Zoometric characterization of native “Copetonas” hens in indigenous communities

Resumen

Objective. To zoometrically characterize a population of “Copetona” native hens to assess their degree of racial uniformity and detect possible evidence of crossbreeding with commercial breeds in the municipality of San Andrés Larráinzar, Chiapas.

Design/Methodology/Approach: Twenty-three zoometric traits were measured in 50 adult hens from 16 production units across three communities. The coefficient of variation (CV) was calculated for each variable, and principal component analysis (PCA) and hierarchical cluster analysis (Ward’s method) were performed to identify morphological groupings. Five zoometric indices were computed and compared among groups using ANOVA followed by Tukey’s test.

Results. The population exhibited high phenotypic heterogeneity. Seven traits showed low variability (CV < 10%), nine displayed moderate variability (CV = 10–20%), and six showed high variability (CV > 20%), particularly those related to fleshy appendages (comb and wattles). Cluster analysis revealed three distinct morphological groups: small hens lacking native features (GCH), small hens retaining “Copetona” traits (GCC), and medium-sized hens showing signs of exotic introgression (GCM). The cranial index differed significantly (p ≤ 0.05) among groups, with the GCC group presenting the highest values.

Implications. The pronounced variability and the formation of distinct morphological groups indicate ongoing genetic erosion caused by introgression from commercial breeds. The absence of selection criteria and the introduction of exotic birds threaten the conservation of this local genetic resource.

Conclusions. The studied “Copetona” hen population shows a marked loss of breed uniformity, supporting the hypothesis of genetic dilution due to crossbreeding with commercial lines. Immediate conservation actions focusing on the selection of native phenotypes and the restriction of exotic genotypes are urgently needed.