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Steurer M, Ruther J, Pokorny T. Behavioural consequences of intraspecific variability in a mate recognition signal. Proc Biol Sci 2024; 291:20232518. [PMID: 38444335 PMCID: PMC10915540 DOI: 10.1098/rspb.2023.2518] [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: 11/09/2023] [Accepted: 02/08/2024] [Indexed: 03/07/2024] Open
Abstract
Mate recognition is paramount for sexually reproducing animals, and many insects rely on cuticular hydrocarbons (CHCs) for close-range sexual communication. To ensure reliable mate recognition, intraspecific sex pheromone variability should be low. However, CHCs can be influenced by several factors, with the resulting variability potentially impacting sexual communication. While intraspecific CHC variability is a common phenomenon, the consequences thereof for mate recognition remain largely unknown. We investigated the effect of CHC variability on male responses in a parasitoid wasp showing a clear-cut within-population CHC polymorphism (three distinct female chemotypes, one thereof similar to male profiles). Males clearly discriminated between female and male CHCs, but not between female chemotypes in no-choice assays. When given a choice, a preference hierarchy emerged. Interestingly, the most attractive chemotype was the one most similar to male profiles. Mixtures of female CHCs were as attractive as chemotype-pure ones, while a female-male mixture negatively impacted male responses, indicating assessment of the entire, complex CHC profile composition. Our study reveals that the evaluation of CHC profiles can be strict towards 'undesirable' features, but simultaneously tolerant enough to cover a range of variants. This reconciles reliable mate recognition with naturally occurring variability.
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Affiliation(s)
- Maximilian Steurer
- Institute of Zoology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Joachim Ruther
- Institute of Zoology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Tamara Pokorny
- Institute of Zoology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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Sun W, Lange MI, Gadau J, Buellesbach J. Decoding the genetic and chemical basis of sexual attractiveness in parasitic wasps. eLife 2023; 12:e86182. [PMID: 37431891 PMCID: PMC10435230 DOI: 10.7554/elife.86182] [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: 01/14/2023] [Accepted: 07/10/2023] [Indexed: 07/12/2023] Open
Abstract
Attracting and securing potential mating partners is of fundamental importance for reproduction. Therefore, signaling sexual attractiveness is expected to be tightly coordinated in communication systems synchronizing senders and receivers. Chemical signaling has permeated through all taxa of life as the earliest and most widespread form of communication and is particularly prevalent in insects. However, it has been notoriously difficult to decipher how exactly information related to sexual signaling is encoded in complex chemical profiles. Similarly, our knowledge of the genetic basis of sexual signaling is very limited and usually restricted to a few case studies with comparably simple pheromonal communication mechanisms. The present study jointly addresses these two knowledge gaps by characterizing two fatty acid synthase genes that most likely evolved by tandem gene duplication and that simultaneously impact sexual attractiveness and complex chemical surface profiles in parasitic wasps. Gene knockdown in female wasps dramatically reduces their sexual attractiveness coinciding with a drastic decrease in male courtship and copulation behavior. Concordantly, we found a striking shift of methyl-branching patterns in the female surface pheromonal compounds, which we subsequently demonstrate to be the main cause for the greatly reduced male mating response. Intriguingly, this suggests a potential coding mechanism for sexual attractiveness mediated by specific methyl-branching patterns in complex cuticular hydrocarbon (CHC) profiles. So far, the genetic underpinnings of methyl-branched CHCs are not well understood despite their high potential for encoding information. Our study sheds light on how biologically relevant information can be encoded in complex chemical profiles and on the genetic basis of sexual attractiveness.
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Affiliation(s)
- Weizhao Sun
- Institute for Evolution & Biodiversity, University of Münster, HüfferstrMünsterGermany
| | - Michelle Ina Lange
- Institute for Evolution & Biodiversity, University of Münster, HüfferstrMünsterGermany
| | - Jürgen Gadau
- Institute for Evolution & Biodiversity, University of Münster, HüfferstrMünsterGermany
| | - Jan Buellesbach
- Institute for Evolution & Biodiversity, University of Münster, HüfferstrMünsterGermany
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Chikami Y, Okuno M, Toyoda A, Itoh T, Niimi T. Evolutionary history of sexual differentiation mechanism in insects. Mol Biol Evol 2022; 39:6618292. [PMID: 35820410 PMCID: PMC9290531 DOI: 10.1093/molbev/msac145] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Alternative splicing underpins functional diversity in proteins and the complexity and diversity of eukaryotes. An example is the doublesex gene, the key transcriptional factor in arthropod sexual differentiation. doublesex is controlled by sex-specific splicing and promotes both male and female differentiation in holometabolan insects, whereas in hemimetabolan species, doublesex has sex-specific isoforms but is not required for female differentiation. How doublesex evolved to be essential for female development remains largely unknown. Here, we investigate ancestral states of doublesex using Thermobia domestica belonging to Zygentoma, the sister group of Pterygota, that is, winged insects. We find that, in T. domestica, doublesex expresses sex-specific isoforms but is only necessary for male differentiation of sexual morphology. This result supports the hypothesis that doublesex initially promoted male differentiation during insect evolution. However, T. domestica doublesex has a short female-specific region and upregulates the expression of vitellogenin homologs in females, suggesting that doublesex may already play some role in female morphogenesis of the common ancestor of Pterygota. Reconstruction of the ancestral sequence and prediction of protein structures show that the female-specific isoform of doublesex has an extended C-terminal disordered region in holometabolan insects but not in nonholometabolan species. We propose that doublesex acquired its function in female morphogenesis through a change in the protein motif structure rather than the emergence of the female-specific exon.
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Affiliation(s)
- Yasuhiko Chikami
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan.,Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Miki Okuno
- Division of Microbiology, Department of Infectious Medicine, School of Medicine, Kurume University, 67 Asahi-machi, Kurume, Fukuoka, 830-0011, Japan
| | - Atsushi Toyoda
- Comparative Genomics Laboratory, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan.,Advanced Genomics Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Takehiko Itoh
- School of Life Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 152-8550, Japan
| | - Teruyuki Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan.,Department of Basic Biology, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, 38 Nishigonaka, Myodaiji, Okazaki, Aichi, 444-8585, Japan
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