This book is the first to report that research in allogenics/xenogenics has conclusively shown that fishes have retained bisexual potency even after sexual maturity and spermiation. The XY genotype found in the unexpected female phenotypes sired by supermales (Y1Y2) and androgenic males (Y2Y2) points out the need to employ sex specific molecular markers to identify the true genotype of a juvenile, which matures either as a male or female, depending upon the sex of its pair (female or male) and thereby critically assessing the environmental role in sex determination. This book is meant to assist molecular biologists in the search of sex determining gene(s), fishery biologists endeavouring to develop techniques for profitable monosex aquaculture and ecologists interested in conservation of fishes and their genomes.
Table of Contents
Gonadal origin, eggs and sperm; Chromosomes and heterogamety; Prevalence of gonochorism; Escape from Muller’s ratchet; Multiple parentage and genetic diversity; Prelude
Cytogenetics and Sex Chromosomes
Chromosomes and genomes; Cytogenetics; Heterogamety
Hybridization and Sex Ratio
Extent of hybridizations; Hybrid identification; Viability and fertility; Introgressive hybridization; Sex ratio
Gynogenesis and Consequences
Gynogenics types; Purity of gynogenics; Survival and gamety; Fertility and F1 sex ratio; Sex ratio and departures
Androgenesis and Autosomes
Production methods; Survival; Fertility; Overriding autosomes
Triploidy and sterility
Types of triploids; Survival and sex ratio; Male’s fertilizability; Female sterility
Tetraploidy and polyploidy
Survey and history; Scope for polyploidization; Tetraploid types; True induced tetraploids; Polyploidy; Intraploid hybridizations; Unreduced "gamete bank"
Allogenesis and xenogenesis
Primordial Germ Cells (PGCs); PGC transplantation system; PGCs in hybrid embryos; PGCs in heterospecific embryos; Spermatogonial Stem Cells (SSCs); Renewal of SSCs; SSC transplantation system; Relevance of PGCs and SSCs; Surgical gonadectomy
Sex changers and hermaphroditism
Extant of hermaphroditism; Sex change in gonochores; Sex allocation; Sex changing age; Genetic or environment?
Unisexualism and reproductive modes
Mutational meltdown; Exploration of reproductive modes; Squalius alburnoides; Males in unisexuals
Genetic sex determination
Molecular markers; Sex chromosomes; Sexonomics; Sex changers; Polygenic sex determination; Concluding remarks