5.29.2008

random thought for the day

The effects of inbreeding may be mitigated in plant populations by a phenomenon known as purging of genetic load. Over time, inbred plants show decreased fitness followed by a rebound in certain fitness traits, and can exhibit higher fitness than the original population (Crnokrak and Barrett 2002). Darwin first noticed this in his breeding experiments with Ipomoea. This phenomenon is referred to as purging the genetic load, and may be a way in which plants are able to decrease frequency of deleterious alleles in a population. This has been extensively tested under laboratory and greenhouse conditions, however fewer studies have been conducted in the field to determine if this is an important phenomenon in natural populations.

2 comments:

Rich Beckman said...

I'm just an uneducated (scientifically) but interested reader.

I can't help but notice that what you describe in this post seems similar to what PZ describes about the "Japanese puffer fish, or fugu".

http://www.seedmagazine.com/news/2008/05/random_acts_of_evolution_1.php

Are these completely different phenomena or not?

Bridget said...

Interesting question. Plants are known to have LOTS of "junk DNA" and thus are likely not undergoing the same process as fugu. It does bring up a concept I've struggled with though. What controls the phenomenon we've observed? Is it changes in the regulatory region or changes in the genes? Recent works by a fellow grad student (yet to be published) suggested that regulatory changes are responsible for at least the cases she looked at. I look forward to more sequenced plant genomes so the issue can be looked into further. Really cool stuff!