Evidence for selfing in a vertebrate from whole-genome sequencing

Area of Science:

• * Evolutionary biology
• * Reproductive strategies
• * Ichthyology

Background:

• * Asexual reproduction, including parthenogenesis, is increasingly documented across vertebrate taxa.
• * Self-fertilization (selfing) is exceptionally rare in vertebrates, with only one known case in the mangrove killifish (Kryptolebias marmoratus).
• * Cichlid fish exhibit diverse sex determination and reproductive strategies, including sequential hermaphroditism.

Purpose of the Study:

• * To investigate a potential case of facultative selfing in the cichlid fish Benitochromis nigrodorsalis.
• * To confirm uniparental reproduction and analyze genetic evidence supporting selfing in this species.

Main Methods:

• * Laboratory observation of a wild-caught Benitochromis nigrodorsalis individual producing offspring without a mating partner.
• * Genome-wide single-nucleotide polymorphism (SNP) data analysis of the parent and its offspring.

Main Results:

• * Confirmation of uniparental reproduction in the studied Benitochromis nigrodorsalis individual.
• * Reduced overall heterozygosity in offspring compared to outbred individuals, with retained maternal heterozygosity around 51%.
• * Heterozygosity patterns exclude automixis (e.g., terminal or central fusion) as the parthenogenetic mechanism.

Conclusions:

• * Facultative selfing is demonstrated in Benitochromis nigrodorsalis, a species previously considered biparentally reproducing.
• * This reproductive flexibility may enhance survival and evolutionary success by ensuring reproduction when mates are absent.
• * The findings expand the known repertoire of reproductive strategies within cichlid fishes.