Growth, maturation and survival of frogs Rana temporaria L.

A total of 1560 breeding frogs were collected in three consecutive years at sites in the west of Ireland. Alt were weighed and measured and the ages of 702 individuals were determined by skeletochronology. The length-weight relationship differed between gravid females, spent females and males, with the gravid females showing the largest weight gain for any increase in length. The majority of males bred for the first time at two years, but most females delayed maturity until they were a year older. While the two-year olds were of similar size, the females subsequently grew at a faster rate and achieved larger maximal sizes than the males. However, both sexes exhibited a decelerating growth rate with age. There was no apparent difference between the sexes in post-maturation survival, which was estimated to be about 50% annually. The oldest frogs were seven years old.     

Environmental and management factors controlling the potentially invasive native species Violet Kunzea (Kunzea parvifolia)

Violet Kunzea (Kunzea parvifolia), a native shrub of eastern Australia, is reputed to form dense thickets in areas that have undergone significant landscape modification, and has been listed as an invasive native species for which clearing is permitted under the Native Vegetation Act 2003 (NSW). We quantified factors controlling its abundance in 81 sites within the Braidwood region of NSW, on the basis of 36 strata reflecting soil landscape, topographic position, aspect and canopy cover. Within each study site 34 variables describing environmental, disturbance, management and vegetation attributes were measured using a transect sampling technique and landowner surveys. An analysis of these data indicated that, in the sites we surveyed, Violet Kunzea is a common shrub present at relatively high mean levels of cover (44%), with no preferred topographic position or aspect. There were no significant associations between management activities such as slashing or grazing, and the cover of Violet Kunzea. Multiple regression modelling indicated that overstorey cover was the key variable explaining variation in the cover of Violet Kunzea, with an increase in cover of the shrub as overstorey cover declined. We conclude that a reduction in overstorey cover results in an increase in Violet Kunzea abundance as competition is removed, and the subsequent suppression of overstorey regeneration sets up a feedback loop facilitating the further expansion of Violet Kunzea and the contraction of overstorey cover. Approaches to the management of this species will therefore require long‐term commitments to conserve and restore overstorey cover.     

Production of auto-anti-idiotype antibody during the normal immune response. XI. Ficoll-induced variations in auto-anti-idiotype production during the response to 2,4,6-trinitrophenyl-Ficoll

The responses to 2,4,6-trinitrophenyl conjugates of different Ficoll preparations differ with respect to the magnitude of the accompanying auto-anti-idiotype (Id) response in both mice and chickens. Evidence is presented that reduced auto-anti-Id production in the chicken is due to the activation of suppressor activity by some preparations of Ficoll.