Evolution makes the world less ragged

Date:
July 9, 2020
Source:
University of Connecticut
Summary:
How does evolution impact ecological patterns? It helps smooth out
the rough edges, say researchers. A new review of the history of
ecological and evolutionary research establishes a framework to
better understand evolution's impact on ecosystem patterns.



FULL STORY ==========================================================================
How does evolution impact ecological patterns? It helps smooth out the
rough edges, says UConn Ecology and Evolutionary Biology Professor Mark
Urban. Urban led an international team of researchers through a review
of the history of ecological and evolutionary research to establish
a framework to better understand evolution's impact on ecosystem
patterns. The research is published as a perspective in the Proceeding
of the National Academy of Sciences.


========================================================================== Urban says the project started years ago in the course of his field
research when he encountered a trend that he had trouble explaining.

"Ever since I was a grad student I've been thinking about how evolution
across landscapes happens, and then how it affects the ecology of those systems. At some point I was struggling to describe a pattern that I
was seeing in the amphibian system I work in," he says.

Urban explains that historically, ecologists and evolutionary biologists
have worked fairly isolated from one another. The reason is due to
assumptions that evolution happens over time periods and distances
that have little immediate impact on ecological systems. Ecologists
and evolutionary biologists go to their own academic meetings and
conferences and publish in their own journals, says Urban, and as
a result, members of the fields rarely collaborate. However, Urban
suspected the explanation for the puzzling pattern he was seeing relied
on a merging of the disciplines.

Urban partnered with colleagues from across the globe, calling on experts
from evolutionary biology and ecology, to tackle the question. The
project involved an extensive review of the literature, a process that
Urban says at times felt unending, yet quite fun. The process was also
exciting because early on, the researchers began to notice patterns
supporting their hypothesis that local adaptation alters spatial patterns.

Sean Giery, co-author and a former UConn post-doctoral researcher who's
now an Eberly Research Fellow at Pennsylvania State University says,
"Finding new evidence in old scientific papers was always rewarding. And collectively, these efforts show that the effects of evolution on how
much communities and ecosystems vary across landscapes simply can't be overlooked." The impetus for the undertaking, Urban says, came from a
familiar figure: the salamander.



========================================================================== Salamander populations adapt to predators via different strategies --
from changes in body shape and size to the types and quantities of foods
that they eat, which suggests a connection between evolution and ecology.

"In particular, I got excited by the evolution of foraging traits,
because that could have a clear ecological impact," Urban says.

For example, Urban found that salamanders evolve to forage more in a
pond with limited resources, and as a result they amplify the original ecological pattern of low resources by eating more of the already
limited resources. In other cases, local adaptation of other traits
dampens existing spatial patterns.

Urban next turned to the existing literature to find out how general
these patterns were, not just in salamanders, but in everything from
bacteria to birds.

Based on a review of 500 studies, the authors found evolutionary
adaptations at the local level can amplify, dampen, or even create new ecological patterns across landscapes. They identified 14 different
mechanisms that affect the direction of evolution's impact, but overall
the researchers found that evolution tended to dampen or smooth out
variations.

"Evolution clearly plays an important role at these large scales,
especially by reducing the effects of abiotic factors and biotic
interactions that can limit the abundance and distribution of species. By dampening the impacts of these effects, evolution tends to reduce
ecological heterogeneity across space," says Giery.



==========================================================================
Adds Urban: "Our exhaustive review indicated that evolution
usually dampens ecological spatial patterns, characterizing 85% of
studies. Consequently, we do not observe the true spatial heterogeneity
of nature because evolution has smoothed it out and hidden its rough
edges. Evolution makes the world less ragged, which to me is a pretty
cool take-home message." An example of the smoothing can be seen again
with salamanders, says Urban: "The salamanders that ate more also tended
to dampen out the effect of the predator on the overall diversity
of species across ponds. The prey salamander was eating different
species than the predator, so in the end evolution actually maintains
similar diversities of species across ponds even though, ecologically,
the predator strongly decreases diversity." Urban says these spatial
patterns can be seen everywhere: "The interesting thing to me is that
anyone can walk through nature and see these spatial patterns -- maybe different vegetation types. We see all of this spatial variation and
we think of it as just being ecological or physical, just part of the environment and that's it. But that environmental spatial variation may
be affected by the evolution of the organisms in the environment and
that is what we are finding in experiments around world." Giery says,
"I'm pleased to have been a part of this project. And I'm excited to
see how our efforts will influence the way people think about the
role of evolution in ecological dynamics in space. This seems like
one of those rare instances where a relatively simple idea is still transformative. Working on developing this idea has changed how I see
and think about natural systems. I imagine our perspective will have
the same impact on others." Urban says the next step is experiments to
further test the framework. The hope is the coauthors and readers will
go out and test this: "We are really just at the tip of the iceberg."

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


========================================================================== Journal Reference:
1. Mark C. Urban, Sharon Y. Strauss, Fanie Pelletier, Eric
P. Palkovacs,
Mathew A. Leibold, Andrew P. Hendry, Luc De Meester, Stephanie M.

Carlson, Amy L. Angert, Sean T. Giery. Evolutionary origins for
ecological patterns in space. Proceedings of the National Academy
of Sciences, 2020; 201918960 DOI: 10.1073/pnas.1918960117 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200709105232.htm

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