Biology subjects

Head, M. L.

Publications and source records attributed to Head, M. L..

3 recordsLinked to original sources

bioRxiv2024

Does early-life food shortage alter the effect of elevated temperature on female life history?

O_LIGlobal warming is reducing prey availability in many aquatic systems, raising questions about the combined effects of higher temperatures and lower food availability on fish life histories and reproductive output. C_LIO_LIIn ectotherms, higher temperatures accelerate growth and promote an earlier onset of reproduction. However, when fish have less food during development, resource depletion might constrain these temperature-driven processes. C_LIO_LIWe manipulated water temperature (24 or 28{degrees}C) and early-life food availability (control or restricted) for female guppies (Poecilia reticulata). We measured how both factors affected key life history traits (growth, reproduction, survival, self-maintenance). C_LIO_LIHigher temperature significantly affected female life histories. Females at 28{degrees}C matured at a larger size, but then grew more slowly and produced fewer, smaller offspring than females at 24{degrees}C. The effect of temperature on reproduction persisted even after controlling for body size, suggesting there was a shift in the fecundity-size relationship. C_LIO_LIAdult mortality was greater at 28{degrees}C. Higher temperature also resulted in a longer gut, potentially enhancing resource acquisition, but a higher temperature did not affect immunity or telomere length of the surviving females. C_LIO_LIEarly-life food shortage affected very few traits, except for a weak interaction with temperature that affected total fecundity. At 28{degrees}C, females that experienced early-life food restriction produced fewer offspring than females with continual food supply. No such diet effect occurred at 24{degrees}C. C_LIO_LIOur results suggest that tropical fish may be severely impacted by increased temperatures (i.e., decreased reproduction with increased morality), but are likely to be resilient to brief periods of food limitations during early development. C_LIO_LIInterestingly, early-life food shortage caused a reduction in total offspring number but only at 28{degrees}C, suggesting that global prey decline might exacerbate the negative effects of a warming climate on stock recruitment of tropical fish. C_LI

ecology↗

bioRxiv2024

Effects of inbreeding and elevated rearing temperatures on strategic sperm production

Males often strategically modify their rate of sperm production based on the social context, but it remains unclear how environmental and genetic factors shape this plasticity. In freshwater ecosystems, high ambient temperatures often lead to isolated pools of hotter water in which inbreeding occurs. Higher water temperatures and inbreeding can impair fish development, potentially disrupting sperm production. We used guppies (Poecilia reticulata) to investigate how developmental temperature (26 {degrees}C or 30 {degrees}C) and male inbreeding status (inbred, outbred) influence sperm production in the absence or presence of a female (i.e., sperm priming response). We also tested if sperm priming was affected by whether the female was a relative (sister), and whether she was inbred or outbred. A higher rearing temperature had no effect on the rate of sperm production or the priming response. Inbred males produced significantly more sperm in the presence of an unrelated, outbred female than when no female was present. Conversely, outbred males did not alter sperm production in response to female presence or relatedness. In addition, inbred males showed marginally greater sperm production when exposed to an unrelated female that was outbred rather than inbred, but no difference when exposed to an inbred female that was unrelated versus related. Together, only inbred males increased sperm production in response to the presence of a female, but this depended on her being outbred. This suggests stronger sexual selection on inbred males to allocate ejaculate resources, perhaps due to greater benefits when mating with outbred females in better condition.

evolutionary biology↗

bioRxiv2020

The role of maternal effects on offspring performance in familiar and novel environments

Maternal effects are an important evolutionary force that may either facilitate adaptation to a new environment or buffer against unfavourable conditions. The degree of variation in traits expressed by siblings from different mothers is frequently sensitive to environmental conditions. This could generate a Maternal-by-Environment interaction (MxE) that could inflate estimates of Genotype-by-Environment effects (GxE). We aimed to test for environment-specific maternal effects (MxE) using a paternal full-sib/half-sib breeding design in the seed beetle Callosobruchus maculatus, where we split and reared offspring from the same mother on two different bean host types - original and novel. Our quantitative genetic analysis indicated that maternal effects were very small on both host types for all the measured life-history traits. There was also little evidence that maternal oviposition preference for a particular host type predicted her offsprings performance on that host. Further, additive genetic variance for most traits was relatively high on both hosts. While there was higher heritability for offspring reared in the novel host, there was no evidence for GxEs, and most cross-host genetic correlations were positive. This suggests that offspring from the same family ranked similarly for performance on both host types. Our results point to a genetic basis of host adaptation in the seed beetle, rather than maternal effects. Even so, we encourage researchers to test for potential MxEs because, due to a lack of testing, it remains unclear how often they arise.

evolutionary biology↗