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Does evolutionary innovation in pharyngeal jaws lead to rapid lineage diversification in labrid fishes? - PubMed

  • ️Thu Jan 01 2009

Does evolutionary innovation in pharyngeal jaws lead to rapid lineage diversification in labrid fishes?

Michael E Alfaro et al. BMC Evol Biol. 2009.

Abstract

Background: Major modifications to the pharyngeal jaw apparatus are widely regarded as a recurring evolutionary key innovation that has enabled adaptive radiation in many species-rich clades of percomorph fishes. However one of the central predictions of this hypothesis, that the acquisition of a modified pharyngeal jaw apparatus will be positively correlated with explosive lineage diversification, has never been tested. We applied comparative methods to a new time-calibrated phylogeny of labrid fishes to test whether diversification rates shifted at two scales where major pharyngeal jaw innovations have evolved: across all of Labridae and within the subclade of parrotfishes.

Results: Diversification patterns within early labrids did not reflect rapid initial radiation. Much of modern labrid diversity stems from two recent rapid diversification events; one within julidine fishes and the other with the origin of the most species-rich clade of reef-associated parrotfishes. A secondary pharyngeal jaw innovation was correlated with rapid diversification within the parrotfishes. However diversification rate shifts within parrotfishes are more strongly correlated with the evolution of extreme dichromatism than with pharyngeal jaw modifications.

Conclusion: The temporal lag between pharyngeal jaw modifications and changes in diversification rates casts doubt on the key innovation hypothesis as a simple explanation for much of the richness seen in labrids and scarines. Although the possession of a secondarily modified PJA was correlated with increased diversification rates, this pattern is better explained by the evolution of extreme dichromatism (and other social and behavioral characters relating to sexual selection) within Scarus and Chlorurus. The PJA-innovation hypothesis also fails to explain the most dominant aspect of labrid lineage diversification, the radiation of the julidines. We suggest that pharyngeal jaws might have played a more important role in enabling morphological evolution of the feeding apparatus in labrids and scarines rather than in accelerating lineage diversification.

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Figures

Figure 1
Figure 1

Time-calibrated phylogeny (chronogram) of labrid fishes based on mitochondrial and nuclear sequences. Filled circles indicate fossil-calibrated nodes (Table 7). Bars indicate 95% HPD for divergence time estimates. Focal nodes indicated by circles (Table 1). Posterior probabilities for all focal nodes was 90%. Scale bar at the bottom is in million of years since the present.

Figure 2
Figure 2

Lineage through time plots of early history of labrids, scarids, and two subclades identified by MEDUSA analysis as diversifying exceptionally rapidly (Fig. 3). Proportion of clade history is measured from the root node of each clade.

Figure 3
Figure 3

Phylogenetic placement of diversification rate shifts and pharyngeal jaw modifications. Tip clade richness follows names with warmer colored tip triangles indicate subclades with greater species richness. Numbered branches indicate position of two diversification rate increases. Origin of labroid pharyngeal jaw apparatus (PJM) and parrotfish pharyngeal mill (PM) indicated by black rectangles. Tree backbone is taken from Figure 1. Species richness and taxonomic membership of major subclades given in Table 8.

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References

    1. Bellwood DR, Wainwright PC. In: Coral Reef Fishes. Sale PF, editor. San Diego: Academic Press; 2002. The history and biogeography of fishes on coral reefs; pp. 5–32.
    1. Westneat MW, Wainwright PC, Bellwood DR. Diversity of mechanical design for feeding in labrid fishes. Amer Zool. 1999;39:100A–100A.
    1. Wainwright PC, Bellwood DR, Westneat MW, Grubich JR, Hoey AS. A functional morphospace for the skull of labrid fishes: patterns of diversity in a complex biomechanical system. Biol J Linn Soc. 2004;82:1–25. doi: 10.1111/j.1095-8312.2004.00313.x. - DOI
    1. Westneat MW, Alfaro ME, Wainwright PC, Bellwood DR, Grubich JR, Fessler J, Clements KD, Smith L. Local phylogenetic divergence and global evolutionary convergence of skull function in reef fishes of the family Labridae. Proc R Soc B. 2005;272:993–1000. doi: 10.1098/rspb.2004.3013. - DOI - PMC - PubMed
    1. Westneat MW, Alfaro ME. Phylogenetic relationships and evolutionary history of the reef fish family Labridae. Mol Phylogenet Evol. 2005;36:370–390. doi: 10.1016/j.ympev.2005.02.001. - DOI - PubMed

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