The male reproductive cycle of three species of Australian vespertilionid bat

Abstract

The male reproductive cycles of three species of vespertilionid bat (Nyctophilus geoffroyi, N. major, and Vespadelus regulus) are described. Descriptions are based on the degree of testicular and cauda epididymal development estimated from ®eld captures, and for N. geoffroyi, on histological examination of ®xed specimens and assays of their testicular testosterone concentrations. All species were found to undergo a dissociated pattern of reproduction; the activity of the testes and accessory glands of reproduction were asynchronous. Spermatogenesis occurred in summer/early autumn (December±March) and testes generally regressed before mating began in autumn (March±May). Spermatozoa were stored in the cauda epididymides during the mating period. Leydig cells of N. geoffroyi involuted prior to mating but the prostate gland remained enlarged and secretory during winter (June±August), regressing in late spring (November). Testicular testosterone concentrations were greatest when Leydig cells were maximally enlarged, and concentrations were low during the mating period. The reproductive cycle of all species apparently involved asynchrony between primary and secondary sexual function, which is typical of vespertilionid bats inhabiting temperate latitudes. As mating occurs when sperm stores cannot be replenished, selection for prudent sperm allocation may be expected.

Gross and Morphometric Anatomy of the Male Reproductive System of Bats (Eidolon helvum)

“…The mean dimension of testes observed in this study was contrary to the findings of [29], who reported 20 by 18 mm in adult male bat. The change observed in testicular size agrees with the findings of [19, 30], who reported that maximum testicular size is associated with maximal spermatic activity in the adult bats. The increase in testicular mass and dimension as seen in these studies has a great influence and role to play in male spermatogenesis as reported by [31, 32].…”

Hybridization Hotspots at Bat Swarming Sites

“…However, in seasonally breeding species, such as temperate bats, testes recrudesce, and it cannot be excluded that they would only do this if sperm production is costly in some way. Furthermore, in many bats mating occurs after testes have regressed so males cannot replenish their sperm supplies [56]. In such a case they should allocate ejaculates prudently, but all that is needed for polygyny (or even promiscuity) is to have larger ejaculate storage for more matings.…”

Thermoregulatory Behavior of Tree-Roosting Chocolate Wattled Bats (Chalinolobus Morio) During Summer and Winter

“…Like many bats in the temperate zone, copulation by male C. morio takes place in early winter and spermatozoa are stored by the female during hibernation until ovulation and fertilization in spring Note the larger daily range and higher T skin relative to T a in the male bat compared to the female. (Hosken et al 1998;Kitchener and Coster 1981;Phillips and Inwards 1985;Racey 1982). Thus, the frequent arousals observed for male C. morio may have allowed them to find and copulate with females.…”