L' Annee biologique最新文献

The ant gardens of tropical America constitute one of the most unique forms of plant-insect associations. The ants that initiate these gardens belong to a limited number of species disparate from a phylogenetic point of view, but having the following two behavioural characteristics: (1) the capacity to build an arboreal nest rich in humus; and (2) an attraction towards the fruits and/or seeds of epiphytes that they retrieve to the nest and incorporate into its walls. The seeds then germinate, and produce a root system that reinforces the nest structure. The demographic growth of the ant colony is accompanied by an increase in the size of the nest which is the result of (1) the constant provisioning of diverse materials and seeds, and (2) the growth of the root system. Moreover, the volume of the ant garden increases as the host tree grows. An ant garden is an association which benefits both the ants and the epiphytes. In addition to the structural role played by their roots, the epiphytes often provide nourishment to the ants living in the ant gardens through fruits and extra-floral nectaries. In return, the ants disseminate the epiphyte seeds and protect the epiphytes from eventual defoliators. Different ant species can be found in the same garden. Such cohabitation can be the result of parabiosis, but, in the oldest gardens, certain ants are the secondary residents that partially or entirely excluded the ants that initiated the garden. An ant garden constitutes a relatively stable nesting site, something rather rare in this environment, such that different parts of the garden can be occupied by numerous Arthropods (including other social insects such as stingless-bees) on the condition that these insects can cohabit with the ants. As such, an ant garden can constitute a veritable microecosystem. While it is not possible to demonstrate a strict or obligate interspecific relationship between ant and plant species, only several rare species among the numerous neotropical epiphytes are involved and a certain number of preferences can be underlined. We present here in detail the characteristics of the ant gardens initiated in French Guiana by the parabiotic associations Crematogaster limata parabiotica/Camponotusfemoratus, and by the ants Pachycondyla goeldii and Odontomachus mayi.

Calcified structures such as otoliths have been used successfully for estimating the age of teleost fishes for many years. Otoliths record age as well as annual and/or seasonal events in the lives of fish and they are an important source of life history information. Otoliths have been found to contain characteristics that are stock specific. Elemental composition might be useful for identifying non-mixing groups of fish that may be regarded as separate stocks for fisheries management. Examination of otolith microstructure has been used to study early life history. Papers describe the use of otolith microstructure combined with chemical analysis to assess the relative significance of environmental variables: feeding frequency, photoperiod and temperature, migration from freshwater to marine water, pollution, etc. Otoliths are the first calcified structures that appear during the early development of fish and they provide a more adequate record of the growth history than scales. Otoliths represent the black box of teleost fish.