Climate change makes seals more genetically diverse: Lack of food is causing pups to be smaller and less likely to survive
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Climate change is making Antarctic seals more genetically diverse, according to new research.
Scientists found because food is getting scarcer, pups are born smaller and those that survive are breeding later.
However, female seals with less diverse genes are breeding more and their pups are less likely to survive in the changing environment.
Climate change is making Antarctic seals (stock image pictured) more genetically diverse, claims study Scientists found because food is getting scarcer, pups are born smaller and those that survive are breeding later. And, female seals with less diverse genes are breeding more and their pups are less likely to survive
A genetic analysis found Antarctic fur seals have dramatically altered in shape because of the drop in availability of tiny krill which they feast on.
STUDYING THE DIVERSITY OF SEALS
The researchers looked at data going back to 1981 to assess changes over generations of female fur seals on South Georgia in the South Atlantic Ocean.
Females who did survive to motherhood were likely to be more genetically diverse - a condition known scientifically as 'heterozygous' and linked with higher fitness in many species.
But their pups will only have the same advantage if they too are heterozygous - a characteristic not inherited.
It depends on which male the female mates with and so arises mostly through chance.
So, many seals are born not heterozygous and are so less able to cope with the changing environment.
Krill rely on the plankton which grows on the shrinking sea ice.
Dr Jaume Forcada, of the British Antarctic Survey, said: 'Compared with 20 years ago, we can see female fur seals are now born with a lower weight.
'Those that survive and return to breed tend to be the bigger ones and they have their first pup later in life than they used to.
'Such changes are typically associated with food stress.'
Decades of data collected at South Georgia show how changes in the seal population have occurred over time with changes in krill availability.
Even if krill is very abundant, environmental variation determines its availability in the seals' feeding grounds, claim the researchers.
The researchers looked at data going back to 1981 to assess changes over generations of female fur seals. Females who did survive to motherhood were likely to be more genetically diverse and linked with higher fitness. But their pups only have the same advantage if they too have these genes
'This environmental variation is driven by the climate which impacts local atmospheric, sea ice and oceanographic conditions.'
Environmental change is expected to affect many species and biological systems throughout the world so the study, published in Nature, could have relevance for other threatened creatures.
Dr Joe Hoffman, of Bielefeld University in Germany, said: 'We found over the last two decades the proportion of breeding females highly heterozygous has increased as these individuals are more likely to survive the changing conditions.
'However in this case the seals do not appear to be evolving because surviving females do not pass their high heterozygosity on to their offspring.
'Therefore - with each new generation - the process of selection has to start all over again with only those individuals that happen to be born more heterozygous having a good chance of survival.
'As the climate continues to change many fur seal pups are not surviving to adulthood and the population is declining.'
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