The speciation view: Disentangling multiple causes of adaptive and non‐adaptive radiation in terms of speciation

Abstract

Biological diversification often includes burst of lineage splitting. Such “radiation” has been known to act as evolutionary arenas with the potential to generate unique phylogenetic clusters and further novel groups. Although these radiations when accompanied by ecological diversification, so‐called “adaptive radiation” have persisted as a central premise in evolutionary biology, the ecological and genetic mechanism of such rapid diversification has remained unclear. There are several critical definitions for the pattern of adaptive radiation, and those provide delimitation of adaptive and non‐adaptive radiation. That being said, only a few studies have provided any clear demarcations in our understanding of the adaptive and non‐adaptive causes of radiation from the mechanism of speciation. Here, we review the current consensus for the causes of adaptive radiation, especially along with the recent theoretical synthesis of “ecological speciation.” Further, we suggest the signature of adaptive and non‐adaptive radiation in the earliest stages of diversification from the viewpoint of speciation. These criteria from the speciation view are useful to find the cases with the signatures of adaptive/non‐adaptive radiation.

The potential role of spatial sorting in speciation and adaptive radiations

“…In Table 1, we provide a summary of studies highlighting a role for spatial sorting in generating phenotypic change associated with dispersal, which suggests this may be a more general mechanism of evolution change. Herein, we connect spatial sorting to the rich and complex evolutionary mechanisms reviewed by Matsubayashi and Yamaguchi (2022), which must be considered as we try to understand the processes that promote and impede speciation and adaptive radiations.…”

“…Matsubayashi and Yamaguchi (2022) review our understanding of the adaptive and non‐adaptive causes of radiations—defined as bursts of lineage splitting generating unique phylogenetic clusters and novel groups of species (Gavrilets & Losos, 2009). They describe two approaches to the study of radiations and their underlying causes.…”

Reply to Kagawa's comment: Quantifying mixture modes of evolutionary radiations

“…In this reply and Matsubayashi and Yamaguchi (2022), we intend to bring a new perspective to adaptive and non‐adaptive radiations from the mechanical aspect of the evolution of reproductive isolation. Considering that ecological speciation itself is fragile (Gow et al, 2006), ecological and phenotypic patterns in the same evolutionary radiation change over time from the pattern of non‐adaptive radiation to that of adaptive radiation, and vice versa.…”

Adaptive and non‐adaptive causes of radiation: Is adaptation a harsh mistress of diversity?

“…The speciation view: Disentangling multiple causes of adaptive and non‐adaptive radiation in terms of speciation (Matsubayashi and Yamaguchi, 2022).…”