Data compilation study investigates the temperature control on the sexual size dimorphism within 85 diverse arthropod species and reveals that, on average, the sexes show similar relative (proportional) temperature–body size (T–S) responses.
Differences in body size between males and females, termed Sexual Size Dimorphism (SSD), can be marked within animal and plant species. While the degree of size difference can be affected by environmental conditions, until now the effect of temperature on SSD in ectotherms has not been extensively examined. In the most comprehensive analysis of its type to date, published this week in Proceedings of the Royal Society B, the Centre for Ocean Life’s Andrew Hirst, together with QMUL PhD student Curtis Horne, and Liverpool University’s David Atkinson, compare the effects of temperature during development of adult body size in males and females of 85 diverse arthropod species.
Including species from 17 arthropod orders, and covering a wide range of animal body sizes and variation in the degree of SSD, and differences in the sign of their response to warming (shrinking or enlarging with elevated temperatures), they conclude that the sexes show similar proportional changes in size on average. This suggests that temperature-size response may generally have equivalent fitness costs and benefits in both sexes of a species, yet given that juvenile density, and food quantity and quality, commonly result in greater size plasticity in females, these other environmental factors likely have different adaptive effects on SSD.
The paper is now available online from the Proceedings of the Royal Society B website. Curtis’ photograph of a dance fly (above) is featured on the front cover:
Hirst A.G., Horne C.R. & Atkinson D. (2015). Equal temperature-size responses of the sexes are widespread in arthropod species. Proceedings of the Royal Society B: Biological Sciences, 282, 20152475.