Stronger predation intensity and impact on prey communities in the tropics

Abstract

The hypothesis that biotic interactions strengthen toward lower latitudes provides a framework for linking community-scale processes with the macroecological scales that define our biosphere. Despite the importance of this hypothesis for understanding community assembly and ecosystem functioning, the extent to which interaction strength varies across latitude and the effects of this variation on natural communities remain unresolved. Predation in particular is central to ecological and evolutionary dynamics across the globe, yet very few studies explore both community-scale causes and outcomes of predation across latitude. Here we expand beyond prior studies to examine two important components of predation strength: intensity of predation (including multiple dimensions of the predator guild) and impact on prey community biomass and structure, providing one of the most comprehensive examinations of predator-prey interactions across latitude. Using standardized experiments, we tested the hypothesis that predation intensity and impact on prey communities were stronger at lower latitudes. We further assessed prey recruitment to evaluate the potential for this process to mediate predation effects. We used sessile marine invertebrate communities and their fish predators in nearshore environments as a model system, with experiments conducted at 12 sites in four regions spanning the tropics to the subarctic. Our results show clear support for an increase in both predation intensity and impact at lower relative to higher latitudes. The predator guild was more diverse at low latitudes, with higher predation rates, longer interaction durations, and larger predator body sizes, suggesting stronger predation intensity in the tropics. Predation also reduced prey biomass and altered prey composition at low latitudes, with no effects at high latitudes. Although recruitment rates were up to three orders of magnitude higher in the tropics than the subarctic, prey replacement through this process was insufficient to dampen completely the strong impacts of predators in the tropics. Our study provides a novel perspective on the biotic interaction hypothesis, suggesting that multiple components of the predator community likely contribute to predation intensity at low latitudes, with important consequences for the structure of prey communities.

From Plates to Baits: Using a Remote Video Foraging System to Study the Impact of Foraging on Fouling Non-Indigenous Species

“…In the Madeira Archipelago, S. cretense is abundant from the surface to 50 m depth and constitutes an important fraction of coastal fish biomass [88]. Along with Thalassoma pavo (Linnaeus 1758), Boops boops (Linnaeus 1758) and Chromis limbata (Valenciennes 1833), S. cretense is one of the most common fish grazers [88] and thus plays an important ecological role by influencing the structure of fouling and shallow sessile communities in Madeira [89,90]. In this pilot study, the role played by S. cretense in the marina of Quinta do Lorde during RVFS trials matches this pattern and corroborates its importance in shaping fouling communities.…”

Biotic resistance or invasional meltdown? Diversity reduces invasibility but not exotic dominance in southern California epibenthic communities

“…Biotic and abiotic factors not examined here are known to in uence epibenthic community structure and composition. While studies have demonstrated that predation may have strong impacts on epibenthic community composition (Vieira et al 2012;Oricchio et al 2016;Freestone et al 2021), its role in modulating exotic establishment is debated. In epibenthic communities, predation might serve to limit the establishment (Dumont et al 2011;Collin and Johnson 2014;Rogers et al 2016;Kremer and da Rocha 2016;Leclerc et al 2020) or dominance of exotic organisms, as predators tend to target poorly-defended, soft-bodied chordates (Kremer and da Rocha 2016), which were characteristics of the species that we found to be primary drivers of changes in exotic abundance and dominance.…”

Woodpecker drum evolution: An analysis of covariation in elements of a multicomponent acoustic display among and within species

“…We calculated standard error and P-values for our model using the bootstrap method (boot.sims = 1000), and only considered percentile slope estimates to be significantly different from zero if P < 0.05 for five model iterations. It is not necessary to correct for multiple testing when using quantile regression because calculating slopes at multiple percentiles (τ values) is not repeated testing of the same statistical hypothesis (Spear and Mordecai 2018;Virta et al 2019;Freestone et al 2021).…”