Eukaryotic species exist, but not in the way we predicted they should Another talk in this conference is entitled "The Prokaryotic Species Problem is Even Worse". In this talk I will attempt to convince the audience that actually eukaryote species behave much worse than we believed even ten years ago. It was a seductive idea that eukaryote species were independent evolutionary units, but new genomic data strongly disproves this. The main reasons for this are twofold: (1) Eukaryotes have invented meiotic sex which carries out 50:50 mixes of a pair of lineages, often in every generation. (2) Meiotic sex between pairs of organisms from different species, although rarer than sex within species, can be sufficiently frequent to create major phylogenetic discordance. It's still unclear how extensively meiotic exchange might blur the eukaryotic tree of life, but suggestive new genomic data tend to show that species, and even non-sister species, might often exchange substantial fractions of their genomes. Meiotic sex is more likely to be successful among closely related species than distant species. Therefore, rapid evolutionary radiations, such as those that led to the origins of our planet's major groups of animals and plants, will have been the most prone to genetic exchange.
Eukaryotic species exist, but not in the way we predicted they should