Functional Diversification within a Predatory Species Flock

Abstract

Ecological speciation is well-known from adaptive radiations in cichlid fishes inhabiting lentic ecosystems throughout the African rift valley and Central America. Here, we investigate the ecological and morphological diversification of a recently discovered lotic predatory Neotropical cichlid species flock in subtropical South America. We document morphological and functional diversification using geometric morphometrics, stable C and N isotopes, stomach contents and character evolution. This species flock displays species-specific diets and skull and pharyngeal jaw morphology. Moreover, this lineage appears to have independently evolved away from piscivory multiple times and derived forms are highly specialized morphologically and functionally relative to ancestral states. Ecological speciation played a fundamental role in this radiation and our data reveal novel conditions of ecological speciation including a species flock that evolved: 1) in a piscivorous lineage, 2) under lotic conditions and 3) with pronounced morphological novelties, including hypertrophied lips that appear to have evolved rapidly.

Morphometric variation of the Herichthys bartoni (Bean, 1892) species group (Teleostei: Cichlidae): How many species comprise H. labridens (Pellegrin, 1903)?

“…Similar results were found by Genner et al (2007), who used geometric morphometrics of 25 landmarks from the body coupled with molecular markers and were able to discriminate between four putative sympatric species of the genus Diplotaxodon, which had previously been identified only by their nuptial coloration. However, geometric morphometrics could also have restrictions; for example, in a recent study of a flock species of the genus Crenicichla from Uruguay, Burress et al (2013) failed to find significant differences among shapes from the 25 landmarks of the body evaluated, although they found significant differences in the geometric morphometrics of the lower pharyngeal plate. In conclusion, the results of this study regarding geometric morphometrics allow support for the recent proposal of De la Maza-Benignos & Lozano-Vilano (2013) that H. labridens s.l.…”

Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

“…Lip hypertrophy is often associated with grazing rocky surfaces and with incipient species in lentic cichlids (Elmer et al, 2010;Burress et al, 2013). Whereas lip hypertrophy is common in lentic cichlids (Elmer et al, 2010), it is known in just a few lotic species, e.g., Gymnogeophagus labiatus, G. pseudolabiatus, and Crenicichla tendybaguassu.…”

Diet and ecomorphological relationships of four cichlid species from the Cuiabá River basin

“…In addition, Chaetobranchopsis australis and Crenichla vittata showed more-divergent diets, consuming zooplankton and fish, respectively. Chaetobranchopsis australis, is already known to be zooplantivorous (Winemiller et al, 1995;Mérona & Rankin de Mérona, 2004), while C. vittata and other species of the same genus are known to be piscivorous (Burress et al, 2013a(Burress et al, , 2013b(Burress et al, , 2015. Among Crenicichla species (adult individuals), the piscivory degree varies between primary piscivorous (eat only fishes) and secundary piscivorous (eat macroinvertebrates and fishes) (Burress et al, 2013a(Burress et al, , 2013b(Burress et al, , 2015.…”

“…The studied species are the Chaetobranchini Chaetobranchopsis australis Eigenmann & Ward, 1907, the Cichlasomatini Cichlasoma dimerus (Heckel, 1840 and the two Geophagini, Crenicichla vittata Heckel, 1840 and Satanoperca pappaterra (Heckel, 1840). Some studies about ecomorphology and/or diet of these species have been performed in other regions (Winemiler et al, 1995;Mérona & Rankin-de Mérona, 2004;Burress et al, 2013a). However, studies showing the relationship between the food size and the morphology of the gill rakers are poorly evaluated among cichlids.…”