Evolutionary rescue of niche constructors from habitat exploitation: Fecundity costs can promote rescue

Organisms can improve their fitness by modifying their environments-a process known as (positive) niche construction. Since niche construction is inherently costly, requiring time and energy to perform, niche constructors are vulnerable to displacement by non-niche-constructing invaders that exploit the constructed habitats. One way constructors could avoid such displacement is by adapting to withstand the invaders and thus undergoing evolutionary rescue. Here, we first analytically approximate the probability that a niche-constructing population-one building reproductive habitats-undergoes evolutionary rescue from habitat exploitation by an invading species. Then, we evaluate the approximation under two different fitness costs of construction: a fecundity cost and a mortality cost. We find that fecundity costs are not only less harmful than mortality costs but can even promote rescue compared with no costs by reducing the rate at which constructors attempt reproduction and thus construction. The resulting lower habitat density slows invasion, which then buys constructors more time to mutate. This invasion-slowing benefit can be stronger if the fecundity cost, instead of deriving from construction, stems from niche destruction, where organisms destroy their own habitats. Our results suggest that the same fitness costs rendering constructors vulnerable to habitat exploitation can help rescue constructors from such exploitation.