Miehls A L J, Peacor S D, Valliant L, McAdam A G
Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI, USA.
NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, USA.
J Evol Biol. 2015 May;28(5):1091-102. doi: 10.1111/jeb.12632. Epub 2015 Apr 22.
Invasive species are one of the greatest threats to ecosystems, and there is evidence that evolution plays an important role in the success or failure of invasions. Yet, few studies have measured natural selection and evolutionary responses to selection in invasive species, particularly invasive animals. We quantified the strength of natural selection on the defensive morphology (distal spine) of an invasive zooplankton, Bythotrephes longimanus, in Lake Michigan across multiple months during three growing seasons. We used multiple lines of evidence, including historic and contemporary wild-captured individuals and palaeoecology of retrieved spines, to assess phenotypic change in distal spine length since invasion. We found evidence of temporally variable selection, with selection for decreased distal spine length early in the growing season and selection for increased distal spine length later in the season. This trend in natural selection is consistent with seasonal changes in the relative strength of non-gape-limited and gape-limited fish predation. Yet, despite net selection for increased distal spine length and a known genetic basis for distal spine length, we observed little evidence of an evolutionary response to selection. Multiple factors likely limit an evolutionary response to selection, including genetic correlations, trade-offs between components of fitness, and phenotypic plasticity.
入侵物种是生态系统面临的最大威胁之一，有证据表明进化在入侵的成败中起着重要作用。然而，很少有研究测量入侵物种，特别是入侵动物的自然选择以及对选择的进化反应。我们在三个生长季节的多个月份里，对密歇根湖中的一种入侵浮游动物——长刺网纹溞的防御形态（远端刺）的自然选择强度进行了量化。我们使用了多条证据，包括历史和当代野生捕获个体以及回收刺的古生态学，来评估入侵以来远端刺长度的表型变化。我们发现了随时间变化的选择证据，在生长季节早期选择较短的远端刺长度，而在季节后期选择较长的远端刺长度。这种自然选择趋势与非口裂限制和口裂限制鱼类捕食相对强度的季节性变化一致。然而，尽管对增加远端刺长度有净选择，且远端刺长度有已知的遗传基础，但我们几乎没有观察到对选择的进化反应的证据。多种因素可能限制了对选择的进化反应，包括遗传相关性、适合度各组成部分之间的权衡以及表型可塑性。
