Homoplasy as an Evolutionary Process: An Optimistic View on the Recurrence of Similarity in Evolution

Abstract

AbstractIn the cladistic literature, there is a recurrent perspective that considers homoplasy as something undesirable. Homoplasy, according to this view, is believed to obscure homologies that may lead to synapomorphies. Some cladists often call homoplasies an ad hoc hypothesis or an “error in our preliminary assignment of homology.” Consequently, homoplasy is generally regarded negatively, hindering further investigations, because it matters little whether a character subject to homoplasy is a convergence, a parallelism, or a reversal, since they all fall within the problematic homoplastic category. Nixon and Carpenter developed one of the recent arguments supporting this vision. In this context, I will argue that phylogenetics, being a part of evolutionary biology, must be compatible with its principles. Therefore, I will discuss the idea that homoplasy is more complex than just nonhomology, sometimes even constituting evidence of common ancestry (e.g., parallelism). I will put forward the thesis that it is crucial to differentiate instances of convergence, parallelism, and reversions by incorporating recent advances from EvoDevo research. Ultimately, this approach aims to demonstrate that evolutionary biology and phylogenetics mutually complement each other and assist in providing different lines of evidence that can be used to test different evolutionary hypotheses.