Integrating ecological dynamics, population genetics and landscape structure in a theoretical study of range shifting.

预测物种将如何应对气候变化是当今生物学家面临的最大挑战之一。我们希望能够预测一个物种是否能够在目前的范围内适应不断变化的气候条件，或者当新的地区变得适合气候时，它是否能够迁移到新的地区。英国蝴蝶的证据表明，随着气候变暖，一些物种已经在向北迁移，而其他物种的反应似乎没有那么快。为什么不同的物种会有不同的行为？有许多可能的原因，但目前预测物种未来分布的模型中几乎没有包括这些原因。大多数预测未来物种分布的模型都将一个物种孤立地考虑，并使用气候包络方法--本质上，它们建立了一个物种今天所占据的气候条件，并预测该物种将出现在未来发现该气候的任何地方。这种方法提供了一个很好的起点，但它忽略了几个可能非常重要的生物过程。例如。一些物种可能不善于扩散，可能无法像气候变化那样迅速地改变它们的活动范围。物种之间可能存在相互作用；蝴蝶可能具有非常好的分散能力，但如果它的食物植物没有，那么食物植物的范围转移可能会施加限制。进化过程可能也很重要，这项工作将研究这些过程。现有的生态模型将被扩展，以便纳入遗传和进化过程。最初，我们将引入中性遗传多样性--也就是说，不会改变生物适应性的替代基因将存在于不同的个体中。我们将观察在气候变化期间，由于物种分布的变化，种群内中性遗传多样性的程度是如何变化的。我们还将引入对当地环境条件的适应，并进行模拟实验，看看它如何改变物种的能力，以跟上变化的步伐。一些物种已经被观察到正在进化，以至于它们能够更快地改变它们的活动范围。例如，一些蝴蝶和蟋蟀在穿越英国向北迁徙时，分散能力增强。我们将使用我们的模型框架来研究在气候变化期间其他特征可能会如何演变。

Predicting how species will respond to climate change is one of the greatest challenges facing biologists today. We want to be able to predict whether a species will be able to adapt within its current range to changing climatic conditions, or whether it will be able to move to new regions as they become climatically suitable. Evidence for British butterflies suggests that some species are already moving northwards as the climate warms, while others appear not to be responding as fast. Why might different species behave differently? There are many possible reasons, and few of these are currently included in models that make predictions regarding the future distribution of species. Most models that make predictions regarding future species distributions consider one species in isolation and use a climate envelope approach - essentially they establish the climatic conditions occupied by a species today and predict that the species will occur wherever that climate is found in the future. This method provides a good starting point, but it ignores several biological processes that may be extremely important. For example. some species may be poor at dispersing and may not be able to alter their range as rapidly as the climate change. There are likely to be interactions between species; a butterfly may have very good dispersal abilities but if its food plant doesn't, then the range shifting of the food plant may impose a limitation. Evolutionary processes may also be important, and it is these that this work will investigate. An existing ecological model will be extended so that incorporates genetic and evolutionary processes. Initially we will introduce neutral genetic diversity - that is alternate genes that do not modify an organisms fitness will be present within different individuals. We will look to see how the degree of neutral genetic diversity within a population changes during a period of climate change due to species changing their distributions. We will also introduce adaptation to local environmental conditions, and run simulation experiments to see how it modifies a species ability to keep pace with the change. Some species are already being observed to evolve such that they are able to change their ranges more rapidly. For example, some butterflies and crickets have involved increased dispersal ability as they move northwards through Britain. We will use our model framework to investigate how other characteristics might be expected to evolve during a period of climate change.