Sexual size dimorphism, morphological traits and jump performance in seven species of desert fleas (Siphonaptera)

Abstract

Jump performance was studied in seven flea species (Xenopsylla conformis mycerini, Xenopsylla ramesis, Xenopsylla dipodilli, Parapulex chephrenis, Synosternus cleopatrae pyramidis, Nosopsyllus iranus theodori and Stenoponia tripectinata medialis). Jump length was compared among individuals, between sexes and among species, and an examination made of whether: (1) there is a consistent difference in jump performance between male and female fleas; (2) sexual dimorphism in body size affects jump performance; (3) there is a size-specific difference in jump performance among species; (4) there are morphological correlates of jumping ability among individuals, between sexes and among species. Males were smaller than females in all species and size dimorphism did not increase with increasing body size. In all species, except S. t. medialis, both absolute and size-specific jumping abilities of the males were less than those of the females. Males and females of S. t. medialis demonstrated similar jumping ability despite their body size difference. The best jumpers were S. c. pyramidis, N. i. theodori and S. t. medialis, whereas X. dipodilli as well as female X. c. mycerini and X. ramesis demonstrated the poorest ability to jump. Female:male performance ratio differed among species, being the highest in X. c. mycerini and X. ramesis, and the lowest in S. t. medialis. The proportion of the overall dimorphism in jumping ability that was owing to size differences between males and females was low, ranging from 0.10 to 0.34. No correlation between jumping ability and pleural height or length of hind coxa, femur and tibia was found in any species, except in X. dipodilli. Interspecific comparisons using size-corrected and phylogeny-controlled values did not show any relationship between jumping ability and any morphological trait. Fleas occupying habitats with a soft sandy substrate were better jumpers than those living in habitats with a hard stony substrate.