The difficulty of studying speciation lies firstly in the difficulty of defining a species: « A fly in a wine glass » . No consensus exists, a possible definition is "a group of individuals sharing a common gene pool, isolated from other groups" .
Hakuna makubaliano ipo, ufafanuzi inawezekana ni "kundi la watu kubadilishana kawaida gene pool, pekee kutoka makundi mengine".