Variable life history characteristics along an altitudinal gradient in three species of Australian grasshopper.

Variation in life history characteristics was examined in three closely related species of univoltine grasshopper, Praxibulus sp., Kosciuscola cognatus and K. usitatus, along three altitudinal transects in South East Australia. With increasing altitude females lay fewer eggs in total over the summer season but lay their eggs in larger clutches. This pattern of variation, which is not related to variation in egg size, is observed both between and within species. The relationship between clutch size and altitude is similar in all three species but quite distinct reproductive strategies are maintained between species even where different species are found together at the same altitude. It is proposed that both the length and predictability of the summer growing season could be impratant in determining the evolution of life history characteristics along the altitudinal gradient.