August 14, 2018
Source: University of Illinois at
Urbana-Champaign
Habitat loss, habitat
fragmentation and the loss of genetic diversity are the three main factors
driving the extinction of many wild species, and the few eastern massasauga
rattlesnakes remaining in Illinois have certainly suffered two of the three. A
long-term study of these snakes reveals, however, that -- despite their
alarming decline in numbers -- they have retained a surprising amount of
genetic diversity.
The new findings are reported in
the journal Copeia.
"Despite occurring in small,
fragmented populations, eastern massasaugas in Illinois do not show genetic
evidence of inbreeding," said Illinois Natural History Survey postdoctoral
researcher Sarah J. Baker, who led the new research.
The genetic analysis did reveal,
however, the loss of several rare versions of genes over the course of the
10-year study, which ended in 2012. Such losses can signal the early stages of
local extinction, Baker said.
In 2015, the U.S. Fish and
Wildlife Service listed the eastern massasauga as a threatened species nationally.
Massasaugas are endangered in Illinois.
The widespread conversion of
prairie to row-crop agriculture and the construction of the Carlyle Lake dam in
central Illinois were among the biggest assaults on massasauga populations in
the state, said INHS herpetologist Michael Dreslik, a coauthor of the study.
"The lake was constructed as
an impoundment of the Kaskaskia River in 1967 and flooded bottomland
habitat," he said. "The remaining massasaugas are now clustered in
wet prairies containing crayfish burrow complexes that shelter the snakes.
These represent the only remaining suitable habitat patches for them.”
The construction of Carlyle Lake
did not result in a genetic "bottleneck," however, Baker said.
"Bottlenecks can occur when
a large population is quickly reduced in size, causing a loss of genetic
diversity," she said.
Despite the positive findings,
the snakes are likely to become locally extinct without significant
intervention, the researchers said. According to a 2017 estimate, the largest
subpopulation of wild massasaugas remaining in Illinois includes 26-69 snakes.
"Previous studies propose
that a total population of at least 100 is required for short-term maintenance
of genetic diversity, and a population of 1,000 is needed to ensure long-term
conservation," Baker said. "Conservation and management actions that
can increase population size should be enacted as soon as possible to preserve
the remaining genetic diversity and ensure the persistence of the species in
Illinois."
Story Source:
Materials provided
by University of Illinois at Urbana-Champaign.
Note: Content may be edited for style and length.
Journal Reference:
Sarah J. Baker, Whitney J. B.
Anthonysamy, Mark A. Davis, Michael J. Dreslik, Marlis R. Douglas, Michael E.
Douglas, Christopher A. Phillips. Temporal Patterns of Genetic Diversity in an
Imperiled Population of the Eastern Massasauga Rattlesnake (Sistrurus
catenatus). Copeia, 2018; 106 (3): 414 DOI: 10.1643/CG-17-682
Posts
No comments:
Post a Comment
You only need to enter your comment once! Comments will appear once they have been moderated. This is so as to stop the would-be comedian who has been spamming the comments here with inane and often offensive remarks. You know who you are!