Généralités et Environnement

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Date : Wed 27 May 2009 08:15:07

"Différences d'agressivité et de valeur sélective entre morphes de plumage chez la buse variable (Buteo buteo)"

Behavioral Ecology
Volume: 20 Issue: 1 Pages: 180-185 JAN-FEB 2009

Aggression and fitness differences between plumage morphs in the
common buzzard (Buteo buteo)

M. Boerner and O. Krüger

Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK

Abstract: Genetic plumage polymorphism in birds is increasingly recognized as a potentially important trait influencing birds' life histories. In the common buzzard Buteo buteo, the 3 color morphs vary in lifetime reproductive success (LRS), but the proximate mechanisms leading to these differences are unknown. We first confirmed the stability of the fitness differences found previously, using a greatly extended LRS data set. To find potential causes for these differences, we experimentally studied variation in aggressive behavior of the morphs, both against an interspecific predator and intraspecific competitors. The morphs showed substantial variation in aggressive behavior. Light-colored males were most aggressive toward an interspecific predator, followed by intermediate and dark males. In females, this pattern was reversed, resulting in @#$%&-related differences of aggression in 2 morphs. When defending their territory against intraspecific competitors, no absolute difference in aggression was found, but the morphs reacted strongest toward intruders of a morph similar to their own. This suggests that aggression differs both between and within morphs, leading to a complex pattern on the population level. Coupled with the strong fitness differences, our results suggest that the genetic basis of the polymorphism has far-reaching behavioral consequences.


Bonne lecture

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Envoyé par : FB (Adresse IP journalisée)

Date : Thu 28 May 2009 09:10:47

"Effets de la reproduction en cours sur la survie apparente, la dispersion, et la reproduction future chez l'hirondelle rustique mis en évidence par des modèles de capture-recapture multi-états"

Journal of Animal Ecology
Volume 78 Issue 3, Pages 625 - 635

Effect of current reproduction on apparent survival, breeding dispersal, and future reproduction in barn swallows assessed by multistate capture–recapture models

Michael Schaub 1,2* and Johann von Hirschheydt 1

1 Swiss Ornithological Institute, CH-6204 Sempach, Switzerland ; and
2 Institute of Ecology and Evolution – Conservation Biology, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland

ABSTRACT

* 1.

Theoretical models predict a negative effect of current reproduction on breeding dispersal, survival and future reproduction, and many studies confirm these predictions. Yet, results of most previous studies may be difficult to interpret because the fate of the affected individuals cannot always be observed. Detection is almost always imperfect and some individuals emigrate from the study area, resulting in biased estimates of both survival and dispersal.
* 2.

Most studies bypass these problems with strong assumptions. We use a multistate capture–recapture model that does not require these assumptions. States are defined based on classes of reproductive success and on observed dispersal events within the study area. By accounting for imperfect detection within the study area, the model allows estimation of the effect of reproductive success on apparent survival, dispersal probabilities within the study area and the annual transition probabilities among classes of reproductive success. Based on an assumption about the estimate of real survival, the model allows the estimation of total dispersal that is not specific to a fixed study area.
* 3.

We applied this model to capture–recapture data of 2262 adult barn swallows (Hirundo rustica) sampled from 1997–2004 in eight local populations in Switzerland.
* 4.

We found that dispersal within the study area decreased with increasing reproductive success in both @#$%&, that reproductive success was not affected by preceding dispersal and that apparent survival of females but not of males increased with increasing reproductive success. Apparent survival of females with high reproductive success was identical to apparent survival of males suggesting that this estimate of apparent survival (0·48) was close to true survival. Total breeding dispersal was generally higher in females and it increased with decreasing reproductive success in both @#$%&. Current reproductive success depended on reproductive success in the preceding year suggesting that individual differences were of importance.
* 5.

Our study highlights that reproductive success was an important factor affecting breeding dispersal and population turnover. While unsuccessful males mainly remained in the local populations, many unsuccessful females left them. Population turnover of adult swallows was mainly due to unsuccessful females.


Joli, non ?
Bonne lecture

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