Teaching old cells new tricks

Schlosser, Gerhard. (2021). Teaching old cells new tricks. In Gerhard Schlosser, Evolutionary origin of sensory and neurosecretory cell types: Vertebrate cranial placodes, Volume 2. Boca Raton: CRC Press.

Abstract

This second introductory chapter clarifies conceptual issues relating to homology and evolutionary innovation and illustrates them with examples from sensory evolution. The first part of the chapter introduces the general concepts of character identity, homology and evolutionary innovation, while the second part applies these general concepts to the evolution of cell types. It is argued that characters can only be tracked through evolving lineages (allowing to identify homologs), if characters are conceptualized as independently evolving units. This in turn requires that characters are genetically individuated, meaning that they have at least a partially different genetic basis from other characters. Cell types are then introduced as a particular kind of independently evolving unit (or character). The identity of a cell type is typically determined by a core regulatory network (CoRN) of cross-regulating genes (often encoding transcription factors). Cell types in different species remain the same (homologous) as long as they retain the same CoRN, even though downstream target genes may change. Novel cell types originate, when a new CoRN is established either by duplication and divergence of a preexisting CoRN or by recombination and redeployment of genes previously used for other functions.

Publisher

CRC Press

Rights

Attribution-NonCommercial-NoDerivatives 4.0 International

cbn

Collections

Zoology (Book Chapters)