Seasonal changes in the testis, accessory glands and ejaculate characteristics of the southern hairy‐nosed wombat, Lasiorhinus latifrons (Marsupialia: Vombatidae)

Abstract

Most mammals exhibit seasonal variation in the reproductive capacity of one or both sexes. While the female southern hairy‐nosed wombat Lasiorhinus latifrons is a known seasonal breeder, the extent of seasonality in the male has not been documented. To examine this, gross body measurements including scrotal diameter and the dimensions of the accessory gland bulge were recorded and male reproductive tracts were examined between 1993 and 2000. Testes, epididymides and accessory glands from all males were dissected free of connective tissue and weighed. In addition, matched semen samples were collected over four time points in 2000 corresponding to the breeding season (September), immediately post‐breeding season (November), during the non‐breeding season (January), and immediately before the onset of the next breeding season (June) as determined from female reproductive status. Semen was collected by electro‐ejaculation and analysed for volume, sperm number and motility characteristics. Ejaculate volume, total ejaculate sperm number, percentage motile sperm, and the sperm motility rating and index were all significantly elevated in September and significantly lower in November and January. This correlated with a significant increase in body weight, peri‐cloacal gland width, and the weights of the prostate, Cowper's glands, urethral bulb and crus penis. The data confirm that male reproduction in the southern hairy‐nosed wombat, like that of the female, is highly seasonal with a peak in reproductive capacity occurring in August–September and a reduction by November.

Reproduction in male swamp wallabies (Wallabia bicolor): puberty and the effects of season

“…Similarly prostate weight and 5α‐dihydrotestosterone content of the prostate increase during the breeding season and there is evidence that metabolic activity of the prostate also increases at this time (Gilmore, 1969; Curlewis & Stone, 1985). Similar observations have recently been made in the southern hairy‐nosed wombat ( Lasiorhinus latifrons ) in which seasonal changes in accessory glands and semen quality were linked to reduced levels of circulating androgens and Leydig cell regression but testicular weight and spermatogenesis showed no seasonal change (Taggart et al. 2005).…”

“…Many seasonally breeding male marsupials show no change in testicular or epididymal weights but large changes have been reported in accessory gland weights and plasma testosterone concentrations (Gilmore, 1969; Merchant & Calaby, 1981; Inns, 1982; Curlewis & Stone, 1985; Nogueira, 1988; Hamilton et al. 2000; Taggart et al. 2005) but this is the first report of a species that breeds continuously in the wild in which the males display distinct seasonal changes.…”

Seasonal changes in reproductive development in male spiny mice (Acomys spinosissimus) from South Africa

“…However, reproduction in male A. spinosissimus commenced well before the onset of the rains and during the months with the lowest ambient temperatures, intimating that male recrudescence of reproduction may be less affected by weather conditions than in females. In contrast to opportunistic breeders such as R. pumilio (Jackson and Bernard, 2006), males of strongly seasonal species appear to cease reproduction similarly to females, as breeding opportunities are doubtful outside of the breeding season and maintaining reproductive activity is unlikely to be advantageous (Bronson and Heideman, 1994;Taggart et al, 2005). The same may hold for A. spinosissimus, in that males discontinue breeding activities during the time that females are not reproductively active, although environmental conditions may allow male reproduction.…”

Wombat reproduction (Marsupialia; Vombatidae): an update and future directions for the development of artificial breeding technology

“…the structural organisation of sperm head components) MacCallum (2004) CW _ Gross anatomy and testicular histology of the reproductive tract and sperm morphology \ Examined the urogenital system (i.e. for the development of an AI protocol) Taggart et al (2005) SHNW _ Seasonal changes in the testis, accessory glands and ejaculate characteristics Hogan et al (2010a) SHNW _ Seasonal changes in prostate and bulbourethral gland size no evidence to support this pattern in the wombat (Paris et al 2002, West et al 2004, Hogan et al 2010b.…”