Date:
April 18, 2017
Source:
The City University of New York
If
you are raised by other species, then how do you know who you are? Although
heterospecific foster parents rear brood parasitic brown-headed cowbird chicks,
juvenile cowbirds readily recognize and affiliate with other cowbirds. That's
because they have a secret handshake or password. Specifically, the
"password" hypothesis helps explain this paradox of species
recognition: Social recognition processes in brood parasites are initiated by
exposure to a password: in the case of cowbirds, a specific chatter call. A new
study appearing in the Journal of Experimental Biology describes the neural
basis for password-based species recognition in cowbirds.
Roughly
1% of bird species are obligate brood parasites. Female obligate brood
parasites shirk parental care duties by laying their eggs in the nests of other
females. This breeding strategy is extremely successful for the female parasite
but raises questions, particularly with respect to species recognition. For
instance, how does a juvenile bird that is not raised by familial members come
to recognize its own species and avoid imprinting on the host species that
cared for it from the day it hatched? One possibility is that young brood
parasites use a password to identify conspecifics, and learning about
species-specific signals occurs only after the password is used to find
conspecifics.
Researchers
have now demonstrated the neural basis for password-based species recognition
in an obligate brood parasite. They showed that the auditory forebrain regions
in cowbirds, which respond selectively to learned vocalizations, such as songs,
also respond selectively to non-learned chatter. However, if the password is
not used to locate other cowbirds, the young brood parasite will mis-imprint on
its host species -- a process manifested in the brain by elevated gene
induction in response to the host's song.
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