Genetics question... Help in Applying Hardy-Weinberg Equilibrium

[Fat Bottom Gurl]

A friend and I are having a genetics discussion. The discussion was sparked after another person spoke about inbreeding of chickens and how these chickens are doing very well 47 generations later. The person asked if there were other scenarios where inbred populations were healthy.

My friend gave the Florida panther as an example of how inbreeding is detrimental. The Florida panther risks extinction due to geographic isolation of the taxon, habitat loss, population decline and associated inbreeding have resulted in significant loss of genetic variability and health of the population (see http://www.panthersociety.org/restore.html)


I gave an example of the Newfoundland moose. Newfoundland, Canada boosts a thriving moose population based upon 4 founders of 2 males and 2 females placed on the island in 1904. Subsequent moose population derived from these 4 founders has not seen any problems related to inbreeding. In fact, they are an extreme danger to motorists.

http://www.bbc.co.uk/nature/animals/features/223index.shtml

My friend agreed that there are numerous examples of populations successfully started with only a few founders, but qualified it with the Hardy-Weinberg equilibrium. Shouldn't this principle also be applied to the panther example? If so - why do the moose thrive, while the panther does not? Could it be that habitat plays an extremely important role?

For more information on the Hardy-Weinberg equilibrium go here:

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/H/Hardy_Weinberg.html

Thanks,
Deb

 

[Dymanic]

My friend agreed that there are numerous examples of populations successfully started with only a few founders, but qualified it with the Hardy-Weinberg equilibrium.

"Qualified it"? Can you be more specific? Take a look at the

---------------------------------
"...circumstances in which the Hardy-Weinberg law may fail to apply. There are five:

mutation
gene flow
genetic drift
nonrandom mating
natural selection"
---------------------------------

and consider how likely it is for a population of organisms in the wild not to be subject to one or more of these effects. "Biology must be handled with mathematics, not as mathematics".

why do the moose thrive, while the panther does not?

There could be a million reasons. But Hardy-Weinberg doesn't say anything about thriving, just that allele distributions will remain constant unless something makes them change.

 

[Fat Bottom Gurl]

Thanks Dynanic - I was talking with someone else about this and realize that the application of the HW equilibrium applies only to the calculation of gene frequencies and nothing to do with fittness.

Perhaps the 4 founders of the Nfld. moose didn't have many deleterious recessives.

Deb

 

[PatKelley]

It can also depend upon the initial variablity of the population, in addition to the recessive alleles. A root stock taken from a really diverse population will fare better than one taken from a limited, inbred population.

Cheetahs are a good example. They have low genetic variablity across their population, pointing to a narrowing or low population level sometime recently with few unrelated founders.

 

[Fat Bottom Gurl]

It can also depend upon the initial variablity of the population, in addition to the recessive alleles. A root stock taken from a really diverse population will fare better than one taken from a limited, inbred population.

Cheetahs are a good example. They have low genetic variablity across their population, pointing to a narrowing or low population level sometime recently with few unrelated founders.

This is an interesting link about cheetahs and genetic bottlenecking.
http://www.worldbook.com/wc/popup?p...ion&page=html/cheetah_biology.html&direct=yes

Deb