Polygyny in the Willow Warbler Phylloscopus trochilus in Swedish Lapland

Neergaard, Raimo; Arvidson, Bengt

doi:10.1111/j.1474-919x.1995.tb03220.x

Cited by 12 publications

(5 citation statements)

References 13 publications

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“…2007). Annual variation in the time of male settlement might be related to variation in ASR (Neergaard & Arvidson 1995). However, protandry is also associated with levels of extra‐pair paternity (Coppack et al .…”

Section: Results and Reviewmentioning

confidence: 99%

“…Recent models, backed by field observations, suggest that protandry is likely to be associated with, and may be the result of, male-skewed sex ratios, and that protogyny, the rarely observed earlier arrival of females, is only likely to occur when the sex ratio is balanced or female-dominated (Kokko et al 2006, Amrhein et al 2007). Annual variation in the time of male settlement might be related to variation in ASR (Neergaard & Arvidson 1995). However, protandry is also associated with levels of extra-pair paternity (Coppack et al 2006) and sexual plumage dimorphism (Rubolini et al 2004), both of which might also be related to the ASR.…”

Section: Causes and Predictors Of Asr Variationmentioning

confidence: 99%

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Adult sex ratios in wild bird populations

Donald¹

2007

Ibis

418

540

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Offspring sex ratios in wild bird populations, and the extent to which they vary from the equality expected by random genotypic sex determination, have received much recent attention. Adult sex ratios (ASRs) in wild birds, on the other hand, remain very poorly described, and many of the questions about them posed by Ernst Mayr in 1939 remain unanswered. This review assesses population-level sex ratio patterns in wild bird populations, with an emphasis on the ASR. A quantitative assessment of over 200 published estimates of ASR, covering species from a wide range of taxa, regions and habitats, supported Mayr's assertion that skewed ASRs are common in wild bird populations. On average, males outnumbered females by around 33%, and 65% of published estimates differed significantly from equality. In contrast, populationlevel estimates of offspring sex ratio in birds did not generally differ from equality, and mean ASR across a range of wild mammal species was strongly female-skewed. ASR distortion in birds was significantly more severe in populations of globally threatened species than in nonthreatened species, a previously undescribed pattern that has profound implications for their monitoring and conservation. Higher female mortality, rather than skewed offspring sex ratio, is the main driver of male-skewed ASRs in birds, and the causes and implications of this are reviewed. While estimates of ASR in wild bird populations may be subject to a number of biases, which are discussed, there is currently no quantitative evidence that an ASR of one male to one female represents the norm in birds. A better understanding and reporting of ASRs in wild bird populations could contribute greatly to our understanding of population processes and could contribute much to theoretical and applied research and conservation.

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Section: Results and Reviewmentioning

confidence: 99%

Section: Causes and Predictors Of Asr Variationmentioning

confidence: 99%

Adult sex ratios in wild bird populations

Donald¹

2007

Ibis

418

540

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“…Particularly in northern Scandinavia, very few nestlings and juvenile willow warblers return to breed in study plots in subsequent years (Cuadrado & Hasselquist 1994; Neergaard & Arvidson 1995). With such high natal dispersal, one would expect gene flow to homogenize allele frequencies at selectively neutral loci.…”

Section: Discussionmentioning

confidence: 99%

The use of AFLP to find an informative SNP: genetic differences across a migratory divide in willow warblers

2002

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We used the amplified fragment length polymorphism (AFLP) method to obtain genetic markers distinguishing two subspecies of willow warblers Phylloscopus trochilus that have different migratory behaviours but are not differentiated in mitochondrial DNA or at several microsatellite loci. With the inverse-polymerase chain reaction (PCR) approach we converted a dominant AFLP-marker to a codominant single nucleotide polymorphism (SNP). Across Scandinavia we typed 621 birds at the SNP locus AFLP-WW1 and we found a sigmoid change in allele frequencies centred around 62 degrees latitude. North of the latitudinal cline was a west-east cline. Both clines are narrower than one would expect from dispersal distances in willow warblers, which suggests that these are maintained by selection. The latitudinal cline at the locus AFLP-WW1 is paralleled by changes in several other traits, all of which might be maintained by a single selective force. The most plausible selection factor that we have identified is selection against hybrids because of inferior migratory behaviour. The selective force maintaining the east-west cline is less obvious. We discuss alternatives to the selection scenario, involving colonization history and asymmetric gene flow.

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“…The Willow Warbler is a socially monogamous species, although polygyny is not uncommon (eg. Lawn 1983, M011er 1986, Neergaard & Arvidsson 1995. The nest is placed on the ground.…”

Section: Methodsmentioning

confidence: 99%

Male parental care promotes early fledging in an open‐nester, the Willow Warbler Phylloscopus trochilus

Bjrnstad

Lifjeld

1996

Ibis

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The importance of male parental care to female reproductive success was investigated in the monogamous Willow Warbler Phylloscopus trochilus by removing the male parent at two different stages of the breeding cycle. Females that were widowed at the start of egg‐laying continued breeding and managed to raise their brood on their own with no apparent reductions in numbers fledged or fledgling body‐mass. The widowed females compensated for the loss of male assistance by increasing their own food provisioning rate as compared with control females. However, widows spent less time brooding the small young, and the growth rate of nestlings was reduced. In nests where the male parent was removed 7 days after the eggs hatched, the subsequent growth rate of nestlings was still affected, which suggests that male care is influential throughout the nestling period. On average, broods reared by widows fledged 2 days later than did broods of control females. An extension of the nestling period may appreciably affect reproductive success, since 68% of nests failed due to predation, mostly during the nestling period. We suggest that the main role of male parental care in the Willow Warbler is to assure a high growth rate of nestlings, which leads to early fledging and hence a reduced risk of nest predation.

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Polygyny in the Willow Warbler Phylloscopus trochilus in Swedish Lapland

Cited by 12 publications

References 13 publications

Adult sex ratios in wild bird populations

Adult sex ratios in wild bird populations

The use of AFLP to find an informative SNP: genetic differences across a migratory divide in willow warblers

Male parental care promotes early fledging in an open‐nester, the Willow Warbler Phylloscopus trochilus

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