Grant: Discovery Grants Program - Individual

We have a poor understanding of when and how natural selection modifies the outcome of sexual selection (their interaction). This makes it difficult to predict the product of selection, a problem that is exacerbated under environmental perturbation. My long-term objective is to illuminate how natural selection via abiotic conditions and sexual selection through both males and females interact to influence gamete ecology and evolution.******Males take risks to potentially mate and winners may be so successful that they become sperm deficient, yet due to post-copulatory sexual selection many fail to sire offspring. Sexual selection operates in both internal and external fertilizers, but external sperm also encounter natural selection, via variable abiotic conditions that modulate sperm behaviour. The interaction between sexual and natural selection at the gamete level is unexplored. Can males cheat female strategies? Can males influence sperm performance of rivals? Does any of this depend on abiotic conditions? ******Using external fertilizers, my research examines the interactions between male and female gametes experiencing both sexual and natural selection in the fertilization micro-environment. The research transcends species and provides insight into reproductive dynamics that have ecological (recruitment), evolutionary (hybridization) and conservation (captive breeding) implications.******Progress will be achieved from 3 short-term objectives:******(1) Males produce more sperm than are necessary for fertilization and for unknown reasons there is great within-ejaculate variation in sperm form and function. A fertilization tradeoff exists between sperm swimming speed and longevity, and these different sperm can influence offspring quality. However whether such patterns are influenced by abiotic conditions in external fertilizers is not known. My team will determine if sperm that maintain swimming longevity under stressful conditions produce superior quality offspring.******(2) Recent discoveries of chemically modified sperm behaviour include female-cue mediated conspecific sperm preferences. We do not know how pliable the underpinnings of this are and thus the overall evolutionary importance. We will determine if mechanisms have costs and breakdown in populations where they are not needed, whether interactions with stressful abiotic conditions destroy sexual selection, and whether patterns are so evolutionarily important that they evolve at the intraspecific level.******(3) The importance of seminal fluid chemistry to a male's sperm function is known for some internal fertilizers, but how one's seminal fluid influences other individuals is poorly understood. We will determine if seminal fluid alters processes of female mediated sperm competition, and if males that are chosen mates evolve mechanisms to reduce paternity of sneaker males that use alternative reproduction strategies.