AuthorsYearTitleJournal pdfSource
Koslicki & Novakpre-printExact probabilities for the indeterminacy of complex networks as perceived through press perturbationsarXivlink
Novak, Wolf, Coblentz & Shepardpre-printQuantifying predator dependence in the functional response of generalist predatorsbioRxivlink
Krumhanl, Okamoto, Rassweiler, Novak,...+31 & Byrnes2016Global patterns of kelp forest change over the past half-centuryPNAS113(48): 13785-13790pdflink
Novak, Yeakel, Noble, Doak, Emmerson, Estes, Jacob, Tinker & Wootton2016Characterizing species interactions to understand press perturbations: What is the community matrixAREES47: 409-432pdflink
Iles & Novak2016Complexity increases predictability in allometrically-constrained food websAmerican Naturalist188: 87-98pdf
Stier, Samhouri, Novak, Marshall, Ward, Holt & Levin2016Ecosystem context and historical contingency in apex predator recoveriesScience AdvancesE1501769pdflink
Wolf, Novak & Gitelman2015 (pre-print)Bayesian characterization of uncertainty in species interaction strengthsPeerJ PrePrint3:e1717pdflink
Borelli, Allesina, Amarasekare, Arditi, Chase, Damuth, Holt, Logefet, Novak, Rohr, Rossberg, Spencer, Tran & Ginzburg2015Selection on stability across ecological scales.TREE30(7): 417-425pdflink
Terry & Novak2015Where does the time go: Mixing and the depth-dependent distribution of fossil ages.Geology43: 487-490pdf
Novak & Tinker2015Time-scales alter the inferred strength and temporal consistency of intraspecific diet specialization.Oecologia178: 61-74pdf
Beas-Luna, Novak, Carr, Tinker, Black, Caselle, Hoban, Malone, Iles2014An online database for informing ecological network models: ONE9(10): e109356pdflink
Novak2013Trophic omnivory across a productivity gradient: intraguild predation theory and the structure and strength of species interactions.ProcB280: 20131415pdf
Kenner, Estes, Tinker, Bodkin, Cowen, Harrold, Hatfield, Novak, Rassweiler & Reed2013A multi-decade time series of kelp forest community structure at San Nicolas Island, California.Ecology (Data paper)94(11): 2654pdflink
Yeakel, Guimarães, Novak, Fox-Dobbs & Koch2012Probabilistic patterns of interaction: The effects of link-strength variability on food-web structure.Journal of the Royal Society Interface9: 3219-3228pdf SOMlink
Twardochleb, Novak & Moore2012
Using the functional response of a consumer to predict biotic resistance to invasive prey.Ecological Applications
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22(4): 1162–1171pdflink
Tinker, Guimarães, Novak, Marquitti, Bodkin, Staedler, Bentall & Estes2012Structure and mechanism of diet specialization: testing models of individual variation in resource use with sea otters.Ecology Letters15(5): 475-483pdf SOMlink
Novak, Moore & Leidy2011Nestedness patterns and the dual nature of community reassembly in California streams: a multivariate permutation-based approach.Global Change Biology17: 3714-3723pdflink
Yeakel, Novak, Guimarães, Dominy, Koch, Ward, Moore & Semmens2011Merging resource availability with isotope mixing models: the role of neutral interaction assumptions.PLoS One6(7): e22015pdflink
Novak, Wootton, Doak, Emmerson, Estes & Tinker2011Predicting community responses to perturbations in the face of imperfect knowledge and network complexity.Ecology (Concepts & Synthesis)
Highlighted by F1000
92(4): 836-846pdflink
Yeakel, Stiefs, Novak & Gross2011Generalized modeling of ecological population dynamics.Theoretical Ecology
Highlighted by F1000
4(2): 179-194pdflink
Bolnick, Amarasekare, Araújo, Bürger, Levine, Novak, Schreiber, Urban & Vasseur 2011Why intraspecific trait variation matters in community ecology.TREE26(4): 183-191pdflink
DeAngelis, Wolkowicz, Lou, Jian, Novak, Svanbäck, Araújo, Jo & Cleary2011The effect of travel loss on evolutionarily stable distributions of populations in space.American Naturalist178(1): 15-29pdflink
Novak2010Estimating interaction strengths in nature: experimental support for an observational approach.Ecology91(8): 2394-2405pdflink
Novak & Wootton2010Using experimental indices to quantify the strength of species interactions.Oikos119: 1057-1063pdf
Novak & Wootton2008Estimating nonlinear interaction strengths: an observational method for species-rich food webs.Ecology (Report)89(8): 2083-2089pdflink
Doak, Estes, Halpern, Jacob, Lindberg, Lovvorn, Monson, Tinker, Williams, Wootton, Carroll, Emmerson, Micheli & Novak2008Understanding and predicting ecological dynamics: are major surprises inevitable?Ecology (Concepts & Synthesis)89(4): 952-961pdflink
Novak2004Diurnal activity in a group of Gulf of Maine decapods.Crustaceana77(5): 603-620pdflink


Dissertations, Honors projects & Reports


Moulvi2014Complex networks in kelp forest ecosystems: Visualizing big dataOSUURSA Engagepdf
Shepard2016Using stable isotopes to quantify species interaction strengthsOSUHonors thesispdf
Bingham2016Sensitive barnacles: A case study for collaborative sustainable fishery developmentOSUHonors thesispdf

Two elements of food webs add significantly to their complexity: The presence of trophic omnivores and the nonlinear nature of predator-prey interactions. I introduce a new observational method for estimating the strengths of species interactions that accounts for the indeterminacy of omnivorous indirect effects and the saturating functional responses that predators exhibit. I present an empirical support for the method’s accuracy by applying it to two populations of the predatory whelk, Haustrum (= Lepsiella) scobina, that is common to the rocky intertidal shores of New Zealand, and comparing these interaction strength estimates with those derived from experimental manipulations of H. scobina’s populations.
I then test two key predictions of intraguild predation theory by investigating how species abundances, food web structure and species interactions strengths change across six omnivorous food webs along a gradient of productivity present around New Zealand’s coastline. I find that the intermediate predator, H. scobina, is the superior competitor for shared prey, as predicted by theory. Counter to theory, however, I show that it is the omnivorous whelk, H. haustorium, that is the superior competitor when all prey are considered, and that H. scobina’s abundance increases with increasing productivity. My analyses reveal clear and regular cross-gradient shifts in interactions that can be incorporated into future modeling efforts.
Finally, I ask to what degree whelk feeding rates are saturated with respect to prey densities and, by extending and parameterizing the classic Rosenzweig-MacArthur model, ask whether empirical interactions are nonlinear enough to affect the stability of whelk-prey dynamics. Results indicate that feeding rates are not strongly saturated and that increasing diet richness has a non-additive effect on a predator’s saturation such that alternative prey have a stabilizing effect on whelk-prey dynamics. I thereby offer a new mechanism by which generalist predators stabilize the dynamics of their species-rich food webs.
My dissertation brings empirical data to bear on the importance of omnivory and the nonlinear nature of trophic interactions. Furthering our understanding of these food web features can contribute much to both the conceptual and applied goals of ecology.