How the type of anthropogenic change alters the consequences of ecological traps

Abstract

Understanding altered ecological and evolutionary dynamics in novel environments is vital for predicting species responses to rapid environmental change. One fundamental concept relevant to such dynamics is the ecological trap, which arises from rapid anthropogenic change and can facilitate extinction. Ecological traps occur when formerly adaptive habitat preferences become maladaptive because the cues individuals preferentially use in selecting habitats lead to lower fitness than other alternatives. While it has been emphasized that traps can arise from different types of anthropogenic change, the resulting consequences of these different types of traps remain unknown. Using a novel model framework that builds upon the Price equation from evolutionary genetics, we provide the first analysis that contrasts the ecological and evolutionary consequences of ecological traps arising from two general types of perturbations known to trigger traps. Our model suggests that traps arising from degradation of existing habitats are more likely to facilitate extinction than those arising from the addition of novel trap habitat. Importantly, our framework reveals the mechanisms of these outcomes and the substantial scope for persistence via rapid evolution that may buffer many populations from extinction, helping to resolve the paradox of continued persistence of many species in dramatically altered landscapes.

Figure 1.

Changes in population growth (N_t+1/N_t), habitat selection () and habitat preference () over time for two types of ecological traps under different amounts of trap habitat created (ha). Grey shading denotes initial dynamics that occur prior to trap formation. Marginal means from 37 500 simulations are shown for each type of trap. Brown line, 100; orange line, 300; green line, 500; dark green line, 700; blue line, 900.

Figure 2.

Partitioning the effects of two types of ecological traps under different amounts of trap habitat created (ha) using the Price equation. The Price equation partitions effects based on the selection effect, Cov(w_i,z_i), and transmission effects, shown here as transmission of habitats selected E(w_iΔz_i) and habitat preference E(w_iΔg_i). Figure formatting is the same as figure 2. Brown line, 100; orange line, 300; yellow line, 500; green line, 700; blue line, 900.

Figure 3.

Population outcomes in response to two types of ecological traps as a function of: (a,b) the amount of trap habitat created (ha); (c,d) initial population size (N); (e,f) errors in transmission of preference (σ²); and (g,h) strength of initial preference (g_int). For each scenario, initial landscape conditions were composed of the same amount of high-quality and moderate-quality habitat. Outcomes were defined as population extinction (white region) when N = 0, escape (black region) when N > 0 and population preference for low-quality habitat was eliminated, or persistence (grey region) when N > 0 and preference for low-quality habitat remained.