Skewed soldier sex ratio in termites: Testing the size-threshold hypothesis

T. Bourguignon, Yoshinobu Hayashi, T. Miura

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Social insect colonies contain multiple phenotypes, i. e. castes, and this caste polyphenism is often linked to sexual dimorphism. Unlike social hymenopterans, both termite sexes are diploid and contribute to helper-type tasks within the colony. Nonetheless, a biased sex ratio is frequently observed in termites, especially in soldiers. To explain this bias in soldier sex ratio, Matsuura (Evol. Ecol. 20: 565-574, 2006) postulated the existence of a size threshold for workers molting into soldiers. Under the influence of sexual size dimorphism (SSD), such a threshold was considered to indirectly favor one sex. We conducted a literature survey of sex ratio among termite soldiers and tested this size-threshold hypothesis using data for 67 termite species from a variety of termite lineages. We demonstrated the existence of a size threshold for individuals molting into soldiers, resulting in the acquisition of soldiers of only one sex in species exhibiting strong SSD. In species exhibiting weak SSD, the size threshold skews the sex ratio of soldiers, but does not necessarily cause the loss of one sex. Finally, we observed a prevalence of single-sex soldiers in the Termitidae, regardless of SSD, suggesting that the ancestral developmental mechanisms that constrain soldier differentiation from one sex are maintained in certain extant species.

Original languageEnglish
Pages (from-to)557-563
Number of pages7
JournalInsectes Sociaux
Volume59
Issue number4
DOIs
Publication statusPublished - 2012 Jul 10
Externally publishedYes

Fingerprint

termite
Isoptera
sex ratio
dimorphism
gender
testing
molting
caste
insect colonies
Termitidae
social insects
sexual dimorphism
social insect
diploidy
Hymenoptera
phenotype

Keywords

  • Caste polymorphism
  • Isoptera
  • Phylogeny
  • Sexual dimorphism
  • Termite evolution

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Insect Science

Cite this

Skewed soldier sex ratio in termites : Testing the size-threshold hypothesis. / Bourguignon, T.; Hayashi, Yoshinobu; Miura, T.

In: Insectes Sociaux, Vol. 59, No. 4, 10.07.2012, p. 557-563.

Research output: Contribution to journalArticle

@article{8983ba229c6f478fbf0a3f8898b23645,
title = "Skewed soldier sex ratio in termites: Testing the size-threshold hypothesis",
abstract = "Social insect colonies contain multiple phenotypes, i. e. castes, and this caste polyphenism is often linked to sexual dimorphism. Unlike social hymenopterans, both termite sexes are diploid and contribute to helper-type tasks within the colony. Nonetheless, a biased sex ratio is frequently observed in termites, especially in soldiers. To explain this bias in soldier sex ratio, Matsuura (Evol. Ecol. 20: 565-574, 2006) postulated the existence of a size threshold for workers molting into soldiers. Under the influence of sexual size dimorphism (SSD), such a threshold was considered to indirectly favor one sex. We conducted a literature survey of sex ratio among termite soldiers and tested this size-threshold hypothesis using data for 67 termite species from a variety of termite lineages. We demonstrated the existence of a size threshold for individuals molting into soldiers, resulting in the acquisition of soldiers of only one sex in species exhibiting strong SSD. In species exhibiting weak SSD, the size threshold skews the sex ratio of soldiers, but does not necessarily cause the loss of one sex. Finally, we observed a prevalence of single-sex soldiers in the Termitidae, regardless of SSD, suggesting that the ancestral developmental mechanisms that constrain soldier differentiation from one sex are maintained in certain extant species.",
keywords = "Caste polymorphism, Isoptera, Phylogeny, Sexual dimorphism, Termite evolution",
author = "T. Bourguignon and Yoshinobu Hayashi and T. Miura",
year = "2012",
month = "7",
day = "10",
doi = "10.1007/s00040-012-0252-8",
language = "English",
volume = "59",
pages = "557--563",
journal = "Insectes Sociaux",
issn = "0020-1812",
publisher = "Birkhauser Verlag Basel",
number = "4",

}

TY - JOUR

T1 - Skewed soldier sex ratio in termites

T2 - Testing the size-threshold hypothesis

AU - Bourguignon, T.

AU - Hayashi, Yoshinobu

AU - Miura, T.

PY - 2012/7/10

Y1 - 2012/7/10

N2 - Social insect colonies contain multiple phenotypes, i. e. castes, and this caste polyphenism is often linked to sexual dimorphism. Unlike social hymenopterans, both termite sexes are diploid and contribute to helper-type tasks within the colony. Nonetheless, a biased sex ratio is frequently observed in termites, especially in soldiers. To explain this bias in soldier sex ratio, Matsuura (Evol. Ecol. 20: 565-574, 2006) postulated the existence of a size threshold for workers molting into soldiers. Under the influence of sexual size dimorphism (SSD), such a threshold was considered to indirectly favor one sex. We conducted a literature survey of sex ratio among termite soldiers and tested this size-threshold hypothesis using data for 67 termite species from a variety of termite lineages. We demonstrated the existence of a size threshold for individuals molting into soldiers, resulting in the acquisition of soldiers of only one sex in species exhibiting strong SSD. In species exhibiting weak SSD, the size threshold skews the sex ratio of soldiers, but does not necessarily cause the loss of one sex. Finally, we observed a prevalence of single-sex soldiers in the Termitidae, regardless of SSD, suggesting that the ancestral developmental mechanisms that constrain soldier differentiation from one sex are maintained in certain extant species.

AB - Social insect colonies contain multiple phenotypes, i. e. castes, and this caste polyphenism is often linked to sexual dimorphism. Unlike social hymenopterans, both termite sexes are diploid and contribute to helper-type tasks within the colony. Nonetheless, a biased sex ratio is frequently observed in termites, especially in soldiers. To explain this bias in soldier sex ratio, Matsuura (Evol. Ecol. 20: 565-574, 2006) postulated the existence of a size threshold for workers molting into soldiers. Under the influence of sexual size dimorphism (SSD), such a threshold was considered to indirectly favor one sex. We conducted a literature survey of sex ratio among termite soldiers and tested this size-threshold hypothesis using data for 67 termite species from a variety of termite lineages. We demonstrated the existence of a size threshold for individuals molting into soldiers, resulting in the acquisition of soldiers of only one sex in species exhibiting strong SSD. In species exhibiting weak SSD, the size threshold skews the sex ratio of soldiers, but does not necessarily cause the loss of one sex. Finally, we observed a prevalence of single-sex soldiers in the Termitidae, regardless of SSD, suggesting that the ancestral developmental mechanisms that constrain soldier differentiation from one sex are maintained in certain extant species.

KW - Caste polymorphism

KW - Isoptera

KW - Phylogeny

KW - Sexual dimorphism

KW - Termite evolution

UR - http://www.scopus.com/inward/record.url?scp=84867577001&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84867577001&partnerID=8YFLogxK

U2 - 10.1007/s00040-012-0252-8

DO - 10.1007/s00040-012-0252-8

M3 - Article

AN - SCOPUS:84867577001

VL - 59

SP - 557

EP - 563

JO - Insectes Sociaux

JF - Insectes Sociaux

SN - 0020-1812

IS - 4

ER -