Do spermathecal morphology and inter-mating interval influence paternity in the polyandrous beetle Tribolium castaneum?

• Published in: Behaviour Vol. 143; no. 5; pp. 643 - 658
• Main Authors: Bernasconi, Giorgina, Brostaux, Yves, Meyer, Eric P, Arnaud, Ludovic
• Format: Journal Article Web Resource
• Language: English
• Published: The Netherlands Brill 2006; BRILL
• Subjects: Animal ethology; Beetles; BEHAVIOUR; Biologi; Biological and medical sciences; Biological Sciences; CONFOCAL MICROSCOPY; CRYPTIC FEMALE CHOICE; Ecology; Ekologi; Entomologie & lutte antiravageur; Entomology & pest control; Female animals; Fundamental and applied biological sciences. Psychology; Insect morphology; Life sciences; Male animals; Mathematical intervals; Mating behavior; Natural Sciences; Naturvetenskap; Protozoa. Invertebrata; Psychology. Psychoanalysis. Psychiatry; REPRODUCTION; Reproductive success; Sciences du vivant; SEXUAL SELECTION; Sperm competition; SPERM STORAGE; Spermatheca; Spermatozoa; TRIBOLIUM CASTANEUM; Spermatozoa; sperm storage; Choice; Coleoptera; Insecta; Confocal microscopy; Tenebrionidae; Cryptic; Mating; cryptic female choice; Reproduction; Polyandry; Tribolium castaneum; Laboratory study; Sexual selection; Sexual behavior; Spermateca; Paternity; Breeding behavior; Mating system; Storage; Arthropoda; Morphology; behaviour; Invertebrata; Interval
• ISSN: 0005-7959; 1568-539X; 1568-539X
• DOI: 10.1163/156853906776759538

Abstract In polyandrous insects, postcopulatory sexual selection is a pervasive evolutionary force favouring male and female traits that allow control of offspring paternity. Males may influence paternity through adaptations for sperm competition, and females through adaptations facilitating cryptic female choice. Yet, the mechanisms are often complex, involving behaviour, physiology or morphology, and they are difficult to identify. In red flour beetles (Tribolium castaneum), paternity varies widely, and evidence suggests that both male and female traits influence the outcome of sperm competition. To test the role of spermathecal morphology and of sperm storage processes on the outcome of sperm competition, we mated each of 26 virgin females with two males, one of which carrying a phenotypic marker to assign offspring paternity. We manipulated the interval between mating with the first and the second male, to create different conditions of sperm storage (overlapping and non-overlapping) in the female reproductive tract. To investigate the role of sperm storage more closely, we examined the relationship between paternity and spermathecal morphology in a subset of 14 experimental females. In addition, we also characterized variation in spermathecal morphology in three different strains, wildtype, Chicago black and Reindeer. No significant influence of the intermating interval was found on the paternity of the focal male, although the direction of the difference was in the expected direction of higher last male paternity for longer intervals. Moreover, paternity was not significantly associated with spermathecal morphology, although spermathecal volume, complexity, and tubule width varied significantly and substantially among individuals in all investigated strains.