title: Population dynamics of American horseshoe crabs--historic climatic events and recent anthropogenic pressures.
abstract: Populations of the American horseshoe crab, Limulus polyphemus, have declined, but neither the causes nor the magnitude are fully understood. In order to evaluate historic demography, variation at 12 microsatellite DNA loci surveyed in 1218 L. polyphemus sampled from 28 localities was analysed with Bayesian coalescent-based methods. The analysis showed strong declines in population sizes throughout the species' distribution except in the geographically isolated southern-most population in Mexico, where a strong increase in population size was inferred. Analyses suggested that demographic changes in the core of the distribution occurred in association with the recolonization after the Ice Age and also by anthropogenic effects, such as the past overharvest of the species for fertilizer or the current use of the animals as bait for American eel (Anguilla rostrata) and whelk (Busycon spp.) fisheries. This study highlights the importance of considering both climatic changes and anthropogenic effects in efforts to understand population dynamics--a topic which is highly relevant in the ongoing assessments of the effects of climate change and overharvest.
authors.affiliation: Ecology and Genetics, Department of Biological Sciences, Aarhus University, DK-8000, Aarhus, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Faurby
authors.forename: Tim L
authors.initials: TL
authors.lastname: King
authors.forename: Matthias
authors.initials: M
authors.lastname: Obst
authors.forename: Eric M
authors.initials: EM
authors.lastname: Hallerman
authors.forename: Cino
authors.initials: C
authors.lastname: Pertoldi
authors.forename: Peter
authors.initials: P
authors.lastname: Funch
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D057231:Climate Change; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D006737:Horseshoe Crabs / Q000235:genetics*; D015810:Linkage Disequilibrium; D018895:Microsatellite Repeats; D008957:Models, Genetic; D011156:Population Density; D011157:Population Dynamics; D017422:Sequence Analysis, DNA