Evaluating thermal niche overlap of a predator–prey system: Do spiders choose suboptimal temperatures in pursuit of prey?

Abstract

Ectotherm predators and their prey could potentially respond differently to habitat temperatures. Predators might select higher temperatures to increase their probability of capture while prey could select lower or higher temperatures that may enhance their escape capability. We used a combination of field and laboratory analyses to characterise the thermal niches of predator species and their potential arthropod prey. We studied a predator–prey system in northern Chile using a common desert-dwelling spider Loxosceles laeta and three potential prey: a tenebrionid beetle Psammetichus costatus (Coleoptera), Pycnoscelus surinamensis (Blattodea) and Porcellio laevis (Isopoda). Results showed that the predator L. laeta selects warmer temperatures (T_p = 27.22 ± 4.87°C) in laboratory and lower temperatures in field conditions (T_s = 20.8 ± 1.59°C), with low temperatures in the morning and high temperatures at night. The three prey species had lower and different preferred temperatures than the predator in laboratory conditions. However, we found a high overlap in the thermal niche between the predator and their prey in field conditions, whereby the predator selected similar temperatures to its prey, one exception being P. laevis that chooses completely different habitat temperatures. This suggests that predators look for their prey in places with low temperatures that are not thermally suitable for them, whereas the prey may use this strategy of selecting low temperatures to evade potential predators.