Table 1.
Lists and numbers of Species of the Subgenus Alpinobombus from previous taxonomic revisions.a
Fig 1.
Global Sampling of the Subgenus Alpinobombus.
Grey spots show sample sites for the 4345 specimens examined (Alpinobombus species are unknown from the tropics or from the southern hemisphere; collections listed in Table A in S1 File); black spots show the sites for the 173 samples with COI barcodes; and question marks show the sites for doubtful records (specimens supposedly from sites that combine low latitude with low elevation). Polar projection, North Pole (starred) at the centre of the map. Terrestrial national boundaries and the Arctic Circle are shown as narrow grey lines. Image created in ArcGIS using World_Shaded_Relief basemap which is Copyright 2014 ESRI.
Fig 2.
Recognising Species of the Subgenus Alpinobombus with GMYC.
The 173 sequences reduced to 46 unique COI-barcode haplotypes on a BEAST ultrametric gene tree (outgroups not shown). The single threshold (T = -0.0041) from the GMYC model is shown by the vertical grey bar and the intersecting lineages are interpreted as subtending nine prospective species (black spots show the coalescent node for each species). The tree is the Bayesian ultrametric maximum-clade-credibility tree from a sample of trees after 1% burn-in from 2 billion generations of the MCMC algorithm in BEAST. Values next to the nodes are Bayesian posterior probabilities showing branch support. Each haplotype is represented by one of the longest sample sequences, labelled with a species name, a code that consists of an identifier from the project database and (after the hyphen) from the BOLD database, followed by its geographic origin.
Fig 3.
Recognising Species of the Subgenus Alpinobombus with Bayesian GMYC.
The 173 sequences reduced to 46 unique COI-barcode haplotypes on one BEAST ultrametric gene tree (outgroups not shown). The posterior probability distribution (right, colour scale far right) is plotted against a sample tree from BEAST (left) to provide a ‘heat’ map of the probabilities that haplotypes are conspecific by bGMYC. Black spots show the coalescent node for each species from Fig 2.
Fig 4.
Recognising Species of the Subgenus Alpinobombus with Bayesian PTP.
The 46 unique COI-barcode haplotypes as in Fig 2 on a MrBayes metric gene tree with the Bayesian PTP solution with highest support, showing nine prospective species (black spots show the coalescent node for each species; outgroups not shown). The tree is the maximum-clade-credibility tree after 1% burn-in from 100 million generations of the MCMC algorithm in MrBayes. Values above the nodes are PTP Bayesian support values that all daughter haplotypes belong to a single species population; values below the nodes are Bayesian posterior probabilities showing branch support. Haplotype selection and labels as in Fig 2. The scale bar for branch lengths shows 0.02 substitutions per base position.
Fig 5.
Estimate of phylogeny for species of the subgenus Alpinobombus.
Estimated using a linked-tree BEAST analysis of COI-barcode and PEPCK exon and intron sequences for each species. Values below the nodes are Bayesian posterior probabilities showing branch support. Numbers above the nodes show the estimated dates of divergence events in Ma (millions of years before the present) calibrated with a molecular estimate for the date of divergence between the subgenus Alpinobombus and the subgenus Bombus s. str. from Hines (2008) and grey bars show the 95% confidence limits on the estimated dates of divergence.
Table 2.
PEPCK polymorphisms.a
Fig 6.
Colour Patterns of the Subgenus Alpinobombus.
Simplified diagrams [26] representing the principal variation in colour patterns of the hair on the female dorsum coded as two two-state characters: UP, unbanded pale tail; BP, banded pale tail; BD, banded dark tail; with hair colours: yellow, yellow or yellow-brown hair; orange, orange-red or white hair; dark grey, black hair. Only female patterns are shown because females make up the majority of samples for social bumblebees, although male patterns are similar. Photos show: (left) B. alpinus and (right) B. hyperboreus. Photos by (left) A. Staverløkk and (right) G. Holmström.
Fig 7.
Distribution of Colour Patterns of the Subgenus Alpinobombus.
Pie diagrams (UP/BP/BD) show relative frequencies of colour patterns (black, UP; white, BP; grey, BD) from a sample of 1646 colour-coded specimens with coordinates by regions (clockwise from the top): Greenland (n = 27), Canada and Alaska (n = 257), southern Rockies (n = 25), Russia excluding Murmansk Province (Kola Peninsula) (n = 654), Altai and Sayan (n = 6), Scandinavia and Murmansk (n = 643), and Alps (n = 34). Spot diagrams show the occurrence of each colour pattern: grey circles show all sites represented in the sample, while black spots show those sites in which each colour pattern is recorded: unbanded pale tail (UP n = 329); yellow-banded pale tail (BP n = 1029); yellow-banded dark tail (BD n = 288). Map projection and other symbols as for Fig 1. Image created in ArcGIS using World_Shaded_Relief basemap which is Copyright 2014 Esri.
Table 3.
Principal Colour Patterns for each Species of the Subgenus Alpinobombus.a
Fig 8.
Evolution of Colour Patterns of the Subgenus Alpinobombus.
Reconstruction of ancestral states by parsimony in Mesquite for two colour-pattern characters each with two states (Fig 6) among species based on the estimate of phylogeny in Fig 5, several of which are polymorphic and show both states for both characters. Above: banding colour pattern, with yellow spots showing yellow-banded (B) populations, black spots showing unbanded (U) populations, mixed yellow/black spots showing polymorphic populations, mixed yellow/grey spots showing uncertain polymorphic/monomorphic populations (*for B. alpinus, males from the Alps often have a yellow-banded pattern although this is rare among females). Below: tail colour pattern, with orange spots showing populations with pale (P: orange or white) hair on the tail, black spots showing populations with dark (D: black) hair on the tail, mixed orange/black spots showing polymorphic populations.
Fig 9.
Disagreement among Groups of the Subgenus Alpinobombus Based on Three Character Sets.
Above, set diagrams for the different but nested groups within Alpinobombus based on exoskeletal morphology (in grey) and based on genes (in black). Below, set diagrams for the different and mostly overlapping groups based on the colour patterns of the hair of the dorsum (in grey) and based on genes (in black). Areas of intersection of sets occupied by bumblebee samples are shown in grey. Abbreviations for colour patterns: BP, yellow-banded pale-tailed; UP, unbanded pale-tailed; and BD, yellow-banded dark-tailed.