Bees win in survival wars
Hosts and parasites in evolutionary battle over millions of years
Date:
April 5, 2022
Source:
Flinders University
Summary:
Like diseases affecting humans, parasites can wage a deadly
evolutionary 'arms race' against their hosts. But can hosts and
parasites upgrade their weapons at the same rate?
FULL STORY ==========================================================================
Like diseases affecting humans, parasites can wage a deadly evolutionary
"arms race" against their hosts. But can hosts and parasites upgrade
their weapons at the same rate?
==========================================================================
This can be a very unequal battle for two reasons. If the parasite is
too successful it will wipe out its host, and therefore lose its only
means of surviving. At the same time, evolutionary "wars" between hosts
and their parasites depend on their rates of evolution; we can think of
that as their ability to 'upgrade their weapons'.
Flinders University researchers examined this conundrum by examining a
social bee (Exoneura) and its social parasite, another bee (Inquilina).
"These parasitic species spend their entire life cycle within the nest
of the host species and have extreme adaptations to social parasitism,
they are not able to survive without their hosts," says first author Dr
Nahid Shokri- Bousjein in an article in Ecology and Evolution.
The ability of species to adapt to existential challenges depends on
their ability to 'discover' new strategies via random mutations. The more individuals in a species, the greater the likelihood that a favorable
mutation will arise amongst one of them, and that means that species
with larger populations should generally win any "wars" against their
enemies. So what happens when species and their parasites or pathogens
have very different population sizes? "We can see this problem play
out with COVID-19. The virus has a much bigger population size than its
host (us!), so its ability to evolve around our defenses is great,"
says Dr Shokri-Bousjein. "We see this in terms of new COVID variants
emerging and then spreading." But what happens when the pathogen has
very small population sizes? "In our previous studies, we found that the population sizes of the parasite species are an order of magnitude lower
than their host. Surprisingly, our analyses of molecular data showed that
rates of evolution were similar between host and parasite." Flinders University Associate Professor Mike Schwarz says that "evolutionary
wars between species and their enemies may be much more complex than
we have thought. Large population sizes might allow more strategies to
arise, but maybe the critical issue is how effective those strategies
are. Species like these bee social parasites are on the very edge of
survival: they might tell us something about how you can survive when
your very existence is under threat.
There might be some lessons we can learn from these bees as we deal with
the covid-19 pandemic."
========================================================================== Story Source: Materials provided by Flinders_University. Note: Content
may be edited for style and length.
========================================================================== Journal Reference:
1. Nahid Shokri Bousjein, Simon M. Tierney, Michael G. Gardner,
Michael P.
Schwarz. Does effective population size affect rates of molecular
evolution: Mitochondrial data for host/parasite species pairs
in bees suggests not. Ecology and Evolution, 2022; 12 (2) DOI:
10.1002/ece3.8562 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/04/220405092731.htm
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