1,223 research outputs found
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
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