Interannual variation in effective number of breeders and estimation of effective population size in long-lived iteroparous lake sturgeon (Acipenser fulvescens) THUY YEN DUONG,* KIM T. SCRIBNER,* † PATRICK S. FORSYTHE, † 1 JAMES A. CROSSMAN* 2 and EDWARD A. BAKER ‡ *Department of Fisheries and Wildlife, Michigan State University, 13 Natural Resources, East Lansing, MI 48824, USA, †Department of Zoology, Michigan State University, 13 Natural Resources, East Lansing, MI 48824, USA, ‡Michigan Department of Natural Resources, 488 Cherry Creek Road, Marquette, MI 49855, USA Abstract Quantifying interannual variation in effective adult breeding number (N b ) and rela- tionships between N b , effective population size (N e ), adult census size (N) and popula- tion demographic characteristics are important to predict genetic changes in populations of conservation concern. Such relationships are rarely available for long- lived iteroparous species like lake sturgeon (Acipenser fulvescens). We estimated annual N b and generational N e using genotypes from 12 microsatellite loci for lake sturgeon adults (n = 796) captured during ten spawning seasons and offspring (n = 3925) collected during larval dispersal in a closed population over 8 years. Inbreeding and variance N b estimated using mean and variance in individual repro- ductive success derived from genetically identified parentage and using linkage dis- equilibrium (LD) were similar within and among years (interannual range of N b across estimators: 41–205). Variance in reproductive success and unequal sex ratios reduced N b relative to N on average 36.8% and 16.3%, respectively. Interannual variation in N b / N ratios (0.27–0.86) resulted from stable N and low standardized variance in reproduc- tive success due to high proportions of adults breeding and the species’ polygamous mating system, despite a 40-fold difference in annual larval production across years (437–16 417). Results indicated environmental conditions and features of the species’ reproductive ecology interact to affect demographic parameters and N b /N. Estimates of N e based on three single-sample estimators, including LD, approximate Bayesian com- putation and sibship assignment, were similar to annual estimates of N b . Findings have important implications concerning applications of genetic monitoring in conser- vation planning for lake sturgeon and other species with similar life histories and mat- ing systems. Keywords: demographic parameters, effective number of breeders, effective population size, iteroparity, lake sturgeon, linkage disequilibrium Received 9 June 2011; revision received 6 November 2012; accepted 7 November 2012 Introduction Effective population size (N e ) is the number of individ- uals in a theoretically ‘ideal’ population exhibiting the same magnitude of genetic drift and inbreeding as a population of size N (Wright 1931; Nunney 1993; Charlesworth 2009). N e reflects the effects of evolution- ary processes on population levels of genetic diversity and therefore has been an important conceptual focus Correspondence: Thuy Yen Duong, College of Aquaculture and Fisheries, Cantho University, 3/2 street, Cantho City, Viet- nam. Fax: +84 710 3830323; E-mail: duongyen@msu.edu or thuyyen@ctu.edu.vn 1 Present address: Department of Natural and Applied Sciences, University of Wisconsin – Green Bay, Green Bay, WI 54311, USA 2 Present address: BC Hydro, 601 18th Street, Castlegar, BC, Canada V1N 2N1 © 2013 Blackwell Publishing Ltd Molecular Ecology (2013) 22, 1282–1294 doi: 10.1111/mec.12167