Social modulation of sex steroid concentrations in the urine of male cichlid fish Oreochromis mossambicus

The relationship between urinary concentrations (free + sulfates + glucuronides) of the steroids testosterone (T), 11-ketotestosterone (11KT), 17α, 20ß-dihydroxy-4-preg- nen-3-one (17,20ß-P) and 17a,20a-dihydroxy-4-preg- nen-3-one (17,20α-P), and the social behavior of males of the cichlid fish Oreochromis mossambicus was inves- tigated. After 8 days of isolation none of the steroids were good predictors of social dominance developed after subsequent formation of all-male groups. One day after group formation dominance indexes were good predictors of the urine concentrations of all sex steroids. Dominance indexes and androgen concentrations mea- sured after all-male group formation were positively cor- related with territoriality, courtship rate, and nest size. Similar relationships were found for progestins with the exception that they were not correlated with courtship rate. All-male group formation was also accompanied by an increase in urinary sex steroid concentrations in fish that became territorial and a decrease in non-territorial fish with the exception of T, which increased in both groups. Addition of ovulating females caused steroid concentrations to return to levels near isolation, except for 17,20α-P in territorials, which underwent a large in- crease. Thus, social interactions may have an important modulatory effect on sex steroid concentrations in O. mossambicus

Estructura de Gestión Universitaria: una mirada empírica en la Universidad Nacional de Córdoba

Se ha generalizado la idea de que el cambio permite la supervivencia de la organización, que de otra manera se vería amenazada, desencadenado una era de transformación organizacional. Conformada la necesidad de la adaptación, resulta inminente definir los requerimientos que guiarán el cambio. En este trabajo, se aborda la discusión sobre un cambio del tipo no estructural en el marco de la Universidad Nacional de Córdoba. Para ello se presentan evidencias que justifica una transformación que no alcance a modificar sustancialmente la estructura de gestión actual

Analysis of conditional contingency using ACTUS2 with examples from studies of animal behavior

In this paper we present ACTUS2, the second version of ACTUS (Analysis of Contingency Tables Using Simulation). ACTUS2 has many new features, including analysis of data in which dependencies that make some combinations of properties impossible are hypothesized. Because ACTUS2 explicitly simulates such hypotheses, it can be used without loss of accuracy to analyze small amounts of data in large tables with many zeros or very low frequencies. We illustrate these features with two studies of animal behavior: interactions of male individuals with other individuals in groups of captive, mature Triturus marmoratus pygmaeus (newts); and agonistic interactions between pairs of male juvenile Diplodus sargus (the sparid fish, white sea-bream). Both significantly frequent, and significantly infrequent, co-occurrences that had biologically meaningful interpretations were revealed

Genetic evidence fails to discriminate between Macroramphosus gracilis Lowe 1839 and Macroramphosus scolopax Linnaeus 1758 in Portuguese waters

Fish belonging to the genus Macroramphosus are distributed throughout the Atlantic, Indian and PaciWc oceans. Some authors consider this genus monotypic, Macroramphosus scolopax being the only valid species. Other authors consider (based on several morphological and ecological characters) that another species (Macroramphosus gracilis) exists and occurs frequently in sympatry with the Wrst one. Intermediate forms are also reported in literature. In this paper, using the mitochondrial control region and the nuclear Wrst S7 intron markers, we failed to Wnd genetic diVerences between individuals considered to belong to both species as well as the intermediate forms. Our results suggest that in the northeastern Atlantic, Macroramphosus is represented by a single species, M. scolopax, with diVerent morphotypes interbreeding in the sampling areas