1 - 10 %
||Yakimowski SB, Rieseberg LH. The role of homoploid hybridization in evolution: a century of studies synthesizing genetics and ecology. Am J Bot. 2014 Aug101(8):1247-58. doi: 10.3732/ajb.1400201 p.1248 left column 4th paragraphPubMed ID25156978
||Schwenk K, Brede N, Streit B. Introduction. Extent, processes and evolutionary impact of interspecific hybridization in animals. Philos Trans R Soc Lond B Biol Sci. 2008 Sep 12 363(1505):2805-11. doi: 10.1098/rstb.2008.0055.PubMed ID18534946
||Abstract: "[Investigators] revisit Stebbins' views on the frequency of hybridization, the evolution of hybrid sterility, and the evolutionary importance of transgressive segregation, introgression, and homoploid hybrid speciation in the context of contemporary evidence. Floristic surveys indicate that ∼10% of plant species hybridize, suggesting that natural hybridization is not as ubiquitous as Stebbins argued."
||P.1248 left column 4th paragraph: "Current estimates of the proportion of animal species that hybridize range from 1 to 10%, and in contrast to plants, no taxonomic bias in hybridization has been detected (primary source). Thus, hybridization is still considered more common in plants than animals, and Stebbins was correct that some plant groups are associated with a higher propensity for hybridization. However, he may have overstated the ubiquity of hybridization in plants."