Hermaphroditism in fishes: an annotated list of species, phylogeny, and mating system

Abstract

Fewer than 1% of vertebrate species are hermaphroditic, and essentially all of these are fishes. Four types of hermaphroditism are known in fishes: simultaneous (or synchronous) hermaphroditism (SH), protandry (male-to-female sex change; PA), protogyny (female-to-male sex change; PG), and bidirectional sex change (BS or reversed sex change in protogynous species). Here we present an annotated list of hermaphroditic fish species from a comprehensive review and careful re-examination of all primary literature. We confirmed functional hermaphroditism in more than 450 species in 41 families of 17 teleost orders. PG is the most abundant type (305 species of 20 families), and the others are much less abundant, BS in 66 species of seven families, SH in 55 species of 13 families, and PA in 54 species of 14 families. The recently proposed phylogenetic tree indicated that SH and PA have evolved several times in not-closely related lineages of Teleostei but that PG (and BS) has evolved only in four lineages of Percomorpha. Examination of the relation between hermaphroditism type and mating system in each species mostly supported the size-advantage model that predicts the evolution of sequential hermaphroditism. Finally, intraspecific variations in sexual pattern are discussed in relation to population density, which may cause variation in mating system.

Faster juvenile growth promotes earlier sex change in a protandrous hermaphrodite (barramundi Lates calcarifer)

“…In addition to primary females, some barramundi are known to skip spawning as males 30 , which may lead to increased growth and hence size in future spawning seasons 36 . In contrast, primary males are similarly widespread among protogynous fishes, a phenomenon which appears to be linked to population density (see 3 ). Moreover, gonochoristic males (i.e.…”

“…Sex-changing species may breed initially as males before transitioning into females (protandry), or vice-versa (protogyny), with some species also capable of bi-directional sex change 1 . Among fishes, sex change is less common than gonochorism (fixed sexes) but is nonetheless taxonomically widespread across at least 41 teleost families (> 450 species), including species that support significant commercial fisheries (e.g., shads, barramundi, wrasses, groupers) 2 , 3 . Because the sexes are not evenly distributed throughout age and size classes in hermaphroditic species, extrinsic factors (e.g., hydrology, water temperature, etc.)…”

Multiple sex chromosomes in teleost fishes from a cytogenetic perspective: state of the art and future challenges

“…Teleost fishes encompass more than half of the extant vertebrate biodiversity [6,7], making this group extremely attractive for studying a variety of evolutionary subjects, including genome and karyotype evolution. They also represent one of the most diverse animal groups in terms of sex determination and differentiation [8][9][10][11][12][13]. Fish sex chromosomes typically represent early phases of differentiation with no pronounced changes in their morphology, size and genetic content [8,9,14], although there are exceptions particularly in Neotropical fishes (e.g.…”

Idea Paper: Effects of gonad type and body mass on the time required for sex change in fishes

“…Sex change is a well-known phenomenon in plants and animals (Policansky 1982). Female-to-male and male-to-female sex changes have been observed in teleost fishes (Kuwamura et al 2020). Sex change may span over several days to a few months, depending on the species and direction of sex change.…”