Sperm availability in the sea and
the evolution of mating strategies

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Male Strongylocentrotus franciscanus spawning
Three Strongylocentrotus species co-occur but have different  gamete traits and gamete performance

     External fertilization (releasing eggs and sperm into the water) is the likely ancestral mating strategy, but little is known about the fate of released gametes in nature. Using a combination of laboratory studies, field experiments, and theoretical models, I have been investigating the probability of fertilization under a variety of environmental and demographic conditions using a group of temperate sea urchins off the coast of British Columbia, Canada. Specifically, I am interested in how egg and sperm traits influence patterns of fertilization in nature and how selection on these traits varies as a function of sperm availability. Most recently, this work has focused on three topics. (1) Exploring the reproductive success and variance in success of males and females under a range of spawning densities using microsatellite markers to determine patterns of maternity and paternity; (2) Examining sex differences in spawning behavior and how that influences patterns of reproductive success; and (3) Determining the relative influence of gamete genotype (gamete recognition proteins) and phenotype (physical traits) on reproductive success in the sea. The overarching goal of this work is to provide insight into the evolution of sexual dimorphism.

Relevant Publications:

2015  Stapper, A.P., P. Beerli and D.R. Levitan. Assortative mating drives linkage-disequilibrium between sperm and egg recognition proteins in the sea urchin Strongylocentrotus purpuratus. Molecular Biology and Evolution. Advanced access msv010v2 [PDF].

2014  Kosman, E.T. and D.R. Levitan. Sperm competition and the evolution of gametic compatibility in externally fertilizing taxa. Molecular Human Reproduction doi:1093/molehr/gau069 [PDF].

2012  Levitan, D. R. Contemporary evolution of sea urchin gamete-recognition proteins: experimental evidence of density-dependent gamete performance predicts shifts in allele frequencies over time. Evolution 66:1722-1736 [PDF].

2011  Simon, T. N., and D. R. Levitan. Measuring fertilization success of broadcast-spawning marine invertebrates within seagrass meadows. Biological Bulletin 220:32-38 [PDF].

2010  Reuter, K. E., and D. R. Levitan. Influence of sperm and phytoplankton on spawning in the echinoid Lytechinus variegatus. Biological Bulletin 219:198-206 [PDF].

2010 Tomaiuolo, M. and D. R. Levitan. Modeling how reproductive ecology can drive protein diversification and result in linkage-disequilibrium between sperm and egg proteins. American Naturalist 176:12-25 [PDF]

2010 Levitan, D.R. and A.P. Stapper. Simultaneous positive and negative frequency dependent selection on sperm bindin, a gamete recognition protein in the sea urchin Strongylocentrotus purpuratus. Evolution 64:785-797 [PDF]

2010 Lotterhos, K. And D.R. Levitan. Gamete release and spawning behavior in broadcast spawning marine invertebrates. Pages 99-120 (J. Leonard ed.) The evolution of primary sexual characters. Oxford University Press

2010 Levitan, D.R. Sexual selection in external fertilizers. Pages 365-378 in (D.F. Westneat and C.W. Fox eds.) Evolutionary Behavioral Ecology. Oxford University Press

2008 Levitan, D.R. Gamete traits influence the variance in reproductive success, the intensity of sexual selection, and the outcome of sexual conflict among congeneric sea urchins. Evolution 62:1305-1316 [PDF]

2007 Tomaiuolo, M., T.F. Hansen, D. R. Levitan. A theoretical investigation of sympatric evolution of temporal reproductive isolation as illustrated by marine broadcast spawners. Evolution 61:2584-2595 [PDF]

2007 Levitan, D.R., C.P. terHorst, N.D. Fogarty. The risk of polyspermy in three congeneric sea urchins and its implications for gametic incompatibility and reproductive isolation. Evolution 61:2007-2014 [PDF]

2006 Levitan, D.R. and D.L. Ferrell. Selection on gamete recognition proteins depends on sex, density and genotype frequency. Science 312:267-269 [PDF] [On-line Supplement PDF]

2006 Levitan, D.R. Relationship between egg size and fertilization success in broadcast spawning marine invertebrates. Integrative and Comparative Biology 46:298-311 [PDF]

2005 Levitan, D.R. The distribution of male and female reproductive success in a broadcast spawning marine invertebrate. Integrative and Comparative Biology 45:848-855 [PDF]

2005 Levitan, D.R. Sex specific spawning behavior and its consequences in an external fertilizer. American Naturalist 165:682-694 [PDF]

2004 McCartney, M.A., K. Brayer and D.R. Levitan. Polymorphic microsatellite lo ci from the red urchin, Strongylocentrotus franciscanus, with comments on heterozyogote deficit. Molecular Ecology Notes 4: 226-228 [PDF]

2004 Levitan, D.R. Density-dependent Sexual Selection in External Fertilizers: Variances in Male and female Reproductive Success Along the Continuum from Sperm Limitation to Sexual Conflict in the Sea Urchin Strongylocentrotus franciscanus.American Naturalist 164:298-309 [PDF]

2002 Levitan, D.R. The relationship between conspecific fertilization success and reproductive isolation among three congeneric sea urchins. Evolution 56:1599-1609 [PDF]

2002 Levitan, D.R. Density-dependent selection on gamete traits in three congeneric sea urchins. Ecology 83:464–479 [PDF]

2001 Levitan, D.R. and S.D. Irvine. Fertilization selection on egg and jelly-coat size in the sand dollar Dendraster excentricus. Evolution 55:2479-2483 [PDF]

2001 Farley, G.S. and D.R. Levitan. The role of jelly coats in sperm-egg encounters, fertilization success, and selection on egg size in echinoids. American Naturalist 157:626-236 [PDF]

2000 Levitan, D.R. Optimal egg size in marine invertebrates: theory and phylogenetic analysis of the critical relationship between egg size and development time in echinoids. American Naturalist 156:175-192 [PDF]

2000 Levitan D.R. Sperm velocity and endurance trade-off and influence fertilization in the sea urchin Lytechinus variegatus. Proceedings of the Royal Society of London: Biological Sciences 267:531-534 [PDF]

1998 Levitan, D.R. Does Bateman's Principle apply to broadcast-spawning organisms? Egg traits influence in situ fertilization rates among congeneric sea urchins. Evolution 52:1043-1056 [PDF]

1998 Levitan, D.R. Sperm limitation, sperm competition and sexual selection in external fertilizers. Pages 173-215 in (T. Birkhead and A. Moller eds) Sperm Competition and Sexual Selection. Academic Press. [PDF]

1998 Levitan, D.R. and M.A. Sewell. Male abundance and fertilization success in free-spawning marine invertebrates: Review of the evidence and fisheries implications. In Proceedings of the North Pacific symposium on Invertebrate Stock Assessment and Management. Edited by G.S. Jamieson and A. Campbell. Canadian Special Publication in Fisheries and Aquatic Science 125:159-164.

1996 Levitan, D.R. Effects of gamete traits on fertilization in the sea and the evolution of sexual dimorphism. Nature 382:153-155 [PDF]

1996 Levitan, D.R. Predicting optimal and unique egg sizes in free-spawning marine invertebrates. American Naturalist 148:174-188 [PDF]

1995 Levitan, D.R. The ecology of fertilization in free-spawning invertebrates. Pages 123-156 in (L. McEdward ed.) Ecology of Marine Invertebrate Larvae. CRC Press.

1995 Levitan, D.R. and C.M. Young. Reproductive success in large populations: empirical measures and theoretical predictions of fertilization in the sea biscuit Clypeaster rosaceus. Journal of Experimental Marine Biology and Ecology 190:221-241 [PDF]

1995 Levitan, D.R. and C. Petersen. Sperm limitation in the sea. Trends in Ecology and Evolution 10:228-231 [PDF]

1993 Levitan, D.R. The importance of sperm limitation to the evolution of egg size in marine invertebrates. American Naturalist 141:517-536 [PDF]

1992 Sewell, M.A. and D.R. Levitan. Fertilization success in a natural spawning of the dendrochirote sea cucumber Cucumaria miniata. Bulletin of Marine Science 51:161-166

1992 Levitan, D.R., M.A. Sewell, and F.-S. Chia. How distribution and abundance influencefertilization success in the sea urchin Strongylocentrotus franciscanus. Ecology 73:248-254 [PDF]

1991 Levitan, D.R. Influence of body size and population density on fertilization success and reproductive output in a free-spawning invertebrate. Biological Bulletin 181:261-268 [PDF]

1991 Levitan, D.R., M.A. Sewell, and F.- S. Chia. Kinetics of fertilization in the sea urchin Strongylocentrotus franciscanus: interaction of gamete dilution, age, and contact time.  Biological Bulletin 181:371-378 [PDF]

1988 Levitan, D.R. Asynchronous spawning and aggregative behavior in the sea urchin Diadema antillarum Philippi.  In (R.D. Burke et al. eds.) Echinoderm Biology, pp 181-186, A.A. Balkema Press, Rotterdam [PDF]