Jon Havenhand researches the evolutionary ecology of reproduction in marine invertebrates, focussing on intra-specific variation in fertilization and larval viability and the role of ocean acidification.
Description of research activities
Jon Havenhand’s research focuses on the evolution of early life-history characteristics in marine invertebrates. This ranges from investigations of gamete-compatibilties in broadcast-spawning species, to the selective benefits of different larval forms.
Fertilization and Larval Ecology of marine invertebrates
The majority of marine animals release their gametes freely into the water-column, where they fertilize, and develop. This process is neither simple nor risk-free: gametes can face many difficulties locating each other and fertilizing successfully. Gamete dilution can be a big problem, but sometimes eggs may also be exposed to too many sperm - leading to death of the embryo. Once gametes have encountered each other successfully, a variety of compatibility mechanisms may determine which individual’s sperm is most likely to bind, penetrate, and fertilize the egg. Not surprisingly, a variety of adaptations have evolved in response to these selective pressures, and much recent theory has focussed on this.
Fertilized embryos also face a number of challenges - not least because they’re usually unprotected and easy prey for many planktivorous predators. In some species embryos may develop rapdily without feeding into larvae that settle and metamorphose within hours of fertilization. In others, embryos develop as longer-term larvae that feed and grow in the plankton for many weeks before settling to the seabed and metamorphosing into a juvenile.
The great variety of larval forms in marine invertebrates was comprehensively classified only 60 years ago by Gunnar Thorson. Since that time the ecology and evolution of reproduction in marine invertebrates has been a focus of research, not least because the different energetic costs, survival probabilities, dispersal capacities and behaviours of these different larval forms have deep significance for population dynamics, gene-flow, and adaptation in marine species. Jon currently works with several closely related aspects of this area:
- patterns, causes and consequences of variation in sperm:egg compatibility
- effects of ocean acidification on early life-history stages of marine invertebrates - including the assessment of non-significant results
- impacts of larval type on the energetics of adult populations
Jon is pursuing these research interests in collaboration with a number of Masters and PhD students as well as several leading international researchers.
