Abstract
Long-term effective population size is expected, and has been shown, to correlate positively with various measures of population fitness. Here we examine the interacting effects of population size (as a surrogate for genetic factors) and prey consumption rates (as a surrogate for environmental quality) on fecundity in two sympatric species of wolf spider, Rabidosa punctulata and Rabidosa rabida. Population size was estimated in each of seven genetically isolated populations in each of 3 years using mark-recapture methods. Fecundity was estimated as the mean number of live offspring produced by ∼15 females sampled from each population of each species each year for 3 years. Prey consumption rates were estimated by sampling ∼300 spiders per population per year and assaying the proportion of spiders with prey. Larger populations have higher fecundity and more genetic diversity than smaller populations. Variation among populations in fecundity for a given year could be attributed most strongly to differences in population size, with variation in prey consumption rates and the interaction between population size and prey consumption playing smaller but still important roles. During the most stressful environmental conditions, the smallest populations of both species experienced disproportionately low-fecundity rates, more than doubling the estimated number of lethal equivalents during those years. The evidence presented in this paper for inbreeding-environment interactions at the population level and further evidence for a log-linear relationship between population size and fitness have important implications for conservation.
Similar content being viewed by others
References
Armbruster P, Reed DH (2005) Inbreeding depression in benign and stressful environments. Heredity 95:235–242
Beddington JR, Hassell MP, Lawton JH (1976) The components of arthropod predation II: the predator rate of increase. J Anim Ecol 45:165–185
Beerli P (1998) Estimation of migration rates and effective population sizes in geographically structured populations. In: Carvalho GR (ed) Advances in molecular ecology. IOS Press, Amsterdam, pp 39–54
Briskie JV, Mackintosh M (2004) Hatching failure increases with severity of population bottlenecks in birds. Proc Nat Acad Sci USA 101:558–561
Burnham KP, Anderson DR (2002) Model Selection and multimodel inference: a practical information-theoretic approach. Springer, New York, USA
Cassel A, Windig J, Nylin S, Wiklund C (2001) Effects of population size and food stress on fitness-related characters in the scarce heath, a rare butterfly in western Europe. Conserv Biol 15:1667–1673
Caughley G (1994) Directions in conservation biology. J Anim Ecol 63:215–244
Da Silva A, Luikart G, Yoccoz NG, Cohas A, Allainé (2006) Genetic diveristy-fitness correlation revealed by microsatellite analyses in European alpine marmots (Marmota marmota). Conserv Genet 7:371–382
Davis RA, Roberts JD (2005) Embryonic survival and egg numbers in small and large populations of the frog Heleioporus albopunctatus in Western Australia. J Herpetol 39:133–138
Dieringer D, Schlotterer C (2003) Microsatellite analyser (MSA): a platform independent analysis tool for large microsatellite data sets. Mol Ecol Notes 3:167–169
Fagan WF, Holmes EE (2006) Quantifying the extinction vortex. Ecol Lett 9:51–60
Falconer DS, Mackay TFC (1996) Introduction to quantitative genetics, 4th edn. Addison Wesley Longman, Essex, UK
Gaggiotti OE, Lange O, Rassmann K, Gliddons C (1999) A comparison of two indirect methods for estimating average levels of gene flow using microsatellite data. Mol Ecol 8:1513–1520
Gilligan DM, Briscoe DA, Frankham R (2005) Comparative losses of quantitative and molecular genetic variation in finite populations of Drosophila melanogaster. Genet Res 85:47–55
Goudet J (2001) FSTAT, a program to estimate and test gene diversities and fixation indices (version 2.9.3). Available at http://www.unil.ch/izea/softwares/fstat.html
Hartl DL, Clark AG (1997) Principles of Population Genetics, 3rd edn. Sinauer Associates, Sunderland, MA, USA
Hensen I, Oberprieler C (2005) Effects of population size on genetic diversity and seed production in the rare Dictamnus albus (Rutaceae) in central Germany. Conserv Genet 6:63–73
Heschel MS, Paige KN (1995) Inbreeding depression, environmental stress, and population size in scarlet gilia (Ipomopsis aggregata). Conserv Biol 9:126–133
Keller LF (1998) Inbreeding and its fitness effects in an insular population of song sparrows (Melospiza melodia). Evolution 52:240–250
Kessler A (1973) Relation between egg production and food consumption in species of the genus Pardosa (Lycosidae, Araneae) under experimental conditions of food-abundance and food-shortage. Oecologia 8:93–109
Lande R (1988) Genetics and demography in biological conservation. Sci 241:1455–1460
Lande R (1993) Risks of population extinction from demographic and environmental stochasticity and random catastrophes. Am Nat 142:911–927
Leimu R, Mutikainen P (2005) Population history, mating system, and fitness variation in a perennial herb with a fragmented distribution. Conserv Biol 19:345–356
Lesbarrères D, Primmer CR, Laurila A, Merilä J (2005) Environmental and population dependency of genetic variability-fitness correlations in Rana temporaria. Mol Ecol 14:311–323
Lu Y, Waller DM, David P (2005) Genetic variability is correlated with population size and reproduction in American wild rice (Zizania palustris Var. Palustris, Poaceae) populations. Am J Bot 92:990–997
O’Grady JJ, Brook BW, Reed DH, Ballou JD, Tonkyn DW, Frankham R (2006) Realistic levels of inbreeding depression strongly affect extinction risk in wild populations. Biol Conserv 133:42–51
Pimm SL, Redfearn A (1988) The variability of population densities. Nature 334:613–615
Pluess AR, Stöcklin J (2004) Genetic diversity and fitness in Scabiosa columbaria in the Swiss Jura in relation to population size. Conserv Genet 5:145–156
Puurtinen M, Knott KE, Suonpää S, van Ooik T, Kaitala V (2004) Genetic variability and drift load in populations of an aquatic snail. Evolution 58:749–756
Ramirez MG, Saunders TA (1999) Allozyme diversity in non-social spider: pattern process and conservation implications. J Insect Conserv 3:327–340
Reed DH (2004) Extinction risk in fragmented habitats. Anim Conserv 7:181–191
Reed DH (2005) Relationship between population size and fitness. Conserv Biol 19:563–568
Reed DH (2007) Effects of population size on population viability: From mutation to environmental catastrophes. In: Carroll SP, Fox CW (eds) Conservation biology: evolution in action. Oxford University Press, UK (in press)
Reed DH, Frankham R (2001) How closely correlated are molecular and quantitative measures of genetic variation? A meta-analysis. Evolution 55:1095–1103
Reed DH, Frankham R (2003) Correlation between population fitness and genetic diversity. Conserv Biol 17:230–237
Reed DH, O’Grady JJ, Ballou JD, Frankham R (2003a) Frequency and severity of catastrophic die-offs in vertebrates. Anim Conserv 6:109–114
Reed DH, O’Grady JJ, Brook BW, Ballou JD, Frankham R (2003b) Estimates of minimum viable population sizes for vertebrates and factors influencing those estimates. Biol Conserv 113:23–34
Slatkin M, Barton NH (1989) A comparison of three indirect methods for estimating average levels of gene flow. Evolution 43:1349–1368
Whitlock M, McCauley DE (1999) Indirect estimation of gene flow and migration: FST ≠ 1 / (4Nm + 1). Heredity 82:117–125
Wise CA, Ranker TA, Linhart YB (2002) Modeling problems in conservation genetics with Brassica rapa: Genetic variation and fitness in plants under mild, stable conditions. Conserv Biol 16:1542–1554
Wright S (1951) The general structure of populations. Ann Eugen 15:323–354
Acknowledgments
We would like to thank Allison Derrick, Christian Felton, Alex Teoh and Winter Williams for help collecting spiders. Bianca Lowe photographed and measured spiders for many of the heritability estimates. Paul Lago kindly identified mantispids for us. Martín Ramírez and an anonymous reviewer provided useful suggestions on a previous draft of this paper. We thank the University of Mississippi for providing funding for this research.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Reed, D.H., Nicholas, A.C. & Stratton, G.E. Inbreeding levels and prey abundance interact to determine fecundity in natural populations of two species of wolf spider. Conserv Genet 8, 1061–1071 (2007). https://doi.org/10.1007/s10592-006-9260-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10592-006-9260-4