Age-Specific Reproductive Strategies and Delayed Embryonic Development in an Old World Fruit Bat, Ptenochirus jagori

Abstract

Ptenochirus jagori (Megachiroptera, Pteropodidae) is a tropical cynopterine fruit bat restricted to the Philippine islands. Samples of bats were obtained over 4 years, and reproductive tracts were preserved and examined using standard histological techniques. Reproductive status also was recorded for bats captured, marked. and released. A facultative post-implantational delay in embryonic development was detected in young P. jagori females reproducing for the first time. The delay occurred at the stage of gastrulation and could last up to 5 months. Adult females showed little evidence of a delay in development. With this delay, young females gave birth only once in their first year and synchronized parturitions with those of adults. Adult females had a gestation period of 4 months and gave birth twice a year, once in late March and early April and once in August. Morphology of early development was similar to that of other cynopterine fruit bats. The evolution and significance of a post-implantational delay in development are discussed.

Birth synchrony in greater spear‐nosed bats (Phyllostomus hastatus)

“…Bats possess a variety of mechanisms that can vary the timing of reproductive events, which may serve to synchronize reproduction in some tropical species Heideman & Powell, 1998;Racey & Entwistle, 2000). Females of some bat species store sperm for as long as 7 months after copulation before fertilization occurs and/or delay implantation of the zygote, although neither of these strategies has yet been con®rmed in a phyllostomid bat (Racey, 1982;Racey & Entwistle, 2000).…”

Reproduction of the long‐tongued nectar bat Macroglossus minimus (Pteropodidae) in Brunei, Borneo

“…2007, C. minutus (Kofron 1997), Eidolon helvum (Mutere 1965), Haplonycteris fischeri (Heideman 1988), Otopteropus cartilagonodus (Heideman et al 1993) and Ptenochirus jagori (Heideman and Powell 1998). Further investigation may reveal this particular reproductive strategy to be more widespread within the family.…”

Seasonality and synchrony of reproduction in three species of nectarivorous Philippines bats

“…Their production of two young bracketing the dry season and early wet season places greater total energetic and nutritional demands on these parous adult females. In addition, these two reproductive bouts may be more stressful on females or their offspring [14], as much greater portions of the highly demanding periods of late pregnancy, lactation, and weaning will generally fall outside of flowering peaks. Inexperienced young females may maximize lifetime fitness by minimizing energetic demands and risks to survival during their first reproductive attempt, while more experienced older females increase reproductive success by higher investment in offspring and with higher risks to themselves [9,14].…”

“…Using methods modified from those developed by Heideman [9] we compare reproductive timing between age classes, among years, and among species. The objectives were to (1) test for seasonality and synchrony in the timing of births within each species, (2) test for evidence for age-specific reproductive strategies within species [14], and (3) test the hypothesis that all three species of nectarivore follow the same seasonal strategy. The resampling methods were found to be an improvement over previous analytical approaches, as significant synchrony and seasonality of births were identified and some significant differences were observed between age classes or years.…”