By Zachary Gotthardt
SC Staff Writer
On Friday, April 18, Dr. Stephen Mech from Albright College presented his work on what he calls ecological genetics.
Dr. Mech emphasized how useful ecological genetics can be for analyzing animal populations.
Rather than focusing on a select few individuals, ecological genetics looks at the population as a whole over a longer period of time, which can be more cost effective and efficient.
After giving an overview on the theory of population genetics, he summarized three studies in which he assisted.
Dr. Mech focuses his studies on anthropogenic effects on population genetics.
Anthropogenic effects are those that result from human activity.
He believes that anthropogenic effects can be categorized in three ways.
The first effect that humans have on wildlife is range shifts.
A range shift occurs when an animal population changes the location of its habitat.
Range shifts can occur immediately through habitat destruction or alteration.
They can also occur gradually over time, such as when animals move due to climate change.
The home range of the population is changed, and the population must have some sort of evolutionary plasticity to withstand this change.
The second form of anthropogenic effects is introductions and hybridizations.
Humans are the major cause of invasive and introduced species.
When a new species is introduced, the ecosystem must adapt to its presence.
Most often, the entire ecology of the area is altered and species can become extinct.
In rare cases, the introduced species are able to interbreed with a similar, preexisting population.
The dynamics of the ecosystem change even more as a second new species is introduced.
The final anthropogenic effect is habitat fragmentation.
This occurs when an environment is divided or broken up into several spatially separated smaller habitats.
Human practices are capable of completely changing the physical parameters of an ecosystem.
For example, clear-cut logging creates open areas where there was previously forest.
While there is an obvious change in the ecosystem, there can be unforeseen changes in the adjacent environments.
Some owl species are extremely reluctant to fly over open fields, and because of habitat fragmentation, may be required to cross open spaces in order to find sufficient resources.
Urbanization is even more dramatic, and oftentimes the altered ecosystem is incapable of supporting much in terms of animal populations.
Dr. Mech has examined these effects extensively over the course of his career.
At the biocolloquium, he cited three specific examples.
One of these studies looked at the hybrid zone between the Black-capped chickadee and the Carolina chickadee.
These two species readily hybridize, and, in the process, create a large amount of genetic diversity.
Females of both species generally prefer the males Carolina chickadees.
This leaves the male Black-capped chickadees in the area of hybridization, where the two populations overlap, evolutionarily unsuccessful.
Recent data suggests that both populations are exhibiting a range shift northward, and the hybridization zone is also relocating as well.
Previously, Dr. Mech and his colleagues had hypothesized that the genetic variation depended upon location, but their hypothesis must be reevaluated if the hybridization zone itself can move.
The most likely factor for this range shift is anthropogenic climate change.
Dr. Mech has also examined the introduction of a new species of tiger salamander in certain areas of the southwest.
The salamander was very similar to other salamander populations, but unique in its genetics and endemic to a smaller area. It was also a favored bait species among fishermen.
After they were finished fishing, fishermen would dump their unused live bait into the water, thus introducing a new species to the area.
However, the fishermen were also spreading a virus that infected the salamanders.
The introduced species was evolutionarily adapted to this virus, but the similar native populations were not, and were affected as a result.
The native populations were forced to cope with increased competition and a new pathogen, both of which would not have been possible without human interference.
Dr. Mech’s most cherished work centered on red vole conservation.
The voles he examined were forest specialists, and preferred the interior of forests.
His study inspected the dependency of these voles upon continuous stretches of forest, which they used for travel.
The study concluded that semi-narrow corridors of intact forest, which acted to connect two larger sections of forest, increased movement between the patches of forest.
While this conclusion may seem obvious, there is no definitive proof without a study such as this.
This information can be used to create new habitats for threatened or endangered species in forests used for logging.
With proper techniques, math and technology, we can use population genetics to better understand our effects on the animal world, as well as aid in the restoration of species affected by human activities.
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