Cheater genotypes in the parthenogenetic ant Pristomyrmex punctatus

Abstract

Cooperation is subject to cheating strategies that exploit the benefits of cooperation without paying the fair costs, and it has been a major goal of evolutionary biology to explain the origin and maintenance of cooperation against such cheaters. Here, we report that cheater genotypes indeed coexist in field colonies of a social insect, the parthenogenetic ant Pristomyrmex punctatus. The life history of this species is exceptional, in that there is no reproductive division of labour: all females fulfil both reproduction and cooperative tasks. Previous studies reported sporadic occurrence of larger individuals when compared with their nest-mates. These larger ants lay more eggs and hardly take part in cooperative tasks, resulting in lower fitness of the whole colony. Population genetic analysis showed that at least some of these largebodied individuals form a genetically distinct lineage, isolated from cooperators by parthenogenesis. A phylogenetic study confirmed that this cheater lineage originated intraspecifically. Coexistence of cheaters and cooperators in this species provides a good model system to investigate the evolution of cooperation in nature.

Public goods dilemma in asexual ant societies

“…Colonies of P. punctatus were collected from Kihoku, Mie Prefecture, central Japan (34.2°N, 136.3°E) (39,40), on June 4 and 5, 2011, during the early to middle period of their reproductive season. Five colonies containing a substantial number of cheaters served as the source colonies for the experiment.…”

“…Reproductive division of labor is realized through age polyethism (or temporal castes) among workers, where younger workers reproduce and engage in inside-nest tasks, such as brood care, and older workers cease reproduction and shift to outside-nest tasks, such as foraging (38). Cheater individuals, which constitute a single intraspecific lineage in the field (39,40), engage in few tasks except for reproduction (41). In addition, these individuals show several characteristics that are typical in queens of other ants, such as having more ovarioles, a larger body size, and three conspicuous ocelli (39)(40)(41)(42).…”

“…Cheater individuals, which constitute a single intraspecific lineage in the field (39,40), engage in few tasks except for reproduction (41). In addition, these individuals show several characteristics that are typical in queens of other ants, such as having more ovarioles, a larger body size, and three conspicuous ocelli (39)(40)(41)(42). Using experimental colonies with varying proportions of cheaters, we tested whether the fitness of cheaters and workers in a colony of P. punctatus conformed to the framework of the public goods dilemma.…”

When does cheating pay? Worker reproductive parasitism in honeybees

“…Thelytoky has already led to the evolution of specialised social parasites as in the Cape honeybee A. m. capensis (Goudie and Oldroyd, 2014) and the ant Pristomyrmex punctatus (Dobata et al, 2009. In the Cape honeybee the consequences of the parasitic lineage are devastating.…”

Genetic reincarnation of workers as queens in the Eastern honeybee Apis cerana

“…Thelytoky has already led to the evolution of specialised social parasites as in the Cape honeybee A. m. capensis (Goudie and Oldroyd, 2014) and the ant Pristomyrmex punctatus (Dobata et al, 2009;Dobata et al, 2011). In the Cape honeybee the consequences of the parasitic lineage are devastating.…”