Reinforcement and learning

Abstract

Evidence has been accumulating to support the process of reinforcement as a potential mechanism in speciation. In many species, mate choice decisions are influenced by cultural factors, including learned mating preferences (sexual imprinting) or learned mate attraction signals (e.g., bird song). It has been postulated that learning can have a strong impact on the likelihood of speciation and perhaps on the process of reinforcement, but no models have explicitly considered learning in a reinforcement context. We review the evidence that suggests that learning may be involved in speciation and reinforcement, and present a model of reinforcement via learned preferences. We show that not only can reinforcement occur when preferences are learned by imprinting, but that such preferences can maintain species differences easily in comparison with both autosomal and sex-linked genetically inherited preferences. We highlight the need for more explicit study of the connection between the behavioral process of learning and the evolutionary process of reinforcement in natural systems.

Sexual imprinting on ecologically divergent traits leads to sexual isolation in sticklebacks

“…Our results provide new insight into the role of imprinting in speciation, providing an explanation for the conflicting evidence from previous theoretical and empirical studies of imprinting [9,10,42]. It is not imprinting per se that generates sexual isolation but imprinting that is linked to ecological differences, such as when parental traits underlying mate preference are subject to ecologically divergent selection.…”

Early song discrimination by nestling sparrows in the wild

“…Thus, the development of discrimination prior to fledging could reduce learning errors in species recognition, particularly in sympatric populations of sister species. An important question is whether such mechanisms to reduce learning errors evolve as a consequence of reinforcement (Servedio et al, 2009). While there are no currently recognized hybrid zones between golden-crowned sparrows and white-crowned sparrows, patterns of mitochondrial introgression suggest that hybridization may have occurred in the recent past (Weckstein et al, 2001).…”

Females learn from mothers and males learn from others. The effect of mother and siblings on the development of female mate preferences and male aggression biases in Lake Victoria cichlids, genus Mbipia

“…This still requires reproductive isolation, but frequency-dependent selection does not need to drive the divergence. While the imprinting behaviour of the females could cause strong assortative mating patterns in both scenarios of speciation (Verzijden et al 2005;Servedio et al 2008), the male-male interactions are not assortative at all times. The cross-fostering experiment may be an unlikely situation in nature; however, at an incipient speciation stage, hybridisation may be more common, and mixed broods resembling our experiment can easily occur.…”