Host plant adaptation and the evolution of thermal reaction norms

Abstract

For most ectotherms, increasing the rearing temperature reduces the final (adult) body size, producing a negative slope for the thermal reaction norm. Recent studies show that this relationship may be reversed under conditions of low resource quality, producing a positive slope for the thermal reaction norm. If populations or species differ in the degree of evolutionary adaptation to a resource, how does this differential adaptation alter their thermal reaction norms? We used a common garden experiment with the tobacco hornworm, Manduca sexta, to address this question. We examined the thermal reaction norms for body size of two populations of M. sexta that differ in their evolutionary exposures to an atypical, low-quality resource (devil's claw; Proboscidea louisianica), but have comparable exposures to a typical, high-quality resource (tobacco; Nicotiana tabacum). Both populations had increased mean larval mortalities and development times when reared on devil's claw compared with tobacco, but the magnitudes of these increases differed between populations. Both populations had similar, negatively sloped thermal reaction norms on the typical, high-quality resource (tobacco), but had divergent, non-negative thermal reaction norms on the atypical, low-quality resource (devil's claw): the population with the longer evolutionary history of exposure to the atypical resource exhibited a flat (rather than positive) reaction norm. These results suggest that population differences in host plant adaptation can predictably influence the slopes of thermal reaction norms.

Increased temperature reduces herbivore host‐plant quality

“…Such deficiencies hinder gaining a better understanding of herbivore performance in relation to climate change. For instance, in the herbivorous larvae of Manduca sexta, nutrition and secondary plant compounds have been found to even reverse the slopes of thermal reaction norms for body size (Diamond & Kingsolver, , ). Thus, interactions between temperature and nutrition are of a potentially high ecological importance, as both often co‐vary in nature (Slansky, ).…”

The influence of diet on the duration and thermal sensitivity of development in the linden bug Pyrrhocoris apterusL. (Heteroptera: Pyrrhocoridae)

“…These patterns may be dissimilar in different parts of a species' distribution range. A significant triple interaction of temperature, diet and geographical origin in the control of Manduca sexta larval development is reported (Diamond & Kingsolver, ). In addition, a number of studies find no significant effect of diet on temperature‐dependent development (Levesque et al , ; Bárnet, ; Jalali et al , ; Berger et al , ), probably because the alternative diets used are nutritionally similar.…”

“…The response can be stronger or weaker, in that the rate can be sensitive (plastic) to temperature to a varying extent. Several studies describe the simultaneous effects of temperature and diet by using the concept of reaction norm, in terms of lesser or greater thermal sensitivity of growth and development on different diets (Petersen et al , ; Kingsolver et al , ; Diamond & Kingsolver, , ; Janković‐Tomanić & Lazarević, ; Berger et al , ). Another approach is rooted in a traditional ecophysiological concept of the sum of effective temperatures (or, more correctly, the sum of degree‐days) required for the completion of development.…”

The influence of warming on the biogeographic and phylogenetic dependence of herbivore–plant interactions

“…Increasing temperatures could influence consumer-resource interactions with respect to coevolutionary history (Diamond & Kingsolver, 2012). For example, Diamond and Kingsolver (2012) demonstrated that herbivore populations with different evolutionary exposures to host plants varied in their responses to these plants under different temperature.…”

“…Increasing temperatures could influence consumer-resource interactions with respect to coevolutionary history (Diamond & Kingsolver, 2012). For example, Diamond and Kingsolver (2012) demonstrated that herbivore populations with different evolutionary exposures to host plants varied in their responses to these plants under different temperature. Studies have also linked altered temperature to the movement (Walther et al, 2009), establishment success (Chown et al, 2012), and spread (Stachowicz, Terwin, Whitlatch, & Osman, 2002) of species beyond their natural ranges.…”