Reproductive seasonality of the nyala Tragelaphus angasi; The interaction of light, vegetation phenology, feeding style and reproductive physiology

In Ndumu Game Reserve, South Africa, it was found that nyala males exhibited no seasonal sexual cycle. Although conceptions occurred throughout the year, there was a bimodal pattern of conceptions with the peaks in autumn and spring.
After referring to other African bovids which also have bimodal patterns of reproductive activity, it was concluded that the cues for the two peaks are as yet unknown but must be provided by light or photoperiod. The factors which ultimately decide the amplitude of the peaks are vegetation phenology and feeding style of the animal. In nyala, peaks are masked by the occurrence of post-partum oestrous cycles and a gestation period of approximately 7 months.     

Automatic recording of the growth rates of continuously cultured microorganisms

A procedure which establishes steady states in cultures of microorganisms and also provides continuous automatic recording of their growth rates is described.     

Abiotic factors influencing embryonic development, egg hatching, and larval orientation in the reindeer warble fly, Hypoderma tarandi

Wild-caught, tethered females of the reindeer warble fly, Hypoderma tarandi (L.) (= Oedemagena tarandi (L.)), (Diptera, Oestridae) were stimulated to oviposit on hairs of a reindeer hide. Newly laid eggs incubated at constant temperatures and relative humidities hatched within 3 days to 2 weeks, depending on the experimental conditions. Over a range of 7-40 degrees C, hatching only occurred between 20 and 37 degrees C. Eggs held at 100% relative humidity had lower hatchability and longer time to hatch relative to eggs held at 77% relative humidity. The average number of degree-days for hatching was 50.35. Between 20 and 33 degrees C there was a temperature-dependent linear trend in developmental rate, and the proportion of eggs hatching was highest, and least variable, at the mid-temperature ranges. The temperature range found in the natural host micro-habitat where H. tarandi commonly affix their eggs (close to the skin at the base of a host hair) was consistent with the experimental temperature treatments that produced the highest hatching rate. Newly emerged larvae displayed positive thermotaxis, while showing no phototaxic or geotaxic behaviour. Results indicate that constraints of the host environment, coupled with temperature-dependent hatching success, may impose a selective pressure on oviposition behaviour.