CONTENT - International Society of Zoological Sciences

ICZ2008 – Abstracts S17
Sex differences in cognition
Susan D Healy and Anjanette Harris
Institute of Evolutionary Biology, Kings Buildings, EH3 9JT,
Edinburgh, UK
Tests of spatial cognition produce the best substantiated of the
purported differences in cognitive abilities between males and
females (mammals). Although there are at least seven extant
hypotheses as to why this sex difference might have evolved,
there are few data to differentiate amongst them. Additionally,
although the difference is always in the male’s favour, even spatial
cognition tests do n! ot always result in a sex difference. There are
at least two hormonal explanations for this, due to the effects of
sex steroids and stress hormones on cognitive performance. For
example, fluctuations in oestrogen across an oestrous or
menstrual cycle result in lower spatial performance by females, but
only at certain stages of that cycle. Female performance will, then,
may be as good as males at some stages of the cycle and poorer
at others. Additionally, or alternatively (it is not yet clear), stress
has a differential impact on males and females, such that cognitive
performance in females is typically poorer under acute stress
conditions. We argue that stress, as imposed via the testing
situation (often a Morris water maze task) may explain the
occurrence of sex differences in spatial condition in the laboratory
rat, at least. If so, we suggest that the laboratory rat (and, perhaps
laboratory testing) is not an appropriate model system for
addressing questions on th! e evolution of sex differences in
spatial cognition in mammals.
Ecological factors involved within adjustment of European
hedgehog (Erinaceus europaeus) to urbanization
Pauline Hubert 1,2 , Romain Julliard 3 , Sylvie Biagianti 1 and Marie-
2, 4
Lazarine Poulle
1 Laboratoire d’éco-toxicologie, EA 2099, URVVC, Université de
Reims Champagne-Ardenne, 51687 Cedex 2 Reims, France
2 Centre de Recherche et de Formation en Eco-éthologie (2C2A-
CERFE), 5 rue de la Héronnière, 08240 Boult-aux-Bois, France
3 Centre de Recherche sur la Biologie des Populations d’Oiseaux
(CRBPO), Muséum national d’Histoire naturelle, 55 rue Buffon,
75005 Paris, France
4 Laboratoire de Parasitologie - Mycologie, EA3800, IFR 53,
Université de Reims Champagne Ardenne, 51100 Reims, France.
European hedgehog is a wild mammal considered as an "urban
adapter” since it is able to maintain and even increase its
population despite urbanization. Adjustment of its populations to
specific conditions of the urban environment, especially through an
increase of their density, is an important indicator of the ecological
plasticity of the species. The objective of the present study was to
identify the ecological factors responsible for the density of
hedgehog population being higher in cities than in the countryside.
The study was conducted on a 4213 ha area located in the
Ardennes region, North-eastern France. It includes the Sedan city
(21000 inhabitants) and the neighbouring rural area. Forty three
transects of 500m each were spread out on the study area in order
to perform visual catch of hedgehog at night, with infrared
binoculars. Transects were walked twelve times from June 2006 to
October 2007, leading to 127 encounters. General Linear Models
(GLM) were built to identify the ecological factors explaining the
number of individuals observed per transect. Tested variables
were i) earthworm and arthropod biomass per transect (main food
resource) estimated with sampling methods applied to the 5 types
of habitat present in the study area, ii) presence of pet food and
anti-slug pellet or pesticides obtained by means of a verbal
questionnaire and iii) proximity of a badger, Meles meles sett
(hedgehog’s predator). Hedgehog density, estimated from distance
of hedgehog localisations to transects, and importance of factors
explaining hedgehog presence were then compared between
urban and rural areas.
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Some aspects of the Great Warbler' behavior in wet land
(Romania)
Constantin Ion
Bd. Carol I, no. 20A, Faculty of Biology, 700505, IASI, Romania
The Great Reed Warbler is one of the most common warbler form
the wet areas of Romania. It can be found especially around the
reeds beds plain and it is visiting our country form spring until
autumn. The spring migration takes place in the second part of
April. At the end of the April –the beginning of May, the great reed
warbler males start to delimitate the nesting territories.
These territories cover generally a surface of 100-250 m ². The
territoriality behavior can be seen as a form of aggression and also
competition, when individuals of the same species compete for a
mate and for environmental resources (food, shelter, from
predators, wind and heavy rain).
While delimit the territory these birds manifest the supremacy of
one warbler to another through emitting complex songs and
showing intimidating positions.
The establishment of the warbler territory is closely connected with
the meteorological conditions of the environment in which they live.
Rain or low temperatures are the main factors detrimental to the
establishment of territories. These territories can be contiguous
from one warbler to another or buffer spaces may exists between
them. We observed that territories have an opening to grassland
were they catch insects, and another opening towards the open
water were they take shelter, favor the success of the reproduction.
The building of the nest last 5-6 days, the deposition of the eggs
( 4-5 ) takes place 3-6 days (one egg - one day). The female is
hatching 10-14 days. After 30 days the chicks became good flying
and able to have an independent life.
The great reed warbler´s behavior is correlated with the breeding
stage. If the warblers have eggs, they leave the nest when a male
comes around. If the warblers have broods in their nest, they will
become very agitate, aggressive, and will try to sting the male in
order to defend the chicks.
Individual fate within an ant clone: the nature vs. nurture
debate under the microscope
Emmanuel Lecoutey, Fabien Ravary, Nicolas Châline and Pierre
Jaisson
Université Paris 13, Laboratoire d’Ethologie Expérimentale et
Comparée UMR CNRS 7153, 99 av. JB Clément, 93430-
Villetaneuse, France
The life cycle of some insular populations of the Asian tropical ant
species Cerapachys biroi Forel is likely to be unique worldwide. In
effect, these populations lost males and queens and maintain
themselves through the workers’ parthenogenesis. Moreover, all
the individual workers oviposit, participate to reproduction, making
copies of themselves, at least during the first weeks of their adult
life (Ravary & Jaisson, 2004). Eggs are laid altogether in a short
round, which results in a cyclic production of generations of
workers (Ravary & Jaisson, 2002). All workers of a same
generation are homogenous concerning age as they hatch
together within in a few hours. The C. biroi callow workers usually
stay within the nest displaying nursing behaviour and then become
foragers while aging. This species feed exclusively on ant brood of
alien ant species which makes easy to control strictly their diet at
the laboratory. Finally, hierarchy as well as worker polymorphism
(potential causes of division of labour) are absent within colonies.
These life history characteristics together allowed us to set up an
experimental design in which young workers of the same clone
and of the same age were reared in the same conditions, except
for the foraging experience: 50% were let to catch preys whereas
50% were not permitted to get a foraging success. Then, the fate
of these individuals was dramatically oriented accordingly: those
who experienced foraging successes became foragers and those
who experienced foraging failures turned towards nursing tasks
(Ravary et al. 2007). This direct demonstration of the role of
experience in the determinism of social behaviour reminds recent
knowledge about cell differentiation within organisms (Chang et al.
2007) and may contribute to revive the superorganismic
conception of insect societies (Wilson & Sober 1989).