Behavioural response to song and genetic divergence in two subspecies of white-crowned sparrows (Zonotrichia leucophrys).
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2017-06
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Divergence in sexual signals may drive reproductive isolation between lineages, but behavioural barriers can weaken in contact zones. Here, we investigate the role of song as a behavioural and genetic barrier in a contact zone between two subspecies of white-crowned sparrows (Zonotrichia leucophrys). We employed a reduced genomic data set to assess population structure and infer the history underlying divergence, gene flow and hybridization. We also measured divergence in song and tested behavioural responses to song using playback experiments within and outside the contact zone. We found that the subspecies form distinct genetic clusters, and demographic inference supported a model of secondary contact. Song phenotype, particularly length of the first note (a whistle), was a significant predictor of genetic subspecies identity and genetic distance along the hybrid zone, suggesting a close link between song and genetic divergence in this system. Individuals from both parental and admixed localities responded significantly more strongly to their own song than to the other subspecies song, supporting song as a behavioural barrier. Putative parental and admixed individuals were not significantly different in their strength of discrimination between own and other songs; however, individuals from admixed localities tended to discriminate less strongly, and this difference in discrimination strength was explained by song dissimilarity as well as genetic distance. Therefore, we find that song acts as a reproductive isolating mechanism that is potentially weakening in a contact zone between the subspecies. Our findings also support the hypothesis that intraspecific song variation can reduce gene flow between populations.
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Lipshutz, Sara E, Isaac A Overcast, Michael J Hickerson, Robb T Brumfield and Elizabeth P Derryberry (2017). Behavioural response to song and genetic divergence in two subspecies of white-crowned sparrows (Zonotrichia leucophrys). Molecular ecology, 26(11). pp. 3011–3027. 10.1111/mec.14002 Retrieved from https://hdl.handle.net/10161/28452.
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Sara E Lipshutz
Our research focuses on the evolution of behavior across weird and wonderfully diverse species of birds. This work bridges “muddy boots” experimental fieldwork with a variety of molecular and computational approaches in genetics, genomics, neuroscience, and endocrinology. We have several research foci:
1. Female perspectives in biology. Cultural biases shape our predictions for how and why animals behave the way they do, and female animals have historically been neglected in biological research. We study the evolution of female competition across diverse avian species, ranging from social polyandry to monogamy in shorebirds and songbirds. Critically, hypotheses derived from studying males (i.e. testosterone focus) do not explain interspecific variation in female aggression. We use population genomic and transcriptomic data to evaluate the proximate causes and ultimate consequences of female competition.
2. Global change biology. In the age of the Anthropocene, animals are facing evolutionary unprecedented environmental changes. Sensory pollutants like anthropogenic noise and artificial light at night can alter animal physiology, behavior, and ecology on a rapid timescale. Behavior flexibility and adaptation may lead the way in helping animals respond to novel challenges. We investigate why some individuals and species may be better prepared to face global change.
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