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Kay T, Helleu Q, Keller L. Iterative evolution of supergene-based social polymorphism in ants. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210196. [PMID: 35694755 PMCID: PMC9189498 DOI: 10.1098/rstb.2021.0196] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 03/08/2022] [Indexed: 12/16/2022] Open
Abstract
Species commonly exhibit alternative morphs, with individual fate being determined during development by either genetic factors, environmental cues or a combination thereof. Ants offer an interesting case study because many species are polymorphic in their social structure. Some colonies contain one queen while others contain many queens. This variation in queen number is generally associated with a suite of phenotypic and life-history traits, including mode of colony founding, queen lifespan, queen-worker dimorphism and colony size. The basis of this social polymorphism has been studied in five ant lineages, and remarkably social morph seems to be determined by a supergene in all cases. These 'social supergenes' tend to be large, having formed through serial inversions, and to comprise hundreds of linked genes. They have persisted over long evolutionary timescales, in multiple lineages following speciation events, and have spread between closely related species via introgression. Their evolutionary dynamics are unusually complex, combining recessive lethality, spatially variable selection, selfish genetic elements and non-random mating. Here, we synthesize the five cases of supergene-based social polymorphism in ants, highlighting interesting commonalities, idiosyncrasies and implications for the evolution of polymorphisms in general. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Tomas Kay
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Quentin Helleu
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
| | - Laurent Keller
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
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Kjeldgaard MK, Eyer PA, McMichael CC, Bockoven AA, King JT, Hyodo A, Boutton TW, Vargo EL, Eubanks MD. Distinct colony boundaries and larval discrimination in polygyne red imported fire ants (Solenopsis invicta). Mol Ecol 2021; 31:1007-1020. [PMID: 34747530 DOI: 10.1111/mec.16264] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 10/28/2021] [Accepted: 11/02/2021] [Indexed: 11/30/2022]
Abstract
Evaluating the factors that promote invasive ant abundance is critical to assess their ecological impact and inform their management. Many invasive ant species show reduced nestmate recognition and an absence of boundaries between unrelated nests, which allow populations to achieve greater densities due to reduced intraspecific competition. We examined nestmate discrimination and colony boundaries in introduced populations of the red imported fire ant (Solenopsis invicta; hereafter, fire ant). Fire ants occur in two social forms: monogyne (colonies with a single egg-laying queen) and polygyne (colonies with multiple egg-laying queens). In contrast with monogyne nests, polygyne nests are thought to be interconnected due to the reduced antagonism between non-nestmate polygyne workers, perhaps because polygyne workers habituate the colony to an odour unique to Gp-9b -carrying adults. However, colony boundaries and nestmate discrimination are poorly documented, particularly for worker-brood interactions. To delimit boundaries between field colonies, we correlated the exchange of a 15 N-glycine tracer dissolved in a sucrose solution with social form. We also evaluated nestmate discrimination between polygyne workers and larvae in the laboratory. Counter to our expectations, polygyne colonies behaved identically to monogyne colonies, suggesting both social forms maintain strict colony boundaries. Polygyne workers also preferentially fed larval nestmates and may have selectively cannibalized non-nestmates. The levels of relatedness among workers in polygyne colonies was higher than those previously reported in North America (mean ± standard error: 0.269 ± 0.037). Our study highlights the importance of combining genetic analyses with direct quantification of resource exchange to better understand the factors influencing ant invasions.
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Affiliation(s)
| | - Pierre-André Eyer
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Collin C McMichael
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Alison A Bockoven
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Joanie T King
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Ayumi Hyodo
- Department of Ecology and Conservation Biology, Texas A&M University, College Station, Texas, USA
| | - Thomas W Boutton
- Department of Ecology and Conservation Biology, Texas A&M University, College Station, Texas, USA
| | - Edward L Vargo
- Department of Entomology, Texas A&M University, College Station, Texas, USA
| | - Micky D Eubanks
- Department of Entomology, Texas A&M University, College Station, Texas, USA
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Yang F, Shao R, Zhao J, Li L, Wang M, Zhou A. Cadmium exposure disrupts the olfactory sensitivity of fire ants to semiochemicals. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 287:117359. [PMID: 34020258 DOI: 10.1016/j.envpol.2021.117359] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/08/2021] [Accepted: 05/10/2021] [Indexed: 06/12/2023]
Abstract
Ants are eusocial insects and have evolved sensitive chemosensory systems for social communication. However, the effect of heavy metal contamination on the olfactory sensitivity of ants remains largely unknown. Here, we investigated the survival and olfactory response of Solenopsis invicta under cadmium (Cd) exposure. As a result, exposure to dietary Cd at different concentrations (100, 300 and 500 mg/L) caused higher Cd accumulation and lower survival of the ants compared with the control (0 mg/L). Cd exposure induced diverse expression patterns of odor binding protein genes (SiOBPs) in S. invicta antenna. Specifically, the expression of SiOBP4, SiOBP11, SiOBP12 and SiOBP16 was increased by 1.84-, 1.14-, 0.83- and 1.76-fold, respectively, at 300 mg/L Cd, while SiOBP7 and SiOBP9 were suppressed as Cd concentration increased. Electroantennography (EAG) and behavioral bioassays were performed to further evaluate the effect of Cd contamination on the olfactory sensitivity of S. invicta workers to 2, 4, 6-trimethylpyridine (TMP) and 2-ethyl-3,6(5)-dimethylpyrazine (EDP), the two frequent functional semiochemicals for S. invicta. The results showed that under no Cd exposure, S. invicta workers exhibited strong EAG response and apparent residing repellence to TMP and EDP, but Cd exposure suppressed EAG response and deprived the behavioral repellence to TMP and EDP of the workers, suggesting that Cd exposure decreases the olfactory sensitivity of S. invicta to these two functional semiochemicals. Further fluorescence competitive binding assay revealed that SiOBP7 had strong binding affinity to TMP and EDP, suggesting that the decrease in olfactory sensitivity may be attributed to the inhibitory effect of Cd exposure on SiOBP7. Overall, our results suggest that Cd exposure may not only directly decrease the survival of ants, but also affect their olfactory recognition.
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Affiliation(s)
- Fuxiang Yang
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Rui Shao
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jing Zhao
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lei Li
- Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, 571101, China
| | - Manqun Wang
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Aiming Zhou
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
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Murakami T, Paris C, Chirino M, Sasa C, Sakamoto H, Higashi S, Sato K. Unusual chromosome numbers and polyploidy in invasive fire ant populations. Genetica 2021; 149:203-215. [PMID: 34282482 DOI: 10.1007/s10709-021-00128-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 07/14/2021] [Indexed: 11/25/2022]
Abstract
Fire ants (Solenopsis invicta Buren in J Ga Entomol Soc 7:1-26, 1972), an invasive alien ant species, first spread from South America to the United States in the 1930s, the southern part of the United States by the end of the twentieth century, Oceania, Taiwan, and China in the twenty-first century, and finally to Japan and South Korea in 2017. As these ants have significant negative economic, human health, and environmental impacts, the purpose of this research was to accumulate cytogenetic information regarding fire ants and provide basic data for developing management strategies for their control. Fire ants were collected from invasive populations from Taiwan, Florida (USA), and Buenos Aires (Argentina), and a native population from Puerto Iguazu (Argentina), their point of origination, and analyzed with regard to chromosome number, morphology, and polyploidy, silver-stained nucleolar organizer regions (Ag-NORs), and 18S rDNA and telomere fluorescence in situ hybridization (FISH). The results showed that (1) fire ants from invaded populations differed in chromosome morphology compared to those from native populations; (2) the Florida and Taiwanese fire ant populations evinced greater variability in chromosome numbers and polyploidy variations; (3) the Taiwanese population exhibited significantly increased Ag-NOR signals in interphase cells, with signal number significantly positively correlating with distance from native populations; and (4) substantial diversity of signals was also apparent following 18S rDNA and telomere FISH analyses. Variation in these characteristics were hypothesized to be due to (1) the effect of hybridizations and interbreeding between closely related species or genetically distant populations, and (2) the potential effect of large amounts of insecticides sprayed for pest control.
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Affiliation(s)
- Takahiro Murakami
- Institution of Decision Science for a Sustainable Society, Kyushu University, Motooka 744, Fukuoka, 8190395, Japan.
| | | | | | - Chifune Sasa
- Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Hironori Sakamoto
- Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
- Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, Onogawa 16-2, Tsukuba, Ibaraki, 305-0053, Japan
| | - Seigo Higashi
- Environmental Earth Science, Hokkaido University, Sapporo, Hokkaido, Japan
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Wei Z, Ortiz-Urquiza A, Keyhani NO. Altered Expression of Chemosensory and Odorant Binding Proteins in Response to Fungal Infection in the Red Imported Fire Ant, Solenopsis invicta. Front Physiol 2021; 12:596571. [PMID: 33746766 PMCID: PMC7970113 DOI: 10.3389/fphys.2021.596571] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 02/08/2021] [Indexed: 01/21/2023] Open
Abstract
Social insects have evolved acute mechanisms for sensing and mitigating the spread of microbial pathogens within their communities that include complex behaviors such as grooming and sanitation. Chemical sensing involves detection and transport of olfactory and other chemicals that are mediated by at least two distinct classes of small molecular weight soluble proteins known as chemosensory- and odorant binding proteins (CSPs and OBPs, respectively) that exist as protein families in all insects. However, to date, a systematic examination of the expression of these genes involved in olfactory and other pathways to microbial infection has yet to be reported. The red imported fire ant, Solenopsis invicta, is one of the most successful invasive organisms on our planet. Here, we examined the temporal gene expression profiles of a suite of S. invicta CSPs (SiCSPs1-22) and OBPs (SiOBPs1-16) in response to infection by the broad host range fungal insect pathogen, Beauveria bassiana. Our data show that within 24 h post-infection, i.e., before the fungus has penetrated the host cuticle, the expression of SiCSPs and SiOBPs is altered (mainly increased compared to uninfected controls), followed by suppression of SiCSP and select SiOBP expression 48 h post-infection and mixed responses at 72 h post-infection. A smaller group of SiBOPs, however, appeared to respond to fungal infection, with expression of SiOBP15 consistently higher during fungal infection over the time course examined. These data indicate dynamic gene expression responses of CSPs and OBPs to fungal infection that provide clues to mechanisms that might mediate detection of microbial pathogens, triggering grooming, and nest sanitation.
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Affiliation(s)
- Zhang Wei
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering, Key Laboratory of Green Pesticide and Agricultural Bioengineering, Ministry of Education, Guizhou University, Guiyang, China.,Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, United States
| | - Almudena Ortiz-Urquiza
- Department of Biosciences, College of Science, Swansea University, Swansea, United Kingdom
| | - Nemat O Keyhani
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL, United States
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Cohen P, Privman E. The social supergene dates back to the speciation time of two Solenopsis fire ant species. Sci Rep 2020; 10:11538. [PMID: 32665692 PMCID: PMC7360596 DOI: 10.1038/s41598-020-67999-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 05/21/2020] [Indexed: 12/14/2022] Open
Abstract
Colony social organization of multiple Solenopsis fire ant species is determined by a supergene with two haplotypes SB and Sb, which are similar to X/Y sex chromosomes. The ancestral monogyne (single-queen) social form has been associated with homozygous SB/SB queens, while queens in colonies with the derived polygyne (multi-queen) social structure are heterozygous SB/Sb. By comparing 14 Solenopsis invicta genomes and the outgroup S. fugax, we dated the formation of the supergene to 1.1 (0.7-1.6) million years ago, much older than previous estimates, and close to the estimated time of speciation of the two socially polymorphic species S. invicta and S. richteri. We also used 12 S. invicta and S. richteri genomes to compare the evolutionary distances between these species and the distances between the social haplotypes, and found them to be similar. A phylogenetic analysis suggested that the monophyletic Sb clade is more closely related to S. richteri SB haplotypes than to S. invicta SB haplotypes. We conclude that the formation of the supergene occurred concomitantly with the process of speciation of the Solenopsis socially-polymorphic clade, and hypothesize that the Sb variant first arouse in one incipiently-speciating population and then introgressed into the other populations or species.
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Affiliation(s)
- Pnina Cohen
- Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Haifa, Israel
| | - Eyal Privman
- Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Haifa, Israel.
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Qiu HL, Qin CS, Fox EGP, Wang DS, He YR. Differential Behavioral Responses of Solenopsis invicta (Hymenoptera: Formicidae) Workers Toward Nestmate and Non-Nestmate Corpses. JOURNAL OF INSECT SCIENCE (ONLINE) 2020; 20:5877675. [PMID: 32725158 PMCID: PMC7387867 DOI: 10.1093/jisesa/ieaa069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Indexed: 06/11/2023]
Abstract
The removal of corpses (aka 'necrophoric behavior') is critical to sanitation in ant colonies. However, little is known about differences in the necrophoric responses of Solenopsis invicta workers towards corpses of nestmates and non-nestmates. We introduced corpses of S. invicta workers from either intracolony (i.e., nestmate) or intercolony (i.e., non-nestmate) origin at the entrance of artificial nests, and recorded workers' aggressive responses and necrophoric behaviors for analysis. Solenopsis invicta workers displayed distinct responses towards corpses of different origins. Specifically, resident workers were more likely to remove fresh non-nestmate corpses than nestmate corpses, but there was no difference regarding corpses that had been dead for 15 min or longer. Resident workers reacted more aggressively to, and removed more quickly, fresh non-nestmate corpses than corpses of their nestmates. On the other hand, there was no significant difference in the removal time between nestmate and non-nestmate corpses that had been dead for 15 min or longer. Resident workers always displayed stronger aggressiveness towards non-nestmate corpses than nestmate corpses, excepting to corpses that had been dead for 6 h, which elicited a response. No significant correlation between the removal times and aggressiveness levels were detected in any treatments. It remains to be tested whether this differential response is adaptive in how it influences colony fitness and competition.
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Affiliation(s)
- Hua-Long Qiu
- Guangdong Provincial Key Laboratory of Silviculture, Protection and Utilization/Guangdong Academy of Forestry, Guangzhou, Guangdong, China
| | - Chang-Sheng Qin
- Guangdong Provincial Key Laboratory of Silviculture, Protection and Utilization/Guangdong Academy of Forestry, Guangzhou, Guangdong, China
| | - Eduardo G P Fox
- Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - De-Sen Wang
- College of Agriculture, South China Agricultural University, Guangdong, Guangzhou, China
| | - Yu-Rong He
- College of Agriculture, South China Agricultural University, Guangdong, Guangzhou, China
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Dang V, Cohanim AB, Fontana S, Privman E, Wang J. Has gene expression neofunctionalization in the fire ant antennae contributed to queen discrimination behavior? Ecol Evol 2019; 9:12754-12766. [PMID: 31788211 PMCID: PMC6875580 DOI: 10.1002/ece3.5748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Revised: 09/18/2019] [Accepted: 09/23/2019] [Indexed: 12/12/2022] Open
Abstract
Queen discrimination behavior in the fire ant Solenopsis invicta maintains its two types of societies: colonies with one (monogyne) or many (polygyne) queens, yet the underlying genetic mechanism is poorly understood. This behavior is controlled by two supergene alleles, SB and Sb, with ~600 genes. Polygyne workers, having either the SB/SB or SB/Sb genotype, accept additional SB/Sb queens into their colonies but kill SB/SB queens. In contrast, monogyne workers, all SB/SB, reject all additional queens regardless of genotype. Because the SB and Sb alleles have suppressed recombination, determining which genes within the supergene mediate this differential worker behavior is difficult. We hypothesized that the alternate worker genotypes sense queens differently because of the evolution of differential expression of key genes in their main sensory organ, the antennae. To identify such genes, we sequenced RNA from four replicates of pooled antennae from three classes of workers: monogyne SB/SB, polygyne SB/SB, and polygyne SB/Sb. We identified 81 differentially expressed protein-coding genes with 13 encoding potential chemical metabolism or perception proteins. We focused on the two odorant perception genes: an odorant receptor SiOR463 and an odorant-binding protein SiOBP12. We found that SiOR463 has been lost in the Sb genome. In contrast, SiOBP12 has an Sb-specific duplication, SiOBP12b', which is expressed in the SB/Sb worker antennae, while both paralogs are expressed in the body. Comparisons with another fire ant species revealed that SiOBP12b' antennal expression is specific to S. invicta and suggests that queen discrimination may have evolved, in part, through expression neofunctionalization.
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Affiliation(s)
- Viet‐Dai Dang
- Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
- Biodiversity Taiwan International Graduate Program, Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
- Department of Life ScienceNational Taiwan Normal UniversityTaipeiTaiwan
- Department of ZoologySouthern Institute of EcologyVietnam Academy of Science and TechnologyHochiminhVietnam
| | - Amir B. Cohanim
- Department of Evolutionary and Environmental BiologyInstitute of EvolutionUniversity of HaifaHaifaIsrael
| | - Silvia Fontana
- Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
- Biodiversity Taiwan International Graduate Program, Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
- Department of Life ScienceNational Taiwan Normal UniversityTaipeiTaiwan
| | - Eyal Privman
- Department of Evolutionary and Environmental BiologyInstitute of EvolutionUniversity of HaifaHaifaIsrael
| | - John Wang
- Biodiversity Research CenterAcademia SinicaTaipeiTaiwan
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Ross KG, Shoemaker D. Unexpected patterns of segregation distortion at a selfish supergene in the fire ant Solenopsis invicta. BMC Genet 2018; 19:101. [PMID: 30404617 PMCID: PMC6223060 DOI: 10.1186/s12863-018-0685-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 10/12/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The Sb supergene in the fire ant Solenopsis invicta determines the form of colony social organization, with colonies whose inhabitants bear the element containing multiple reproductive queens and colonies lacking it containing only a single queen. Several features of this supergene - including suppressed recombination, presence of deleterious mutations, association with a large centromere, and "green-beard" behavior - suggest that it may be a selfish genetic element that engages in transmission ratio distortion (TRD), defined as significant departures in progeny allele frequencies from Mendelian inheritance ratios. We tested this possibility by surveying segregation ratios in embryo progenies of 101 queens of the "polygyne" social form (3512 embryos) using three supergene-linked markers and twelve markers outside the supergene. RESULTS Significant departures from Mendelian ratios were observed at the supergene loci in 3-5 times more progenies than expected in the absence of TRD and than found, on average, among non-supergene loci. Also, supergene loci displayed the greatest mean deviations from Mendelian ratios among all study loci, although these typically were modest. A surprising feature of the observed inter-progeny variation in TRD was that significant deviations involved not only excesses of supergene alleles but also similarly frequent excesses of the alternate alleles on the homologous chromosome. As expected given the common occurrence of such "drive reversal" in this system, alleles associated with the supergene gain no consistent transmission advantage over their alternate alleles at the population level. Finally, we observed low levels of recombination and incomplete gametic disequilibrium across the supergene, including between adjacent markers within a single inversion. CONCLUSIONS Our data confirm the prediction that the Sb supergene is a selfish genetic element capable of biasing its own transmission during reproduction, yet counterselection for suppressor loci evidently has produced an evolutionary stalemate in TRD between the variant homologous haplotypes on the "social chromosome". Evidence implicates prezygotic segregation distortion as responsible for the TRD we document, with "true" meiotic drive the most likely mechanism. Low levels of recombination and incomplete gametic disequilibrium across the supergene suggest that selection does not preserve a single uniform supergene haplotype responsible for inducing polygyny.
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Affiliation(s)
- Kenneth G. Ross
- Department of Entomology, University of Georgia, Athens, GA USA
| | - DeWayne Shoemaker
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN USA
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10
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Schradin C, Hayes LD, Pillay N, Bertelsmeier C. The evolution of intraspecific variation in social organization. Ethology 2018. [DOI: 10.1111/eth.12752] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Carsten Schradin
- Université de Strasbourg CNRS IPHC UMR 7178 Strasbourg France
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Witwatersrand South Africa
| | - Loren D. Hayes
- Department of Biology, Geology, and Environmental Sciences University of Tennessee at Chattanooga Chattanooga Tennessee
| | - Neville Pillay
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Witwatersrand South Africa
| | - Cleo Bertelsmeier
- Department of Ecology and Evolution University of Lausanne Lausanne Switzerland
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Pracana R, Levantis I, Martínez‐Ruiz C, Stolle E, Priyam A, Wurm Y. Fire ant social chromosomes: Differences in number, sequence and expression of odorant binding proteins. Evol Lett 2017; 1:199-210. [PMID: 30283649 PMCID: PMC6121795 DOI: 10.1002/evl3.22] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 07/17/2017] [Accepted: 07/27/2017] [Indexed: 12/14/2022] Open
Abstract
Variation in social behavior is common yet our knowledge of the mechanisms underpinning its evolution is limited. The fire ant Solenopsis invicta provides a textbook example of a Mendelian element controlling social organization: alternate alleles of a genetic element first identified as encoding an odorant binding protein (OBP) named Gp-9 determine whether a colony accepts one or multiple queens. The potential roles of such a protein in perceiving olfactory cues and evidence of positive selection on its amino acid sequence made it an appealing candidate gene. However, we recently showed that recombination is suppressed between Gp-9 and hundreds of other genes as part of a >19 Mb supergene-like region carried by a pair of social chromosomes. This finding raises the need to reassess the potential role of Gp-9. We identify 23 OBPs in the fire ant genome assembly, including nine located in the region of suppressed recombination with Gp-9. For six of these, the alleles carried by the two variants of the supergene-like region differ in protein-coding sequence and thus likely in function, with Gp-9 showing the strongest evidence of positive selection. We identify an additional OBP specific to the Sb variant of the region. Finally, we find that 14 OBPs are differentially expressed between single- and multiple-queen colonies. These results are consistent with multiple OBPs playing a role in determining social structure.
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Affiliation(s)
- Rodrigo Pracana
- School of Biological and Chemical SciencesQueen Mary University of LondonE1 4NSLondonUnited Kingdom
| | - Ilya Levantis
- School of Biological and Chemical SciencesQueen Mary University of LondonE1 4NSLondonUnited Kingdom
| | - Carlos Martínez‐Ruiz
- School of Biological and Chemical SciencesQueen Mary University of LondonE1 4NSLondonUnited Kingdom
| | - Eckart Stolle
- School of Biological and Chemical SciencesQueen Mary University of LondonE1 4NSLondonUnited Kingdom
| | - Anurag Priyam
- School of Biological and Chemical SciencesQueen Mary University of LondonE1 4NSLondonUnited Kingdom
| | - Yannick Wurm
- School of Biological and Chemical SciencesQueen Mary University of LondonE1 4NSLondonUnited Kingdom
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12
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Tissue, developmental, and caste-specific expression of odorant binding proteins in a eusocial insect, the red imported fire ant, Solenopsis invicta. Sci Rep 2016; 6:35452. [PMID: 27765943 PMCID: PMC5073229 DOI: 10.1038/srep35452] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/28/2016] [Indexed: 11/13/2022] Open
Abstract
Insects interact with the surrounding environment via chemoreception, and in social insects such as ants, chemoreception functions to mediate diverse behaviors including food acquisition, self/non-self recognition, and intraspecific communication. The invasive red imported fire ant, Solenopsis invicta, has spread worldwide, displaying a remarkable environmental adaptability. Odorant binding proteins (OBPs) are chemical compound carriers, involved in diverse physiological processes including odor detection and chemical transport. S. invicta contains a highly divergent 17-member OBP gene family, that includes an ant-specific expansion and the social organization implicated Gp-9 (OBP3) gene. A systematic gene expression analysis of the SiOBP repertoire was performed across social caste (workers, male and female alates), tissues (antennae, head, thorax, and abdomen), and developmental stages (egg, larvae, and pupae), revealing that although SiOBPs were expressed in the antennae, the major regions of expression were in the head and thorax across all castes, and the abdomen in male and female alates. SiOBPs were very highly expressed in female alates and at somewhat lower levels in male alates and workers. SiOBPs were differentially expressed, with unique signatures in various castes and tissues, suggesting functionality of SiOBPs beyond olfaction Expression patterns of SiOBP subgroups also showed relationships with their evolutionary relatedness.
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Trible W, Ross KG. Chemical communication of queen supergene status in an ant. J Evol Biol 2015; 29:502-13. [PMID: 26644320 DOI: 10.1111/jeb.12799] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 11/11/2015] [Accepted: 11/20/2015] [Indexed: 12/21/2022]
Abstract
Traits of interest to evolutionary biologists often have complex genetic architectures, the nature of which can confound traditional experimental study at single levels of analysis. In the fire ant Solenopsis invicta, the presence of a Mendelian 'supergene' is both necessary and sufficient to induce a shift in a fundamental property of social organization, from single-queen (monogyne) to multiple-queen (polygyne) colonies. This selfish genetic element, termed the Social b (Sb) supergene, contains > 600 genes that collectively promote its fitness by inducing the characteristic polygyne syndrome, in part by causing polygyne workers to accept only queens bearing the Sb element (a behaviour termed 'worker Sb discrimination'). Here, we employ a newly developed behavioural assay to reveal that polygyne workers, many of which bear the Sb element, employ chemical cues on the cuticle of queens to achieve worker Sb discrimination, but we found no evidence for such pheromonally mediated worker Sb discrimination in monogyne workers, which universally lack the Sb element. This polygyne worker Sb discrimination was then verified through a 'green beard' effect previously described in this system. We thus have demonstrated that the Sb element is required both for production of relevant chemical cues of queens and for expression of the behaviours of workers that collectively result in worker Sb discrimination. This information fills a critical gap in the map between genotype and complex phenotype in S. invicta by restricting the search for candidate genes and molecules involved in producing this complex social trait to factors associated with the Sb element itself.
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Affiliation(s)
- W Trible
- The Rockefeller University, New York, NY, USA
| | - K G Ross
- Department of Entomology, University of Georgia, Athens, GA, USA
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14
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Si-CSP9 regulates the integument and moulting process of larvae in the red imported fire ant, Solenopsis invicta. Sci Rep 2015; 5:9245. [PMID: 25784646 PMCID: PMC4363891 DOI: 10.1038/srep09245] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/25/2015] [Indexed: 01/18/2023] Open
Abstract
Chemosensory proteins (CSPs) have been predicted to be involved in development;
however, direct evidence for their involvement is lacking, and genetic basis is
largely unknown. To determine the function of the chemosensory protein 9
(Si-CSP9) gene in Solenopsis invicta, we used RNA interference to
silence Si-CSP9 in 3rd-instar larvae. The 3rd-instar larvae failed to shed
their cuticle after being fed Si-CSP9-directed siRNA, and expression
profiling of RNAi-treated and untreated control larvae showed that 375 genes were
differentially expressed. Pathway enrichment analysis revealed that 4 pathways
associated with larval development were significantly enriched. Blast analysis
revealed that one fatty acid amide hydrolase (FAAH) gene was up-regulated and
4 fatty acid synthase (FAT) genes and one protein kinase DC2 gene
(PKA) were down-regulated in the enriched pathways. Significantly higher
expression of these genes was found in 4th-instar larvae, and Pearson correlation
analysis of the expression patterns revealed significant relationships among
Si-CSP9, PKA, FAAH, and FAT1-4. Moreover, we confirmed that
expression levels of Si-CSP9, FAAH, and FAT1-4 were significantly
reduced and that the development of 3rd-instar larvae was halted with PKA
silencing. These results suggest that Si-CSP9 and PKA may be involved
in the network that contributes to development of 3rd-instar larvae.
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15
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Lucas C, Nicolas M, Keller L. Expression of foraging and Gp-9 are associated with social organization in the fire ant Solenopsis invicta. INSECT MOLECULAR BIOLOGY 2015; 24:93-104. [PMID: 25315753 DOI: 10.1111/imb.12137] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The aim of this study was to investigate levels of expression of two major genes, the odorant binding protein Gp-9 (general protein-9) and foraging, that have been shown to be associated with behavioural polymorphisms in ants. We analysed workers and young nonreproductive queens collected from nests of the monogyne (single reproductive queen per nest) and polygyne (multiple reproductive queens) social forms of Solenopsis invicta. In workers but not young queens, the level of foraging expression was significantly associated with social form and the task performed (ie localization in the nest or foraging area). The level of expression of Gp-9 was also associated with social form and worker localization. In addition there was a higher level of expression of the Gp-9(b) allele compared with the Gp-9(B) allele in the heterozygote workers and the young nonreproductive queens. Finally, in the polygyne colonies the level of expression of foraging was not significantly associated with the Gp-9 genotype for either workers or young nonreproductive queens, suggesting that both genes have independent non-epistatic effects on behaviour in S. invicta.
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Affiliation(s)
- C Lucas
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland; Institut de Recherche sur la Biologie de l'Insecte (UMR 7261), CNRS, University of Tours, Tours, France
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16
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Abstract
The genetic basis for animal social organization is poorly understood. Fire ants provide one of the rare cases where variation in social organization has been demonstrated to be under genetic control, which amazingly, segregates as a single Mendelian locus. A recent genetic, genomic, and cytological analysis revealed that this locus actually consists of over 600 genes locked together in a supergene that possesses many characteristics of sex chromosomes. The fire ant social supergene also behaves selfishly, and an interesting evolutionary question is whether the genes incorporated first into the social supergene were those for social adaptation, selfish genetic drive, or something else. In depth, functional molecular genetic analysis in fire ants and comparative genomics in other closely related socially polymorphic species will be required to resolve this question.
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Affiliation(s)
- Yu-Ching Huang
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
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17
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Horn KC, Eubanks MD, Siemann E. The effect of diet and opponent size on aggressive interactions involving caribbean crazy ants (Nylanderia fulva). PLoS One 2013; 8:e66912. [PMID: 23776702 PMCID: PMC3679061 DOI: 10.1371/journal.pone.0066912] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 05/13/2013] [Indexed: 11/18/2022] Open
Abstract
Biotic interactions are often important in the establishment and spread of invasive species. In particular, competition between introduced and native species can strongly influence the distribution and spread of exotic species and in some cases competition among introduced species can be important. The Caribbean crazy ant, Nylanderia fulva, was recently introduced to the Gulf Coast of Texas, and appears to be spreading inland. It has been hypothesized that competition with the red imported fire ant, Solenopsis invicta, may be an important factor in the spread of crazy ants. We investigated the potential of interspecific competition among these two introduced ants by measuring interspecific aggression between Caribbean crazy ant workers and workers of Solenopsis invicta. Specifically, we examined the effect of body size and diet on individual-level aggressive interactions among crazy ant workers and fire ants. We found that differences in diet did not alter interactions between crazy ant workers from different nests, but carbohydrate level did play an important role in antagonistic interactions with fire ants: crazy ants on low sugar diets were more aggressive and less likely to be killed in aggressive encounters with fire ants. We found that large fire ants engaged in fewer fights with crazy ants than small fire ants, but fire ant size affected neither fire ant nor crazy ant mortality. Overall, crazy ants experienced higher mortality than fire ants after aggressive encounters. Our findings suggest that fire ant workers might outcompete crazy ant workers on an individual level, providing some biotic resistance to crazy ant range expansion. However, this resistance may be overcome by crazy ants that have a restricted sugar intake, which may occur when crazy ants are excluded from resources by fire ants.
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Affiliation(s)
- Katherine C. Horn
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America
| | - Micky D. Eubanks
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
| | - Evan Siemann
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America
- * E-mail:
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18
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Vieira FG, Forêt S, He X, Rozas J, Field LM, Zhou JJ. Unique features of odorant-binding proteins of the parasitoid wasp Nasonia vitripennis revealed by genome annotation and comparative analyses. PLoS One 2012; 7:e43034. [PMID: 22952629 PMCID: PMC3428353 DOI: 10.1371/journal.pone.0043034] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 07/16/2012] [Indexed: 12/22/2022] Open
Abstract
Insects are the most diverse group of animals on the planet, comprising over 90% of all metazoan life forms, and have adapted to a wide diversity of ecosystems in nearly all environments. They have evolved highly sensitive chemical senses that are central to their interaction with their environment and to communication between individuals. Understanding the molecular bases of insect olfaction is therefore of great importance from both a basic and applied perspective. Odorant binding proteins (OBPs) are some of most abundant proteins found in insect olfactory organs, where they are the first component of the olfactory transduction cascade, carrying odorant molecules to the olfactory receptors. We carried out a search for OBPs in the genome of the parasitoid wasp Nasonia vitripennis and identified 90 sequences encoding putative OBPs. This is the largest OBP family so far reported in insects. We report unique features of the N. vitripennis OBPs, including the presence and evolutionary origin of a new subfamily of double-domain OBPs (consisting of two concatenated OBP domains), the loss of conserved cysteine residues and the expression of pseudogenes. This study also demonstrates the extremely dynamic evolution of the insect OBP family: (i) the number of different OBPs can vary greatly between species; (ii) the sequences are highly diverse, sometimes as a result of positive selection pressure with even the canonical cysteines being lost; (iii) new lineage specific domain arrangements can arise, such as the double domain OBP subfamily of wasps and mosquitoes.
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Affiliation(s)
- Filipe G. Vieira
- Departament de Genètica and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - Sylvain Forêt
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
- Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Xiaoli He
- Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
| | - Julio Rozas
- Departament de Genètica and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - Linda M. Field
- Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
| | - Jing-Jiang Zhou
- Department of Biological Chemistry and Crop Protection, Rothamsted Research, Harpenden, Hertfordshire, United Kingdom
- * E-mail:
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Fischman BJ, Woodard SH, Robinson GE. Molecular evolutionary analyses of insect societies. Proc Natl Acad Sci U S A 2011; 108 Suppl 2:10847-54. [PMID: 21690385 PMCID: PMC3131825 DOI: 10.1073/pnas.1100301108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The social insects live in extraordinarily complex and cohesive societies, where many individuals sacrifice their personal reproduction to become helpers in the colony. Identifying adaptive molecular changes involved in eusocial evolution in insects is important for understanding the mechanisms underlying transitions from solitary to social living, as well as the maintenance and elaboration of social life. Here, we review recent advances made in this area of research in several insect groups: the ants, bees, wasps, and termites. Drawing from whole-genome comparisons, candidate gene approaches, and a genome-scale comparative analysis of protein-coding sequence, we highlight novel insights gained for five major biological processes: chemical signaling, brain development and function, immunity, reproduction, and metabolism and nutrition. Lastly, we make comparisons across these diverse approaches and social insect lineages and discuss potential common themes of eusocial evolution, as well as challenges and prospects for future research in the field.
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Affiliation(s)
| | | | - Gene E. Robinson
- Program in Ecology, Evolution, and Conservation Biology
- Department of Entomology
- Institute for Genomic Biology, and
- Neuroscience Program, University of Illinois, Urbana, IL 61801
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20
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Gotzek D, Robertson HM, Wurm Y, Shoemaker D. Odorant binding proteins of the red imported fire ant, Solenopsis invicta: an example of the problems facing the analysis of widely divergent proteins. PLoS One 2011; 6:e16289. [PMID: 21305009 PMCID: PMC3031547 DOI: 10.1371/journal.pone.0016289] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 12/10/2010] [Indexed: 11/18/2022] Open
Abstract
We describe the odorant binding proteins (OBPs) of the red imported fire ant, Solenopsis invicta, obtained from analyses of an EST library and separate 454 sequencing runs of two normalized cDNA libraries. We identified a total of 18 putative functional OBPs in this ant. A third of the fire ant OBPs are orthologs to honey bee OBPs. Another third of the OBPs belong to a lineage-specific expansion, which is a common feature of insect OBP evolution. Like other OBPs, the different fire ant OBPs share little sequence similarity (∼ 20%), rendering evolutionary analyses difficult. We discuss the resulting problems with sequence alignment, phylogenetic analysis, and tests of selection. As previously suggested, our results underscore the importance for careful exploration of the sensitivity to the effects of alignment methods for data comprising widely divergent sequences.
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Affiliation(s)
- Dietrich Gotzek
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
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21
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Wyatt TD. Pheromones and signature mixtures: defining species-wide signals and variable cues for identity in both invertebrates and vertebrates. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2010; 196:685-700. [PMID: 20680632 DOI: 10.1007/s00359-010-0564-y] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 07/10/2010] [Accepted: 07/20/2010] [Indexed: 02/07/2023]
Abstract
Pheromones have been found in species in almost every part of the animal kingdom, including mammals. Pheromones (a molecule or defined combination of molecules) are species-wide signals which elicit innate responses (though responses can be conditional on development as well as context, experience, and internal state). In contrast, signature mixtures, in invertebrates and vertebrates, are variable subsets of molecules of an animal's chemical profile which are learnt by other animals, allowing them to distinguish individuals or colonies. All signature mixtures, and almost all pheromones, whatever the size of molecules, are detected by olfaction (as defined by receptor families and glomerular processing), in mammals by the main olfactory system or vomeronasal system or both. There is convergence on a glomerular organization of olfaction. The processing of all signature mixtures, and most pheromones, is combinatorial across a number of glomeruli, even for some sex pheromones which appear to have 'labeled lines'. Narrowly specific pheromone receptors are found, but are not a prerequisite for a molecule to be a pheromone. A small minority of pheromones act directly on target tissues (allohormone pheromones) or are detected by non-glomerular chemoreceptors, such as taste. The proposed definitions for pheromone and signature mixture are based on the heuristic value of separating these kinds of chemical information. In contrast to a species-wide pheromone, there is no single signature mixture to find, as signature mixtures are a 'receiver-side' phenomenon and it is the differences in signature mixtures which allow animals to distinguish each other.
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22
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Wurm Y, Wang J, Keller L. Changes in reproductive roles are associated with changes in gene expression in fire ant queens. Mol Ecol 2010; 19:1200-11. [PMID: 20163551 DOI: 10.1111/j.1365-294x.2010.04561.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In species with social hierarchies, the death of dominant individuals typically upheaves the social hierarchy and provides an opportunity for subordinate individuals to become reproductives. Such a phenomenon occurs in the monogyne form of the fire ant, Solenopsis invicta, where colonies typically contain a single wingless reproductive queen, thousands of workers and hundreds of winged nonreproductive virgin queens. Upon the death of the mother queen, many virgin queens shed their wings and initiate reproductive development instead of departing on a mating flight. Workers progressively execute almost all of them over the following weeks. To identify the molecular changes that occur in virgin queens as they perceive the loss of their mother queen and begin to compete for reproductive dominance, we collected virgin queens before the loss of their mother queen, 6 h after orphaning and 24 h after orphaning. Their RNA was extracted and hybridized against microarrays to examine the expression levels of approximately 10,000 genes. We identified 297 genes that were consistently differentially expressed after orphaning. These include genes that are putatively involved in the signalling and onset of reproductive development, as well as genes underlying major physiological changes in the young queens.
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Affiliation(s)
- Yannick Wurm
- Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
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