title: Abundance and phenology patterns of two pond-breeding salamanders determine species interactions in natural populations.
abstract: Phenology often determines the outcome of interspecific interactions, where early-arriving species often dominate interactions over those arriving later. The effects of phenology on species interactions are especially pronounced in aquatic systems, but the evidence is largely derived from experimental studies. We examined whether differences in breeding phenology between two pond-breeding salamanders (Ambystoma annulatum and A. maculatum) affected metamorph recruitment and demographic traits within natural populations, with the expectation that the fall-breeding A. annulatum would negatively affect the spring-breeding A. maculatum. We monitored populations of each species at five ponds over 4 years using drift fences. Metamorph abundance and survival of A. annulatum were affected by intra- and interspecific processes, whereas metamorph size and date of emigration were primarily influenced by intraspecific effects. Metamorph abundance, snout-vent length, date of emigration and survival for A. maculatum were all predicted by combinations of intra- and interspecific effects, but often showed negative relationships with A. annulatum metamorph traits and abundance. Size and date of metamorphosis were strongly correlated within each species, but in opposite patterns (negative for A. annulatum and positive for A. maculatum), suggesting that the two species use alternative strategies to enhance terrestrial survival and that these factors may influence their interactions. Our results match predictions from experimental studies that suggest recruitment is influenced by intra- and interspecific processes which are determined by phenological differences between species. Incorporating spatiotemporal variability when modeling population dynamics is necessary to understand the importance of phenology in species interactions, especially as shifts in phenology occur under climate change.
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA. tlarkf@missouri.edu.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Anderson
authors.affiliation: Department of Environmental Conservation, University of Massachusetts, Amherst, MA, 01003, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hocking
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Conner
authors.affiliation: National Institute for Mathematical and Biological Synthesis, University of Tennessee, 1122 Volunteer Blvd., Suite 106, Knoxville, TN, 37996, USA.
authors.forename: Julia E
authors.initials: JE
authors.lastname: Earl
authors.affiliation: Division of Natural Resource Management and Ecology, Paul Smiths College, Paul Smiths, NY, 12970, USA.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Harper
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Osbourn
authors.affiliation: Illinois Natural History Survey Prairie Research Institute, University of Illinois, 1916 S Oak Street, Champaign, IL, 61820, USA.
authors.forename: William E
authors.initials: WE
authors.lastname: Peterman
authors.affiliation: Department of Natural Resources and the Environment, University of Connecticut, 1376 Storrs Road., Unit 4087, Storrs, CT, 06269-4087, USA.
authors.forename: Tracy A G
authors.initials: TAG
authors.lastname: Rittenhouse
authors.affiliation: Division of Biological Sciences, University of Missouri, Columbia, MO, 65211, USA.
authors.forename: Raymond D
authors.initials: RD
authors.lastname: Semlitsch
mesh_terms: D000557:Ambystoma / Q000145:classification / Q000502:physiology*; D000818:Animals; D001947:Breeding; D057231:Climate Change; D017753:Ecosystem; D008675:Metamorphosis, Biological; D061005:Ponds; D011157:Population Dynamics; D012098:Reproduction; D012621:Seasons; D013045:Species Specificity; D014562:Caudata / Q000502:physiology