Reproduction in a changing world: how do rising temperatures affect reproductive capacity?

• Applicant: Dr. Claudia Fricke
• Subject Area: Evolution, Anthropology
• Term: from 2017 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 386851856

Climate change poses a major threat to biodiversity and we are just beginning to see the first signs of its impact on species distribution, persistence and phenology. In ectotherms behaviour, physiology and distribution of species are profoundly affected by temperature and this group of animals is expected to be particularly vulnerable to rising temperatures. While ecological and phenological consequences of rising temperatures have been studied, have we largely failed to investigate the impact on reproduction. It is well known that particularly male fertility can be severely affected by temperature, however the ecological and evolutionary consequences of this temperature induced sterility have rarely been considered. Often though male fertility is disproportionately affected and sterility occurs at temperatures below those impairing somatic function in animals. Thus individuals can suffer from impaired reproduction before they are physically affected by high temperatures. With this research program I want to rectify this important gap in our knowledge and investigate a) how species adapted to different environments differ in their sensitivity of temperature-induced infertility; b) what are the underlying molecular mechanisms of this temperature-induced infertility; c) are males and females similarly affected and d) whether this sensitivity can evolve such that males can maintain fertility even under rising temperatures. I will achieve these goals by performing experiments using three Drosophila species measuring male and female reproductive success at different temperatures. I will combine phenotypic assays of male fertilisation success at different temperatures with a proteomics approach to elucidate the underlying molecular basis. I will further conduct an experimental evolution study exposing Drosophila melanogaster to different thermal regimes and measure the resulting phenotypic and genetic changes. This research program will provide an estimate of temperature dependent changes in male and female fecundity and investigate the phenotypic expression and genetic basis of this phenomenon. Estimating potential impairments in male and female fecundity is vital for a better understanding of long-term effects on individual fitness and at the population level. These data will not only inform us of the vulnerability of a basic biological process to rising temperatures but also whether temperature dependent reduction in male fertility might threaten species persistence.

• DFG Programme: Research Grants