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Jeff Aman
Tigers:
Now and Forever
Introduction
In the last fifty years Tiger populations have drastically dropped due to
habitat destruction and poaching. In an effort to successfully breed endangered
animals, such as the tiger, a somewhat new field of genetics has been greatly
researched. This new field is called Conservation genetics. The main goal of
conservation genetics is to develop effective management strategies for the
conservation of endangered species. One of the most important strategies is
maintaining genetic diversity within the captive tiger population. The loss of genetic
diversity is accounted for by three main reasons; population bottlenecks, random
genetic drift, and inbreeding. A population bottleneck is a crash in the size of the
population. Tigers have obviously seen a huge population drop in recent years.
Random genetic drift is a random process in which the allele frequencies in the
population change over time. Random genetic drift is a part of nature but is much
more severe for smaller populations than large populations. Inbreeding is when two
animals with similar genetic makeup mate.
Studies and Results
The Missing Link Foundation was founded with the desire to increase the
genetic diversity of tigers in captivity. Gene diversity compares gene diversity in the
captive population with the original amount of gene diversity in the founders.
Founders are tigers that were born in the wild and later captured and brought to
the zoo. The founders have no known relatives among the captive tigers. A healthy
population of tigers can only survive by sharing a large gene pool. With a large
gene pool the tigers can continue to evolve and filter their way around
environmental factors. Unfortunately many of the current captive tiger populations
suffer from hip-dysplasia , cross-eyes, weakened immune systems, abnormalities
and birth defects. A group of scientists at the Tiger Missing Link Foundation have
been considering how advances in the freezing of sperm, embryos, and tissues may
be useful for managing the world’s dwindling tiger population. The scientists are
researching an idea that has been looked at for almost 20 years. The idea is using
techniques that have been used to improve livestock production and overcome
human infertility problems for years. The idea is a Genome Resource Bank. The
Genome Resource Bank could be used as a tool against losing more genetic variation
from both captive and wild populations. The scientists think that gene diversity
could be spread more efficiently in captive and wild populations. In the future it
may be possible to artificially inseminate females living in the wild using sperm
from tigers in other areas. These techniques are not futuristic; there just aren’t any
Genome Resource Banks for endangered species.
Conclusions and Significance
The current gene diversity in tigers is not looking too terribly bad. The
question is whether breeding programs will be able to maintain gene diversity.
Currently gene diversity ranges from 92% diverse for Sumatran Tigers to 96%
diverse for Siberian Tigers. However, the breeding programs must continue to get
more genes from wild tigers. Without new genes the gene diversity in the captive
breeding programs will slowly start to decline. The authors agree that creating a
Genome Resource Bank would be an extremely complicated feat. However,
scientists believe that if a Genome Resource Bank for tigers were created it would be
a major jump in conservation genetics. The banks would be a major leap in
creating gene diversity in needed for the well being of tigers in the future.
My Comments
In my opinion tigers are a beautiful and meaningful species that deserve a
chance to survive. It is ironic to me that in order to survive tigers must rely on
humans when humans are the reason they are endangered. I think the Genome
Resource Bank seems to be an extremely good idea and should be further
researched. Nature is very important in this world. It is estimated that in the next
one hundred years fifty percent of all living organisms, (except humans) will be
endangered or extinct. It is a shame that as the most dominant and intelligent life
form on the planet humans cannot find a way to live in harmony with nature. I feel
it is our duty to protect and try to save not only tigers, but also all endangered
species. They are apart of why our world is so beautiful. We would be ignorant if
we turn our back on the animals of this world. It is time we do what ever it takes to
preserve Mother Nature.
Bibliography
Tiger Missing Link Foundation- Scientific Team- B. Warner, Dr. Zweib, Ph. D.,
Cheri Bell, B.S., Dr. Abdulrahman.
Research in Conservation Genetics
URL:
http://www.tigerlink.org/organ.html
Tiger Handbook
Captive Breeding Criteria
URL:
http://www.5tigers.org/adventures/handbook/d2b.htm
Genetics of Small Populations
Captive Breeding
URL:
http://www.science.mcmaster.ca/biology/CBCN/genetics/fos_tig6.htm