LTREB: Long-term Research in Environmental Biology: Microevolution in the Fast Lane

整合模式和过程一直是进化生物学的一个关键但令人沮丧的目标。分析现存种群的快速进化为整合进化模式和进化过程提供了独特的手段。为此，每年从阿拉斯加洛贝格湖采集的三种棘鱼（Gasterosteus aculeatus）的样本将用于研究快速进化。这个种群是由溯河产卵的自然入侵建立的（即，在1982年当地的棘鱼种群被灭绝后，自1990年以来，每年都对它进行采样，并对所有样本的侧板表型进行评分。侧板是修改后的鳞片，在身体的每一侧形成一排盔甲。侧板变形（即，完整、部分、低）和低形态板数是可遗传的，受到强烈的自然选择，并在北美西部表现出广泛的适应性地理变异。本研究将记录最大进化速率、进化变化的轨迹和瞬时多态性的模式。这些模式可以与已知的进化机制相结合。在许多相似的种群中，低变体的频率增加和它们的平均板数下降可以用自然选择来解释。根据原Loberg湖棘鱼种群灭绝前的板块表型，并与其他湖泊棘鱼种群进行比较，Loberg湖种群的侧向板块分化应继续下去，直到低形态被固定，平均板块数下降到每侧约5个。这项研究将提供一个异常详细的快速表型进化的影响，在物种形成和冰后期适应性辐射的threespine刺鱼分歧的说明。它将补充正在进行的古生物学、功能形态学、自然选择、遗传学、生物地理学和G。刺肌它将延长一系列年度样本，在这些样本中可以研究板块和其他性状的快速进化以及性状相关性。

0211391BellLTREBIntegrating pattern and process has always been a crucial but frustrating objective forevolutionary biology. Analysis of rapid evolution in extant populations provides a unique meansto integrate evolutionary pattern and process. To that end, annual samples from the Loberg Lake,Alaska population of threespine stickleback fish, Gasterosteus aculeatus, will be used to studyrapid evolution. This population was founded by a natural invasion of anadromous (i.e., sea run)stickleback after the native stickleback population was exterminated in 1982. It has beensampled annually since 1990, and lateral plate phenotypes have been scored in all samples.Lateral plates are modified scales that form a single row of armor on each side of the body.Lateral plate morphs (i.e., complete, partial, low) and low morph-plate number are heritable,subject to strong natural selection, and exhibit extensive adaptive geographic variation in westernNorth America. This study will document maximum evolutionary rates, the trajectory of evolutionarychange, and patterns of transient polymorphism. These patterns can be integrated with knownevolutionary mechanisms. The increasing frequency of low morphs and their declining meanplate number can be explained by natural selection in many similar populations. Based on the plate phenotypes of the original Loberg Lake stickleback population before it was exterminated and comparison to other lake stickleback populations, lateral platedivergence should continue in the Loberg Lake population until the low morph is fixed and meanplate number declines to about five per side. This LTREB award will support continued annual sampling of the Loberg Lake population.This study will provide an unusually detailed account of rapid phenotypic evolution with implications for divergence during speciation and post-glacial adaptive radiation of threespine stickleback. It will complement ongoing research in paleontology, functional morphology, natural selection, genetics, phylogeogaphy, and developmental evolutionary biology of G. aculeatus. It will prolong a long series of annual samples in which rapid evolution of plates and other traits and trait correlations can be studied.