Social Relationships in a Group of Captive Wolves

The social organization of a group of wolves in a large outdoorenclosure was followed through several breeding seasons. Duringthe breeding season conflicts become more frequent and the socialhierarchy obvious. The more dominant animals restrict courtshipactivities by inferior wolves of their own sex. However, apparentlyas a correlate of their position, two alpha males have shownless mating activity than other males. Mate preferences exhibitedby animals of both sexes also limit the number of matings. Thepreferences appear related to the social hierarchy existingwhen an animal matures. Cultural transmission of social statusis suggested by some changes in ranking of wolves raised inthe woods at Brookfield. Temporary removal of the original alphamale and death of the original alpha female appear to have promotedchanges in social order and an increase in actual mating combinations.The probable consanguineous nature of wolf groups and facetsof the social behavior suggest that some form of group selectioncould be operative in the wild.     

An in situ experimental column for the study of vertical migration in plankton

SUMMARY. 1. An experimental column that can be installed in situ to manipulate the behaviour of planktonic organisms is described.
2. The column incorporates a profiling system for collecting water samples and measuring water temperature, oxygen and underwater light, and can be fitted with a battery-powered lighting unit for 'photoperiod' experiments.
3. Tests showed that this equipment can be rapidly deployed from a small boat to enclose a relatively undisturbed column of water.
4. Experiments with planktonic rotifers showed that the pattern of vertical migration recorded inside the column was very similar to that recorded outside.     

The effect of gibberellins on the storage life of plantains

Dipping plantain fruits in gibberellins (GA_4/7 or GA₃) delayed the ripening of individual fruits by approximately 50%, the two treatments being equally effective. Measurement of the preclimacteric period (PCP) by increased respiration showed that plantain fruits vacuum infiltrated with GA_4/7 (10^-5 M) gave an extension of 37% in the PCP under high humidity. No effect was observed at low humidity. The use of gibberellins on plantain storage is discussed.     

The effects of elevated CO2 concentrations on the root growth of Lolium perenne and Trifolium repens grown in a FACE* system

Lolium perenne and Trifolium repens were grown in a Free Air CO₂ Enrichment (FACE) system at elevated (600 μimol mol-¹) and ambient (340 μmol mol-¹) carbon dioxide concentrations during a whole growing season. Using a root ingrowth bag technique the extent to which CO₂ enrichment influenced the growth of L, perenne and T. repens roots under two contrasting nutrient regimes was examined. Root ingrowth bags were inserted for a fixed time into the soil in order to trap roots. It was also possible to follow the mortality of roots in bags inserted for different time intervals. Root ingrowth of both L. perenne and T. repens increased under elevated CO₂ conditions. In L. perenne, root ingrowth decreased with increasing nutrient fertilizer level, but for T. repens the root ingrowth was not affected by the nutrient application rate. Besides biomass measurements, root length estimates were made for T, repens. These showed an increase under elevated CO₂ concentrations. Root decomposition appeared to decrease under elevated CO₂ concentrations. A possible explanation for this effect is the observed changes in tissue composition, such as the increase in the carbon: nitrogen ratio in roots of L. perenne at elevated CO₂ concentrations.