Does thermal physiology explain the ecological and evolutionary success of invasive species? Lessons from ladybird beetles
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Date
2018
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Abstract
Background: Several hypotheses have been proposed to explain invasive species success. Much of the research in this field has been conducted at the ecosystem or community level. Physiological traits are usually ignored, although they may play a role. As invasiveness has been correlated with species range expansion, it has been assumed - but scarcely tested - that species with greater physiological thermotolerances could be more invasive and colonize more habitats.
Aims: We assessed the responses of native (Eriopis chilensis) and invasive (Harmonia axyridis, Hippodamia variegata) coccinellids to thermal stress in central Chile after a period of acclimation. We tested and compared their thermal tolerances, their acclimation responses, and the consequences of these on fitness.
Results: Upper and lower lethal temperatures were not significantly different among species and no species was able to increase its lethal limits following acclimation. Our results suggest a trade-off between the 'difference between lower and higher thermal tolerances' and 'ability to acclimate'. However, we also observed significant differences in critical temperatures. Harmonia axyridis had lower critical thermal maxima than the other species, which is in line with aestivation behaviour seen in the field. In addition, H. axyridis has a higher critical thermal minimum than the other two species, which matches its rapid ongoing invasion into the southern (cooler) part of Chile. Similarly, H. axyridis has better egg-laying capabilities than the other two species.
Conclusions: Physiological and life-history traits do play a role in the invasion success of these coccinellids. Also, the interplay between physiological and life-history traits is fundamental to any understanding of invasive species success in the recipient community under a global climate change scenario.
Aims: We assessed the responses of native (Eriopis chilensis) and invasive (Harmonia axyridis, Hippodamia variegata) coccinellids to thermal stress in central Chile after a period of acclimation. We tested and compared their thermal tolerances, their acclimation responses, and the consequences of these on fitness.
Results: Upper and lower lethal temperatures were not significantly different among species and no species was able to increase its lethal limits following acclimation. Our results suggest a trade-off between the 'difference between lower and higher thermal tolerances' and 'ability to acclimate'. However, we also observed significant differences in critical temperatures. Harmonia axyridis had lower critical thermal maxima than the other species, which is in line with aestivation behaviour seen in the field. In addition, H. axyridis has a higher critical thermal minimum than the other two species, which matches its rapid ongoing invasion into the southern (cooler) part of Chile. Similarly, H. axyridis has better egg-laying capabilities than the other two species.
Conclusions: Physiological and life-history traits do play a role in the invasion success of these coccinellids. Also, the interplay between physiological and life-history traits is fundamental to any understanding of invasive species success in the recipient community under a global climate change scenario.
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Keywords
Coccinellidae, ecological and evolutionary physiology, global climate change, invasive species, thermal tolerance