Intraspecific trait variation and changing life-history strategies explain host community disease risk along a temperature gradient

Abstract

Predicting how climate change will affect disease risk is complicated by the fact that changing environmental conditions can affect disease through direct and indirect effects. Species with fast-paced life-history strategies often amplify disease, and changing climate can modify life-history composition of communities thereby altering disease risk. However, individuals within a species can also respond to changing conditions with intraspecific trait variation. To test the effect of temperature, as well as inter- and intraspecifc trait variation on community disease risk, we measured foliar disease and specific leaf area (SLA; a proxy for life-history strategy) on more than 2500 host (plant) individuals in 199 communities across a 1101 m elevational gradient in southeastern Switzerland. There was no direct effect of increasing temperature on disease. Instead, increasing temperature favoured species with higher SLA, fast-paced life-history strategies. This effect was balanced by intraspecific variation in SLA: on average, host individuals expressed lower SLA with increasing temperature, and this effect was stronger among species adapted to warmer temperatures and lower latitudes. These results demonstrate how impacts of changing temperature on disease may depend on how temperature combines and interacts with host community structure while indicating that evolutionary constraints can determine how these effects are manifested under global change. This article is part of the theme issue ‘Infectious disease ecology and evolution in a changing world’.

Contrasting effects of sheep and cattle grazing on foliar fungal diseases by changing plant community characteristics

“…Selective removal of non-hosts, or low-competence hosts, should increase the prevalence of disease on the remaining high competence hosts, whereas removal of highly competent hosts is likely to reduce disease (Borer et al, 2009;Johnson et al, 2013). A key predictor of pathogen infection in many contexts is host pace of life, with fast growing plant and animal hosts suffering more infection (Cappelli et al, 2020;Cronin et al, 2010;Halliday et al, 2023;Johnson et al, 2012).…”

“…Selective removal of non‐hosts, or low‐competence hosts, should increase the prevalence of disease on the remaining high competence hosts, whereas removal of highly competent hosts is likely to reduce disease (Borer et al., 2009; Johnson et al., 2013). A key predictor of pathogen infection in many contexts is host pace of life, with fast growing plant and animal hosts suffering more infection (Cappelli et al., 2020; Cronin et al., 2010; Halliday et al., 2023; Johnson et al., 2012). According to the leaf economics spectrum, “fast‐growing” plants with rapid growth, short leaf life spans and high specific leaf area (SLA), invest relatively little in defences, while “slow‐growing” species, with longer leaf life spans, slower growth rate and low SLA, invest more resources into defences (Reich, 2014; Wright et al., 2004).…”

Infectious disease ecology and evolution in a changing world

“…Disease spread can also depend on how temperature interacts with traits in host communities [20,21]. In a thorough field study set in the Swiss Alps, Halliday et al [22] found-complex relationships between trait variation in plant communities driven by temperature gradients and prevalence of infection in those communities. Together, these three studies highlight that to predict disease dynamics under climate change, we should consider multiple traits at the interface of host-pathogen interactions and their variation within species and communities.…”