Publications by authors named "Jennifer R Hodge"

6 Publications

  • Page 1 of 1

Anatomical basis of diverse jaw protrusion directionality in ponyfishes (Family Leiognathidae).

J Morphol 2021 03 13;282(3):427-437. Epub 2021 Jan 13.

Department of Evolution and Ecology, University of California Davis, Davis, California, USA.

Protrusion of the oral jaws is a key morphological innovation that enhances feeding performance in fishes. The mechanisms of protrusion and the basis of variation in its magnitude are well studied, but little attention has been paid to the functional morphology of protrusion directionality, despite wide variation among teleost species from slightly dorsal to strongly ventral. Ponyfishes (Leiognathidae) comprise a group of 52 species that exhibit striking diversity in the directionality of jaw protrusion, providing a promising system for exploring its underlying basis in a single clade. We examined the anatomical basis of protrusion directionality by measuring eight traits associated with the size and positioning of oral jaw bones. Measurements were made on cleared and stained specimens of 20 ponyfish species, representing every major lineage within the family. Species fell into three nonoverlapping clusters with respect to directionality including dorsal, rostral, and ventral protruders. A key correlate of protrusion direction is the anterior-posterior position of the articular-quadrate jaw joint. As the joint position moves from a posterior to a more anterior location, the orientation of the relaxed mandible rotates from an almost horizontal resting position to an upright vertical posture. Abduction of the mandible from the horizontal position results in ventrally directed protrusion, while the more upright mandible rotates to a position that maintains dorsal orientation. The resting orientation of the premaxilla and maxilla, thus, vary consistently with protrusion direction. Mouth size, represented by length of the mandible and maxilla, is a second major axis of variation in ponyfishes that is independent of variation in protrusion directionality.
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http://dx.doi.org/10.1002/jmor.21314DOI Listing
March 2021

Do key innovations unlock diversification? A case-study on the morphological and ecological impact of pharyngognathy in acanthomorph fishes.

Curr Zool 2020 Oct 2;66(5):575-588. Epub 2020 Sep 2.

Department of Biological Sciences, Clemson University, Clemson, SC, 29634, USA.

Key innovations may allow lineages access to new resources and facilitate the invasion of new adaptive zones, potentially influencing diversification patterns. Many studies have focused on the impact of key innovations on speciation rates, but far less is known about how they influence phenotypic rates and patterns of ecomorphological diversification. We use the repeated evolution of pharyngognathy within acanthomorph fishes, a commonly cited key innovation, as a case study to explore the predictions of key innovation theory. Specifically, we investigate whether transitions to pharyngognathy led to shifts in the rate of phenotypic evolution, as well as shifts and/or expansion in the occupation of morphological and dietary space, using a dataset of 8 morphological traits measured across 3,853 species of Acanthomorpha. Analyzing the 6 evolutionarily independent pharyngognathous clades together, we found no evidence to support pharyngognathy as a key innovation; however, comparisons between individual pharyngognathous lineages and their sister clades did reveal some consistent patterns. In morphospace, most pharyngognathous clades cluster in areas that correspond to deeper-bodied morphologies relative to their sister clades, whereas occupying greater areas in dietary space that reflects a more diversified diet. Additionally, both Cichlidae and Labridae exhibited higher univariate rates of phenotypic evolution compared with their closest relatives. However, few of these results were exceptional relative to our null models. Our results suggest that transitions to pharyngognathy may only be advantageous when combined with additional ecological or intrinsic factors, illustrating the importance of accounting for lineage-specific effects when testing key innovation hypotheses. Moreover, the challenges we experienced formulating informative comparisons, despite the ideal evolutionary scenario of multiple independent evolutionary origins of pharyngognathous clades, illustrates the complexities involved in quantifying the impact of key innovations. Given the issues of lineage specific effects and rate heterogeneity at macroevolutionary scales we observed, we suggest a reassessment of the expected impacts of key innovations may be warranted.
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http://dx.doi.org/10.1093/cz/zoaa048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7705508PMC
October 2020

Correlated Evolution of Sex Allocation and Mating System in Wrasses and Parrotfishes.

Am Nat 2020 07 22;196(1):57-73. Epub 2020 May 22.

In accordance with predictions of the size-advantage model, comparative evidence confirms that protogynous sex change is lost when mating behavior is characterized by weak size advantage. However, we lack comparative evidence supporting the adaptive significance of sex change. Specifically, it remains unclear whether increasing male size advantage induces transitions to protogynous sex change across species, as it can within species. We show that in wrasses and parrotfishes (Labridae) the evolution of protogynous sex change is correlated with polygynous mating and that the degree of male size advantage expressed by polygynous species influences transitions between different types of protogynous sex change. Phylogenetic reconstructions reveal strikingly similar patterns of sex allocation and mating system evolution with comparable lability. Despite the plasticity of sex-determination mechanisms in labrids, transitions trend toward monandry (all males derived from sex-changed females), with all observed losses of protogyny accounted for by shifts in the timing of sex change to prematuration. Likewise, transitions in mating system trend from the ancestral condition of lek-like polygyny toward greater male size advantage, characteristic of haremic polygyny. The results of our comparative analyses are among the first to confirm the adaptive significance of sex change as described by the size-advantage model.
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http://dx.doi.org/10.1086/708764DOI Listing
July 2020

Colour pattern divergence in reef fish species is rapid and driven by both range overlap and symmetry.

Ecol Lett 2019 Jan 22;22(1):190-199. Epub 2018 Nov 22.

College of Science and Engineering, James Cook University, Townsville, 4811, Australia.

Signal divergence is an important process underpinning the diversification of lineages. Research has shown that signal divergence is greatest in species pairs that possess high geographic range overlap. However, the influence of range-size differences within pairs is less understood. We investigated how these factors have shaped signal divergence within brightly coloured coral reef butterflyfishes (genus: Chaetodon). Using a novel digital imaging methodology, we quantified both colouration and pattern using 250 000 sample points on each fish image. Surprisingly, evolutionary age did not affect colour pattern dissimilarity between species pairs, with average differences arising in just 300 000 years. However, the effect of range overlap and range symmetry was significant. Species-pair colour patterns become more different with increasing overlap, but only when ranges are similar in size. When ranges differ markedly in area, species-pair colour patterns become more similar with increasing overlap. This suggests that species with small ranges may maintain non-colour-based species boundaries.
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http://dx.doi.org/10.1111/ele.13180DOI Listing
January 2019

Ecology shapes the evolutionary trade-off between predator avoidance and defence in coral reef butterflyfishes.

Ecol Lett 2018 07 9;21(7):1033-1042. Epub 2018 May 9.

Department of Evolution and Ecology, University of California Davis, Davis, CA, 95616, USA.

Antipredator defensive traits are thought to trade-off evolutionarily with traits that facilitate predator avoidance. However, complexity and scale have precluded tests of this prediction in many groups, including fishes. Using a macroevolutionary approach, we test this prediction in butterflyfishes, an iconic group of coral reef inhabitants with diverse social behaviours, foraging strategies and antipredator adaptations. We find that several antipredator traits have evolved adaptively, dependent primarily on foraging strategy. We identify a previously unrecognised axis of diversity in butterflyfishes where species with robust morphological defences have riskier foraging strategies and lack sociality, while species with reduced morphological defences feed in familiar territories, have adaptations for quick escapes and benefit from the vigilance provided by sociality. Furthermore, we find evidence for the constrained evolution of fin spines among species that graze solely on corals, highlighting the importance of corals, as both prey and structural refuge, in shaping fish morphology.
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http://dx.doi.org/10.1111/ele.12969DOI Listing
July 2018

The role of peripheral endemism in species diversification: evidence from the coral reef fish genus Anampses (Family: Labridae).

Mol Phylogenet Evol 2012 Feb 23;62(2):653-63. Epub 2011 Nov 23.

School of Marine and Tropical Biology, James Cook University, Townsville, Qld 4811, Australia.

We examined how peripherally isolated endemic species may have contributed to the biodiversity of the Indo-Australian Archipelago biodiversity hotspot by reconstructing the evolutionary history of the wrasse genus Anampses. We identified three alternate models of diversification: the vicariance-based 'successive division' model, and the dispersal-based 'successive colonisation' and 'peripheral budding' models. The genus was well suited for this study given its relatively high proportion (42%) of endemic species, its reasonably low diversity (12 species), which permitted complete taxon sampling, and its widespread tropical Indo-Pacific distribution. Monophyly of the genus was strongly supported by three phylogenetic analyses: maximum parsimony, maximum likelihood, and Bayesian inference based on mitochondrial CO1 and 12S rRNA and nuclear S7 sequences. Estimates of species divergence times from fossil-calibrated Bayesian inference suggest that Anampses arose in the mid-Eocene and subsequently diversified throughout the Miocene. Evolutionary relationships within the genus, combined with limited spatial and temporal concordance among endemics, offer support for all three alternate models of diversification. Our findings emphasise the importance of peripherally isolated locations in creating and maintaining endemic species and their contribution to the biodiversity of the Indo-Australian Archipelago.
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http://dx.doi.org/10.1016/j.ympev.2011.11.007DOI Listing
February 2012