and dipterans from 2.4% to 20.0%. Contrary to predictions, we found no associations between parasite prevalence and grasshopper sex or size. Although there was an association between prevalence of both nematodes and dipterans with year of coll...

In alpine Australia, Orthoptera are abundant, dominant herbivores, important prey species, and hosts for parasites and parasitoids. Despite the central role of orthopterans in alpine ecosystems, the impact of parasites on orthopteran populations is under-explored. In this study we describe the relationship between parasite prevalence and host sex, body size and year of collection. We accessed an existing, preserved collection of 640 Kosciuscola tristis collected from across its range between 2007 and 2011. Upon dissection we collected juvenile parasites and used molecular tools to identify them to three families (Nematoda; Mermithidae, and Arthropoda: Diptera: Tachinidae and Sarcophagidae). The prevalence of nematodes ranged from 3.5% to 25.0% and dipterans from 2.4% to 20.0%. Contrary to predictions, we found no associations between parasite prevalence and grasshopper sex or size. Although there was an association between prevalence of both nematodes and dipterans with year of collection, this is likely driven by a small sample size in the first year. Our results provide a foundation for future studies into parasite prevalence within the alpine environment and the abiotic factors that might influence these associations.