COLLABORATIVE RESEARCH: RUI: SINK OR SWIM: PHENOMIC AND TRANSCRIPTOMIC DIVERSIFICATION OF SCULPINS (TELEOSTEI: COTTIDAE) ENDEMIC TO LAKE BAIKAL, SIBERIA

古老的湖泊是生物多样性的热点，是数千种独特物种的家园，这些物种具有非凡的身体形态和功能。贝加尔湖拥有超过1,500种在地球上其他地方找不到的物种，是研究新物种产生过程的理想环境。贝加尔湖生物多样性热点也是一个地理异常，因为全球物种多样性通常在极地附近下降。尽管贝加尔湖是世界上最古老、最深、最大的湖泊，但其独特的物种多样性的进化历史仍然知之甚少。这个项目研究了杜父鱼的进化历史，杜父鱼是一组主要生活在底部的冷水鱼，在贝加尔湖历史的相对较短的时期内定居在贝加尔湖。贝加尔杜父鱼是唯一适应生活在一个古老的湖泊，已经演变成多种开放水域和深水形式。该项目的重点是确定这种变异的分子基础，包括通过世代进化的基因序列和发育过程中发生的基因表达变化。从这项研究中获得的新信息可以与正在进行的对其他古代湖泊鱼类的研究进行比较，以确定解释这些独特生态系统适应的统一过程。贝加尔杜父鱼代表了世界上最北端的古代湖泊生态系统中的脊椎动物辐射，估计至少有33种物种在过去200万年内进化。骨骼形态和身体组成的快速多样化表明，这支经历了生态释放流生活的祖先，但系统发育分析迄今仅限于一个单一的遗传位点。通过对所有湖泊生境和周围流域的系统调查，将产生贝加尔杜父鱼的基因组清单。贝加尔湖的支流也将取样，以寻找假定的祖先杜父鱼种群。将从假定中性（RADseq）和功能性（RNAseq）基因座的序列变体生成时间校准的物种树。基因表达表型将被绘制在基因组上，以推断表型和生态变化的相对速率。如果在贝加尔湖的支流中发现一个假定的祖先种群，这个系统将提供一个前所未有的机会来了解使某些群体易于适应辐射的遗传因素。

Ancient lakes are biodiversity hotspots, home to thousands of unique species with an extraordinary diversity of body forms and functions. With more than 1,500 species found nowhere else on the planet, Lake Baikal is an ideal environment to study the processes that resulted in creation of new species. The Baikal biodiversity hotspot is also a geographical anomaly, because global species diversity normally declines near polar regions. Despite Baikal's renown as the world's oldest, deepest, and largest lake, the evolutionary history of its unique species diversity remains poorly understood. This project examines the evolutionary history of sculpins, a group of primarily bottom-dwelling cold water fishes that colonized Baikal within a relatively short period of the lake's history. Baikal sculpins are uniquely adapted to life in an ancient lake, having evolved multiple open-water and deep-water forms. This project is focused on identifying the molecular basis for such variation, including gene sequences that evolve through generations and gene-expression changes that occur during development. New information gained from this study can be compared to ongoing research on fishes from other ancient lakes, in order to identify unifying processes that explain adaptation in these unique ecosystems.Baikal sculpins represent the world's northernmost vertebrate radiation within an ancient lake ecosystem, with at least 33 species estimated to have evolved within the past two million years. Rapid diversification of skeletal morphology and body composition suggests that this clade has undergone ecological release from a stream-living ancestor, but phylogenetic analysis has thus far been limited to a single genetic locus. A genomic inventory of Baikal sculpins will be generated through systematic surveys of all lake habitats and the surrounding watershed. Tributaries to Baikal will also be sampled in the search for a putative ancestral sculpin population. A time-calibrated species tree will be generated from sequence variants at presumed neutral (RADseq) and functional (RNAseq) loci. Gene expression phenotypes will be mapped on the phylogeny to infer relative rates of phenotypic and ecological change. If a putative ancestral population is discovered in the tributaries to Lake Baikal, this system will offer an unprecedented opportunity to understand the genetic factors that predispose certain groups to adaptive radiation.