Functional modularity in lake-dwelling characin fishes of Mexico

Claudia Patricia Ornelas-García; Amando Bautista; Fabian Herder; Ignacio Doadrio

doi:10.7717/peerj.3851

Functional modularity in lake-dwelling characin fishes of Mexico

PeerJ. 2017 Sep 22:5:e3851. doi: 10.7717/peerj.3851. eCollection 2017.

Authors

Claudia Patricia Ornelas-García¹, Amando Bautista², Fabian Herder³, Ignacio Doadrio⁴

Affiliations

¹ Colección Nacional de Peces, Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico.
² Centro Tlaxcala de Biología de la Conducta, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico.
³ Sektion Ichthyologie, Zoologisches Forschungsmuseum Alexander Koenig, Bonn, Germany.
⁴ Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales, Madrid, Spain.

Abstract

Modular evolution promotes evolutionary change, allowing independent variation across morphological units. Recent studies have shown that under contrasting ecological pressures, patterns of modularity could be related to divergent evolution. The main goal of the present study was to evaluate the presence of modular evolution in two sister lacustrine species, Astyanax aeneus and A. caballeroi, which are differentiated by their trophic habits. Two different datasets were analyzed: (1) skull X-rays from 73 specimens (35 A. aeneus and 38 A. caballeroi) to characterize skull variation patterns, considering both species and sex effects. For this dataset, three different modularity hypotheses were tested, previously supported in other lacustrine divergent species; (2) a complete body shape dataset was also tested for four modularity hypotheses, which included a total of 196 individuals (110 Astyanax aeneus and 86 A. caballeroi). Skull shape showed significant differences among species and sex (P < 0.001), where Astyanax caballeroi species showed an upwardly projected mandible and larger preorbital region. For the skull dataset, the modularity hypothesis ranked first included three partitioning modules. While for the complete body dataset the best ranked hypothesis included two modules (head vs the rest of the body), being significant only for A. caballeroi.

Keywords: Astyanax; Functional morphology; Geometric morphometrics; Modularity; Trophic diversity.

Grants and funding

Claudia Patricia Ornelas-García was supported by CONACyT. This study received support from the project CGL2010-15231. The publication fee was funded by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). This study was also supported by the project CONACYT INFR-2016-01-269382. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.