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Arthur T Knackerbracket has found the following story:
Cooperatively breeding birds and fish may have evolved the adaptive ability to reduce the size of their eggs when helpers are available to lighten the parental load, a new study suggests. The findings indicate that in some species, the social environment may influence female reproductive decisions even prior to the birth of offspring.
According to the research from the University of Cambridge, females in species such as the sociable weaver, superb fairy-wren and daffodil cichlid fish, tend to produce smaller eggs when help with rearing offspring is at hand compared to when parents are on their own.
The authors of the paper, which was published today in the journal PeerJ, looked at data from 12 studies on 10 species of cooperatively breeding vertebrates in order to analyse the relationship between the number of helpers present and egg size. The reduction in egg size in relation to helper availability was stronger in species where mothers also reduce the energy they put into post-natal care when other members of the social group are available to help protect, incubate and feed offspring after laying.
The findings suggest that breeding females, by laying smaller, less energy-consuming eggs and providing less food to offspring at the nest, may conserve energy to increase their own chances of survival to the next year or to have the next set of offspring sooner. If helpers compensate for the reduced investment into the current offspring, this could lead to females producing more offspring in total over the course of their lifetimes.
The relationship between egg size and helper number in cooperative breeders: a meta-analysis across species (open, DOI: 10.7717/peerj.4028) (DX)
(Score: 2) by frojack on Friday November 24 2017, @06:50PM (1 child)
Reproductive decisions by birds? Seriously, once they fall for the prettiest male all decisions are over.
There is nothing left to decide, especially about egg size.
The issue here could just as well be reversed, and the social attention is due to the fact that the eggs are all small (for whatever reason) and the only way they survive as a species is by taking care of the offspring of the few females that managed to successfully breed.
No, you are mistaken. I've always had this sig.
(Score: 0) by Anonymous Coward on Friday November 24 2017, @10:30PM
Songbirds are pretty drab.
Last Spring, I had a Mockingbird who hung out hereabouts.
He had quite a repertoire and the little bastard kept it up into the wee hours.
If he didn't get laid, I can't imagine why.
In previous seasons, I've had Swallows set up housekeeping closeby.
Again, one whole lot of chirping by the guys to convince the gals that they were the fittest.
...and rubbing slits is only the 1st step.
Once the kids are hatched, there's a bunch of foraging for food to feed the brats.
If the kids aren't well fed, the genes of lousy providers don't make it into successive generations.
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