Ecological and evolutionary success in a parthenogenetic praying mantis: population genetics and reproductive strategy

Abstract

Abstract Brunneria borealis, a praying mantid endemic to North America, is wingless, and among more than 2400 worldwide is the only one consisting entirely of parthenogenetic females. In spite of the putative handicaps associated with low vagility and parthenogenetic reduction in genetic variation, this mantid is both abundant and widely distributed along the coastline of North America from eastern Texas to North Carolina. We sampled populations across the mantid’s geographic range to discover clues to its ecological and evolutionary success: (1) the specific genetic mechanism of parthenogenesis, and (2) reproductive output. We found no variation in the mitochondrial COI gene among specimens collected over the extensive geographic range, suggesting recent establishment of this range. Surprisingly, observed heterozygosity in nuclear DNA was higher than expected for most loci, and together with SNP data suggest automictic thelytoky with central fusion for populations originating recently from a single individual. Reproduction was remarkable for its long duration: oviposition of multiple oothecae from a single female (up to six oothecae over 56 days), and time between successive emergences of nymphs from individual oothecae (mean = 31.6+4.75 days) would spread out life history stages in a population, potentially mitigating low egg viability (mean = 14+4.0% of eggs hatched per ootheca) by ensuring survival in a seasonal environment with temporally irregular availability of suitable prey.