The advantages and evolution of a morphological novelty

@article{Benkman1991TheAA,
  title={The advantages and evolution of a morphological novelty},
  author={Craig W. Benkman and Anna K. Lindholm},
  journal={Nature},
  year={1991},
  volume={349},
  pages={519-520}
}
THE role of selective agents in the origin of evolutionary novelties has been controversial1–3 and has remained outside the realm of experiments. Here we experimentally determine both the benefits of a single trait and the advantages accrued during the presumed sequence of evolutionary steps leading to the fully specialized structure. By comparison of red crossbills (Loxia curvirostra, L.), in which the mandibular crossing has been removed, with controls and with the related but less… 

Are the ratios of bill crossing morphs in result of frequency-dependent selection?

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The direction the lower mandible curves in crossbills (Loxia) is an example of a discrete polymorphism and it is hypothesized that the 1:1 ratio results from negative frequency-dependent selection favouring the rarer morph.

Are the ratios of bill crossing morphs in crossbills the result of frequency-dependent selection?

TLDR
The direction the lower mandible curves in crossbills (Loxia) is an example of a discrete polymorphism and it is hypothesized that the 1:1 ratio results from negative frequency-dependent selection favouring the rarer morph.

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TLDR
This study considers the evolution of bill size of one sibling species of red crossbill (L. curvirostra complex) that Groth (1993) designates as type 5 and makes use of the partitioning suggested by Arnold (1983) where first the relationship between the trait and some measure of performance is estimated and then performance is related to fitness.

DIVERGENT SELECTION DRIVES THE ADAPTIVE RADIATION OF CROSSBILLS

  • C. Benkman
  • Environmental Science
    Evolution; international journal of organic evolution
  • 2003
TLDR
This work quantifies selection on a wild population of red crossbills in the South Hills, Idaho and shows how fitness is related to both bill depth and performance, which supports a key tenet of the ecological theory of adaptive radiations.

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TLDR
Divergence as a result of coevolution is greater at lower latitude where crossbill–conifer interactions have been less interrupted by Pleistocene events, and indicates that cone crop fluctuations do not prevent crossbills and conifers from coevolving.

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TLDR
A feature of the beak specifically adapted for ectoparasite control is shown, significantly enhancing the efficiency of preening for parasite control in rock pigeons.

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TLDR
It is concluded that mandible crossing direction may have uncharacteristically low heritability, but it cannot rule out that it is nongenetically determined.

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TLDR
The hypothesis that the presence of red squirrels affects the occurrence of coevolution between red crossbills and Rocky Mountain lodgepole pine and thereby provides a mechanism giving rise to a geographic mosaic of selection is tested.

Natural selection and age-related variation in morphology of a colonial bird

Unusual climatic events often lead to intense natural selection on organisms. Whether episodic selection events result in permanent microevolutionary changes or are reversed by opposing selection

An ecological twist on the morphology-performance-fitness axis

TLDR
Claims concerning selection on morphology, performance, and habitat use were supported by data for males but not females, but morphology and performance were not correlated in females.
...

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TLDR
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