Two colors, one species: The case of Melissodes nigroaenea (Apidae: Eucerini), an important pollinator of cotton fields in Brazil

Authors: GRANDO, C - State University Of Campinas; AMON, N - State University Of Campinas; Clough, Steven; GUO, N - State University Of Campinas; WEI, W - University Of Illinois; AZEVEDO, P - University Of Illinois; LOPEZ-URIBE, M - University Of Illinois; ZUCCHI, M - University Of California

Submitted to: Sociobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2018
Publication Date: 10/11/2018
Citation: Grando, C., Amon, N.D., Clough, S.J., Guo, N., Wei, W., Azevedo, P., Lopez-Uribe, M.M., Zucchi, M.I. 2018. Two colors, one species: The case of Melissodes nigroaenea (Apidae: Eucerini), an important pollinator of cotton fields in Brazil. Sociobiology. 64:645-653. https://doi.org/10.13102/sociobiology.v65i4.3464.
DOI: https://doi.org/10.13102/sociobiology.v65i4.3464

Interpretive Summary: Accurate taxonomic determination is a critical step for studies which seek to evaluate community biodiversity. Even though morphological characters are most widely used for species identification, taxonomic classification can be subjected to bias by differences in the person giving the description. For example, differentiation of subtle color differences can be subjective to variable descriptive notes depending on the person making the observation. Therefore, a more scientific approach to taxonomy is the use of DNA sequence analysis, and the association of DNA differences to phenotype. Here, we utilized a DNA approach to examine the phenomenon of color variation in an economically important bee species for pollination in Brazil. Using a DNA barcoding approach, our results indicated that the molecular data do not support the separation of individuals with yellow or black coloration into different species. Both characters should be noted as polymorphic for this species of bee. Our findings describe an important phenotypic variation of an agriculturally important and abundant native pollinator and the study will facilitate the identification of this species in future studies. The publication of this work will encourage other researchers to further investigate whether color is a reliable character for taxonomic delimitation in their groups of interest.

Technical Abstract: Accurate taxonomic delimitation in ecological research is absolutely critical as studies that seek to evaluate levels of biodiversity and qualify human effects on the environment are rapidly undertaken. Coloration is a widely used morphological character for species identification through dichotomous keys. However, taxonomic identification based upon coloration is often unreliable because this character can exhibit high degree of intraspecific variation. In this study, we use a DNA barcoding approach to investigate the interpretation of two color morphs (yellow and dark) in the eucerine bee Melissodes nigroaenea. Our hypothesis is that if significant genetic divergence exists between each morphotype of M. nigroaenea, coloration reflects two distinct evolutionary lineages within this species, which may require taxonomic revision. Our alternative hypothesis is that, if genetic divergence is low between each morphotype of M. nigroaenea, we can attribute this variation to color polymorphism. Our Bayesian phylogenetic reconstruction revealed that both yellow and black individuals clustered together in a highly supported phylogenetic group. Additionally, pairwise genetic distances between M. nigroaenea color morphotypes were lower than 3%. These results indicate that both mesosome color morphs correspond to intraspecific variability within the same evolutionary unit. Together, our results indicate that mesosome coloration is not a reliable character for taxonomic differentiation of these Melissodes species, and that the incorporation of DNA barcoding approaches to taxonomic classification can help resolve some of the problems that originate while relying on purely morphological taxonomy.