title: Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees.
abstract: Our grasp of biodiversity is fine-tuned through the process of revisionary taxonomy. If species do exist in nature and can be discovered with available techniques, then we expect these revisions to converge on broadly shared interpretations of species. But for the primarily arctic bumblebees of the subgenus Alpinobombus of the genus Bombus, revisions by some of the most experienced specialists are unusual for bumblebees in that they have all reached different conclusions on the number of species present. Recent revisions based on skeletal morphology have concluded that there are from four to six species, while variation in colour pattern of the hair raised questions as to whether at least seven species might be present. Even more species are supported if we accept the recent move away from viewing species as morphotypes to viewing them instead as evolutionarily independent lineages (EILs) using data from genes. EILs are recognised here in practice from the gene coalescents that provide direct evidence for their evolutionary independence. We show from fitting both general mixed Yule/coalescent (GMYC) models and Poisson-tree-process (PTP) models to data for the mitochondrial COI gene that there is support for nine species in the subgenus Alpinobombus. Examination of the more slowly evolving nuclear PEPCK gene shows further support for a previously unrecognised taxon as a new species in northwestern North America. The three pairs of the most morphologically similar sister species are separated allopatrically and prevented from interbreeding by oceans. We also find that most of the species show multiple shared colour patterns, giving the appearance of mimicry among parts of the different species. However, reconstructing ancestral colour-pattern states shows that speciation is likely to have cut across widespread ancestral polymorphisms, without or largely without convergence. In the particular case of Alpinobombus, morphological, colour-pattern, and genetic groups show little agreement, which may help to explain the lack of agreement among previous taxonomic revisions.
authors.affiliation: Department of Life Sciences, The Natural History Museum, London, United Kingdom.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Williams
authors.affiliation: Department of General Biology and Ecology, Novosibirsk State University, Novosibirsk, Russia.
authors.forename: Alexandr M
authors.initials: AM
authors.lastname: Byvaltsev
authors.affiliation: Swedish Species Information Centre, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Cederberg
authors.affiliation: Entomological Department (Insectarium), The Moscow Zoo, Moscow, Russia.
authors.forename: Mikhail V
authors.initials: MV
authors.lastname: Berezin
authors.affiliation: Norwegian Institute for Nature Research, Trondheim, Norway.
authors.forename: Frode
authors.initials: F
authors.lastname: Ødegaard
authors.affiliation: Department of Bioscience, Aarhus University, Aarhus, Denmark.
authors.forename: Claus
authors.initials: C
authors.lastname: Rasmussen
authors.affiliation: Gund Institute for Ecological Economics, University of Vermont, Burlington, Vermont, United States of America.
authors.forename: Leif L
authors.initials: LL
authors.lastname: Richardson
authors.affiliation: Key Laboratory for Insect-Pollinator Biology of the Ministry of Agriculture, Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing, China.
authors.forename: Jiaxing
authors.initials: J
authors.lastname: Huang
authors.affiliation: Royal Saskatchewan Museum, Regina, Saskatchewan, Canada.
authors.forename: Cory S
authors.initials: CS
authors.lastname: Sheffield
authors.affiliation: Department of Life Sciences, The Natural History Museum, London, United Kingdom.
authors.forename: Suzanne T
authors.initials: ST
authors.lastname: Williams
mesh_terms: D000818:Animals; D001110:Arctic Regions; D001516:Bees / Q000033:anatomy & histology / Q000145:classification / Q000235:genetics*; D002467:Cell Nucleus / Q000201:enzymology / Q000235:genetics; D003116:Color; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics; D019143:Evolution, Molecular; D005260:Female; D017344:Genes, Insect / Q000235:genetics*; D005843:Geography; D019476:Insect Proteins / Q000235:genetics; D008297:Male; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics; D010802:Phylogeny; D011110:Polymorphism, Genetic; D011157:Population Dynamics; D012880:Skin Pigmentation / Q000235:genetics*; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial; D019476:Insect Proteins; D003576:Electron Transport Complex IV; D019764:Phosphoenolpyruvate Carboxykinase (ATP)