Feedbacks between community assembly and habitat selection shape variation in local colonization

Abstract

Summary1. Non-consumptive effects of predators are increasingly recognized as important drivers of community assembly and structure. Specifically, habitat selection responses to top predators during colonization and oviposition can lead to large differences in aquatic community structure, composition and diversity. 2. These differences among communities due to predators may develop as communities assemble, potentially altering the relative quality of predator vs. predator-free habitats through time. If so, community assembly would be expected to modify the subsequent behavioural responses of colonists to habitats containing top predators. Here, we test this hypothesis by manipulating community assembly and the presence of fish in experimental ponds and measuring their independent and combined effects on patterns of colonization by insects and amphibians. 3. Assembly modified habitat selection of dytscid beetles and hylid frogs by decreasing or even reversing avoidance of pools containing blue-spotted sunfish (Enneacanthus gloriosus). However, not all habitat selection responses to fish depended on assembly history. Hydrophilid beetles and mosquitoes avoided fish while chironomids were attracted to fish pools, regardless of assembly history. 4. Our results show that community assembly causes taxa-dependent feedbacks that can modify avoidance of habitats containing a top predator. Thus, non-consumptive effects of a top predator on community structure change as communities assemble and effects of competitors and other predators combine with the direct effects of top predators to shape colonization. 5. This work reinforces the importance of habitat selection for community assembly in aquatic systems, while illustrating the range of factors that may influence colonization rates and resulting community structure. Directly manipulating communities both during colonization and post-colonization is critical for elucidating how sequential processes interact to shape communities.

Advances, challenges and a developing synthesis of ecological community assembly theory

“…The history of assembly can also lead to alternative dynamical states in which predators and prey can either cycle or not cycle [92]. A history of closed assembly in which a simple community is allowed to mature in the absence of colonization can reduce subsequent colonization when barriers to colonization are removed [99]. This suggests the possibility of historical inertia in the degree of community openness to colonization.…”

Predator Effects in Predator-Free Space: the Remote Effects of Predators on Prey

“…Recent work reveals the potential for remote effects to be important in this context, as habitat selection creates spatial contagion of predator effects into predator-free patches located near predator-containing patches (Resetarits and Binckley 2009). Moreover, predator-mediated habitat selection may interact with community assembly (Kraus and Vonesh 2010), suggesting that remote effects of predators may have context-specific implications for community structure.…”

“…For example, one process affecting metacommunity dynamics is mass effects, whereby competitively inferior species are maintained in a local community due to continual immigration (Leibold et al 2004). By changing rates of immigration, either through altering the number of active migrants Wooster 1994, McIntosh et al 2002), through habitat selection behavior (Resetarits 2005, Resetarits and Binckley 2009, Kraus and Vonesh 2010, or both, remote predators could readily alter the importance of mass effects for determining community composition . The effects of predators on habitat selection by prey can have persistent effects on local community structure even in the presence of strong post-colonization processes (Vonesh et al 2009).…”

“…Although such a proposition that is daunting and rarely realized (Cronin and Reeve 2005), several recent studies can be used as models for future investigations (e.g., Vonesh and Osenberg 2003, Resetarits 2005, Vonesh et al 2009, Kraus and Vonesh 2010.…”

Combinedin situexperimentation and modelling approaches to disentangle processes involved in the earliest stage of community assembly

“…Modelling approaches must be developed to identify and quantify processes (Tilman 1994, Chesson 2000, but quantitative models representing the colonization stage of new substrates by ecological communities are scarce, and even fewer approaches rest on the coupled definition of experimental settings and modelling designs (Drake 1991). Furthermore, studies on early community assembly considered the colonization stage from the single perspective of competition (Leibold et al 2004, Tilman 2004, even if, more recently, some research has started to suggest that the predation process might have a regulatory effect on the species composition of communities (Kraus and Vonesh 2010).…”