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规模（Ne）。Ne反映了一个“理想”种群的规模，该种群每一代经历的随机遗传变化率与所研究的实际种群相同（人口普查规模N）。这个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。有效规模通常比普查规模小得多。随着时间的推移，不平等的性比和生活时间的繁殖成功的方差的波动的人口规模有助于低Ne/N比通常观察到的性质。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，种群也可能会丧失遗传多样性。因此，了解影响Ne的机制、Ne与N和基因流（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。我打算在同域分布的鱼类种群中比较Ne和m的模式，以解开生活史和环境的影响。我还计划重建祖先的人口动态，我将比较历史上的变化Ne和时间的祖先人口瓶颈跨物种，并将这些信息与地理形态过程和过去的气候变化（第四纪）。我们的目标是确定如何相似的当前和历史模式的Ne和m的共存物种的种群，并检查所发挥的作用的生活史和生态与地貌和气候在生产这些模式。野外工作发生在两个截然不同的温带系统：一个北方“鲑鱼”系统，和巴塔哥尼亚系统。两者都在冰川后的景观中被发现。北方鲑科鱼类包括大西洋鲑、溪鳟和纽芬兰和拉布拉多的北极红点鲑。巴塔哥尼亚系统包括两种广泛分布的原生巴塔哥尼亚鱼类。在这两种情况下，物种都存在于各种生态环境中。

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.