Many species of animals use mating traits, such as songs, pheromones, and other signals, to find mates. Thus, producing and preferring appropriate traits is essential for successful reproduction. Acquiring correct traits is a major challenge when they are learned, since this risks mistakenly learning from co-occurring species. Cross-species learning, in turn, can reduce the individual’s chances of mating and erode species differences in mating traits. We know surprisingly little about how cross-species learning is avoided. The overall problem addressed in my project is how and why juvenile songbirds avoid learning the songs of other species.
How individuals avoid mating with members of other species is of theoretical and practical importance. From a theoretical perspective, mating between species can be costly to the affected individuals, leading to evolutionary responses, and, if it is widespread, can lead to the extinction of one of the species. From a practical perspective, human-induced changes to geographic ranges are driving novel instances of contact between formerly isolated species. An understanding of how animals avoid mating with individuals from other species will provide important insights into the outcome of such range shifts.
My project has three main aims, focused on understanding the causes and consequences of early song discrimination in a widespread songbird species, the pied flycatcher. AIM 1: Songbirds can recognize their own species’ songs from a very young age, an ability that influences what songs they are likely to learn and prefer as adults. The first aim of the project is to determine why and how this ability has evolved using a large-scale experiment at multiple populations throughout the European range of the pied flycatcher. This experiment measures the responses of nestling birds to playbacks of songs to test two main hypotheses for the evolution of early song discrimination. AIM 2: The second aim of the project progresses beyond the earliest stages of learning to determine the key periods throughout an individual’s development when they are sensitive to song exposure. Akin to language learning in human children, songbirds are particularly sensitive during certain life stages early in life. Determining when these stages occur will provide insights into how likely individuals are to learn the songs of their own versus other species and, since song learning in birds is our principal model system for understanding language learning in humans, these insights will have broad impacts. AIM 3: The third aim of the project is to determine how species differences in song perception arise in the brain. The songbird auditory system develops to be specifically responsive to the types of sounds produced by members of the same species, making them particularly likely to memorize the songs of their own species. However, we know very little about how and when the auditory system develops species-specific differences. To address this gap, we will use gene expression to assess auditory responses of juvenile pied flycatchers and closely related collared flycatchers to the songs of their own and other species to determine the key brain regions and genes driving species differences.
Now that the project has ended, we have successfully addressed each of these AIMs.
