IS DNA BARCODE INTRASPECIFIC VARIATION ASSOCIATED TO SUBSPECIES DELIMITATION AND PHENOTYPIC VARIATION?

ANA S. BARREIRA; NATALIA C. GARCÍA; PABLO L. TUBARO

Guelph

Congreso; 6th International Barcode of Life Conference; 2015

University of Guelph

Background: DNA barcodes are a powerful tool to discover undetected genetic variation within species across large geographic areas. Subspecies are defined on the basis of phenotypic differentiation across the geographic distribution of the species. However, they are not necessarily related to the occurrence of deep genetic differentiation within species. Birds are an ideal model to assess the relationship between previously described phenotypic variation and neutral genetic markers, such as the mitochondrial COI gene, because of their very well developed taxonomy. We selected 17 pairs of subspecies of Neotropical passerines and took spectrophotometric measurements of plumage colouration, given its frequent use in subspecies delimitation. We used visual models to analyze colour measurements from an avian perspective and assess quantitatively the level of variation in plumage colour in relation to genetic differentiation between subspecies. Results: Plumage colour differentiation between subspecies was highly variable but not related to genetic variation. Some pairs of subspecies showed small levels of genetic differentiation but large levels of phenotypic variation and vice versa. In all cases, the levels of plumage colour variation between subspecies was larger than the colour differentiation threshold perceivable by birds. However, we found large levels of variation in this character within subspecies. Additionally, average genetic divergence in COI in 15 of the 17 pairs of subspecies was larger than the average intraspecific genetic distance found in Neotropical birds. Moreover, two of them had values that were even larger than the average genetic distance between sister species. Significance: Plumage colouration might be subject to selective pressures and therefore does not reflect the variation in neutral markers such as DNA barcodes. Although subspecies delimitations are not a direct measure of the genetic structure within species, they are a good indicator of large levels of diversification that need to be sampled in order for DNA barcodes to capture the entire species variation.