Effective population size and connectivity in fish

进化生物学中的一个基本概念是有效种群大小。Ne反映了每代经历与实际研究人口相同的随机基因变化率的“理想”人口的大小(人口普查大小N)。这一概念是保护遗传学的核心，因为它与近亲繁殖衰退、种群持久性和进化潜力有关。有效人口规模通常比人口普查规模小得多。种群规模随时间的波动、性别比例的不平等以及生命周期生殖成功的差异是自然界中普遍观察到的低Ne/N比率的原因。如此低的比例表明，即使在人口普查规模仍然相对较大的情况下，人口也可能受到遗传多样性丧失的影响。因此，了解影响Ne的机制、其与N的关系以及与基因流(M)的关系及其相互作用对于理解影响生物多样性的机制至关重要。我的长期研究目标是了解影响Ne和m的过程，以及它们与N的关系，并确定Ne可用于预测种群持久性的条件。我打算比较同域鱼类种群的Ne和m的模式，以理清生活、历史和环境的影响。我还计划重建祖先的种群动态；我将比较不同物种的祖先种群瓶颈的历史变化和时间，并将这些信息与地理形态过程和过去的气候变化(第四纪)联系起来。其目的是确定Ne和m的当前和历史模式对于共存物种的种群有多相似，并检查生活史和生态与地貌和气候在产生这些模式中所起的作用。田野工作发生在两个截然不同的温带系统中：北部的“鲑鱼”系统和巴塔哥尼亚系统。这两个都是在冰川后的风景中发现的。北部鲑鱼系统包括大西洋鲑鱼、小河鲑鱼和纽芬兰和拉布拉多的北极炭。巴塔哥尼亚系统由两种分布广泛的本土巴塔哥尼亚鱼类组成。在这两种情况下，物种都出现在不同的生态环境中。

A fundamental concept in evolutionary biology is that of effective population size (Ne). Ne reflects the size of an "ideal" population experiencing the same rate of random genetic change per generation as the actual population under study (census size N). The concept is central to conservation genetics because of its links to inbreeding depression, population persistence and evolutionary potential. Effective sizes are typically much smaller than census sizes. Fluctuating population size over time, unequal sex ratio and variance in life time reproductive success contribute to the low Ne/N ratios commonly observed in nature. Such low ratios suggest that populations may be subject to the loss of genetic diversity even when census sizes are still relatively large. Knowledge of the mechanisms that affect Ne, its relationship with N and with gene flow (m) and their interaction is thus critical for understanding the mechanisms that affect biodiversity. My long term research goals are to understand the processes that affect Ne and m, and their relationship with N, and to identify the conditions under which Ne can be used to predict population persistence. I intend to compare patterns of Ne and m across sympatric populations of fish species to disentangle the influences of life history and environment. I also plan to reconstruct ancestral population dynamics; I will compare historical changes in Ne and timing of ancestral population bottlenecks across species and will relate this information to geo-morphological processes and past climatic changes (Quaternary). The goal is to determine how similar current and historic patterns of Ne and m are for populations of coexisting species and to examine the roles played by life histories and ecologies vs. geomorphology and climate in producing these patterns. Fieldwork takes place in two contrasting temperate systems: A northern "Salmonid" system, and a Patagonian system. Both are found in post-glacial landscapes. The northern salmonid system includes Atlantic salmon, brook trout, and Arctic char in Newfoundland and Labrador. The Patagonian system comprises two widely distributed native Patagonian fishes. In both cases, species are found in a variety of ecological settings.