Colony structure and reproduction in the thelytokous parthenogenetic ant Platythyrea punctata (F. Smith) (Hymenoptera, Formicidae)

Abstract

An important evolutionary characteristic of the formicine subfamily Ponerinae is the occurrence of various alternative reproductive tactics within single species. In Platythyrea punctata Smith, 1858, queens, gamergates and parthenogenetic workers co-occur in the same species. Morphological queens, both alate and dealate, were present in only 29 percent of the colonies collected in Florida, but absent from colonies collected in Barbados and Puerto Rico. One of the six queens which were dissected (three alate and three dealate) was found to be inseminated but not fertile. Instead, in most queenless colonies, a single uninseminated worker monopolized reproduction by means of thelytokous parthenogenesis, i.e., it produced female offspring from unfertilized eggs. A single mated, reproductive worker (gamergate) was found dominating reproduction in the presence of an inseminated alate queen in one of the Florida colonies. Thelytokous parthenogenesis was examined in artificial groups of virgin laboratory-reared workers, where one worker typically monopolized reproduction despite the presence of several individuals with elongated ovaries. In 16 colonies collected in Florida, a total of 66 individuals differed morphologically from queens and workers. Their thorax morphology varied from a worker-like to an almost queenlike structure. We refer to these individuals as "intercastes" (sensu Peeters, 1991a). The remarkable complexity of reproductive strategies renders P. punctata unique within ants.

Lay Eggs, Live Longer: Division of Labor and Life Span in a Clonal Ant Species

“…This association of immobility on the brood pile and reproduction was corroborated by dissecting all workers in six additional colonies (data not shown). This, as well as dissections in a previous study (Schilder et al 1999b) documents that colonies typically contain only one, rarely two, major reproductive egg-layers with fully developed ovaries.…”

“…Colonies were collected between 1994 and 1997 in mainland Florida at Archbold Biological Station, Highlands County, and Vero Beach, St. Lucie County; in spring 1996 at El Verde Station in Luquillo Experimental Forest, Puerto Rico; and in January 1995 in Turner's Hall Woods on Barbados (for details see Schilder et al 1999b). One colony was collected in October 1999 in Santa Rosa National Park in northwestern Costa Rica.…”

“…Previous studies had shown that workers of P. punctata from Florida, Puerto Rico, and Barbados exclusively reproduce by thelytokous parthenogenesis (Schilder et al 1999b;A. Hartmann, unpubl.…”

Comparative Analysis of Worker Reproduction and Policing in Eusocial Hymenoptera Supports Relatedness Theory

“…In this species, workers produce diploid females from unfertilized eggs by thelytokous parthenogenesis, which results in a clonal colony structure (Heinze and Hölldobler 1995;Schilder et al 1999a,b). All individuals are morphologically identical and equally capable of laying eggs, but each colony nevertheless contains only one, or rarely two, egg-layers (Schilder et al 1999b). When additional reproductive workers from orphaned nests are added to colonies they are attacked by other workers (Hartmann et al 2003), and, when the introduced reproductive workers are older than 2 months, also by the resident reproductive (Hartmann et al 2005).…”

Worker policing without genetic conflicts in a clonal ant

“…Although all workers in a P. punctata colony are equally capable of laying eggs, reproduction is monopolized by one (occasionally two) worker while the others forego their own reproduction and instead perform tasks necessary for nest maintenance and brood rearing (18). Because sexual reproduction and recombination appear to be extremely rare or absent, colonies are essentially clones (19).…”