Crimson Elliott
March 7, 2013
Biology 1615-022
Article Summary
Introduction
Genetics and Demography in Biological Conservation, and article by Russell Lande,
is an article that discusses the idea of controlling wild life population through the
ability to predict when a population will con extinct, based solely on the
populations’ genetics.
This is an issue that is being brought to light and addressed because of the
destruction of natural areas, which include habitats for many species and how this is
effecting some species and wiping out their whole populations. So while realizing
there will be populations that continue to be abolished through the destruction of
their natural habitats, the article wanted to look and see how a certain populations
genetics play with the demographic location and how that all effects the rate at
which that population could go extinct.
Within the article Lande discusses the two main genetic factors that they are using
in their research, and four demographic effects that they are considering the most
important. And how those six things combined lead to the conclusion that Lande
was able to reach on how genetics and demographics can effect the extinction of
populations and whether or not through a mathematical equation, is it possible to
predict when that will happen.
Materials & Methods
As discussed, when Lande first set out to test his hypothesis, he picked six ideas or
criteria is wanted to focus on, two of them being genetic and four of them
demographic. The genetic components he picks that were important to him where
those of inbreeding depression and genetic variation within populations. Those on
the demographic side things were Allee Effect, Stochastic demography, Edge effects,
and local extinction and colonization.
To test the genetic side of things, Lande look at Drosphilia, as condition that comes
through inbreeding.
The condition only occurs in small numbers within the
population, though numbers will continue to grow as inbreeding continues and can
eventually prove lethal in some cases. Then while studying the same condition and
looked at genetic variation, in populations and how the some condition can arise
and not be fatal to some species and fatal to others.
There were very unique reasons as to why Lande chose the four demographic
criterion that he did and we will discuss each quickly. The Allee effect is when a
population starts loosing the ability to breed, for non-genetic reasons. Stochiastic
demography is when looking at each individual and what their vital rate is, which is
in essence what is their ability to survive and reproduce compared to others of their
population and what are average vital rates compared to a population in one area
versus another. When Lande discusses the Edge effect, he is actually discussing two
different types; the first of which is the way a habitat deteriorates within a clear
boundary and the second is how a population is dispersed within a boundary. Then
finally when talking about local extinction and colonization, Lande is looking at how
some populations thrive in certain environments, where they might go extinct in
others.
Results
The conclusion that Lande comes to, is basing, or predicting population, completely
on population genetics was a point that was highly unrealistic. It’s unrealistic
because the information, the theory was going to be used to control wild
populations, which is unrealistic because populations are know for being adaptable
and creating a management based on genetics alone wouldn’t work for this reason
and reasons as such.
Lande cam to this conclusion after going through all the results, the problem that
Lande found with a numerical equation, that could predict whether or not a species
were to go extinct of when it was to go extinct where the multiple factors that are
involved. He realized that there were to many factors to be able to build a realistic
model to predict extinction at all.
This research has lead many conservation
biologists to start predicting a species perseverance factor on one factor, rather then
just predicting when a population will actually go extinct.
Discussion & Conclusion
when Lande set out, he was looking to see if there was a way to gauge whether or
not it was possible to predict or even calculate when a population would go extinct.
After looking at six factors, two of those genetic and four of them demographic
Lande came to the conclusion that there were to many variables to be able to
accurately predict when a population would actually be able to come extinct. He
also realized through his research that it would be difficult to use this information to
control wild populations through genetics and demographics. That these variable
and the ability to adapt can greatly change what their initial predictions are about a
populations rate of extinction is, so that it was not possible, with much accuracy,
based on the criterion that he chose to conduct his research.