A new morph of Telmatochromis temporalis (Cichlidae; Cichliformes) from Lake Tanganyika
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ADVANCES IN CICHLID RESEARCH IV
A new morph of Telmatochromis temporalis (Cichlidae; Cichliformes) from Lake Tanganyika Tetsumi Takahashi
Received: 28 July 2020 / Revised: 28 September 2020 / Accepted: 7 October 2020 Ó Springer Nature Switzerland AG 2020
Abstract Telmatochromis temporalis is a cichlid fish endemic to Lake Tanganyika. Two morphs of this species, normal and dwarf, form a good model for the study of ecological speciation through divergent natural selection on body size. This study reports a third morph of this species, slender morph, which was collected from deep waters off Kasenga, Zambia, whereas the normal morph inhabits shallow waters of the same locality. This study examined morphological characters and mitochondrial DNA sequences in 18 populations of the three T. temporalis morphs and two closely related species. The slender morph was
morphologically similar to the normal and dwarf morphs of the same species, but clearly differed from closely related species. Genetic analyses showed that the slender morph was closest to but significantly different from the parapatric normal morph, suggesting reproductive isolation between them. Due to the lack of colour differences between morphs and of obvious geographical barriers between habitats, reproductive isolation between these morphs may be attributed to ecological factors, rather than sexual or geographical segregation. Further studies examining the evolution of the slender morph may deepen our knowledge of initial stages of speciation, like in the dwarf morph.
Handling editor: Sidinei Magela Thomaz Guest editors: S. Koblmu¨ller, R. C. Albertson, M. J. Genner, K. M. Sefc & T. Takahashi / Advances in Cichlid Research IV: Behavior, Ecology and Evolutionary Biology
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10750-020-04433-5) contains supplementary material, which is available to authorised users. T. Takahashi (&) Institute of Natural and Environmental Sciences, University of Hyogo, Yayoigaoka 6, Sanda, Hyogo 669-1546, Japan e-mail: [email protected] T. Takahashi Division of Nature and Environmental Management, Museum of Nature and Human Activities, Yayoigaoka 6, Sanda, Hyogo 669-1546, Japan
Keywords Mitochondrial DNA Morphology Normal morph Parapatric distribution Slender morph
Introduction Lake Tanganyika is the oldest of the lakes in the East African Rift System, and has existed in various forms for 9–20 million years (Tiercelin & Mondeguer, 1991; Cohen et al., 1993). This lake harbours about 250 cichlid fish species, most of which are endemic to the lake and morphologically, ecologically, and genetically diverse (e.g. Takahashi & Koblmu¨ller, 2011; Ronco et al., 2019). Molecular phylogenetic studies have suggested that these endemic cichlids were
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