Demographic Factors and Male Behavioral Plasticity Affect Male and Female Reproduction Success and Temporal Variation in Effective Breeding Number in Lake Sturgeon

Monday, September 9, 2013: 3:40 PM
Pope (Statehouse Convention Center)
Kim T. Scribner , Department of Fisheries & Wildlife and Department of Zoology, Michigan State University, East Lansing, MI
Yen Duong , College of Aquaculture and Fisheries, Cantho University, Cantho, Vietnam
James A. Crossman , Water Licence Requirements, B.C. Hydro, Castlegar, BC, Canada
P Forsythe , Univ. Wisconsin-Green Bay
Edward A. Baker , Michigan Department of Natural Resources and Environment, Marquette, MI
Quantifying inter-annual variation in effective adult breeding number (Nb) and relationships between Nb, effective population size (Ne), adult census size (N) and population 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 Nb and generational Ne using genotypes from 12 microsatellite loci for lake sturgeon adults (n=796) captured during 8 spawning seasons and offspring (n=3,925) collected during larval dispersal in a closed population over 10 years. Inbreeding and variance Nb  derived using multiple estimators were similar within and among years (inter-annual range of Nb: 41-205). Variance in reproductive success and unequal sex ratios reduced Nb relative to N on average 36.8% and 16.3%, respectively. Inter-annual variation in Nb/N ratios (0.27 - 0.86) resulted from stable N and low standardized variance in reproductive 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 Nb/N. Ne may not be approximated as the product of average annual Nb and generation length (g). Therefore, supplemental breeding programs would be ill advised to divide the targeted Ne into a series of (g) annual target effective numbers (Nb).  Results have important implications for genetic monitoring and conservation planning for lake sturgeon and other species with similar life histories and mating systems.