The influence of sociality on the conservation biology of social insects.

Social insects (ants, bees, wasps and termites) as a group are species rich and ecologically dominant. Many are outstanding “ecological engineers”, or providers of “ecosystem services”, or potential bioindicator species. Few social insects are currently formally classified as Threatened, but this is almost certainly due to a lack of information on population sizes and trends in scarce species. The main influence that sociality has on threats faced by social insects is in reducing effective population sizes, increasing population genetic subdivision and possibly reducing levels of genetic variation relative to solitary species. The main influence that sociality has on threats from social insects is via its role in the ecological success of invasive species, which frequently pose a major hazard to native biotas. In some cases, social features underpinning ecological success in the original range almost certainly contribute to the success of invasive social insects. However, recent studies show or strongly suggest that, in some of the most notoriously invasive populations of ants, bees and wasps, novel social traits have arisen that greatly enhance the rate of spread and ecological competitiveness of these populations. Sociality can therefore represent either a liability or an asset in its contribution to the persistence of social insect populations

Environmental influences on distribution of four Sciaenidae species (Actinopterygii, Perciformes) in a tropical bay at Southeastern Brazil

We sampled fish and measured environmental variables in the Sepetiba Bay, a tropical embayment at Southeastern Brazil. The aim was to assess environmental influences on distribution of four abundant species of Sciaenidae Micropogonias furnieri (Desmarest, 1823), Ctenosciaena gracilicirrhus (Metzelaar, 1919), Cynoscion leiarchus (Cuvier, 1830) and Menticirrhus americanus (Linnaeus, 1758) to test the habitat partition hypothesis. Samples were taken between June 1993 and July 1996, at three bay zones (outer, central and inner). Depth was the most important environmental variable to influence fish distribution, followed by transparency. M. furnieri showed significant negative correlation to depth, transparency and salinity, while C. gracilicirrhus showed the opposite situation. The highest densities of C. leiarchus occurred in the lowest temperature, while M. americanus did not showed preferences for any of the examined environmental variables. Spatial separation, mainly between M. furnieri and C. gracilicirrhus, seems to be the strategy developed to coexist in the Sepetiba Bay, with M. furnieri being more adapted to copy with harsh environmental conditions of the inner bay. The other three species, which use mostly the outer bay zone, seem to be restricted to more stable conditions, where influences from oceanic waters are more intense.<br>Foram coletados peixes e medidas as variáveis ambientais na Baía de Sepetiba, uma baía tropical do Sudeste do Brasil. O objetivo foi determinar influências ambientais na distribuição de quatro espécies abundantes de Sciaenidae Micropogonias furnieri (Desmarest, 1823), Ctenosciaena gracilicirrhus (Metzelaar,1919), Cynoscion leiarchus (Cuvier,1830) and Menticirrhus americanus (Linnaeus, 1758) para testar a hipótese de partição do hábitat. Amostragens foram feitas entre Junho de 1993 e Julho de 1996 em três zonas da baía (externa, central e interna). A profundidade foi a mais importante variável ambiental que influenciou a distribuição dos peixes, seguida pela transparência. M. furnieri mostrou uma correlação negativa significante em relação à profundidade, transparência e salinidade, enquanto C. gracilicirrhus evidenciou uma situação oposta. As maiores densidades de C. leiarchus ocorreram nas menores temperaturas, enquanto M. americanus não parece ter preferências por nenhuma das variáveis ambientais examinadas. A separação espacial, principalmente entre M. furnieri e C. gracilicirrhus, parece ser uma estratégia desenvolvida para coexistirem na Baía de Sepetiba, com M. furnieri sendo mais adaptada para suportar as condições ambientais mais difíceis da zona interna. As outras três espécies, que utilizam mais a zona externa, parecem ser restritas às mais estáveis condições, onde influências das águas oceânicas são mais intensas