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

那些能提高生物传播速度的特征，在迅速移居新栖息地的种群中是有利的。如果分散的个体与周围种群中相似的、高度流动的个体交配，这一点尤其正确。这个过程被称为“空间分选”，无论这些基因如何影响种群在新栖息地的适应性，它所产生的后代都是快速分散者。该项目将首次进行空间分选的大规模实地试验，利用红颈soapberry虫（Jadera haematoloma）种群进行快速进化，红颈soapberry虫在过去60年里已经从本地食物植物扩展并适应了非本地食物植物。飓风“哈维”带来的罕见的偶发洪水，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仍然完好无损，使soapberry虫种群的进化时钟倒退。这项研究的结果可以应用于了解入侵物种如何殖民新的栖息地并最终取代本地种群。该项目还将支持有关殖民人口进化的外展公共教育。一个基本问题是血肿瘤种群是如何进化得如此之快的？这个问题的答案可能来自最初殖民者的特征。Soapberry bugs表现出飞行多态性，其中有一个长翅膀的形式，是一个较大的身体的主要分散者，和一个短翅膀的形式，不太好飞行，较小的身体。长翅变种也有更大的口器，这对新的非本地寄主植物有益。该项目将测试观察到的从本地寄主植物（口器较小）到非本地寄主植物（口器较大）的快速适应是否由空间分选促进，而不是由长期表型变异的自然选择促进。为此，将进行实地观察研究、操纵移植实验、对扩散表型的遗传基础进行实验室测试，以及对种群内遗传变异的减少进行基因测试。

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.