Altitudinal variation in behavioural thermoregulation: local adaptation vs. plasticity in California grasshoppers

We investigated the adaptive significance of behavioural thermoregulation in univoltine populations of the grasshopper Melanoplus sanguinipes along an altitudinal gradient in California using laboratory tests of animals raised under different temperatures. Trials consisted of continuous body tempera...

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Bibliographic Details
Published in:Journal of evolutionary biology 2005-07, Vol.18 (4), p.1087-1096
Main Authors: SAMIETZ, J., SALSER, M. A., DINGLE, H.
Format: Article
Language:English
Subjects:
Adaptation
Adaptation, Physiological - physiology
Altitude
Analysis of Variance
Animal behavior
Animals
behaviour
Biophysical Phenomena
Biophysics
Body Temperature
Body Temperature Regulation - physiology
California
ectotherm
Grasshoppers - physiology
Insects
life history
local adaptation
Melanoplus sanguinipes
Models, Biological
Motor Activity - physiology
Temperature
thermoregulation
thermoregulatory behaviour
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Summary:We investigated the adaptive significance of behavioural thermoregulation in univoltine populations of the grasshopper Melanoplus sanguinipes along an altitudinal gradient in California using laboratory tests of animals raised under different temperatures. Trials consisted of continuous body temperature measurements with semi‐implanted microprobes in a test arena, and observation and simultaneous recording of behavioural responses. These responses included mobility, basking and orientation of the body axes (aspect angle) towards a radiation source. Mobility and basking are determined by the altitudinal origin of the parental generation and not by the temperature treatments. With increasing altitude, individuals tend increasingly to raise body temperatures via mobility and increased basking. In contrast, body orientation towards the radiation source is influenced by the temperature treatments but not by the altitude of origin. Individuals experiencing higher temperatures during rearing show a lower tendency to lateral flanking. We conclude that body orientation responses are not adapted locally. In contrast other components of the behavioural syndrome that increase body temperature, such as mobility and basking, are adaptive in response to local selection pressure. The thermoregulatory syndrome of these grasshoppers is an important contribution to life‐history adaptations that appropriately match season lengths.
ISSN:1010-061X
1420-9101
DOI:10.1111/j.1420-9101.2005.00893.x