Dissertation Research: Evolution of Offspring Size in the Trinidadian Guppy Poecilia reticulata

雷兹尼克9801492生物体的许多遗传特征也受到环境的影响。例如，在人类中，个子高的父母往往生下更高的孩子；然而，如果父母个子高的孩子在营养不良的情况下长大，孩子就不会充分发育。为什么有些特征可以被环境条件改变(即可塑性)，而另一些则是不变的，这是进化生物学的一个中心问题。一种假设是，可塑性是适应性的，因为性状的表达会发生变化，以适当地匹配环境条件。然而，只有当种群在一系列环境条件下进化时，这种适应性可塑性才是预期的。或者，如果一个种群是在特定的环境条件下进化的，预计它不会对从未经历过的一系列环境做出适应性反应。孔雀鱼(网纹孔雀鱼)产下活着的幼崽。这些后代出生时的大小会随着母亲面临的环境条件而发生可塑性变化。此外，在经历不同环境条件的种群中，后代的大小在遗传上也不同。通过一系列的实验室和野外实验，我们将测试孔雀鱼后代大小的这些遗传和可塑性变化是否具有适应性。通过研究后代大小对捕食风险、生长速度和后代繁殖率的影响，我们将确定后代大小的变化在多大程度上适合特定的环境或环境范围。通过进一步了解特征的可塑性和固定(遗传)特征是如何演变的，这项研究将增强我们预测生物体将如何对短期和长期环境变化做出反应的能力。

Reznick 9801492Many features of an organism that are genetically based are also subject to environmental influences. In humans, for example, taller parents tend to have taller children; yet if a child of tall parents is raised with poor nutrition, it will not grow to its full potential. Why some traits can be altered by environmental conditions (i.e. are plastic) while others are invariant is a central problem in evolutionary biology. One hypothesis is that plasticity is adaptive because the expression of the trait shifts to appropriately match the environmental conditions. However, this adaptive plasticity is only expected if a population has evolved under a range of environmental conditions. Alternatively, if a population has evolved under a particular environmental condition, it is not expected that it will respond adaptively to range of environments it has never experienced. Guppies (Poecilia reticulata) give birth to live young. The size of these offspring at birth shifts plastically in response to the environmental conditions faced by the mother. In addition, offspring size differs genetically across populations that experience different environmental conditions. Using a series of laboratory and field experiments, we will test whether these genetic and plastic shifts in guppy offspring size are adaptive. By examining the effect of offspring size on predation risk, growth rate and offsprings reproductive rate, we will determine to what extent offspring size variation is suited to a particular environment or range of environments. By furthering our understanding of how both the plastic and fixed (genetic) features of a trait evolve, this study will enhance our ability to predict how organisms will respond to both short- and long-term environmental changes.