Population genetic structure, worker reproduction and thelytokous parthenogenesis in the desert ant Cataglyphis sabulosa

Abstract

In social Hymenoptera, within-colony relatedness is usually high due to the haplodiploid sex-determining system. However, factors such as the presence of multiple reproductive queens (polygyny), multiple queen matings (polyandry) or worker reproduction result in decreased relatedness among workers and the brood they rear, and consequently dilute their inclusive fitness benefits from helping. Here, we investigated population genetic structure, mating system, worker reproduction and parthenogenesis in the desert ant Cataglyphis sabulosa. Analysis of worker genotypes showed that colonies are headed by a single queen, mated with 1-5 males. The inbreeding coefficient within colonies and the levels of relatedness between the queens and their mates were positive, indicating that mating occurs between related individuals. Moreover, the mates of a queen are on average related and contribute equally to worker production. Our analyses also indicate that colonies are genetically differentiated and form a population exhibiting no isolation-by-distance pattern, consistent with the independent foundation of new colonies (that is, without the help of workers). Finally, both ovarian dissections and genetic data on the parentage of males show that workers do not reproduce in queenright colonies; however, they lay both haploid (arrhenotokous males) and diploid (thelytokous females) eggs in queenless colonies. In contrast to the congeneric species C. cursor, where new queens are produced by thelytokous parthenogenesis, female sexuals of C. sabulosa result from classical sexual reproduction.

Mating system and population structure in the desert ant Cataglyphis livida

“…Consequently, relatedness values within-colonies is similar in the three species studied (C. cursor r w-w = 0.42, C. sabulosa r w-w = 0.49, C. livida r w-w = 0.42) (Pearcy et al, 2004a;Timmermans et al, 2008). However, while C. bicolor, C. livida and C. sabulosa show dispersal patterns typical of monogynous species (i.e., nuptial flights and no isolationby-distance; Knaden and Wehner, 2006;Timmermans et al, 2008), females of C. cursor mate close to the nest entrance and found colonies with the help of a worker force in the close vicinity of their natal colony, which results in a strong local population genetic structure (Pearcy et al, 2004a;Clémencet et al, 2005;). An interesting finding of this study is that a proportion of the male-mates of a queen are related to each other in C. livida (r m-m = 0.17).…”

“…However, although colonies of C. cursor are strictly monogynous, young queens mate close to their natal nest and colony reproduction proceeds by budding (Lenoir et al, 1988;Clémencet et al, 2005;Hardy et al, 2008). Second, queens of C. sabulosa and C. cursor are polyandrous with effective mating frequencies of 2.30 and 3.79, respectively (Timmermans et al, 2008;Pearcy et al, 2009). No data are available for the other species of Cataglyphis studied so far.…”

“…Dispersion by colony budding limits female dispersal, what usually results in a pattern of isolation-bydistance. In line with these syndromes, in the polygynous C. mauritanica colonies reproduce by budding and populations are genetically structure (Knaden and Wehner, 2006), while in the monogynous C. sabulosa and C. bicolor colonies are founded independently and no isolationby-distance pattern occurs (Knaden and Wehner, 2006;Timmermans et al, 2008). However, although colonies of C. cursor are strictly monogynous, young queens mate close to their natal nest and colony reproduction proceeds by budding (Lenoir et al, 1988;Clémencet et al, 2005;Hardy et al, 2008).…”

“…Individual ant DNA was extracted by the same protocol as previously reported for other Cataglyphis species (Timmermans et al, 2008). Polymerase chain reaction (PCR) were performed in three different mix (cc26 ?…”

“…Another characteristic of the reproductive biology of Cataglyphis ants is the ability of workers to reproduce by both arrhenotokous and thelytokous parthenogenesis (Cagniant, 1980;Timmermans et al, 2008). Worker reproduction was reported in queenless colonies only.…”