10.5061/DRYAD.FTTDZ08NR
Chirgwin, Evatt
0000-0002-8242-3837
Monash University
Data from: Physical and physiological impacts of ocean warming alter
phenotypic selection on sperm morphology
Dryad
dataset
2019
external fertilisation
gametes
Marine invertebrates
Viscosity
2019-11-18T00:00:00Z
2019-11-18T00:00:00Z
en
https://doi.org/10.1111/1365-2435.13483
98431 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Global warming may threaten fertility, which is a key component of
individual fitness and vital for population persistence. For males,
fertility relies on the ability of sperm to collide and fuse with eggs;
consequently, sperm morphology is predicted to be a prime target of
selection owing to its effects on male function. In aquatic environments,
warming will expose gametes of external fertilisers to the physiological
effects of higher temperature and the physical effects of lower viscosity.
However, the consequences of either effect for fertility, and for
selection acting on sperm traits to maintain fertility, are poorly
understood. Here, we test how independent changes in water temperature and
viscosity alter male fertility and selection on sperm morphology in an
externally-fertilising marine tubeworm. To create five fertilisation
environments, we manipulate temperature to reflect current-day conditions
(16.5°C), projected near-term warming (21°C), and projected long-term
warming (25°C), then adjust two more environments at 21°C and 25°C to the
viscosity of environments at 16.5°C and 21°C, respectively. We then use a
split-ejaculate design to measure the fertility of focal males, and
selection on their sperm, in each environment. Projected changes in
temperature and viscosity act independently to reduce male fertility, but
act jointly to alter selection on sperm morphology. Specifically,
environments resulting from projected warming alter selection on the sperm
midpiece in ways that suggest shifts in the energetic challenges of
functioning under stressful conditions. Selection also targets sperm head
dimensions and tail length, irrespective of environment. We provide the
first evidence that projected changes in ocean temperature and viscosity
will not only impact the fertility of marine external fertilisers, but
expose their gametes to novel selection pressures that may drive them to
adapt in response if gamete phenotypes are sufficiently heritable.