Caste development and sex ratio of the Ryukyu drywood termite Neotermes sugioi and its potential mechanisms

Miyaguni, Yasushi; Agarie, Ayaka; Sugio, Koji; Tsuji, Kazuki; Kobayashi, Keiko

doi:10.1038/s41598-021-94505-w

Cited by 5 publications

(10 citation statements)

References 42 publications

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“…on these results, one can predict an equal numerical sex ratio in the Ishigaki population. However, Miyaguni et al (2021) showed male-biased numerical sex ratios in older developmental stages (pseudergates, nymphs, alates) both in Okinawa and Ishigaki populations. One hypothesis to solve this discrepancy is the annual and seasonal variation in the primary sex ratio of the Ishigaki population.…”

Section: Discussionmentioning

confidence: 91%

“…4.0.2 (R Development Core Team 2020) was used for analyses. We also analyzed the correlation between the presence of a neotenic king and the colony-level sex ratio in N. sugioi, using the previously published field data on the reproductive structure and sex ratios of pseudergates in Okinawa population from May to August (Miyaguni et al, 2021). The data included colonies with a neotenic king and a primary queen (7 colonies).…”

Section: Discussionmentioning

confidence: 99%

“…However, some species show sex ratio bias, the cause of which remains unknown in many cases (Neoh and Lee, 2011). Miyaguni et al (2021) showed that in the Ryukyu dry-wood termite N. sugioi, recently separated from N. koshunensis (Yashiro et al, 2019), numerical sex ratios were biased toward males in pseudergates, nymphs, alates and soldiers (including pre-soldiers) on all islands examined (Figure 1A). In Okinawa population, the sex ratio of alate biomass, as an index of the sex allocation ratio, was biased also toward males.…”

Section: Introductionmentioning

confidence: 99%

“…To clarify the primary sex ratio in field populations, we analyzed microsatellites with male-specific alleles for eggs from the Okinawa and Ishigaki populations. To explore the existence of SGEs causing the male-biased sex ratio of eggs, we performed microsatellite analysis of the eggs produced via cross-breeding between Okinawa and Ishigaki populations, where sex ratios of alates were different in a previous study (Miyaguni et al, 2021). Based on these results, we discussed the relationship between SGEs and biased sex ratios in termites, and suggested that this species can be an important material for studying the relationship between sex ratios and SGEs in termites, and may provide a new steppingstone to elucidate the evolutionary process of the sex determination system in insects.…”

Section: Introductionmentioning

confidence: 99%

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Male’s influence on the primary sex ratio bias in Ryukyu drywood termite

et al. 2023

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Selfish genetic elements (SGEs) increase their transmission efficiency relative to the rest of the individual genome, which is often deleterious to individual fitness. Theoretical studies have suggested that intragenomic conflict over the sex ratio distortion between SGEs and the rest of the genome should lead to the evolution of sex-determining systems. However, in insects, there are relatively few studies other than those on Dipterans, which makes it difficult to understand the role of SGEs in the evolution of insect sex determination. This is partially due to the difficulties in observing SGEs under field conditions. The effect of SGEs is often masked by the counter-evolution of the resistance genes. Interpopulation cross-breeding experiments are effective to detect the SGEs and their resistance genes. If these populations have different SGEs and resistance genes, cross-breeding experiments reveal their existence by collapsing the evolutionary antagonistic state. The Ryukyu drywood termites Neotermes sugioi, distributed in the Ryukyu Islands, show male-biased sex ratios in pseudergates, nymphs, alates and soldiers both in Okinawa and Ishigaki Islands, but different degrees of bias have been reported between the islands. Male-specific microsatellite alleles have been reported in this species, which allowed us to identify the sex of the eggs and young larvae. In this study, we used the microsatellite locus with male-specific alleles to investigate the primary sex ratio of field colonies on Okinawa and Ishigaki islands and the sex ratio of offspring obtained through cross-breeding experiments between the islands. The primary sex ratios of field colonies were male-biased in Okinawa but not in Ishigaki. Cross-breeding experiments showed that Okinawa males tend to have a male-biased sex ratio in their offspring, but Ishigaki males do not. This result is consistent with the hypothesis that the male bias in this species is caused by SGEs, even though termites are phylogenetically distant from Diptera. Accumulation of knowledge on genetic conflicts in a wide range of taxa might be an important step toward elucidating the mechanisms of diversification of sex determination systems in insects.

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Section: Discussionmentioning

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Male’s influence on the primary sex ratio bias in Ryukyu drywood termite

et al. 2023

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“…obs .). To date, evidence of detection and avoidance of nestmate pairings are scarce and inconsistent in termites 12 , 37 , 38 . Inbreeding avoidance can occur through a split sex ratio between colonies, or differences between the sexes in their dispersal range or in their timing of emergence 39 .…”

Section: Discussionmentioning

confidence: 99%

Short and long-term costs of inbreeding in the lifelong-partnership in a termite

Eyer

Vargo

2022

Commun Biol

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Social life and lifelong partner commitments are expected to favor thorough partner choice, as an ill-suited partnership may have long-term consequences, adversely affecting the parents and spanning several cohorts of offspring. Here, we used ~1400 termite incipient colonies to estimate the short- and long-term costs of inbreeding upon the survival of the parents over a 15-month period, their productivity, and the resistance of their offspring toward pathogen pressure. We observed that foundation success was not influenced by the relatedness of partners, but by their levels of microbial load. We showed faster growth in inbred colonies with low levels of microbial load, revealing a potential tradeoff between pathogen defense and offspring production. Yet, inbreeding takes its toll later in colony development when offspring from incipient colonies face pathogen pressure. Although the success of a lifetime partnership is initially determined by the partner’s health, the cost of inbreeding in incipient colonies favors outbred colonies reaching maturity.

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Extinct and extant termites reveal the fidelity of behavior fossilization in amber

Mizumoto,

Hellemans,

Engel

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

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Fossils encompassing multiple individuals provide rare direct evidence of behavioral interactions among extinct organisms. However, the fossilization process can alter the spatial relationship between individuals and hinder behavioral reconstruction. Here, we report a Baltic amber inclusion preserving a female–male pair of the extinct termite species Electrotermes affinis . The head-to-abdomen contact in the fossilized pair resembles the tandem courtship behavior of extant termites, although their parallel body alignment differs from the linear alignment typical of tandem runs. To solve this inconsistency, we simulated the first stage of amber formation, the immobilization of captured organisms, by exposing living termite tandems to sticky surfaces. We found that the posture of the fossilized pair matches trapped tandems and differs from untrapped tandems. Thus, the fossilized pair likely is a tandem running pair, representing the direct evidence of the mating behavior of extinct termites. Furthermore, by comparing the postures of partners on a sticky surface and in the amber inclusion, we estimated that the male likely performed the leader role in the fossilized tandem. Our results demonstrate that past behavioral interactions can be reconstructed despite the spatial distortion of body poses during fossilization. Our taphonomic approach demonstrates how certain behaviors can be inferred from fossil occurrences.

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Caste development and sex ratio of the Ryukyu drywood termite Neotermes sugioi and its potential mechanisms

Cited by 5 publications

References 42 publications

Male’s influence on the primary sex ratio bias in Ryukyu drywood termite

Male’s influence on the primary sex ratio bias in Ryukyu drywood termite

Short and long-term costs of inbreeding in the lifelong-partnership in a termite

Extinct and extant termites reveal the fidelity of behavior fossilization in amber

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