In a replicated experiment, nonbreeding winter populations of Microtus montanus were given supplements of rolled oats coated with 6-methoxybenzoxazolinone, a naturally occurring plant derivative. After 3 weeks of this feeding regime, samples from the populations demonstrated a high incidence of pregnancy in females and testicular hypertrophy in males. Control populations receiving rolled oats coated only with the solvent showed no reproductive activity. These results demonstrate that the presence of 6-methoxybenzoxazolinone in the plant food resource acts as the ultimate cue to trigger reproductive effort in Microtus montanus.

No abstract

A plant-derived cyclic carbamate, 6-methoxybenzoxazolinone, that stimulates reproductive activity in Microtus montanus has been isolated. This nonestrogenic compound may be a naturally occurring environmental cue affecting reproductive cycles in many mammals.

Bermudagrass [Cynodon dactylon (L.) Pers.] is one of the most widely used turfgrasses in the southern region of the USA and is also grown extensively in other tropical and subtropical regions around the world. The development of improved seeded cultivars has stimulated new research into best management practices to produce a high quality bermudagrass stand from seed. Dormant seeding has been used for establishing cool‐season turfgrasses and may be beneficial for the early establishment of seeded bermudagrass cultivars. The objective of this study was to assess the effects of dormant seeding on the establishment of two seeded bermudagrass cultivars, Riviera and Princess 77. Two seeding rates [97.6 and 48.8 kg ha−1 pure live seed (PLS)] of each cultivar were seeded in February, March, April, and May of 2004 and 2005, with February and March considered dormant seeding dates. Date of first germination, seedling density, rate of establishment, and soil temperature data were collected for both years of the study. First germination of dormant‐seeded plots was observed on 22 Apr. 2004 and 11 Apr. 2005 when soil temperatures were 13.6 and 16.2°C, respectively. Princess 77 germinated earlier than Riviera in both years of the study. Seeding date, cultivar, and seeding rate affected seedling density. Dormant‐seeded plots reached full coverage as fast as or faster than traditional seeding dates in both years of the study, demonstrating that dormant seeding can be effectively used to establish bermudagrass from seed.

From 1987 to 1989, the cohort dynamics of Microtus montanus populations were studied at two montane meadow sites approximately 160 km apart, in northwestern Wyoming. The 1987 and 1988 breeding seasons differed markedly from each other. In 1987, melt off occurred in April, and the first cohort was born in May (cohort 1). The entire breeding season was favorable owing to frequent rainfall throughout the summer. Cohort 1 animals grew rapidly and females began breeding at 4–5 weeks of age. Likewise, cohort 2 (June) animals exhibited rapid growth and females were breeding at 7–8 weeks of age. Cohort 3 (July and August) animals grew more slowly and most entered the winter as prepubertal animals of subadult size. At the end of the summer, cohort 3 animals represented >70% of the voles recruited during the breeding season. In 1988, following melt off in late April, precipitation was below normal and the situation intensified to severe drought through the summer. The growth rates of cohort 1 and 2 animals were significantly lower than 1987 growth rates, and very few females attained sexual maturity. At the end of the summer, cohort 3 animals represented <25% of the total recruitment at both study sites. Such apparent phenotypic plasticity of growth and maturation appears to be an evolved adaptive strategy that is responsive to several environmental cues. Both study sites, although widely separated, exhibited virtually identical patterns throughout the study.