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Morphometric and Osteological Methods in Ichthyology Brian Sidlauskas National Evolutionary Synthesis Center Durham, NC

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Presentation on theme: "Morphometric and Osteological Methods in Ichthyology Brian Sidlauskas National Evolutionary Synthesis Center Durham, NC"— Presentation transcript:

1 Morphometric and Osteological Methods in Ichthyology Brian Sidlauskas National Evolutionary Synthesis Center Durham, NC

2 Three main types of morphological study Study of discrete character variation among species –Phylogenetics –Species delimitation Quantification of shape and size variation –Species delimitation –Age and growth studies Studies of character evolution –Phylogenetic comparative methods

3 Systematics of Anostomidae (Characiformes) Laemolyta taeniata Sidlauskas and Vari 2008, Zoological Journal of the Linnean Society Phylogeny Reconstruction

4 Anostomidae & Chilodontidae (~140 spp.) High Morphological Diversity Image credits: B. Chernoff, T. Clark, J. Gery, M. Sabaj, B. Sidlauskas

5 Rhytiodus argenteofuscus Schizodon fasciatus Anatomical differences reveal evolutionary patterns Leporinus cf. ecuadorensis Fifth upper pharyngeal tooth plate

6 Leporinus mormyrops Leporinus fasciatus Illustrations by Tamara Clark

7 123 morphological characters variable among ingroup or informative as to anostomid monophyly informative as to anostomid monophyly Additional 35 informative among outgroups informative among outgroups 29 multistate, all unordered strict consensus of 1312 trees CI = RI = From Sidlauskas and Vari, 2008 Parsimony

8 Leporellus most basal Leporinus paraphyletic ( and difficult to resolve with morphology) Hypomasticus (in Leporinus) monophyletic Abramites within Leporinus Rhytiodus with Schizodon Laemolyta monophyletic and sister to Anostominae sensu Winterbottom (1980) Anostominae very strongly supported Monophyly of Pseudanos uncertain Anostomus paraphyletic New genus Petulanos Parsimony

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10 Consensus Phylogeny from Supermatrix Analysis Synthesis of 463 morphological characters from 14 studies 171 Species Analyzed using Parsimony Ratchet via PaupRat (Sikes and Lewis, 2001) and PRAP (Müller 2004) CURIMATOIDEA ANOSTOMOIDEA From Sidlauskas, in press, Evolution

11 Species Discovery and Delineation From Sidlauskas et al. 2005, Copeia A B

12 Schizodon isognathus Schizodon knerii Schizodon scotorhabdotus new species From Sidlauskas et al. Copeia 2007

13 Leporinus sp. nov. 1? (Brazil, Southern Amazon tributaries) Leporinus sp. Nov. 2? (Suriname) Leporinus cylindriformis, holotype (Brazil, Main Amazon channel)

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15 ALLOMETRY

16 Traditional Linear Morphometrics Geometric Morphometrics Traditional and Geometric Techniques Often Yield Complementary Answers

17 PCA for comparing individuals and testing group membership CVA for recognizing difference between known groups From Sidlauskas, Vari and Mol, in prep

18 Highland fishes measurably more streamlined than lowland fishes Highland fishes measurably more streamlined than lowland fishes Differing allometric trajectories Differing allometric trajectories Consistent with induction by growth in fast water Consistent with induction by growth in fast water Sidlauskas, Chernoff and Machado-Allison 2006, Ichthyological Research

19 21 skull landmarks 21 skull landmarks 171 species, ca specimens 171 species, ca specimens Analyzed with geometric morphometrics Analyzed with geometric morphometrics Curimatidae Curimatella alburna Measuring Morphological MorphologicalDiversity From Sidlauskas, 2007, Evolution

20 Phylomorphospaces Relative Warp Analysis of skull shapes yields positions of species in morphospace Phylogeny links species Squared-change parsimony or likelihood infers position of internal nodes and morphometric distances (Euclidean) between them. Species sorted into diet classes based on literature accounts (Herbivore, Invertivore, Detritivore, etc.) and color coded Reconstruction of diet at internal nodes Relative Warp 1 Relative Warp 2 Sidlauskas, in press, Evolution

21 Sidlauskas in press, Evolution Plotting phylogenies into a morphospace

22 ECOPHYLOMORPHOSPACE

23 Significance Testing via Simulation Simulate morphological evolution –Many possible phylogenies –constant tempo and mode (e.g. single rate Brownian motion) Reconstruct distribution of possible phylomorphospaces Determine how often one generates two clades that differ as greatly as the observed If A/C observed > A/C simulated 95% of the time, then reject the null hypothesis of equal tempo or mode Otherwise, real world consistent with two random outcomes of the same process Unequal tempo?: P from 0.29 to 0.65 Unequal modes?: P from 0.01 to 0.05


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