Trophic ecology of New Zealand triplefin fishes (Family Tripterygiidae) |
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Authors: | David A Feary M Wellenreuther K D Clements |
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Institution: | (1) School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand;(2) Present address: International Network on Water, Environment and Health, PJSC, United Nations University, P.O. Box 17777, Dubai, United Arab Emirates;(3) Section for Animal Ecology, University of Lund, Ecology Building, Solvegatan 36, 223 02 Lund, Sweden;(4) School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand |
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Abstract: | In many vertebrate radiations, food partitioning among closely related taxa is a key factor in both the maintenance of species
diversity and the process of diversification. We compared diet composition and jaw morphology of 18 New Zealand triplefin
species (F. Tripterygiidae) to examine whether species have diversified along a trophic axis. These fishes predominantly utilised
small, mobile benthic invertebrates, and interspecific differences in diet composition appeared to be mainly attributable
to habitat- or size-dependent feeding behaviour. Although there were differences in the relative size of the bones comprising
the oral jaw apparatus between species, the majority showed an apparatus consistent with a relatively high velocity, low force
jaw movement indicative of a diet of evasive prey. Phylogenetic comparative analyses showed that the evolution of jaw lever
ratios and diet breadth was best explained by a non-directional model in which character changes have occurred randomly and
independent of phylogeny. The mode of diet breadth evolution was gradual and the tempo has not accelerated or slowed down
over time. The mode of evolution for the jaw lever ratios has been gradual for the opening but punctuated for the closing
levers, suggesting that evolutionary changes have occurred rapidly for the latter trait. The tempo of trait evolution for
the jaw opening levers has not accelerated or slowed down over time, while the tempo for the jaw closing levers has accelerated
towards the tips of the tree, which is suggestive of species level adaptation. The lack of phylogenetic signal in diet breadth
and jaw lever ratios appears most likely to be a correlated response to the marked habitat diversification in this group,
and is thus the passive outcome of prey availability in species-specific habitat types. Overall, the trophic ecology of New
Zealand’s triplefin fauna parallels the generalist strategy typical of the family worldwide, suggesting that trophic resource
partitioning has not been an important factor in the evolution of these fishes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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