Spontaneous speciation by ploidy elevation: Laboratory synthesis of a new clonal vertebrate

摘要

The transition from diploid (2n) to polyploid (3n, 4n, and so forth), a relatively common process in plants and some animal taxa, represents rapid speciation, as only rarely are hybrids able to form genetically bal anced gametes (1). In vertebrates, poly ploidy is often associated with asexual reproduction: sperm-dependent (gyno genesis, hybridogenesis, and klepto genesis) in amphibians and fish, and sperm-independent (parthenogenesis) in squamate reptiles (2). For the latter, ap proximately 0.6% of known species are parthenogenetic, and, with few exceptions, these arose via hybridization between sexually reproducing progenitors (3). Given the relatively recent origin of most parthenogenetic taxa (2), it should then be possible to recreate parthenogenetic lineages of varying ploidy by hybridizing known progenitors in the laboratory, as has been achieved for some diploid hybrid plant species (4) and unisexual fish and frogs (see ref. 5).