RAPID: Testing the role of spatial sorting as an important driver of rapid adaptive divergence

在迅速殖民新栖息地的种群中，能够提高其扩散速度的生物体的特征可以受到青睐。如果分散的个体与来自周围种群的类似的、高度流动的个体交配，情况尤其如此。这一过程被称为“空间排序”，无论这些基因如何影响种群在新栖息地的适合度，所产生的后代也是快速散布的。该项目将进行第一次大规模的现场空间分选测试，以利用红肩黄莓臭虫(JaDera Haematoloma)的种群产生快速进化，在过去的60年里，这种种群已经从本地食物植物扩大并适应非本地食物植物。飓风哈维罕见的周期性洪灾提供了一个独特的机会，通过导致一些种群灭绝而另一些种群完好无损，来逆转(短暂的)肥皂子种群进化时钟。这项研究的结果可以用来理解入侵物种是如何在新的栖息地定居并最终取代本地种群的。该项目还将支持关于殖民人口进化的外展公共教育。一个根本的问题是，血吸虫种群是如何进化得这么快的？这个问题的答案可能会从最初的殖民者的特征中找到。皂浆虫表现出飞行的多态，其中有长翼的形式，是身体较大的主要分散者，而短翼的形式，在身体较小的情况下飞行不好。长翼变形虫也有更大的口器，这对新的非本地寄主植物有利。该项目将测试观察到的从本地寄主植物到非本地寄主植物的快速适应是否由空间排序促进，而不是通过站在表型变异中的自然选择来促进。为此，将进行实地观察研究、操纵性移植实验、扩散表型遗传基础的实验室测试，以及减少种群内遗传变异的基因测试。

Traits of organisms that enhance their rates of dispersal can be favored in populations that are rapidly colonizing new habitats. This is especially true if the dispersing individuals mate with similar, highly mobile individuals from surrounding populations. This process, termed "spatial sorting", generates offspring that are also rapid dispersers, regardless of how those genes affect the population's fitness in the new habitat. This project will perform the first large-scale field tests of spatial sorting in generating rapid evolution using populations of the red-shouldered soapberry bug (Jadera haematoloma), which has expanded and adapted from native to non-native food plants in the last 60 years. The rare episodic flooding from Hurricane Harvey has provided a unique opportunity to roll back the (short) evolutionary clock on soapberry bug populations by causing some populations to go extinct while others are still intact. Results from this study can be applied to understanding how invasive species colonize new habitats and ultimately displace native populations. This project also will support outreach public education on evolution in colonizing populations. One fundamental question is how could J. haematoloma populations evolve so quickly? The answer to this question may emerge from features of the initial colonizers. Soapberry bugs exhibits a flight polymorphism, where there is a long-winged form that is the main disperser with a larger body, and a short-winged form that does not fly well with a smaller body. Long-wing morphs also have larger mouthparts that are beneficial on the new non-native host plant. This project will test whether the observed rapid adaptation from a native host plant, where smaller mouthparts are favored, to a non-native host plant, where larger mouthparts are favored, was promoted by spatial sorting as opposed to natural selection from standing phenotypic variation. To do this, field observational studies, a manipulative transplant experiment, lab tests of the genetic basis of dispersal phenotypes, as well as genetic tests for reductions in genetic variation within populations will be performed.