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AP Møller

Publications and source records attributed to AP Møller.

6 recordsLinked to original sources
PubMed1999

Retaliatory cuckoos and the evolution of host resistance to brood parasites.

We present a dynamic model of the evolution of host resistance to avian brood parasites, when the latter can retaliate against hosts that reject parasitic eggs. In a verbal model, Zahavi (1979, American Naturalist, 113, 157-159) suggested that retaliatory cuckoos might prevent the evolution of host resistance by reducing the reproductive success of rejecter hosts (i.e. by destroying their eggs or nestlings). Here we develop a model based on the association between the great spotted cuckoo, Clamator glandarius, and its main host, the European magpie, Pica pica, because this is the only system that has provided supportive evidence, to date, for the existence of retaliatory behaviour. Our aims were (1) to derive the conditions for invasion of the retaliation strategy in a nonretaliatory parasite population and (2) to investigate the consequences of retaliation for the evolution of host defence. If we assume a cost of discrimination for rejecter hosts in the absence of parasitism, and a cost paid by a retaliator for monitoring nests, our model shows cyclical dynamics. There is no evolutionarily stable strategy, and populations of both hosts and parasites will cycle indefinitely, the period of the cycles depending on mutation and/or migration rate. A stable polymorphism of acceptors and rejecters occurs only when parasites are nonretaliators. The spread of retaliator parasites drives rejecter hosts to extinction. Copyright 1999 The Association for the Study of Animal Behaviour.

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PubMed1999

Sexual selection for white tail spots in the barn swallow in relation to habitat choice by feather lice.

Many bird species have white spots in their tails or wing feathers, and such characters have been hypothesized to be either reliable signals (handicaps) or amplifiers that facilitate the message of a signal. In barn swallows, Hirundo rustica, the size of the white spots in the tail feathers is sexually dimorphic and positively correlated with feather length. We tested whether such spots act as handicaps or amplifiers. These white spots affect sexual selection in barn swallows, as shown by an experiment in which we randomly subjected males to (1) a considerable reduction of the size of all the spots by the use of a black permanent marker pen, (2) a small reduction of the size of the spots, or (3) no reduction. There was a positive association between spot size and the number of offspring produced per season. The white tail spots were preferred by feather-eating Mallophaga as a feeding site: holes made by Mallophaga were more abundant in the white spots than expected by chance. A habitat choice experiment with Mallophaga on barn swallow tail feathers revealed that they preferred white spots over black parts of the tail feathers. We therefore expected long-tailed male barn swallows to have more Mallophaga than short-tailed males. However, the opposite relationship was observed, indicating that long-tailed males may reliably signal their quality by the presence of large white tail spots without parasite damage. Thus white tail spots in barn swallows appear to be a reliable signal of phenotypic quality. Copyright 1999 The Association for the Study of Animal Behaviour.

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PubMed1999

Morphological Developmental Stability in Plants: Patterns and Causes.

Minor bilateral or radial asymmetry of leaves or flowers, the frequency of phenodeviants, intraindividual variation in repeated characters, and fractal dimensions of morphology are considered to represent measures of developmental instability since deviations from regularity of the phenotype constitute a measure of the inability to maintain developmental precision during ontogeny. First, we review patterns of fluctuating asymmetry in plants and show that levels of asymmetry are considerably greater than in animals. While petal asymmetry tends to decrease with petal size within species, leaf asymmetry tends to increase with leaf size. Intraspecific correlations of petal asymmetry and leaf asymmetry are weakly positive. Second, a meta-analysis of the effects of environmental factors hypothesized to increase asymmetry in leaves and flowers, such as radiation, ultraviolet light, excess artificial fertilizer, pollutants, extreme saline conditions, herbivory, and competition, showed intermediate (i.e., explaining 10% of the variance) to large (i.e., explaining 25% of the variance) effects. Third, a meta-analysis of the effects of genetic factors hypothesized to contribute to increased asymmetry in plants, such as homozygosity, hybridization, mutation, and quantitative genetic differences among individuals, showed variable but usually significant effects, although the number of studies generally was small. Controlled experimental studies of environmental and genetic effects on developmental instability of plants may increase our understanding of the mechanisms causing developmental instability.

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PubMed1998

Nest building is a sexually selected behaviour in the barn swallow.

Females may use male nest building to assess male parental quality, and nest size would then be a sexually selected trait. In the barn swallow, Hirundo rustica, females select their partner by his tail length, a character believed to signal good genes. Both sexes participate in nest building, although male participation is negatively related to his attractiveness as reflected by tail length. We tested the hypothesis that nest building is a sexually selected trait: females paired with males of high parental quality (as shown by the male during nest building) may obtain a mate providing large amounts of parental investment, while, as has been shown previously, females mated to attractive (long-tailed) males will acquire mates with good genetic quality. Therefore, since nest building in barn swallows occurs after mating, we predicted a postmating sexual selection process by which the female invests differentially in reproduction depending on the male's nest-building effort (reflecting his willingness to invest in reproduction). The volume of material in a nest was related to the male's contribution to nest building and, in agreement with our hypothesis, in a multiple regression analysis, male tail length and nest material volume were negatively related to laying date and positively to female investment in reproduction (total number of eggs laid during the breeding season). Moreover, females paired with long-tailed males (which contribute very little to nest building), but using the same amount of nest material as females paired with short-tailed males, reduced the thickness of the nest and hence increased its capacity. Therefore, in the barn swallow two different traits appear to be sexually selected: tail length of males owing to the good genes process and nest-building ability owing to the good parent process. (c) 1998 The Association for the Study of Animal Behaviour.

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