Phenotype-environment associations in common carp, Cyprinus carpio Linnaeus 1758, in the southern coast of the Caspian Sea

The present study was done to investigate the phenotype-environment associations of common carp in the southern coast of the Caspian Sea (Gomishan, Miankaleh, Rezvanshahr, and Anzali Wetland) during winter 2016. The morphometric data of the specimens were procured from their left sides using the Image J and TpsDig2. Both geometric and morphometric methods were applied. The two-block partial least squares was used to examine the relationship between morphological and environmental characteristics. Significant positive correlation (p<0.05) was found between two data sets of morphology and environment, indicating a high level of adaptation for C. carpio in the southern basin of the Caspian Sea. The observed correlation between geometric and environmental data (0.74) was higher than the traditional morphometric-environment correlation (0.50). To the best of our knowledge, this is the first study trying to make a comparison between two methods of morphometric studies in relation to environment, by doing an evenness function on the raw data. The higher level of correlation obtained by geometric data with environmental parameters may imply its advantage in future morph-environment association studies. The obtained results in the present study also can provide basic required information for the wild population conservation strategies in common carp in the southern basin of the Caspian Sea.