Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).

The shift from a diurnal to nocturnal lifestyle in vertebrates is generally associated with either enhanced visual sensitivity or a decreased reliance on vision. Within birds, most studies have focused on differences in the visual system across all birds with respect to nocturnality-diurnality. The...

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Autores principales:	Jeremy R Corfield, Anna C Gsell, Dianne Brunton, Christopher P Heesy, Margaret I Hall, Monica L Acosta, Andrew N Iwaniuk
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2011
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/328f2d8678d04eddbb51c40968fd5a2e
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spelling	oai:doaj.org-article:328f2d8678d04eddbb51c40968fd5a2e2021-11-18T06:48:14ZAnatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).1932-620310.1371/journal.pone.0022945https://doaj.org/article/328f2d8678d04eddbb51c40968fd5a2e2011-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/21860663/?tool=EBIhttps://doaj.org/toc/1932-6203The shift from a diurnal to nocturnal lifestyle in vertebrates is generally associated with either enhanced visual sensitivity or a decreased reliance on vision. Within birds, most studies have focused on differences in the visual system across all birds with respect to nocturnality-diurnality. The critically endangered Kakapo (Strigops habroptilus), a parrot endemic to New Zealand, is an example of a species that has evolved a nocturnal lifestyle in an otherwise diurnal lineage, but nothing is known about its' visual system. Here, we provide a detailed morphological analysis of the orbits, brain, eye, and retina of the Kakapo and comparisons with other birds. Morphometric analyses revealed that the Kakapo's orbits are significantly more convergent than other parrots, suggesting an increased binocular overlap in the visual field. The Kakapo exhibits an eye shape that is consistent with other nocturnal birds, including owls and nightjars, but is also within the range of the diurnal parrots. With respect to the brain, the Kakapo has a significantly smaller optic nerve and tectofugal visual pathway. Specifically, the optic tectum, nucleus rotundus and entopallium were significantly reduced in relative size compared to other parrots. There was no apparent reduction to the thalamofugal visual pathway. Finally, the retinal morphology of the Kakapo is similar to that of both diurnal and nocturnal birds, suggesting a retina that is specialised for a crepuscular niche. Overall, this suggests that the Kakapo has enhanced light sensitivity, poor visual acuity and a larger binocular field than other parrots. We conclude that the Kakapo possesses a visual system unlike that of either strictly nocturnal or diurnal birds and therefore does not adhere to the traditional view of the evolution of nocturnality in birds.Jeremy R CorfieldAnna C GsellDianne BruntonChristopher P HeesyMargaret I HallMonica L AcostaAndrew N IwaniukPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 6, Iss 8, p e22945 (2011)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Jeremy R Corfield Anna C Gsell Dianne Brunton Christopher P Heesy Margaret I Hall Monica L Acosta Andrew N Iwaniuk Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).
description	The shift from a diurnal to nocturnal lifestyle in vertebrates is generally associated with either enhanced visual sensitivity or a decreased reliance on vision. Within birds, most studies have focused on differences in the visual system across all birds with respect to nocturnality-diurnality. The critically endangered Kakapo (Strigops habroptilus), a parrot endemic to New Zealand, is an example of a species that has evolved a nocturnal lifestyle in an otherwise diurnal lineage, but nothing is known about its' visual system. Here, we provide a detailed morphological analysis of the orbits, brain, eye, and retina of the Kakapo and comparisons with other birds. Morphometric analyses revealed that the Kakapo's orbits are significantly more convergent than other parrots, suggesting an increased binocular overlap in the visual field. The Kakapo exhibits an eye shape that is consistent with other nocturnal birds, including owls and nightjars, but is also within the range of the diurnal parrots. With respect to the brain, the Kakapo has a significantly smaller optic nerve and tectofugal visual pathway. Specifically, the optic tectum, nucleus rotundus and entopallium were significantly reduced in relative size compared to other parrots. There was no apparent reduction to the thalamofugal visual pathway. Finally, the retinal morphology of the Kakapo is similar to that of both diurnal and nocturnal birds, suggesting a retina that is specialised for a crepuscular niche. Overall, this suggests that the Kakapo has enhanced light sensitivity, poor visual acuity and a larger binocular field than other parrots. We conclude that the Kakapo possesses a visual system unlike that of either strictly nocturnal or diurnal birds and therefore does not adhere to the traditional view of the evolution of nocturnality in birds.
format	article
author	Jeremy R Corfield Anna C Gsell Dianne Brunton Christopher P Heesy Margaret I Hall Monica L Acosta Andrew N Iwaniuk
author_facet	Jeremy R Corfield Anna C Gsell Dianne Brunton Christopher P Heesy Margaret I Hall Monica L Acosta Andrew N Iwaniuk
author_sort	Jeremy R Corfield
title	Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).
title_short	Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).
title_full	Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).
title_fullStr	Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).
title_full_unstemmed	Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).
title_sort	anatomical specializations for nocturnality in a critically endangered parrot, the kakapo (strigops habroptilus).
publisher	Public Library of Science (PLoS)
publishDate	2011
url	https://doaj.org/article/328f2d8678d04eddbb51c40968fd5a2e
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Anatomical specializations for nocturnality in a critically endangered parrot, the Kakapo (Strigops habroptilus).

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