Sexual Plasticity and Self-Fertilization in the Sea Anemone Aiptasia diaphana

Abstract

Traits that influence reproductive success and contribute to reproductive isolation in animal and plant populations are a central focus of evolutionary biology. In the present study we used an experimental approach to demonstrate the occurrence of environmental effects on sexual and asexual reproduction, and provide evidence for sexual plasticity and inter-clonal fertilization in laboratory-cultured lines of the sea anemone Aiptasia diaphana. We showed that in A. diaphana, both asexual reproduction by pedal laceration, and sexual reproduction have seasonal components. The rate of pedal laceration was ten-fold higher under summer photoperiod and water temperature conditions than under winter conditions. The onset of gametogenesis coincided with the rising water temperatures occurring in spring, and spawning occurred under parameters that emulated summer photoperiod and temperature conditions. In addition, we showed that under laboratory conditions, asexually produced clones derived from a single founder individual exhibit sexual plasticity, resulting in the development of both male and female individuals. Moreover, a single female founder produced not only males and females but also hermaphrodite individuals. We further demonstrated that A. diaphana can fertilize within and between clone lines, producing swimming planula larvae. These diverse reproductive strategies may explain the species success as invader of artificial marine substrates. We suggest that these diverse reproductive strategies, together with their unique evolutionary position, make Aiptasia diaphana an excellent model for studying the evolution of sex.

Contrasting abundance and contribution of clonal proliferation to the population structure of the corkscrew sea anemone Bartholomea annulata in the tropical Western Atlantic

“…; Schlesinger et al. ). Although ~30% of individuals at Grassy Key Quarry (GKQ) in the Florida Keys shared a genotype with at least one other individual, the most common genotype was shared by only four anemones.…”

“…; Grajales & Rodríguez , ), a genus in which individuals often form extensive monoclonal aggregations and are therefore considered pests in the aquarium trade (Schlesinger et al. ). However, individuals of B. annulata are much larger than those of Exaiptasia , and it has been suggested that large body size is linked to low clonal proliferation in some sea anemone species (Shick ).…”

“…Microsatellite primer information developed from the aposymbiotic Exaiptasia pallida transcriptome, including locus name, simple sequence repeat motif (SSR), allele size, number of recovered alleles, primer sequence, and Gen-Bank BLAST result. Ting & Geller 2000;Tkachenko et al 2007;Schlesinger et al 2010). Although~30% of individuals at Grassy Key Quarry (GKQ) in the Florida Keys shared a genotype with at least one other individual, the most common genotype was shared by only four anemones.…”

Population genetic data of a model symbiotic cnidarian system reveal remarkable symbiotic specificity and vectored introductions across ocean basins

“…The dominant reproductive mode in Aiptasia is pedal laceration, an asexual process that allows for rapid local proliferation and includes vertical symbiont transmission from parent to offspring (Muller‐Parker & Davy ; Schlesinger et al . ). Vectored introductions and clonal propagation through pedal laceration may explain the low genotypic diversity of S. minutum (clonality) observed in this study compared with previous work (e.g.…”

Environmental condition related reproductive strategies and sex ratio in hydras

“…Carlon (1999) suggested that species with limited dispersal potential may have high rates of self‐fertilisation. Sexual reproduction between clone mates found in isolated environments, like in small canals inhabited by H. circumcincta , can occur if there are no barriers to self‐fertilisation (Schlesinger et al. 2010).…”