The Reproductive Success of × F Hybrid Females (Amphibia: Salamandridae).

Two large-bodied newt species, and , hybridize in nature across the Balkan Peninsula. Consequences of hybridization upon secondary contact of two species include species displacement and asymmetrical introgression of mtDNA. We set an experimental reciprocal cross of parental species and obtained two genotypes of F hybrids (with or mtDNA). When hybrids attained sexual maturity, they were engaged in mutual crossings and backcrossing with parental species. We followed reproductive traits over two successive years. Our main aim was to explore the reproductive success of F females carrying different parental mtDNA. Additionally, we tested for differences in reproductive success within female genotypes depending on the crossing with various male genotypes (hybrids or parental species). Both female genotypes had similar oviposition periods, number of laid eggs and hatched larvae but different body and egg sizes. Overall reproductive success (percentage of egg-laying females and viability of embryos) was similar for both genotypes. The type of crossing led to some differences in reproductive success within female genotypes. The obtained results suggest that processes that led to exclusion of mtDNA in natural populations may be related to the survival at postembryonic stages of F generation or reproductive barriers that emerged in subsequent hybrid generations.