Community variability in pond metacommunities: interactive effects of predators and isolation on stochastic community assembly

Author(s)

Pelinson, Rodolfo Mei ; Leibold, Mathew A. ; Schiesari, Luis

• Document type: Journal article
• Source: OIKOS; v. 2022, n. 5, p. 13-pg., 2022-03-08.

Abstract

In the absence of environmental heterogeneity, spatial variation among local communities can be mostly attributed to random dispersal, demographic stochasticity and species interactions causing historical contingency in colonization (e.g. priority effects). The consequences of demographic stochasticity and random dispersal are highly dependent on community size, regional richness and local richness, which, along with historical contingency can be strongly affected by spatial isolation and the presence of predators. Here, we tested whether and how the presence of a generalist predatory fish and spatial isolation can change spatial community variability in artificial ponds by manipulating the presence/absence of fish (redbreast tilapia) at three different distances from a source wetland. We then used null models to compute how much the observed community variability within treatments deviates from the expected from randomly reassembled communities (i.e. beta-deviation). We found that spatial isolation can have both negative and positive effects on community variability, and their importance may depend on the presence of predatory fish. Negative effects likely occurred because predatory insects cannot always successfully colonize highly isolated ponds, causing the abundance of herbivores and detritivores to increase, consequently increasing community size, which is known to decrease the importance of demographic stochasticity. However, when fish are absent, the more isolated communities exhibit more community variability than is expected from random community assembly. We believe that such an increase in variability is most likely due to an increase in the importance of historical contingency in colonization, generating more distinct communities in isolated ponds. Such effects were absent in the presence of generalist predatory fish, likely because fish prevented any early colonizing taxa from becoming too abundant. Our findings show that the presence of generalist predators can change how community variability responds to spatial isolation. (AU)

• FAPESP's process: 15/18790-3 - Environmental effects of the pasture-sugarcane conversion and pasture intensification
• Grantee: Luiz Antonio Martinelli
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 17/04122-4 - Effects of local processes and spatial isolation on aquatic community assembly: a simulation of land use intensification
• Grantee: Rodolfo Mei Pelinson
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 18/07714-2 - Effects of land use intensification on freshwater community similarity and beta diversity
• Grantee: Rodolfo Mei Pelinson
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate