Neural mechanisms underlying the evolvability of behaviour

Abstract

The complexity of nervous systems alters the evolvability of behaviour. Complex nervous systems are phylogenetically constrained; nevertheless particular species-specific behaviours have repeatedly evolved, suggesting a predisposition towards those behaviours. Independently evolved behaviours in animals that share a common neural architecture are generally produced by homologous neural structures, homologous neural pathways and even in the case of some invertebrates, homologous identified neurons. Such parallel evolution has been documented in the chromatic sensitivity of visual systems, motor behaviours and complex social behaviours such as pair-bonding. The appearance of homoplasious behaviours produced by homologous neural substrates suggests that there might be features of these nervous systems that favoured the repeated evolution of particular behaviours. Neuromodulation may be one such feature because it allows anatomically defined neural circuitry to be re-purposed. The developmental, genetic and physiological mechanisms that contribute to nervous system complexity may also bias the evolution of behaviour, thereby affecting the evolvability of species-specific behaviour.

Rudimentary substrates for vocal learning in a suboscine

“…The neural and behavioural substrates we described in phoebes may thus represent the vestige of complex vocal-learning circuitry. Alternatively, the forebrain pathways for respiratory control of vocalizations observed in phoebes might have been common to the ancestor of Passeriformes and Psittaciformes and then separately enabled and given rise to vocal learning in oscines and parrots (that is, parallel evolution) 17 .…”

“…The evolutionary origin of complex behavioural traits, such as vocal learning, can be better understood through examination of homologous neural circuits shared by closely related species 17 . To bridge the neuroanatomical link between vocal learners and non-learners, we studied two closely related Passeriformes subgroups: the vocal-learning oscines and non-learning suboscines (Fig.…”

Mice selectively bred for high voluntary wheel running have larger midbrains: support for the mosaic model of brain evolution

“…Of course, changes in brain size alone obviously do not account for all behavioral evolution (e.g. see Katz, 2011).…”

What is comparable in comparative cognition?

“…Electrolocation in weakly electric fish arose independently in the South American and African lineages, where different areas of the brain mediate the analysis of electro-sensory input [23]. Examples of parallel evolution, where behavioural abilities arise independently from homologous structures or genes are also widespread [19,21], and these cases illustrate the difficulty in deducing homology or convergence from mere behavioural abilities even more strongly.…”

“…Finally, a complication in mapping overt behavioural abilities onto phylogenetic trees is that the same (or similar) sensory or cognitive feats might be generated by entirely different mechanisms that have arisen by convergent evolution [19]. On occasion, these are clearly identifiable as instances of convergence when abilities have emerged in highly distinct lineages, such as echolocation in bats and dolphins [20,21] or flexible tool use in primates and corvids [22].…”