Sexual selection and social hierarchy in fishes.

Sexual selection is a crucial element to understand behavioral evolution. Teleost fish have been considered as good models for research on sexual selection in the last decades due to their variety of sexual behavior. Female fish can choose males based on body and behavioral traits, such as body size, body color, ornaments, territorial quality, nest size and courtship behavior. Choices are based upon several types of sensorial inputs, such as visual, chemical, sonorous and electrical signals. Intrasexual selection also acts on females because they can mate with a dominant individual in male-male competitions. For both approaches, there is an expectation regarding the benefits of sexual selection by means of female choice. However, in several cases females do not choose the dominant male. In this mini-review, we present and discuss both intersexual and intrasexual mechanisms of sexual selection in fish and point out that females do not always choose a male for mating.

High intensity social conflict in the Swiss albino mouse induces analgesia modulated by 5-HT1A receptors

Social conflict between mice produces analgesia in the attacked mouse. Both the magnitude and type (opioid or nonopioid) of this analgesia have been related to attack intensity and strain of mouse. In the present study low intensity social conflict (7 bites) did not produce analgesia, whereas high intensity - 30 and 60 bites interactions produced, respectively, short-lasting (5 min) and very short-lasting (1 min) analgesia in Swiss albino mice, when compared with nonaggressive interaction (0 bite). The 30 bites aggressive interaction induced analgesia (AIIA) was not affected by IP injection of either naloxone (5.0 and 7.5 mg/kg) or diazepam (0.5, 1.0, 2.0 and 4.0 mg/kg). However, this attack-induced analgesia was reduced after IP administration of the 5-HT1A agonists, gepirone (0.3 and 3.0 mg/kg) and BAY R 1531 (0.01 mg/kg). These results indicate that the analgesia induced by 30 bites social conflict in Swiss albino mice does not involve opioid and GABA-benzodiazepine (GABA-BZD) mechanisms. In addition, they suggest that high-intensity social conflict activates serotonergic pain modulatory systems that act through 5-HT1A receptors. Copyright (C) 1997 Elsevier B.V.

Molecular and serological detection of Ehrlichia canis and Babesia vogeli in dogs in Colombia

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Youth and social cohesion in Ibero-America: a model in the making. Summary

Includes bibliography

Tendências econômicas e sociais na América Latina e no Caribe em gráficos = Economic and social trends in Latin America and the Caribbean in graphs = Tendencias económicas y sociales en América Latina y el Caribe en gráficos

Incluye Bibliografía

A decade of social development in Latin America, 1990-1999

Includes bibliography

Inclusive Social Protection in Latin America: a comprehensive, rights-based approach

Incluye Bibliografía

Ageing, solidarity and social protection in Latin America and the Caribbean: time for progress towards equality

Includes bibliography

Review of Caribbean economic and social performance in the 1980's and 1990's

Includes bibliography

A system of indicators for monitoring social cohesion in Latin America

Includes bibliography

Social cohesion in Latin America: concepts, frames of reference and Indicators

Includes bibliography

A review of social development in the Caribbean in the nineties: World Summit for Social Development (WSSD)+5

Includes bibliography

Social security in the english-speaking Caribbean

Includes bibliography

Social Security in the United States: Overview and Outlook

Includes bibliography