Understanding the Loss of Maternal Care in Avian Brood Parasites Using Preoptic Area Transcriptome Comparisons in Brood Parasitic and Non-parasitic Blackbirds
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Date
2019-02-13
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Authors
Lynch, Kathleen S.
O’Connell, Lauren A.
Louder, Matthew I. M.
Balakrishnan, Christopher N.
Fischer, Eva K.
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Abstract
Parental care is critical for offspring survival in many species. However, parental behaviors have
been lost in roughly 1% of avian species known as the obligate brood parasites. To shed light on molecular
and neurobiological mechanisms mediating brood parasitic behavior, we compared brain gene expression
patterns between two brood parasitic species and one closely related non-parasitic Icterid (blackbird)
species. Our analyses focused on gene expression changes specifically in the preoptic area (POA), a brain
region known to play a critical role in parental behavior across vertebrates. Using comparative transcriptomic approaches, we identified gene expression patterns associated with brood parasitism. We
evaluated three non-mutually exclusive alternatives for the evolution of brood parasitism: (1) retention of
juvenile-like (neotenic) gene expression, (2) reduced expression of maternal care-related genes in the POA,
and/or (3) increased expression of genes inhibiting maternal care. We find evidence for neotenic expression
patterns in both species of parasitic cowbirds as compared to maternal, non-parasites. In addition, we
observed differential expression in a number of genes with previously established roles in mediating
maternal care. Together, these results provide the first insight into transcriptomic and genetic mechanisms
underlying the loss of maternal behavior in avian brood parasites.
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DOI
10.1534/g3.118.200992