Abstract

ALARCON-DURAN, Iván et al. Morphological diversity in 6 populations of the Silverside Chirostoma humboldtianum. Rev. Mex. Biodiv. [online]. 2017, vol.88, n.1, pp.207-214. ISSN 2007-8706.  https://doi.org/10.1016/j.rmb.2017.01.018.

Populations of Chirostoma humboldtianum inhabit lentic environments along the Lerma-Santiago River basin, from the State of Mexico to Nayarit. The objective of the present study was to describe and analyze with geometric morphometric, the shape of 6 geographically isolated populations of this species (n = 147). The shape showed significant differences (p < .001) among the studied populations; the body height and proximity or separation of dorsal fins are the most important variables in this differentiation. Likewise, it was observed that populations from San Pedro Lagunillas and Tepuxtepec were the most divergent, while those from Tiacaque and Zacapu were the most similar. In addition, the existence of an east-west gradient in centroid size is observed. Morphological differences and the size of the centroid of the organisms are related to the altitude of each site. Thus, morphological variations of the populations of C. humboldtianum suggest the presence of at least 5 morphotypes or phenotypes derived from geographic isolation from its diversification at least 0.52 million of years ago. This work provides new information on the intra-population morphological variation of C. humboldtianum, which may explain in part the diversification of this genus in Mexico.

Keywords : Morphotypes; Temperature; Shape; East-West dispersion; Xochimilco’s Silverside; Chirostoma.

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