Abstract
In attraction tests, ovulated female African catfish were attracted by
the administration of 2.0 ml/L seminal vesicle fluid to the aquarium water, lower doses (0.1 and
0.5 ml/L) were ineffective, and a high concentration (8.0 ml/L) seemed to have a repulsive effect.
After fractination of the fluid, an isolated steroid conjugate fraction appeared to contain the
attractant. No other stimuli beyond this fraction were required to attract groups of female catfish
after ovulation. Other constituents of the fluid such as polysaccharides, proteins, phosholipids and
steroids failed to attract the females. GCMS analysis of the steroid conjugate fraction revealed
the presence of eight different steroid glucuronides. After removal of these steroid glucuronides,
the steroid conjugate lost its attractive effect. According to the quantitative results of the GCMS
analysis a mixture of seven available synthetic steroid glucuronides was composed. This mixture
appeared to have a powerful dose-dependent attractive effect on ovulated females. It is
concluded that a combination of various steroid glucuronides, present in the seminal vesicle fluid,
functions as sex attractant bringing male and female African catfish together shortly before
spawning.
Abstract
Mothering styles are generally assumed to exist, in particular in the
case of primates. However, an experimental procedure to ensure this assumption has been lacking
and, moreover, mothering style was always defined post hoc. The short inter-birth interval and
the possibility to cross-foster make the guinea pig a suitable species that has an advantage over
primates for this type of study.
The maternal behaviour of ten subjects was registered during
mothering of four subsequent litters. To challenge a possible consistency of maternal behaviour
two variables were manipulated: parentage (own young or adopted young) and the condition of
the mothers (pregnant or non-pregnant).
The concordances found suggest that behavioural parameters
necessary to characterize a mothering style in guinea pigs should contain either locomotor,
affiliative or aggressive behaviour. Other behavioural parameters were not found adequate for
characterizing mothering styles.
As significant concordances of maternal behaviour were found,
in spite of the challenges offered, we conclude that guinea-pig mothers consistently differ from
each other and hence that mothering styles' exist in guinea pigs.
Abstract
Previous studies of the effects of parity and social isolation on
maternal behaviour in guinea pigs were either concerned with subsets of maternal behaviour or
based their conclusions on small data sets. The aim of the present experiment was to complement
the description of maternal behaviour by replicating previous studies and adding descriptive details
and effects of the sex of the pups on maternal behaviour. Three groups of females - multiparae
(n=23), primiparae (n=8), and hand reared (primiparae)(n=8) - were compared with regard to a
number of measures concerning maternal behaviour.
Differences among the three groups were fairly small, multiparae
were more active in grooming during the first 10 days and admitted ventrum contact more often
and approached and left the pups less often between days 14 and 24. Hand reared primiparae did
not differ from mother reared primiparae.
Some newly observed aspects of maternal behaviour of guinea pigs
could be noted. These include a number of behaviours as well as the observation that mothers lick
female pups more often in the anogenital region than male pups.
Abstract
The results of previous studies, mostly on primates, showed a
correlation between mothering styles and later explorative behaviour of the young. Based on our
previous study on the existence of mothering styles in guinea pigs we concluded that there are
three main components of maternal behaviour useful for these kind of studies: locomotion,
affiliative and aggressive behaviour. In the present study we examined to what extent these
components were correlated with later explorative behaviour of guinea pig pups. Later explorative
behaviour of 48 pups from 16 mothers was measured after weaning by means of a series of tests
designed to highlight different aspects of exploration.
The results indicate that maternal behaviour does not have a
predominant correlation with later explorative behaviour of the pups. Correlations between
affiliative and aggressive behaviour of the mothers and later explorative behaviour of the pups
were not found. Mothers scoring high on locomotion had pups that showed more explorative
behaviour than the pups of mothers scoring low on locomotion. This correlation, however,was
not linear and only significant for one parameter.
Abstract
Previous studies have shown that maternal behaviour is correlated
with later explorative behaviour of the young. Exploring the eventual effects of maternal
behaviour on the explorative behaviour of young guinea pigs, we examined the effects of
frequency and length of separation bouts between mother and offspring.
For 39 pups daily duration of contact with the mother was kept
constant (17 hours) but the frequency of daily contact (and thus the length of the separation
bouts) varied. Using a split-litter design three groups were created that were separated from the
mother 3, 6 or 9 times each day from day 3 until day 20. Several precautions were taken to avoid
distress of the pups during separation caused by heat loss, social isolation or unfamiliarity with
the separation cage. The development of the explorative behaviour was assessed by means of a
series of tests representing several aspects of explorative behaviour.
All groups showed equal growth during the treatment period. It
is shown that the group separated 3 times for a long period scored higher in explorative behaviour
than the other groups that were separated more often but for shorter periods. In particular
walking, duration of presence, and sniffing in the novel environment were increased compared to
the groups separated 6 or 9 times but were also increased when compared to average scores of
a previous study. It could be shown that individuals were persistent in time with regard to the
maximum distance they entered into a novel environment.
Abstract
In Burgers' Zoo (Arnhem, the Netherlands) a large enclosure was
build to mimic a tropical rain forrest. In this so called Bush' several ponds exist in which guppies
(Poecilia reticulata) can be found. One of these ponds contains caymen and is therefore in a
secluded area of the Bush were other animals can not enter. Among these other animals are
snakebirds (Anhinga melanogaster) which in the rest of the Bush predate on guppies devouring
up to a 1000 guppies a day. After several years it became noticeable that the guppies which were
initially from the same stock, differred between the Cayman pond (without predation) and the
Seacow pond (with predation). Measuring the differences between these populations showed
marked differences in length and coloration. Young from both stock were then raised under
identical conditions and were still found to differ which leads to the conclusion that some of the
differences are genetical and therefore the result of evolution within this semi-natural
environment. The speed of these changes are identical to what has been published about wild
guppies. Furthermore also differences in behaviour between the two populations were
ascertained.
Abstract
To estimate a dominance rank order most ranking methods use a set
of observations obtained during a certain time span disregarding the sequential order in which the
dominance interactions took place. It is implicitly assumed that the dominance relationships are
stable during this observation period, implying that outcomes of interactions reflect the dominance
order rather than influence it. The usefulness of these methods is often hampered by practical and
statistical problems such as disappearing or new individuals and lack of interactions between
certain individuals. In this paper, the Elo-rating method, as used for rating chess-players, is shown
to be a useful tool in the sequential estimation of the dominance strengths (ranks) of individuals
on the basis of the actual sequence of dominance interactions. As such it complements the existing
methods of dominance rank ordination, and is also usable in situations where the existing methods
can not or less fruitfully be applied.
Apart from the methodological aspects, some implications for the
theorethical basis of rank ordination are also briefly discussed.