Invasion biology: comparing scales of local genetic adaptation to exotic predators by prey with high and low dispersal potential

人类活动引起的环境变化使外来掠食者和竞争者将其地理范围扩展到加拿大。例如，1997/98年El Niño期间海水表面温度升高，使亚热带滨蟹的幼虫在加拿大西部海岸蜕变，并捕食四种密切相关的本地蜗牛。这些温带蜗牛物种的壳很容易受到来自热带地区捕食者专门的破壳附属物的攻击。因此，气候驱动的亚热带捕食物种的范围扩大可能导致温带猎物物种的范围缩小，除非它们能迅速进化出更厚的甲壳。这是研究猎物迁徙对亚热带捕食者适应影响的一个很好的系统。这四种潮间带腹足动物在生态学上是相似的，但它们的传播潜力有很大的不同：两种有一个长期的自由游动的幼虫阶段，两种已经失去了自由游动的幼虫阶段，因此只能通过爬行来传播。

Environmental change caused by human activities is allowing exotic predators and competitors to extend their geographical ranges into Canada. For example, increased sea surface temperatures during the 1997/98 El Niño allowed larvae of the subtropical lined shore crab to metamorphose on western Canadian shores and prey on four closely-related species of indigenous snails. These temperate snail species have shells that are vulnerable to the specialized shell-breaking appendages of predators from more tropical regions. Consequently, climate-driven range expansion of subtropical predator species may result in range contraction by temperate prey species unless they can quickly evolve thicker armour. This is an excellent system for studying the effect of prey migration on adaptation to subtropical predators. These four intertidal gastropods are ecologically similar but differ considerably in their dispersal potential: two species have a long-lived free-swimming larval stage and two species have lost the free-swimming larval stage and as a result disperse only by crawling.