Sammendrag
‘Cryptic species’ are nowadays commonplace in systematics, and, with the application of barcoding approaches, increasing numbers of species are shown to be supposedly cryptic. However, the use of the term is inconsistent in the literature. Moreover, processes associated with the formation of cryptic species are generally not taken into account. These processes comprise (I) recent divergence, (II) parallel or (III) convergent phenotypic evolution, or (IV) phenotypic stasis. This causes confusion and imprecision in attempting to resolve the origins, evolutionary trajectories and ecological importance of cryptic species.
Here, we will briefly present these four processes based on a recently proposed conceptual framework for the definition of cryptic species. The four categories differ from each other in their temporal scale, phylogenetic context, and underlying selection. In focusing on the phenomenon of stasis, that is the absence of change over long geological periods, we discuss the overlap between stasis seen in the paleontological record and as observed in cryptic species, and we further consider that the challenge of integrating stasis into current evolutionary thinking is due to several different factors. These include microevolutionary research findings in extant species that seem to indicate abundant variation in both genetic markers and quantitative traits and development. Hence, there are contradictions between micro- and macroevolutionary scales. Cryptic species can provide study systems of extant species, which make it possible to bridge the gap between micro- and macroevolutionary research. Here we discuss this potential and provide an outlook on future research directions exploiting cryptic species.
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