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Re: Sauropod neck evolution in Journal of Zoology

Nice work!
One thing I always wondered is why we dismiss sexual selection when we
do not find dimorphism in the feature supposed to be sexually selected
(only restricting to this feature, not criticizing the work because of
just this). Can not it be a selection of the mate feature that is
common to both sexes? For example, although it is cultural (which may
be irrelevant), and weighted against other features, both sexes in our
species prefer non-fat mates (also non-bald, although among women it
is a less common condition). The brain of both sexes may have a
similar substrate. Finally, lack of dimorphism may conceivably imply
sexual selection of similar features by both sexes, accepting the
presence of variation which may result in dimorphism to be selected

2011/5/16 bh480@scn.org <bh480@scn.org>:
> From: Ben Creisler
> bh480@scn.org
> M.P. Taylor, D.W.E. Hone, M.J. Wedel, & Darren Naish (2011).
> The long necks of sauropods did not evolve primarily through sexual
> selection.
> Journal of  Zoology (advance online publication)
> DOI: 10.1111/j.1469-7998.2011.00824.x
> http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.2011.00824.x/abstract
> It has recently been argued that the elongate necks of sauropod dinosaurs
> evolved primarily through selection for their use as sexual and dominance
> signals, and not as an adaptation for accessing a large ‘feeding envelope’
> as traditionally thought. Here we explore this idea and show that all six
> arguments that have been advanced in support of the sexual selection
> hypothesis are flawed: there is no evidence for sexual dimorphism in the
> necks of sauropods; neither is there any evidence that they were used in
> dominance displays; long necks provided significant survival benefits in
> allowing high browsing and energetically efficient grazing; their fitness
> cost was likely less than has been assumed; their positive allometry
> through ontogeny is uninformative given that ontogenetic allometry is
> common in animals; apparent lack of correlation between neck and leg length
> across phylogeny is illusory due to over-representation of mamenchisaurids
> in a previously analysed dataset, and in any case is not informative as the
> unique morphology of sauropod necks suggests they, rather than legs, may
> have been cheaper to elongate when evolving increased vertical reach. In no
> speciose, morphologically varied, long-lived tetrapod clade has sexual
> selection consistently acted on a single part of the body, and it is
> unlikely that Sauropoda is the exception to this. In summary, there is no
> convincing evidence that sexual selection was the primary force driving the
> evolution of sauropod necks. While a subsidiary role for sexual selection
> cannot be discounted, the traditional hypothesis that sauropod necks
> evolved primarily due to the feeding benefits that they conferred is, by
> comparison, far better supported.
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