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Nicolas Margraf
Australian National University
EcologyLeaf beetleMalurusBotanyBiology
12Publications
10H-index
244Citations
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Publications 12
Newest
#1Gabriela K. Hajduk (Edin.: University of Edinburgh)H-Index: 2
#2Andrew Cockburn (ANU: Australian National University)H-Index: 56
Last. Loeske E. B. Kruuk (ANU: Australian National University)H-Index: 63
view all 6 authors...
: Inbreeding depression plays a major role in shaping mating systems: in particular, inbreeding avoidance is often proposed as a mechanism explaining extra-pair reproduction in socially monogamous species. This suggestion relies on assumptions that are rarely comprehensively tested: that inbreeding depression is present, that higher kinship between social partners increases infidelity, and that infidelity reduces the frequency of inbreeding. Here, we test these assumptions using 26 years of data...
10 CitationsSource
#1Andrew CockburnH-Index: 56
#2Lyanne BrouwerH-Index: 21
Last. Janis L. DickinsonH-Index: 36
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The evolution of cooperation has been a focus of interest for evolutionary biologists for over a hundred years (Darwin 1859; Kropotkin 1908; Williams 1966). While all forms of cooperation challenge the centrality of competition in the process of evolution, cooperative and eusocial breeding systems, where offspring produced by a small number of breeding individuals are reared by nonbreeding helpers or workers, raise some of the most fundamental questions about the level at which selection operate...
22 CitationsSource
#1Andrew Cockburn (ANU: Australian National University)H-Index: 56
#2Lyanne Brouwer (ANU: Australian National University)H-Index: 21
Last. Martijn van de Pol (ANU: Australian National University)H-Index: 22
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Fairy-wrens (genus Malurus) maintain territories year round, and breed cooperatively, with all members of the social group provisioning young. Despite living with several adult males, the breeding female typically cuckolds all of them, seeking fertilisations from extra-group males that provide no care to her offspring, instead caring for the young reared on their own territory. We trace the evolutionary origins and persistence of this extraordinary combination of traits. We argue that the high r...
22 CitationsSource
#1Nicolas Margraf (ANU: Australian National University)H-Index: 10
#2Andrew Cockburn (ANU: Australian National University)H-Index: 56
Cooperative breeding among birds was first discovered in the genus Malurus (Maluridae), the fairy-wrens. Cooperative care arises because male, and sometimes female, offspring remain in their natal territory and help the adults rear offspring. Early uses of data from Superb Fairy-wrens (Malurus cyaneus) to illustrate how kin altruism can explain helping behaviour were based on flawed assumptions. Most importantly, high rates of extra-group mating mean that the helpers often assist adults to which...
15 CitationsSource
#1Sara Calhim (UTU: University of Turku)H-Index: 11
#2Michael C. Double (ANU: Australian National University)H-Index: 26
Last. Andrew Cockburn (ANU: Australian National University)H-Index: 56
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Postcopulatory sexual selection is an important force in the evolution of reproductive traits, including sperm morphology. In birds, sperm morphology is known to be highly heritable and largely condition-independent. Theory predicts, and recent comparative work corroborates, that strong selection in such traits reduces intraspecific phenotypic variation. Here we show that some variation can be maintained despite extreme promiscuity, as a result of opposing, copulation-role-specific selection for...
29 CitationsSource
#1Matthias BorerH-Index: 5
#2Nadir Alvarez (UNIL: University of Lausanne)H-Index: 29
Last. Russell E. Naisbit (University of Fribourg)H-Index: 17
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Abstract The genetic landscape of the European flora and fauna was shaped by the ebb and flow of populations with the shifting ice during Quaternary climate cycles. While this has been well demonstrated for lowland species, less is known about high altitude taxa. Here we analyze the phylogeography of the leaf beetle Oreina elongata from 20 populations across the Alps and Apennines. Three mitochondrial and one nuclear region were sequenced in 64 individuals. Within an mtDNA phylogeny, three of se...
26 CitationsSource
#1Nicolas MargrafH-Index: 10
#2Aline VerdonH-Index: 2
Last. Russell E. NaisbitH-Index: 17
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The challenge in defining conservation units so that they represent evolutionary entities has been to combine both genetic properties and ecological significance. Here we make use of the complexity of the European Alps, with their genetic landscape shaped by geographical barriers and postglacial colonization, to examine the correlation between ecological and genetic divergence. Montane species, because of the fragmentation of their present habitat, constitute extreme cases in which to test if ge...
26 CitationsSource
#1Aline VerdonH-Index: 2
#2Nicolas MargrafH-Index: 10
Last. Russell E. NaisbitH-Index: 17
view all 5 authors...
Choosing the plant on which to lay their eggs is the last act of care that most female herbivorous insects bestow upon their offspring. These decisions play a pivotal role in insect - plant interactions, placing host preference under strong selection and contributing to the diversity of phytophagous insects as one of the first traits to adapt to new hosts. 2. This study presents a test of whether extreme isolation and exposure to different host plants can produce intra-specific divergence in ovi...
16 CitationsSource
#1Karl Gotthard (Stockholm University)H-Index: 27
#2Nicolas MargrafH-Index: 10
Last. Martine RahierH-Index: 16
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hostplant biology. Here we examine host utilization of the chrysomelid beetle Oreinaelongata that shows interpopulation variation in the degree of specialization. We focuson larval behaviour and on what selection pressures may favour the use of two differentlarval host plants (Adenostyles alliariae and Cirsium spinosissimum) in one populationas opposed to specialization onto one of them as is seen in other populations. Theresults suggest that the degree of exploratory foraging behaviour is highe...
18 CitationsSource
#1Nicolas MargrafH-Index: 10
#2B. GautschiH-Index: 1
Last. Martine RahierH-Index: 16
view all 3 authors...
For a study of local adaptations in the Alpine leaf beetle, Oreina elongata, we developed six microsatellite loci and screened them in 305 individuals from 13 populations. All markers were polymorphic with three to 15 alleles per locus. Average observed and expected heterozygosity values were 0.14 and 0.62, respectively. Four markers showed heterozygote deficiency and deviated significantly from Hardy–Weinberg expectations, indicating the presence of null alleles.
2 CitationsSource
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