Page 22 - AWA Vol.42-No.6 issue

FISHERIES AND FISH FARMING

Genetic adaptation to living in warmer waters causes fish

to be obese

Glasgow, said: “Our study is the first
to show the specific genetic changes
caused by adapting to warmer wa-
ters, offering key insights into the im-
pact that climate change could have
on aquatic ecosystems.
“We discovered that while the de-
tailed DNA adaptations to warmer
waters vary between fish popula-
tions, the overall impact of these
changes was similar in all warm
water-adapted fish, with changes to
their body size, appetite and metab-
olism.”

Increasing global temperatures
represent one of the biggest threats to
wildlife, in particular to cold-blood-
ed animals who rely on their environ-
Fish that have adapted to living in ences between those living in cooler ment to regulate their body tempera-
warmer waters show clear physical and warmer waters. The threespine tures. While some fish in the oceans
and genetic differences to fish of the sticklebacks living in warmer waters may be able to migrate to avoid the
same species living at cooler tem- were hyperphagic, a condition that impact of warmer waters, species
peratures. causes excessive hunger and over- in land-locked waters will either be
eating. The geothermal fish also put
New research, led by the University forced to adapt or go extinct.
of Glasgow and published in Nature on more fat stores in the summer in Dr Matthew Brachmann, co-lead
preparation for the winter and hold
Communications, reveals that adap-
tation to warmer waters causes fish onto fat more efficiently during peri- author of the study from the Universi-
to display a range of behaviour and ods of low food availability. ty of Glasgow, said: “Climate change
biological differences including obe- In addition to appearance and be- is already causing rapid tempera-
sity, overeating, and having a lower haviours, the warm water fish also ture increases in our waters, forcing
metabolism. had a range of DNA adaptations. some aquatic life to adapt to survive.
While these genetic changes were However, predicting the extent and
The findings have important impli- impact of adaptation remains chal-
cations for our understanding of the varied across different groups of lenging, as the extremes of global
potential impact of global warming geothermal fish, highlighting the warming have not yet been experi-
unique and unpredictable nature of
on aquatic life.
adaptation to specific environments. enced by most species.
To carry out the study the research However, the research team did dis- “By focusing on indigenous fish
team headed to Iceland, where they cover cellular differences shared by living in different natural water tem-
used the country’s naturally warm all warm water groups. There was peratures in Iceland we have been
geothermal waters as a model for the a key genetic change, at the mapk
impact of climate change. There, the pathway, a signalling mechanism able to show the real-world impact
team studied the threespine stickle- with implications for growth factors of adapting to warmer waters, with
back, a species of fish that common- and stress, was found among all fish adapted populations showing clear
ly lives in both Iceland’s average that had adapted to living in warmer physical, behaviour and genetic
temperature (cooler) waters and its waters, but not in their cold-water changes.”
geothermal waters, where indig- cousins. The geothermal fish also The study, ‘Parallel adaptation to
enous fish have had to adapt to liv- harbour a flipped region of the ge- geothermally-warmed habitats due
ing in unusually warm conditions. nome (inversion) which is not in the to common structural variation and
These warm water conditions reach cold adapted fish that allows them to functional developmental pathways’
upwards of 27.8°C and have been live in geothermally warmed waters. is published in Nature Communica-
described by the researchers as like Both the mapk pathway and the inver- tions. The work was funded by the
‘fish hot tubs’. sion work together to facilitate adap- UKRI Biotechnology and Biological
tation to warming environments.
The researchers studied the be- Sciences Research Council and the
haviour, appearance and genetics Dr Kevin Parsons, co-lead author UKRI Natural Environment Research
of the fish, and found clear differ- of the study from the University of Council. Circle 22 on enquiry card
20 Vol. 42 No. 6