Climatic Gradients of Arms Race Coevolution

Abstract

In nature, spatiotemporally dynamic coevolutionary processes play major roles in the foundation and maintenance of biodiversity. Here, we examined the arms race coevolution involving a seed-eating weevil with a long snout and its camellia plant host with a thick fruit coat (pericarp) throughout the marked climatic gradient observed across the Japanese islands. Results demonstrated that female weevils, which bored holes through camellia pericarps to lay eggs into seeds, had evolved much longer snouts than males, especially in areas in which Japanese camellia pericarps were very thick. The thickness of the plant pericarp was heritable, and the camellia plant evolved a significantly thicker pericarp on islands with the weevil than on islands without it. Across populations with weevils, resource allocation to plant defense increased with increasing annual mean temperature or annual precipitation, thereby geographically differentiating the evolutionary and ecological interactions between the two species. Given that the coevolutionary relationship exhibited appreciable variation across a relatively small range of annual mean temperatures, ongoing global climatic change can dramatically alter the coevolutionary process, thereby changing the ecological interaction between these species.

Coevolution and the Effects of Climate Change on Interacting Species

“…There was thus an increase in plant defense along the environmental gradient. Furthermore, this plant defense increased with decreasing latitude at a greater rate than weevil ovipositor length, suggesting that plants exhibited a larger coevolutionary advantage in environmental conditions with increased prey growth [75]. These results support our theoretical predictions that higher prey intrinsic rates of increase should lead to a coevolutionary advantage to prey, thereby buffering the changes in predator densities driven by climate change.…”

“…For example, in a field experiment, Toju et al [75] documented a climatic gradient in a coevolutionary arms race between the camellia beetle ( Curculio camelliae ) and its host plant, Japanese camellia ( Camellia japonica ). Female beetles use their snout to pierce the camellia fruit pericarp and oviposit eggs into seeds, with oviposition success determined by the length of the beetle's snout and ovipositor relative to the pericarp thickness.…”

Biotic interaction strength and the intensity of selection

“…; Toju et al . ). However, when the relationship between fitness and phenotype is consistent, as we find for crossbills and pines (Benkman & Parchman ), then interaction strength should be related to selection intensity.…”

Running with the Red Queen: the role of biotic conflicts in evolution

“…Indeed, spatial variation is a potential signature of correlated defence and counter-defence trait evolution [25–28] (e.g. as between camellia pericarp thickness and camellia weevil rostrum length; figure 1).…”