Larger brains spur species diversification in birds

Abstract

Evidence is accumulating that species traits can spur their evolutionary diversification by influencing niche shifts, range expansions, and extinction risk. Previous work has shown that larger brains (relative to body size) facilitate niche shifts and range expansions by enhancing behavioral plasticity but whether larger brains also promote evolutionary diversification is currently backed by insufficient evidence. We addressed this gap by combining a brain size dataset for >1900 avian species worldwide with estimates of diversification rates based on two conceptually different phylogenetic‐based approaches. We found consistent evidence that lineages with larger brains (relative to body size) have diversified faster than lineages with relatively smaller brains. The best supported trait‐dependent model suggests that brain size primarily affects diversification rates by increasing speciation rather than decreasing extinction rates. In addition, we found that the effect of relatively brain size on species‐level diversification rate is additive to the effect of other intrinsic and extrinsic factors. Altogether, our results highlight the importance of brain size as an important factor in evolution and reinforce the view that intrinsic features of species have the potential to influence the pace of evolution.

The role of behavioural flexibility in primate diversification

“…Under this scenario, even under the assumption that these behaviours are ancestral to genera, the positive associations we find seem unlikely to support behavioural flexibility promoting diversification as per the behavioural drive hypothesis: behavioural flexibility does not seem to be driving recent, shallow divergences in primates. This contrasts to evidence found in birds (Nicolakakis, et al, 2003;Sol, et al, 2005;Sayol, et al, 2019) and suggests that either there is no generalizable relationship between behaviour and lineage diversification, or that we need to focus on extinction rather than speciation to understand the macro-evolutionary effects of behavioural flexibility in primates.…”

“…recent speciation events or population decline). Three comparative studies have tested for the macro-evolutionary effects of behavioural flexibility on lineage diversification across multiple lineages, all in birds (Nicolakakis, et al, 2003;Sol, et al, 2005-also see Sol, 2003Sayol, et al, 2019). These studies have employed two proposed correlates of behavioural flexibility: brain size relative to body size (a structural measure presumed and shown elsewhere to be associated with behavioural flexibility; e.g.…”

Cerebrotypes in Cephalopods: Brain Diversity and Its Correlation With Species Habits, Life History, and Physiological Adaptations

“…In her original study, Borrelli (2007) attempted to correlate cephalopod' relative brain size with species richness (e.g., Lynch, 1990;Owens et al, 1999;Nicolakakis et al, 2003;Sol et al, 2005;Sayol et al, 2019). Species richness, and possibly subspecies (Sol et al, 2005) appears to be affected by behavioral flexibility, so that taxa appearing more flexible to environmental changes (i.e., opportunistic species) are also those that are represented by a higher number of species as opposed to those characterized by specialist species, and which are less speciose.…”

Host Cognition and Parasitism in Birds: A Review of the Main Mechanisms

“…Because these cognitive functions deeply affect how animals interact with their environment, the study of cognition has long been recognized as central to understand the ecology and evolution of animals. Thus, cognition has been linked to a variety of key eco-evolutionary processes such as range expansions, niche shifts, population dynamics, and adaptive divergence (Sol et al, 2005;Ducatez et al, 2015;Sayol et al, 2016Sayol et al, , 2019Fristoe et al, 2017;Riotte-Lambert et al, 2017). Although cognition is also thought to be essential to eco-evolutionary dynamics in hostparasite systems, evidence remains scarce (but see, e.g., Ader et al, 2006;Gómez-Moracho et al, 2017).…”