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重要而又令人沮丧的目标。对现存种群快速进化的分析为整合进化模式和进化过程提供了独特的手段。为此，来自阿拉斯加洛伯克湖的三条刺鱼种群的年度样本将被用来研究快速进化。这个种群是在1982年本土刺鱼种群灭绝后，由退水型(即海跑)刺鱼的自然入侵而建立的。自1990年以来每年都进行采样，并在所有样本中对侧板表型进行评分。侧板是修改后的鳞片，在身体两侧形成一排盔甲。侧板变形(即完全、部分、低)和低变形板数是可遗传的，受到强烈的自然选择的影响，并在北美西部表现出广泛的适应性地理变异。这项研究将记录最大进化率、进化变化的轨迹和瞬时多态的模式。这些模式可以与知识革命机制相结合。在许多相似的种群中，低形态频率的增加和它们的平均板数的下降可以用自然选择来解释。根据原始洛伯湖刺鱼种群灭绝前的板块表型，以及与其他湖泊刺鱼种群的比较，洛贝湖刺鱼种群的侧向高原分化应该继续下去，直到低形态固定下来，平均板块数下降到每侧5个左右。这项LTREB奖将支持继续对洛伯克湖种群进行年度采样。这项研究将提供异常详细的表型进化，以及对物种形成期间的分歧和三刺鱼冰后适应性辐射的影响。它将补充正在进行的古生物学、功能形态、自然选择、遗传学、系统地理学和发育进化生物学的研究。它将延长一长串的年度样本，在这些样本中可以研究盘子和其他性状的快速演变以及性状之间的相关性。

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.