Causes and consequences of hybridization in mammals

当代气候变化的快速步伐意味着我们可能正在进入一个激烈的自然选择时代。种间杂交通常被认为是气候变化的结果，但它也可能是快速适应的重要机制。这是因为杂交是一种相对快速的获得新基因组合的方法，然后可能在生物体中产生新的性状。在适当的环境条件下，这些新的特征可能会持续在人口中，如果他们赋予一个健身优势。我的研究项目包括测试关于哺乳动物杂交的原因和后果的假设。我和我的同事们观察到北方和南方飞鼠在次级接触区的杂交，由于南方物种的范围扩张，最近在安大略出现了这些物种之间的杂交。我们将使用对南方飞鼠的长期调查数据来测试气候变化是否是范围扩张的重要原因，因此与北方物种杂交。我们还将测试两个假设解释所观察到的杂交模式：进化的生殖障碍，由于缺乏任何历史的空间重叠的情况下，和寄生虫介导的飞鼠物种之间的竞争的影响。我们将使用在松鼠基因组中观察到的基因流模式来测试这些杂交的原因。我们还将开展研究，以评估杂交的一些后果。特别是，我们感兴趣的是杂交对声音信号和北方飞鼠的真菌饮食习惯的影响，这可以帮助森林再生。北方飞鼠在土壤中沉积真菌孢子和固氮细菌，这对氮有限的森林中的树木生长很重要。

The rapid pace of contemporary climate change means that we may be entering an era of intense natural selection. Interspecific hybridization is often considered to be a consequence of climate change, but it is also potentially an important mechanism of rapid adaptation. This is because hybridization is a relatively fast way to arrive at new combinations of genes, which may then produce novel traits in organisms. Under appropriate environmental conditions, these novel traits may persist in the population if they confer a fitness advantage. My research program involves testing hypotheses about the causes and consequences of hybridization in mammals. My colleagues and I have observed hybridization between the northern and southern flying squirrel in a secondary contact zone that has recently emerged between these species in Ontario due to range expansion by the southern species. We will use long-term survey data of the southern flying squirrel to test whether climate change is an important cause of range expansion, and therefore hybridization with the northern species. We will also test two hypotheses explaining the observed pattern of hybridization: the absence of evolved reproductive barriers due to a lack of any historic spatial overlap, and the effects of parasite-mediated competition between flying squirrel species. We will use the patterns of gene flow observed in squirrel genomes to test these causes of hybridization. We will also carry out studies to evaluate some consequences of hybridization. In particular, we are interested in effects of hybridization on acoustic signals and on the fungus-eating habits of the northern flying squirrel, which can aid in forest regeneration. The northern flying squirrel deposits fungal spores and nitrogen-fixing bacteria in the soil, which can be important for tree growth in nitrogen-limited forests.