In the absence of genetic variation, asexual invasive species find new
methods of adapting to their environment

Date:
July 30, 2021
Source:
Wellesley College
Summary:
New research has found that two types of weevils, common yet
invasive beetles in many parts of the world, have been using
epigenetic changes to adapt and respond to different toxins in
the plants they eat. The findings have implications for how we
consider asexual invaders and how successful they can be because
of gene regulation.



FULL STORY ========================================================================== Without the benefits of evolutionary genetic variation that accompany
meiotic reproduction, how does an asexual invasive species adapt over
time to a new environment to survive? In all-female weevil species that
produce only female offspring from unfertilized eggs, the insects'
survival techniques have led to the surprising discovery that these
creatures can pass down gene regulation changes to future generations.


==========================================================================
New research from Wellesley College has found that two types of weevils,
common yet invasive beetles in many parts of the world, have been using epigenetic changes to adapt and respond to different toxins in the
plants they eat. The findings, published in PLOS ONE under the title "Host-Specific Gene Expression as a Tool for Introduction Success
in Naupactus Parthenogenetic Weevils," have implications for how we
consider asexual invaders and how successful they can be because of
gene regulation.

The researchers, led by Andrea Sequeira, Wellesley College Gordon and
Althea Lang '26 Professor of Biological Sciences, collected samples of parthenogenetic, invasive, and polyphagous weevils, Naupactus cervinus
and N.

leucoloma, from Florida, California, and Argentina over the course of five years, starting in 2015. Despite being from different locations within
the United States where they have been introduced, often through commerce,
the weevils are asexual and genetically identical. Yet the team found that
they have uniquely adapted to produce different proteins that allow them
to eat and digest a variety of plants, even those that produce toxins.

Sequeira worked with a talented team: Ava Mackay-Smith, Mary Kate Dornon, Rosalind Lucier, Anna Okimoto, and Flavia Mendonca de Sousa from Wellesley College, and Marcela Rodriguero, Viviana Confalonieri, Analia Lanteri from
the University of Buenos Aires and the Museo de Ciencias Naturales in La
Plata, Argentina. Together, they analyzed patterns of gene expression in
three gene categories that can mediate weevil-host plant interactions
through identification of suitable host plants, short-term acclimation
to host plant defenses, and long-term adaptation to host plant defenses
and their pathogens.

"We found that some host plant groups, such as legumes, appear to be
more taxing for weevils and elicit a complex gene expression response," Sequeira said. "However, the weevil response to taxing host plants shares
many differentially expressed genes with other stressful situations,
such as organic cultivation conditions and transition to novel hosts, suggesting that there is an evolutionarily favorable shared gene
expression regime for responding to different types of stressful
situations." "We also found that mothers are able to 'prime' their
young with these epigenetic changes," lead author and 2020 Wellesley
College alumna Ava Mackay- Smith said. "Originally, we thought that
these changes would only be seen in a single generation. When we studied larvae, who do not yet have mouths or eat plants, we found evidence of
the same proteins and adaptations from their mothers." Sequeira noted
this finding is especially important because classic understanding has
been that in both sexual and asexual reproduction, all epigenetic marks
are erased between generations and each generation starts over.

Mackay-Smith believes that having a better understanding of epigenetic
changes in invasive, asexual species may eventually help regulate or
mitigate their potential negative impact on an environment, native plants,
or crops, for example. "Knowing what is in this insect's repertoire,
you could imagine that since we've now identified the proteins that
are regulated differently, you could target a specific protein and
design a targeted pesticide that removes only that species of weevil,
without harming other native insects or fauna." Both Mackay-Smith and
Sequeira are excited to see that perhaps genetic variation is not the
only form of heritable variation for natural selection to act upon and
that epigenetic processes may increase the evolutionary potential of
organisms in response to stress and other environmental challenges - - adaptations that could be relevant in the context of climate change.

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


========================================================================== Journal Reference:
1. Ava Mackay-Smith, Mary Kate Dornon, Rosalind Lucier, Anna Okimoto,
Flavia
Mendonca de Sousa, Marcela Rodriguero, Viviana Confalonieri,
Analia A.

Lanteri, Andrea S. Sequeira. Host-specific gene expression as a tool
for introduction success in Naupactus parthenogenetic weevils. PLOS
ONE, 2021; 16 (7): e0248202 DOI: 10.1371/journal.pone.0248202 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/07/210730165456.htm

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