Shakarad Mallikarjun, Prasad N G, Gokhale Kaustubh, Gadagkar Vikram, Rajamani M, Joshi Amitabh
Behaviour, Ecology & Evolution Laboratory, Biology Department, Poornaprajna Institute of Scientific Research, P. O. Box 18, Devanahalli-562 110, Bangalore, India.
Biol Lett. 2005 Mar 22;1(1):91-4. doi: 10.1098/rsbl.2004.0261.
In comparisons across Drosophila species, faster pre-adult development is phenotypically correlated with increased pre-adult competitive ability, suggesting that these two traits may also be evolutionary correlates of one another. However, correlations between traits within- and among- species can differ, and in most cases it is the within-species genetic correlations that are likely to act as constraints on adaptive evolution. Moreover, laboratory studies on Drosophila melanogaster have shown that the suite of traits that evolves in populations subjected to selection for faster development is the opposite of the traits that evolve in populations selected for increased pre-adult competitive ability. This observation led us to propose that, despite having a higher carrying capacity and a reduced minimum food requirement for completing development than controls, D. melanogaster populations subjected to selection for faster development should have lower competitive ability than controls owing to their reduced larval feeding rates and urea tolerance. Here, we describe results from pre-adult competition experiments that clearly show that the faster developing populations are substantially poorer competitors than controls when reared at high density in competition with a marked mutant strain. We briefly discuss these results in the context of different formulations of density-dependent selection theory.
在对不同果蝇物种的比较中，成虫前发育速度更快在表型上与成虫前竞争能力增强相关，这表明这两个性状可能也是彼此的进化相关性状。然而，种内和种间性状的相关性可能不同，在大多数情况下，可能是种内遗传相关性对适应性进化起到限制作用。此外，对黑腹果蝇的实验室研究表明，在因发育速度加快而接受选择的种群中进化出的一系列性状，与因成虫前竞争能力增强而接受选择的种群中进化出的性状相反。这一观察结果使我们提出，尽管与对照组相比，因发育速度加快而接受选择的黑腹果蝇种群具有更高的承载能力和更低的完成发育所需最低食物需求量，但由于其幼虫摄食率和尿素耐受性降低，其竞争能力应低于对照组。在此，我们描述了成虫前竞争实验的结果，这些结果清楚地表明，在与一个有标记的突变菌株高密度竞争饲养时，发育较快的种群作为竞争者比对照组差得多。我们在密度依赖选择理论的不同表述背景下简要讨论了这些结果。
