Volume 24, Issue 73, January - June, 2023

Geometric morphometric shape and size analysis of endemic black Clam, Villorita cyprinoides (Gray, 1825) (Mollusca: Bivalvia: Cyrenidae) from Koottayi estuary, Kerala, South India

Jijina K, Anand PP, Neethu CB, Shibu Vardhanan Y^♦

Biochemistry and Toxicology Division, Department of Zoology, University of Calicut, Kerala, India

^♦Corresponding author
Shibu Vardhanan Y, Biochemistry and Toxicology Division, Department of Zoology, University of Calicut, Kerala, India

ABSTRACT

Geometric morphometric allowed us to study the shape, size and asymmetry of the right and left shells of the highly economically important endemic black clam Villorita cyprinoides (Gray, 1825) local population representing the Koottayi estuary, Tirur-Ponnani River, Kerala, South India. As far as we know, nobody has studied the population structure of black clams from southern India and this is the first geometric morphometric analysis of endemic black clam, which provided preliminary information on the population structure of black clam from the Koottayi estuary. Our study area faces a high level of pollution and anthropogenic intervention; apart from that, opens near the Arabian Sea’s Barmouth. Using various multivariate statistical methods, we concluded that right and left shell halves are not of the same size and shape; and asymmetry exists. The high level of pollution and anthropogenic effect may be the reason for the existence of fluctuation asymmetry. Our research will serve as baseline information to evaluate the effects of pollution or environmental stress and human interference on endemic species. Evaluation of morphological variations works as a critical tool for future studies such as developmental instability, natural selection, phenotypic adaptation and evolution.

Keywords: Black clam, endemic species, estuary, geometric morphometrics, phenotypic plasticity, shell shape and size

Species, 2023, 24(73), e33s1521

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DOI: https://doi.org/10.54905/disssi/v24i73/e33s1521

Published: 14 April 2023