Olof Leimar

Olof Leimar

Professor emeritus

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Arbetar vid Zoologiska institutionen
Telefon 08-16 40 56
Besöksadress Svante Arrheniusväg 18 B
Rum D 547
Postadress Zoologiska institutionen: Etologi 106 91 Stockholm


I urval från Stockholms universitets publikationsdatabas
  • Anna Favati, Hanne Løvlie, Olof Leimar.

    The ability to dominate conspecifics and thereby gain access to important resources depends on a number of traits and skills that may be both heritable and influenced by the environment. Experience of dominance relationships during development is a potential source of learning such skills. We here study the relative importance of social experience, personality, and morphological traits on competitive ability in male domestic fowl (Gallus gallus domesticus). By letting males grow up as either a single (dominant) male, as the dominant male of a pair, or as an intermediate ranked male in a group of males, we investigate if competitiveness in social interactions (winning duels) is mainly due to individual qualities or also influenced by social experience. We found that males were consistent over time in their competitive ability. Single raised males were inferior to pair dominant males and group-raised males in competitive ability, while pair dominant and group males did not differ significantly. This indicates that social training is important for future fighting success, but that the social position during development does not have a decisive influence on male fighting success in adulthood. Aggression and comb size, the latter possibly being a proxy for testosterone levels, had a marked effect on competitive ability. Together, our results indicate that certain behavioural and morphological traits are more important than experience of a social position in shaping competitive ability. These findings elucidate the relationship between social dominance and personality.

  • Magne Friberg, Christer Wiklund, Olof Leimar.

    Increasing attention is given to coevolutionary studies and to the role of ecology in local adaptation. The coevolutionary process can act in parallel throughout the distribution of species that interact in similar ecologies, whereas species interacting in varied ecological conditions might coevolve in different directions in different local populations. The butterflies Leptidea sinapis and L. reali have partitioned their niches differently in different parts of their sympatric distribution, with one species being a local habitat generalist in several different regions, and a local specialist in other areas where the sister species has adopted the habitat generalist role. Niche separation is likely independent of resource competition in this phytophagous system, and we study the potential for heterospecific sexual interference competition to redefine the suitability of a habitat and select for niche separation. We used the average female mating success in large outdoor cage experiments that varied both the absolute and relative density of the two species to estimate potential fitness costs of being in local minority. The mating success was unaffected by absolute density (conspecifics/m2) but strongly affected by the proportion of con- and heterospecifics in each cage. The proportion of mated females was ten times higher when a conspecific couple spent the day alone in the cage compared to when the single couple shared the cage with five heterospecific pairs. Being in the minority thus resulted in strong sexual interference from the locally more common competitor. We propose that these Allee effects select for habitat specialisation in the locally rare species as individuals leaving the core population likely suffer decreased fitness from spending time in heterospecific courtship. Hence, habitat suitability might depend less on local resource availability and more on the presence or absence of a local sexual competitor in this system.

  • Anna Favati (et al.).

    Individuals often differ in behavior in a consistent way, i.e. show variation in personality. Understanding the processes explaining the emergence and maintenance of this variation is a major topic in the field of animal behavioral research. Recent theoretical models predict that differences in various 'states' can generate individual variation in behavior. Previous studies have mainly focused on endogenous states like metabolic rate or energy reserves, but theory also suggests that more complex states based on social interactions could play important roles in shaping personality. We have earlier demonstrated short-term status-dependent variation in behavior in the domestic fowl (Gallus gallus domesticus), but whether such behavioral variation remains also after a longer period of time, is unknown. Therefore, we examine the influence of social status on variation in behavior, using experimental manipulation of social status in pairs of male domestic fowl. We scored males in three personality assays (aggression test, novel arena test, novel object test) before and after three weeks in pairs as either dominant or subdominant. We found no support for social status acting as a state that generates variation in personality over this time interval: social status had no significant effect on behavioral responses in personality tests. Instead, we observed individual consistency of behavior despite alteration of social status. Our results suggest that the effect of social environment on behavior is dependent on context and time, and that personality is more important than current social situation for describing individual behavior in stable groups.

Visa alla publikationer av Olof Leimar vid Stockholms universitet

Senast uppdaterad: 22 maj 2018

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