Smith Shelby E, Palkovacs Eric P, Weidel Brian C, Bunnell David B, Jones Andrew W, Bloom Devin D
Department of Biological Sciences Western Michigan University Kalamazoo MI USA.
Department of Ecology & Evolutionary Biology University of California Santa Cruz CA USA.
Evol Appl. 2020 Aug 25;13(10):2630-2645. doi: 10.1111/eva.13063. eCollection 2020 Dec.
Species introductions provide opportunities to quantify rates and patterns of evolutionary change in response to novel environments. Alewives () are native to the East Coast of North America where they ascend coastal rivers to spawn in lakes and then return to the ocean. Some populations have become landlocked within the last 350 years and diverged phenotypically from their ancestral marine population. More recently, alewives were introduced to the Laurentian Great Lakes (~150 years ago), but these populations have not been compared to East Coast anadromous and landlocked populations. We quantified 95 years of evolution in foraging traits and overall body shape of Great Lakes alewives and compared patterns of phenotypic evolution of Great Lakes alewives to East Coast anadromous and landlocked populations. Our results suggest that gill raker spacing in Great Lakes alewives has evolved in a dynamic pattern that is consistent with responses to strong but intermittent eco-evolutionary feedbacks with zooplankton size. Following their initial colonization of Lakes Ontario and Michigan, dense alewife populations likely depleted large-bodied zooplankton, which drove a decrease in alewife gill raker spacing. However, the introduction of large, non-native zooplankton to the Great Lakes in later decades resulted in an increase in gill raker spacing, and present-day Great Lakes alewives have gill raker spacing patterns that are similar to the ancestral East Coast anadromous population. Conversely, contemporary Great Lakes alewife populations possess a gape width consistent with East Coast landlocked populations. Body shape showed remarkable parallel evolution with East Coast landlocked populations, likely due to a shared response to the loss of long-distance movement or migrations. Our results suggest the colonization of a new environment and cessation of migration can result in rapid parallel evolution in some traits, but contingency also plays a role, and a dynamic ecosystem can also yield novel trait combinations.
物种引入为量化生物在新环境中进化变化的速率和模式提供了契机。美洲西鲱原产于北美东海岸，它们会溯河而上到湖泊中产卵，然后返回海洋。在过去350年里，一些种群变成了陆封型，并在表型上与它们的海洋祖先种群产生了分化。最近，美洲西鲱被引入了五大湖（约150年前），但这些种群尚未与东海岸溯河洄游型和陆封型种群进行比较。我们量化了五大湖美洲西鲱95年的觅食性状和整体体型的进化，并将五大湖美洲西鲱的表型进化模式与东海岸溯河洄游型和陆封型种群进行了比较。我们的研究结果表明，五大湖美洲西鲱的鳃耙间距以一种动态模式进化，这与对浮游动物大小的强烈但间歇性的生态进化反馈的响应一致。在最初定殖于安大略湖和密歇根湖之后，密集的美洲西鲱种群可能耗尽了大型浮游动物，这导致美洲西鲱鳃耙间距减小。然而，在随后几十年中，大型非本地浮游动物被引入五大湖，导致鳃耙间距增加，如今五大湖美洲西鲱的鳃耙间距模式与祖先东海岸溯河洄游型种群相似。相反，当代五大湖美洲西鲱种群的口裂宽度与东海岸陆封型种群一致。体型与东海岸陆封型种群呈现出显著的平行进化，这可能是由于对长距离移动或洄游丧失的共同响应。我们的研究结果表明，新环境的定殖和洄游的停止可能导致某些性状的快速平行进化，但偶然性也起作用，动态的生态系统也可能产生新的性状组合。
