Nature study: Ocean life may adapt to climate change, but with hidden
costs
Scientists lead first-of-its-kind evolution experiment on 23 generations
of tiny sea creatures
Date:
March 22, 2022
Source:
University of Vermont
Summary:
A new study shows that some ocean animals may be able evolve
their way out of troubles caused by climate change -- but at a
high cost. By artificially evolving 23 generations of a marine
copepod, Acartia tonsa, a team of scientists found that the tiny
creatures could adapt to the high temperatures and carbon dioxide
levels forecast for the warming oceans. But to get there, the
populations had to spend a lot of their genetic flexibility --
leaving them vulnerable to new stresses, like low food.
FULL STORY ========================================================================== Suppose that we could watch twenty generations of whales or sharks
adapting to climate change -- measuring how they evolve and how their
biology changes as temperatures and carbon dioxide levels rise. That could
tell us a lot about how resilient life in the oceans might be to a warmer world. But it would also take hundreds of years -- not very useful to scientists or policymakers trying to understand our warming world today.
========================================================================== Instead, consider the life of the copepodAcartia tonsa, a tiny and
humble sea creature near the bottom of the food web. It reproduces,
matures, and creates a new generation in about twenty days. Twenty
copepod generations pass in about one year.
A team of six scientists, led by University of Vermont biologist
Melissa Pespeni and postdoctoral scientist Reid Brennan, did just that:
in a first-of- its kind laboratory experiment, they exposed thousands
of copepods to the high temperatures and high carbon dioxide levels
that are predicted for the future of the oceans. And watched as twenty generations passed. Then they took some of the copepods and returned them
to the baseline conditions -- the temperature and CO2 levels that the
first generation started in, which are like ocean conditions today. And
then they kept watching as three more generations passed.
The results, published in the journal Nature Communications, "show that
there is hope," Pespeni says, "but also complexity in how life responds
to climate change." The price of plasticity Her hope comes from the
team's observation that the copepods did not die in the climate-change conditions. Instead, they persisted and even thrived. The scientists --
from UVM; University of Connecticut; GEOMAR Helmholtz Center for Ocean
Research in Germany; and University of Colorado, Boulder -- recorded
many changes in the copepods' genes related to how they manage heat
stress, grow their skeletons in more acidic waters, produce energy,
and other cellular processes affected by climate change. This shows
that these creatures have the capacity in their genetic make-up -- using
the variation that exist in natural populations -- to adapt over twenty generations, evolving to maintain their fitness in a radically changed environment. The team's observations support the idea that copepods --
a globally-distributed group of crustaceans eaten by many commercially important fish species -- could be resilient to the unprecedented rapid
warming and acidification now being unleashed in the oceans by human fossil-fuel use.
The complexity -- "it's a caution, really," Pespeni says -- comes from the team's observation of what happened to the copepods that were returned to
the baseline conditions. These creatures revealed the hidden cost of the earlier twenty generations of adaptation. The flexibility that helped
the copepods to evolve over twenty generations -- what the scientists
call "phenotypic plasticity" -- was eroded when they tried to return to
what had previously been benign conditions. Brought "home," in a sense,
the copepods were less healthy and produced smaller populations. They
were able, after three generations, to re-evolve back to their ancestral conditions -- but they had lost the ability to tolerate limited food
supply and showed reduced resilience to other new forms of stress.
"If copepods or other creatures have to go down this adaptive path --
and spend some of their genetic variation to deal with climate change
-- will they be able to tolerate some new environmental stressor, some
other change in the environment?" Pespeni wonders. Copepods are among a
broad group of species predicted to be resilient to rapid climate change
-- and this new study, supported by the National Science Foundation,
upholds that view.
"But we need to be careful of overly simple models -- about how well
species will do and which ones will persist into the future -- that
look at just one variable," said Reid Brennan who completed this study
in Melissa Pespeni's lab at the University of Vermont and is now at
the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany. And
the scientists' new study of copepods points to a larger truth about
the intricate economy of evolution: There may be unforeseen costs to
quickly evolving in a suddenly-hot world.
========================================================================== Story Source: Materials provided by University_of_Vermont. Original
written by Joshua Brown.
Note: Content may be edited for style and length.
========================================================================== Journal Reference:
1. Reid S. Brennan, James A. deMayo, Hans G. Dam, Michael
B. Finiguerra,
Hannes Baumann, Melissa H. Pespeni. Loss of transcriptional
plasticity but sustained adaptive capacity after adaptation to
global change conditions in a marine copepod. Nature Communications,
2022; 13 (1) DOI: 10.1038/s41467-022-28742-6 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220322150905.htm
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