Sex-Linked Genetic Influence on Caste Determination in a Termite

Abstract

The most ecologically successful and destructive termite species are those with both a nymph caste and an irreversibly wingless worker caste. The early developmental bifurcation separating these castes is widely accepted to be strictly environmentally determined. We present evidence that genotype also influences this process. Offspring from four different crosses of nymph- and worker-derived secondary reproductive individuals had strongly differentiated caste and sex ratios, despite uniform rearing conditions. These data fit an X-linked, one-locus-two-allele model. Of five possible genotypes, one was lethal, two resulted in workers, and two resulted in either nymphs or environmentally determined workers. Caste is thus controlled both by environment and by a complex genetic inheritance pattern.

Physiological variation as a mechanism for developmental caste-biasing in a facultatively eusocial sweat bee

“…The role of development in caste differentiation is well studied among species that are obligately eusocial [6][7][8][9][10][11][12][13]. Although these studies have been extremely valuable, insights into how solitary ground plans were first modified may be obscured by the novel evolutionary pressures arising from obligate reproductive castes [14][15][16][17][18][19][20].…”

Interplay between insulin signaling, juvenile hormone, and vitellogenin regulates maternal effects on polyphenism in ants

“…Even though recent studies revealed genetic influences on caste determination in social insects (reviewed in ref. 26), female caste fate is primarily influenced by environmental factors in most species studied (27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39). In ants, several studies suggested that maternal factors such as temperature or queen age may affect caste determination (40)(41)(42)(43)(44).…”

Neotenic reproductives influence worker caste differentiation in the termite Reticulitermes speratus (Isoptera; Rhinotermitidae)

“…There were extreme differences in the proportions of caste and sex between offspring from different combinations of parents, indicating that genetic factors influenced the developmental commitment to the worker or nymph caste. We also showed that almost all of the offspring produced through parthenogenesis developed into nymphs when they were reared only with tending workers, while 24% of parthenogenetically-produced offspring differentiated into workers when reared with an additional pair of nymphoids (Hayashi et al, 2007). This suggests that the existence of pairs of nymphoids can influence the developmental trajectory of larvae.…”

“…Our previous studies on the Japanese subterranean termites Reticulitermes speratus (Hayashi et al, 2007), R. okinawanus, R. kanmonensis, and R. yaeyamanus (Kitade et al, 2011) provided evidence for genetic influences on caste determination of larvae. In Reticulitermes, each individual becomes either a nymph or a worker after two larval instar stages (Buchli, 1958;Shimizu, 1970;Takematsu, 1992).…”

“…Ergatoids, on the other hand, have not yet been found in extensive surveys of natural colonies (Matsuura et al, 2009;Matsuura et al, 2010), although there is some evidence that they may be present (Shimizu, 1970). In our previous study of R. speratus (Hayashi et al, 2007) we carried out crossing with four possible combinations of ergatoids and nymphoids, and examined caste and sex of their offspring, which were reared under uniform environmental conditions. There were extreme differences in the proportions of caste and sex between offspring from different combinations of parents, indicating that genetic factors influenced the developmental commitment to the worker or nymph caste.…”