Thermal Preference of the Bush Cricket Isophya rizeensis; Testing the Effect of Countergradient Selection


Kuyucu A. C. , Çağlar S. S.

JOURNAL OF INSECT BEHAVIOR, vol.29, no.2, pp.172-189, 2016 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 29 Issue: 2
  • Publication Date: 2016
  • Doi Number: 10.1007/s10905-016-9551-7
  • Title of Journal : JOURNAL OF INSECT BEHAVIOR
  • Page Numbers: pp.172-189

Abstract

Thermal preference is one of the most crucial components of behavioral thermoregulation in ectotherms, and documenting the adaptation of thermal preference carries great importance for studying the evolution of thermal biology. However there are not many studies focusing on the adaptation of thermal preference in elevational and latitudinal gradients. Isophya rizeensis is a color polymorphic bush cricket species endemic to the mountainous region of northeastern Turkey. Populations of this species are distributed in a wide elevational range between 350 and 2300 m. In this study, we hypothesized that the thermal preference of Isophya rizeensis might follow a countergradient variation where crickets from higher altitudes have higher temperature preferences compared to crickets from lower altitudes. To test this hypothesis, thermal preference values (T (pref) ) of crickets from three altitudes groups (low, middle and high) were measured with a thermal gradient experiment. Additionally, body temperatures (T (b) ) and environmental temperatures (T (a) ) were measured in field. Deviation values of T (b) and T (a) from T (pref) were calculated to investigate the extent of thermoregulation. As Isophya rizeensis is color polymorphic species where morphology pattern changes from lighter to darker types with increasing altitude we also tested whether coloration has any effect on temperature excess (T (ex) ) and thermoregulation. Thermal preference values did not differ significantly between three groups and also colouration does not influence the extent of thermoregulation in this species. These results indicate that there is not sufficient evidence for the existence of a countergradient selection related with thermal behavior. However, the deviation of body (D (b) ) and environmental (D (a) ) temperatures suggest that at higher altitudes thermoregulation might be more efficient than lower altitudes.