Genetic drift

[daveyp1970]

Could somebody recommend a book or a paper or papers to read so i can fully understand the concept of genetic drift please.

[mark smyth]

I had to Google what it means http://en.wikipedia.org/wiki/Genetic_drift

[daveyp1970]

I had to Google what it means http://en.wikipedia.org/wiki/Genetic_drift

I have done that also Mark  and looked at a few papers but the more i read the more i take it in...i read and read and then i have the lightbulb moment and i am there...

[Anthony Darby]

I remember a small population of meadow brown butterflies on Crammond Island near Edinburgh becoming isolated for a few years when the causeway was washed away. Genetic drift increased the number of marginal wing spots quite dramatically on this small isolated population, until the causeway was reinstated and then they merged with those on the mainland.

[Maggi Young]

I used to live in Cramond.... near the island - why would a causeway have any effect on a  creature with the ability to fly? It's  only about a quarter of a mile offshore.... 

[Anthony Darby]

Apparently they didn't. It was George Thomson who did the study.

[Martin Baxendale]

I used to live in Cramond.... near the island - why would a causeway have any effect on a  creature with the ability to fly? It's  only about a quarter of a mile offshore.... 

Maybe they just wouldn't fly more than a very short distance over water, instinct telling them they were flying out to sea and shouldn't go any further, but with the causeway in place they could follow that strip of dry land back and forth?

Butterflies from the mainland would have no way of knowing that there was land out there to head for, so no new genetic material reaching the island to mix things up.

[Maggi Young]

Sounds plausible, Martin - except that when the tide is out the island is accessible over sand...... 

[Gerry Webster]

For anyone seriously interested in the theory of genetic drift I suggest John Maynard Smith, Evolutionary Genetics. A good background in biology is required together with a willingness to do some hard intellectual work.

[Martin Baxendale]

Sounds plausible, Martin - except that when the tide is out the island is accessible over sand...... 

Ah! Back to the drawing board then.

[Martin Baxendale]

For anyone seriously interested in the theory of genetic drift I suggest John Maynard Smith, Evolutionary Genetics. A good background in biology is required together with a willingness to do some hard intellectual work.

My son's doing evolutionary genetics at Liverpool University as part of his degree in Ecology and the Environment. I'll see if he's been introduced to genetic drift yet. It'll give us something to talk about at Xmas 

[Guus]

In Campbell/Reece/Mitchell's BIOLOGY you can find a clear explanation on Genetic Drift. Together with bottleneck effects.

Greetings, Guus

[daveyp1970]

In Campbell/Reece/Mitchell's BIOLOGY you can find a clear explanation on Genetic Drift. Together with bottleneck effects.

Greetings, Guus

Thank you Guus and Gerry.

[Rick R.]

Another possibility, but perhaps less probably, is that the environmental change (if indeed there was one) that kept the causeway washed out, also had an effect on butterfly morphology.  Many species change their "spots" or even there sex ratios in response to environmental cues.

[Anthony Darby]

If my memory serves me correctly, the causeway had a grass verge, so the population was continuous with the mainland. When the causeway was washed away this caused the vital break with the mainland. Similar studies have been carried out on small populations is the Scilly Isles. Interestingly, the form in north western Scotland is sufficiently distinct to be given its own subspecies name, Maniola jurtina splendida.