Author : Kuan-Yu Chen
Publisher :
ISBN 13 :
Total Pages : 150 pages
Book Rating : 4.:/5 (976 download)
Book Synopsis Lake Erie Walleye Population Structure and Stock Discrimination Methods by : Kuan-Yu Chen
Download or read book Lake Erie Walleye Population Structure and Stock Discrimination Methods written by Kuan-Yu Chen and published by . This book was released on 2016 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: Both natal philopatry and deviations from natal philopatry (i.e., straying) can play important roles in persistence of migratory populations. While natal philopatry allows for isolation among local breeding populations and the opportunity for local adaptation, straying may provide rescue effects to declining local populations or colonization of new habitats. However, quantification of natal philopatry can be challenging because the migratory behavior and variability therein itself makes tracking individual movement across years difficult. In turn, a key advance that could help narrow this knowledge gap is the development of “markers” that can reliably discriminate among local populations so that homing and straying behavior can be quantified. The central goal herein is to evaluate existing methods and develop appropriate markers for determining natal origins and measuring connectivity among local spawning populations (or spawning stocks) of walleye (Sander vitreus) in western Lake Erie. Toward this end, we selected two commonly-used natural markers, otolith microchemistry and genetics, to quantify natal philopatry and understand population structure and dynamics of the Lake Erie walleye. While otolith microchemistry records the elemental fingerprints of natal origins of individuals, genetic markers can ascertainpopulation membership of individuals owing to divergence of local populations. We expected that if walleye show strong natal philopatry (revealed by otolith microchemistry), population structure could exist among the spawning stocks because natal philopatry is a potential mechanism that drives reproductive isolation. If so, we could also use genetic markers to determine the source stocks of individuals among the stocks, particularly in which otolith elemental fingerprints are undistinguishable. In this study, we first evaluated whether otolith strontium concentration [Sr] can be used as a natural marker to discriminate individuals spawned between two river-spawning sites using both lab-reared and field-collected walleye larvae (Chapter 2). Next, we applied the marker, otolith [Sr], to quantify natal philopatry of adult walleye among the two river-spawning and one reef-spawning sites (Chapter 3). Toward developing genetic stock discrimination markers, we developed an analytical toolkit that allows us to perform assignment tests and evaluate how different factors (i.e., population differentiation, sample sizes of individual and loci) could influence assignment results (Chapter 4). It can help ascertain population membership of individuals and determine whether our data is sufficient to discriminate among populations. Our findings revealed that spawning walleye had high natal homing rates, with about 98% of individuals returning to the natal site to spawn based on the evidences of otolith microchemistry, but the genetic markers (i.e., thousands of SNP loci) did not have enough discriminatory power to ascertain population membership of individuals. The overall correct assignment rates estimated using sole genetic data were only better than random assignment, even though the rates can be improved by integrating genetic and otolith microchemistry data (Appendix A). These results suggested that the connectivity among the walleye spawning stocks might be weak, but the stocks still reflect a weakly differentiated population and hence we were unable to use the newly developed genetic loci as the stock discrimination marker. Despite its insignificant population structure, strong natal homing behavior indicated that they form reproductively isolated stocks and therefore should be managed as separated stocks.
