Meeting Abstract
The external conditions that contributed to the evolution of avian obligate brood parasitism have been well-studied whereas the intrinsic mechanisms are less well understood. Our lab previously identified differentially expressed transcripts specific to the preoptic area (POA) in brood parasitic and a closely related non-parasitic species. We selected six maternal care-related candidate genes and compared their expression in additional hypothalamic regions in parasitic bronzed cowbirds (Molothrus aeneus) and non-parasitic red-winged blackbirds (Agelaius phoeniceus). We compared genes with neuromodulatory and structural functions including mesotocin (avian homolog of oxytocin), arginine vasotocin (homolog of vasopressin), galanin, prostaglandin synthase, stathmin and mesencephalic astrocyte derived neurotrophic factor (MANF). We compared expression patterns of these genes in a pooled sample that contained tissue punches from the lateral hypothalamus, tuberal nucleus, ventral medial hypothalamus, and posterior medial hypothalamus. Results reveal that differential expression of these genes between parasitic and non-parasitic blackbirds is not specific to the POA. We found significant differences between parasite and non-parasite species in all transcripts within these additional hypothalamic regions. These results suggest that the POA is likely not the only brain region that was targeted by evolution to produce this novel behavioral phenotype as additional hypothalamic regions exhibit similar gene expression differences between parasitic and non-parasitic species. Additional studies will examine brain regions within other social behavior-related regions to identify the full suite of neural architecture that may underlie the brood parasitic strategy.
