Wednesday, 20 November 2013

Maternal Effects

Definition of Maternal Effects: a non-genetic influence on the offspring phenotype, based on the environmental conditions experienced by the mother organism. Maternal effects are a type of epigenetic effect.

----Through variations in resource/energy allocation
----Oviposition site (where the mother releases her progeny has an effect on its life history eg. next to food = better, next to other offspring = worse as they are competitors for resources)
----Hormones (hormone levels during oogeneis affect embryo)

(Fowler, 2005): Looked at aphids (greenflies) - found that under a certain predator-induced stress cue, the mothers produced winged offspring. This gave them advantage with dispersibility and fitness through escaping the predator.
----->> mother experience (predator cue) -------->> changes offspring phenotype 
this is relevant to evolution because it influences the dispersibility, gives it a competitive advantage (can get resources easier due to wings) (also can escape predator) - therefore affect other populations through out-competing other species or organism. Also, affect food availability to the predator.... if all offspring are winged and fly away then new food source?
This phenotypic change influences population dynamics and evolution.

Relevance to our Topic: Having the focus of scientific experiments on genetic knock-out and trying to compose genomes will not give us a FULL understanding of organisms, their ecology and evolution. This is (what I think) Denis Noble is saying. Maternal effects are sort of a more knowledgable version of Lamarck's idea about inherited acquired characteristics. Maternal effects mean that two hypothetical offspring of the same species could have the same genes and yet they could develop differently through maternal effects (or any epigenetic effect for that matter). 

Marine example (Campbell et al., 1992): when female rainbow trouts experienced confinement during oogeneis they had higher levels of cortisol (stress hormone) and this resulted in smaller offspring with increased mortality rates. The environmental conditions experiences by the mother affect her offspring mortality ./ life history (smaller offspring = less successful, less likely to outcompete, more likely to be predated, perhaps less resource allocation so less efficient.... etc)

No comments:

Post a Comment