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Body temperature regulation is associated with climatic and geographical variables but not wing pigmentation in two rubyspot damselflies (Odonata: Calopterygidae)

Abstract:

It has been proposed that wing pigmented spots function in temperature control in male calopterygids. Using two rubyspot species Hetaerina americana Fabricius and Hetaerina vulnerata Hagen in Selys, the present study investigated whether (i) wing spot size and colour-modified aspect can predict temperature gain after a cooling event; (ii) wing spot size is related to the temperature needed to fly and how long it takes to initiate flight; and (iii) wing spot size is related to seasonality and altitude. The results obtained do not support any of these relationships. The results also indicate that H. vulnerata can achieve flight at 8 °C less than H. americana. The present study further investigates whether the species differ in their latitudinal and geographical distribution, and respond differently to bioclimatic variables. The results obtained provide support for this particular hypothesis, showing that H. vulnerata inhabits higher altitudes, and is able to tolerate colder environments compared with H. americana. Wing spots in the two Hetaerina species do not help in thermoregulation, although both species show different temperature control abilities. This difference in thermoregulatory ability may enable the species to colonize different environments and reduce interspecific competition.