Current and time-lagged effects of climate on innate immunity in two sympatric snake species.

Lucia L Combrink,Amanda M Sparkman,Anne M Bronikowski,David A W Miller

doi:10.1002/ece3.7273

Lucia L Combrink, Amanda M Sparkman + Show 2 more

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https://doi.org/10.1002/ece3.7273

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Abstract

Changing environments result in alterations at all levels of biological organization, from genetics to physiology to demography. The increasing frequency of droughts worldwide is associated with higher temperatures and reduced precipitation that can impact population persistence via effects on individual immune function and survival.We examined the effects of annual climate variation on immunity in two sympatric species of garter snakes from four populations in California over a seven‐year period that included the record‐breaking drought.We examined three indices of innate immunity: bactericidal competence (BC), natural antibodies (NABs), and complement‐mediated lysis (CL).Precipitation was the only climatic variable explaining variation in immune function: spring precipitation of the current year was positively correlated to Thamnophis sirtalis BC and NABs, whereas spring precipitation of the previous year was positively correlated to T. elegans BC and NABs. This suggests that T. elegans experiences a physiological time‐lag in response to reduced precipitation, which may reflect lack of capital for investment in immunity in the year following a dry year.In general, our findings demonstrate compelling evidence that climate can influence wild populations through effects on physiological processes, suggesting that physiological indices such as these may offer valuable opportunities for monitoring the effects of climate.

Highlights

Increasing global temperatures in recent years have led to rapidly changing environments around the world, often with profound effect on species and their survival
Precipitation was the only climatic variable explaining variation in immune function: spring precipitation of the current year was positively correlated to Thamnophis sirtalis bactericidal competence (BC) and natural antibodies (NABs), whereas spring precipitation of the previous year was positively correlated to T. elegans BC and NABs
|2 alterations in reproductive phenology (e.g., Barnosky et al, 2011; Chen et al, 2011; Janzen et al, 2018; Miller et al, 2018; Stuart et al, 2004; Thomas et al, 2004; Urban, 2015). These changes call for intensive research on diverse species and ecosystems to deepen our understanding of how organisms respond to rising temperatures, changes in precipitation, resource scarcity, and other rapid shifts in environmental variables affecting different levels of biological organization, from physiology to demography to community and ecosystem function

Summary

| INTRODUCTION

Increasing global temperatures in recent years have led to rapidly changing environments around the world, often with profound effect on species and their survival (see Thomas et al, 2004; Walther et al, 2002). Such studies indicate that while numerous environmental factors may affect immune system development, the relationship between environmental change and immune function is unclear and much remains to be learned, especially in wild populations (Brusch et al, 2019; Festa-Bianchet, 1989; Sparkman & Palacios, 2009) In this seven-year study, we examined the impact of the recent California drought on innate immunity in two sympatric species of semi-aquatic garter snakes, Thamnophis sirtalis and T. elegans from four populations around Eagle Lake in northern California. We recorded presence/absence of tail trematode infection by looking for swelling, pinkness, or other abnormalities on the tail (Uhrig et al, 2015)

| MATERIALS AND METHODS

Findings

| DISCUSSION