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Yang W, Cui J, Chen Y, Wang C, Yin Y, Zhang W, Liu S, Sun C, Li H, Duan Y, Song F, Cai W, Hines HM, Tian L. Genetic Modification of a Hox Locus Drives Mimetic Color Pattern Variation in a Highly Polymorphic Bumble Bee. Mol Biol Evol 2023; 40:msad261. [PMID: 38039153 PMCID: PMC10724181 DOI: 10.1093/molbev/msad261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/11/2023] [Accepted: 11/27/2023] [Indexed: 12/03/2023] Open
Abstract
Müllerian mimicry provides natural replicates ideal for exploring mechanisms underlying adaptive phenotypic divergence and convergence, yet the genetic mechanisms underlying mimetic variation remain largely unknown. The current study investigates the genetic basis of mimetic color pattern variation in a highly polymorphic bumble bee, Bombus breviceps (Hymenoptera, Apidae). In South Asia, this species and multiple comimetic species converge onto local Müllerian mimicry patterns by shifting the abdominal setal color from orange to black. Genetic crossing between the orange and black phenotypes suggested the color dimorphism being controlled by a single Mendelian locus, with the orange allele being dominant over black. Genome-wide association suggests that a locus at the intergenic region between 2 abdominal fate-determining Hox genes, abd-A and Abd-B, is associated with the color change. This locus is therefore in the same intergenic region but not the same exact locus as found to drive red black midabdominal variation in a distantly related bumble bee species, Bombus melanopygus. Gene expression analysis and RNA interferences suggest that differential expression of an intergenic long noncoding RNA between abd-A and Abd-B at the onset setal color differentiation may drive the orange black color variation by causing a homeotic shift late in development. Analysis of this same color locus in comimetic species reveals no sequence association with the same color shift, suggesting that mimetic convergence is achieved through distinct genetic routes. Our study establishes Hox regions as genomic hotspots for color pattern evolution in bumble bees and demonstrates how pleiotropic developmental loci can drive adaptive radiations in nature.
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Affiliation(s)
- Wanhu Yang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Jixiang Cui
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Yuxin Chen
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Chao Wang
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Yuanzhi Yin
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Wei Zhang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China
| | - Shanlin Liu
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Cheng Sun
- College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hu Li
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Yuange Duan
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Fan Song
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Wanzhi Cai
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
| | - Heather M Hines
- Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Li Tian
- Department of Entomology and MOA Key Lab of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing 100193, China
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Hines HM, Kilpatrick SK, Mikó I, Snellings D, López-Uribe MM, Tian L. The diversity, evolution, and development of setal morphologies in bumble bees (Hymenoptera: Apidae: Bombus spp.). PeerJ 2022; 10:e14555. [PMID: 36573237 PMCID: PMC9789693 DOI: 10.7717/peerj.14555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/21/2022] [Indexed: 12/24/2022] Open
Abstract
Bumble bees are characterized by their thick setal pile that imparts aposematic color patterns often used for species-level identification. Like all bees, the single-celled setae of bumble bees are branched, an innovation thought important for pollen collection. To date no studies have quantified the types of setal morphologies and their distribution on these bees, information that can facilitate understanding of their adaptive ecological function. This study defines several major setal morphotypes in the common eastern bumble bee Bombus impatiens Cresson, revealing these setal types differ by location across the body. The positions of these types of setae are similar across individuals, castes, and sexes within species. We analyzed the distribution of the two most common setal types (plumose and spinulate) across the body dorsum of half of the described bumble bee species. This revealed consistently high density of plumose (long-branched) setae across bumble bees on the head and mesosoma, but considerable variation in the amount of metasomal plumosity. Variation on the metasoma shows strong phylogenetic signal at subgeneric and smaller group levels, making it a useful trait for species delimitation research, and plumosity has increased from early Bombus ancestors. The distribution of these setal types suggests these setae may serve several functions, including pollen-collecting and thermoregulatory roles, and probable mechanosensory functions. This study further examines how and when setae of the pile develop, evidence for mechanosensory function, and the timing of pigmentation as a foundation for future genetic and developmental research in these bees.
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Affiliation(s)
- Heather M. Hines
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States,Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States
| | - Shelby Kerrin Kilpatrick
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States,Department of Entomology, Texas A & M University, College Station, Texas, United States
| | - István Mikó
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States,Department of Biological Sciences, University of New Hampshire, Durham, New Hampshire, United States
| | - Daniel Snellings
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States,Division of Genetics & Genomics, Boston Children’s Hospital, Boston, Massachusetts, United States
| | - Margarita M. López-Uribe
- Department of Entomology, Pennsylvania State University, University Park, Pennsylvania, United States
| | - Li Tian
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States,Department of Entomology, China Agricultural University, Beijing, China
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Wham BE, Rahman SR, Martinez‐Correa M, Hines HM. Mito-nuclear discordance at a mimicry color transition zone in bumble bee Bombus melanopygus. Ecol Evol 2021; 11:18151-18168. [PMID: 35003664 PMCID: PMC8717287 DOI: 10.1002/ece3.8412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 10/24/2021] [Accepted: 10/29/2021] [Indexed: 11/16/2022] Open
Abstract
As hybrid zones exhibit selective patterns of gene flow between otherwise distinct lineages, they can be especially valuable for informing processes of microevolution and speciation. The bumble bee, Bombus melanopygus, displays two distinct color forms generated by Müllerian mimicry: a northern "Rocky Mountain'' color form with ferruginous mid-abdominal segments (B. m. melanopygus) and a southern "Pacific'' form with black mid-abdominal segments (B. m. edwardsii). These morphs meet in a mimetic transition zone in northern California and southern Oregon that is more narrow and transitions further west than comimetic bumble bee species. To understand the historical formation of this mimicry zone, we assessed color distribution data for B. melanopygus from the last 100 years. We then examined gene flow among the color forms in the transition zone by comparing sequences from mitochondrial COI barcode sequences, color-controlling loci, and the rest of the nuclear genome. These data support two geographically distinct mitochondrial haplogroups aligned to the ancestrally ferruginous and black forms that meet within the color transition zone. This clustering is also supported by the nuclear genome, which, while showing strong admixture across individuals, distinguishes individuals most by their mitochondrial haplotype, followed by geography. These data suggest the two lineages most likely were historically isolated, acquired fixed color differences, and then came into secondary contact with ongoing gene flow. The transition zone, however, exhibits asymmetries: mitochondrial haplotypes transition further south than color pattern, and both transition over shorter distances in the south. This system thus demonstrates alternative patterns of gene flow that occur in contact zones, presenting another example of mito-nuclear discordance. Discordant gene flow is inferred to most likely be driven by a combination of mimetic selection, dominance effects, and assortative mating.
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Affiliation(s)
- Briana E. Wham
- Department of EntomologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- The Pennsylvania State University LibrariesUniversity ParkPennsylvaniaUSA
| | - Sarthok Rasique Rahman
- Department of BiologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- Department of Biological SciencesThe University of AlabamaTuscaloosaAlabamaUSA
| | | | - Heather M. Hines
- Department of EntomologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
- Department of BiologyThe Pennsylvania State UniversityUniversity ParkPennsylvaniaUSA
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