Epigenetic effects of pollution persist for multiple generations in
water fleas

Date:
February 10, 2022
Source:
University of Liverpool
Summary:
A new study has shown that the effects of pollutants can be
transmitted over many generations in water fleas and may persist
long enough to influence the evolutionary process. The research
adds new evidence to the debate on whether environmental influences
can cause heritable changes to an animal's biology.



FULL STORY ==========================================================================
A new study led by University of Liverpool reserchers has shown that the effects of pollutants can be transmitted over many generations in water
fleas and may persist long enough to influence the evolutionary process.


========================================================================== Published in Evolution Letters, the research adds new evidence to the
debate on whether environmental influences can cause heritable changes
to an animal's biology.

Genes passed down from parents to offspring are overlaid by a complex
array of proteins and chemicals that determine how they are expressed -- collectively known as the 'epigenome'.

The epigenome is sensitive to environmental stresses, such as pollution,
which can alter gene expression. Importantly, there is increasing evidence
that these stress-induced changes can be transmitted across generations.

Dr Stewart Plaistow, a Senior lecturer in Evolutionary Biology at the University of Liverpool, explains: "Epigenetic inheritance mechanisms
are controversial in evolutionary biology at the moment because they
provide a possible mechanism for the inheritance of environmental effects alongside traditional Darwinian inheritance.

"Although they are routinely demonstrated in plants they are much more controversial in animals because epigenetic marks are often thought to be
wiped clean during embryo development." In this study, the researchers
looked at one important epigenetic mark, the methylation of cytosine in
DNA, in the water flea Daphnia pulex.



==========================================================================
They demonstrated that exposure of water fleas to low doses of pollutants
had effects on the epigenome that persisted for 15+ generations.

They exposed replicated populations of water fleas to three different freshwater pollutants for 7 months (approximately15 generations),
and then switched half of the populations to clean water for 8 months

15 generations).

They found that all three pollutants led to changes to DNA methylation.

Importantly, some of these changes were detectable not only in the
continually treated Daphnia, but also those that had been switched back
to clean water, implying that these persistent modifications were stably
passed down through the generations, even in the absence of the pollutant.

A follow-up experiment confirmed that three generations after pollutant exposure, phenotypic effects were still detectable.

Dr Ewan Harney, a Marie-Curie fellow at The Institute of Evolutionary
Biology, Barcelona, said: "If these environmentally-induced persistent
changes to the epigenome are able to influence organismal traits like
growth and development, as appears to be the case, epigenetic processes
like DNA methylation may play an important role in rapid adaptation."
Work in the lab is underway to test whether these effects are independent
of genetic background and whether they influence fitness.

The work was funded by the Natural Environment Research Council and
supported by the University's Centre for Genomic Research.

========================================================================== Story Source: Materials provided by University_of_Liverpool. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Ewan Harney, Steve Paterson, He'le`ne Collin, Brian H.K. Chan,
Daimark
Bennett, Stewart J. Plaistow. Pollution induces epigenetic effects
that are stably transmitted across multiple generations. Evolution
Letters, 2022; DOI: 10.1002/evl3.273 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220210084939.htm

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