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Developmental Modes and Developmental Mechanisms can Channel Brain Evolution.

Charvet CJ, Striedter GF - Front Neuroanat (2011)

Bottom Line: We suggest that altriciality facilitates the evolution of telencephalic expansion by delaying telencephalic neurogenesis.We further hypothesize that delays in telencephalic neurogenesis generate delays in telencephalic maturation, which in turn foster neural adaptations that facilitate learning.Overall, we argue that developmental modes have influenced how some lineages of birds increased the size of their telencephalon and that this, in turn, has influenced subsequent changes in brain circuits and behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California Irvine, CA, USA.

ABSTRACT
Anseriform birds (ducks and geese) as well as parrots and songbirds have evolved a disproportionately enlarged telencephalon compared with many other birds. However, parrots and songbirds differ from anseriform birds in their mode of development. Whereas ducks and geese are precocial (e.g., hatchlings feed on their own), parrots and songbirds are altricial (e.g., hatchlings are fed by their parents). We here consider how developmental modes may limit and facilitate specific changes in the mechanisms of brain development. We suggest that altriciality facilitates the evolution of telencephalic expansion by delaying telencephalic neurogenesis. We further hypothesize that delays in telencephalic neurogenesis generate delays in telencephalic maturation, which in turn foster neural adaptations that facilitate learning. Specifically, we propose that delaying telencephalic neurogenesis was a prerequisite for the evolution of neural circuits that allow parrots and songbirds to produce learned vocalizations. Overall, we argue that developmental modes have influenced how some lineages of birds increased the size of their telencephalon and that this, in turn, has influenced subsequent changes in brain circuits and behavior.

No MeSH data available.


Related in: MedlinePlus

A plot of telencephalon volume versus overall brain volume shows that the telencephalon is disproportionately large in parrots, songbirds (i. e., oscine passerines), and anseriform birds (ducks and geese) compared with galliform birds and diverse other avian species. The other avian species in this graph include mainly pigeons, shorebirds and falcons. Data are from Iwaniuk and Hurd (2005).
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Figure 1: A plot of telencephalon volume versus overall brain volume shows that the telencephalon is disproportionately large in parrots, songbirds (i. e., oscine passerines), and anseriform birds (ducks and geese) compared with galliform birds and diverse other avian species. The other avian species in this graph include mainly pigeons, shorebirds and falcons. Data are from Iwaniuk and Hurd (2005).

Mentions: Parrots, songbirds, and anseriform birds (ducks and geese) have evolved a disproportionately large telencephalon compared with many other birds (Figure 1; Portmann, 1947a; Boire and Baron, 1994; Iwaniuk and Hurd, 2005). Although the proportional size of the telencephalon in ducks and geese rivals that in parrots and songbirds, the latter taxa differ from ducks and geese in numerous respects. First, parrots and songbirds are altricial (their hatchlings are fed by their parents), whereas ducks and geese are precocial (their hatchlings feed on their own; Starck and Ricklefs, 1998). Second, parrots and songbirds enlarge their telencephalon by delaying telencephalic neurogenesis (Striedter and Charvet, 2008; Charvet and Striedter, 2009a), whereas ducks and geese enlarge their telencephalon before telencephalic neurogenesis begins (Charvet and Striedter, 2009b). Finally, parrots and songbirds have evolved a set of telencephalic nuclei responsible for vocal learning (Nottebohm, 1972; Nottebohm et al., 1976; Doupe and Kuhl, 1999), whereas anseriform birds have evolved an expanded trigeminal system that is related to feeding (Dubbeldam and Visser, 1987; Gutiérrez-Ibáñez et al., 2009). Thus, anseriform birds differ form parrots and songbirds in their developmental modes, in brain development, in brain anatomy, and in behavior.


Developmental Modes and Developmental Mechanisms can Channel Brain Evolution.

Charvet CJ, Striedter GF - Front Neuroanat (2011)

A plot of telencephalon volume versus overall brain volume shows that the telencephalon is disproportionately large in parrots, songbirds (i. e., oscine passerines), and anseriform birds (ducks and geese) compared with galliform birds and diverse other avian species. The other avian species in this graph include mainly pigeons, shorebirds and falcons. Data are from Iwaniuk and Hurd (2005).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3037498&req=5

Figure 1: A plot of telencephalon volume versus overall brain volume shows that the telencephalon is disproportionately large in parrots, songbirds (i. e., oscine passerines), and anseriform birds (ducks and geese) compared with galliform birds and diverse other avian species. The other avian species in this graph include mainly pigeons, shorebirds and falcons. Data are from Iwaniuk and Hurd (2005).
Mentions: Parrots, songbirds, and anseriform birds (ducks and geese) have evolved a disproportionately large telencephalon compared with many other birds (Figure 1; Portmann, 1947a; Boire and Baron, 1994; Iwaniuk and Hurd, 2005). Although the proportional size of the telencephalon in ducks and geese rivals that in parrots and songbirds, the latter taxa differ from ducks and geese in numerous respects. First, parrots and songbirds are altricial (their hatchlings are fed by their parents), whereas ducks and geese are precocial (their hatchlings feed on their own; Starck and Ricklefs, 1998). Second, parrots and songbirds enlarge their telencephalon by delaying telencephalic neurogenesis (Striedter and Charvet, 2008; Charvet and Striedter, 2009a), whereas ducks and geese enlarge their telencephalon before telencephalic neurogenesis begins (Charvet and Striedter, 2009b). Finally, parrots and songbirds have evolved a set of telencephalic nuclei responsible for vocal learning (Nottebohm, 1972; Nottebohm et al., 1976; Doupe and Kuhl, 1999), whereas anseriform birds have evolved an expanded trigeminal system that is related to feeding (Dubbeldam and Visser, 1987; Gutiérrez-Ibáñez et al., 2009). Thus, anseriform birds differ form parrots and songbirds in their developmental modes, in brain development, in brain anatomy, and in behavior.

Bottom Line: We suggest that altriciality facilitates the evolution of telencephalic expansion by delaying telencephalic neurogenesis.We further hypothesize that delays in telencephalic neurogenesis generate delays in telencephalic maturation, which in turn foster neural adaptations that facilitate learning.Overall, we argue that developmental modes have influenced how some lineages of birds increased the size of their telencephalon and that this, in turn, has influenced subsequent changes in brain circuits and behavior.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California Irvine, CA, USA.

ABSTRACT
Anseriform birds (ducks and geese) as well as parrots and songbirds have evolved a disproportionately enlarged telencephalon compared with many other birds. However, parrots and songbirds differ from anseriform birds in their mode of development. Whereas ducks and geese are precocial (e.g., hatchlings feed on their own), parrots and songbirds are altricial (e.g., hatchlings are fed by their parents). We here consider how developmental modes may limit and facilitate specific changes in the mechanisms of brain development. We suggest that altriciality facilitates the evolution of telencephalic expansion by delaying telencephalic neurogenesis. We further hypothesize that delays in telencephalic neurogenesis generate delays in telencephalic maturation, which in turn foster neural adaptations that facilitate learning. Specifically, we propose that delaying telencephalic neurogenesis was a prerequisite for the evolution of neural circuits that allow parrots and songbirds to produce learned vocalizations. Overall, we argue that developmental modes have influenced how some lineages of birds increased the size of their telencephalon and that this, in turn, has influenced subsequent changes in brain circuits and behavior.

No MeSH data available.


Related in: MedlinePlus