Microsatellites reveal clonal structure of populations of the thelytokous ant Platythyrea punctata (F. Smith) (Hymenoptera; Formicidae)

Abstract

Parthenogenesis is often thought to constitute an evolutionary dead end as compared with sexual reproduction because genetic recombination is limited or nonexistent in parthenogenetic populations. Yet there are many species to demonstrate that parthenogenesis can initially be extremely successful under certain environmental conditions. In this study we used microsatellite markers to investigate the genetic structure of four natural populations of the neotropical thelytokous parthenogenetic ant Platythyrea punctata. Ten dinucleotide microsatellites were isolated from a partial genomic library of P. punctata. Five of these were found to be polymorphic. In a subsequent analysis of 314 workers taken from 51 colonies, we detected low intraspecific levels of variation at all loci, expressed both in the number of alleles detected and heterozygosities observed. Surprisingly, we found almost no differentiation within populations. Populations rather had a clonal structure, with all individuals from all colonies usually sharing the same genotype. Only in one colony from Puerto Rico did some workers have an additional genotype. This low level of genotypic diversity probably reflects the predominance of thelytoky in P. punctata, together with genetic bottlenecks and founder effects. Cross-species amplification of all 10 loci in 29 ant species comprising four different subfamilies yielded positive amplification products in only a limited number of species.

Thelytokous parthenogenesis and its consequences on inbreeding in an ant

“…Interestingly, Baudry et al (2004) reported an average reduction of heterozygosity per generation and per individual (R) of about 0.19, a value well in the range of 0.06-0.33 (mean: 0.21) found in this study. By contrast with C. cursor, Schilder et al (1999) reported that reproduction in parthenogenetic populations of the ant Platythyrea punctata is apomictic. This suggests that different modes of thelytokous parthenogenesis evolved independently in different lineages of the Formicidae.…”

“…Cytological analysis indicated that diploidization results from automictic parthenogenesis with central fusion, that is, the fusion of two of the four meiotic products that have a central position on the spindles and that were separated at the first meiotic division, whereas the two terminal nuclei degenerate (Verma and Ruttner, 1983;Baudry et al, 2004). In ants, thelytokous parthenogenesis has been unambiguously demonstrated in six phylogenetically distant species only: Cataglyphis cursor (Cagniant, 1973), Pristomyrmex pungens (Itow et al, 1984), Cerapachys biroi (Tsuji and Yamauchi, 1995), Platythyrea punctata (Heinze and Hö lldobler, 1995;Schilder et al, 1999), Messor capitatus (Grasso et al, 2000) and Wasmannia auropunctata (Fournier et al, 2005). In the ponerine ant P. punctata, Schilder et al (1999) showed that all individuals belonging to the same population are almost genetically identical to each other, suggesting that thelytokous parthenogenesis is apomictic.…”

“…In ants, thelytokous parthenogenesis has been unambiguously demonstrated in six phylogenetically distant species only: Cataglyphis cursor (Cagniant, 1973), Pristomyrmex pungens (Itow et al, 1984), Cerapachys biroi (Tsuji and Yamauchi, 1995), Platythyrea punctata (Heinze and Hö lldobler, 1995;Schilder et al, 1999), Messor capitatus (Grasso et al, 2000) and Wasmannia auropunctata (Fournier et al, 2005). In the ponerine ant P. punctata, Schilder et al (1999) showed that all individuals belonging to the same population are almost genetically identical to each other, suggesting that thelytokous parthenogenesis is apomictic. In the five other species, the mode of parthenogenesis underlying thelytoky remains unknown.…”

A single locus determines thelytokous parthenogenesis of laying honeybee workers (Apis mellifera capensis)

“…The genetics of thelytoky has also been studied in Plathythyrea puncata (Schilder et al, 1999a, b). This Ponerine ant species shows different modes of reproduction.…”

“…Queens and gamergates ( ¼ mated workers) reproduce sexually or through arrhenotoky, whereas unmated workers can exhibit thelytokous parthenogenesis. There is a high intraspecific variation for the type of reproduction (Heinze and Hö lldobler, 1995;Schilder et al, 1999a).…”