Reproductive endocrinology of the largest Dasyurids: Characterization of ovarian cycles by plasma and fecal steroid monitoring.: Part II. The spotted-tailed quoll ( Dasyurus maculatus)

Abstract

Dasyurids exhibit a range of breeding patterns from semelparity through to an aseasonally polyestrous strategy, but detailed information on the reproductive endocrinology of many species is unavailable. This study aimed to extend our comparative understanding by characterizing the ovarian cycle of the spotted-tailed quoll ( Dasyurus maculatus) through measurement of plasma progesterone, and also to investigate fecal sex steroid monitoring as an alternative, non-invasive technique. Longitudinal profiles revealed a biphasic pattern of plasma progesterone, with a significant pro-estrous pulse (0.97 ± 0.3 ng/ml) up to several weeks prior to onset of the luteal phase (LP). This pro-estrous period was associated with a predominantly cornified vaginal smear, onset of estrus behaviors and copulation. Mean luteal values for plasma progesterone were several fold higher (2.18 ± 1.10 ng/ml) than during the follicular phase (FP) (0.75 ± 0.02 ng/ml), and were sustained for approximately one month. Fecal progestagens and plasma progesterone were significantly positively associated during the estrous cycle. During the breeding period average concentrations of fecal total estrogens and pregnanediol (PgD) were significantly elevated. Ovarian activity during the FP was marked by increases in fecal estrogens, and rises in PgD which were sustained during the LP. In non-mated females the mean duration of the FP was significantly extended, being approximately twice as long (19.4 ± 4.0 d) as for mated females (8.3 ± 1.9 d) indicating coitus has some role in timing of ovulation in this species. This study has provided important new information on the reproductive biology of the female spotted-tailed quoll, and further demonstrated the usefulness of non-invasive endocrine techniques for monitoring ovarian cycles in marsupials.