Morphological adaptations for relatively larger brains in hummingbird skulls

Diego Ocampo, Gilbert Barrantes, J. Albert Uy

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

A common allometric pattern called Haller's Rule states that small species have relatively larger brains and eyes than larger species of the same taxonomic group. This pattern imposes drastic structural changes and energetic costs on small species to produce and maintain a disproportionate amount of nervous tissue. Indeed, several studies have shown the significant metabolic costs of having relatively larger brains; however, little is known about the structural constraints and adaptations required for housing these relatively larger brains and eyes. Because hummingbirds include the smallest birds, they are ideal for exploring how small species evolve morphological adaptations for housing relatively larger brain and eyes. We here present results from a comparative study of hummingbirds and show that the smallest species have the lowest levels of ossification, the most compact braincases, and relatively larger eye sockets, but lower eye/head proportion, than larger species. In contrast to Passerines, skull ossification in hummingbirds correlates with body and brain size but not with age. Correlation of these skull traits with body size might represent adaptations to facilitate housing relatively larger brain and eyes, rather than just heterochronic effects related to change in body size. These structural changes in skull traits allow small animals to accommodate disproportionately larger brains and eyes without further increasing overall head size.

Original languageEnglish (US)
JournalEcology and Evolution
DOIs
StateAccepted/In press - Jan 1 2018

Fingerprint

hummingbirds
skull
brain
eyes
bone formation
structural change
body size
passerine
cost
comparative study
energetics
bird
animal
birds

Keywords

  • braincase
  • eye socket size
  • Haller's rule
  • relative brain size
  • skull ossification

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Nature and Landscape Conservation

Cite this

Morphological adaptations for relatively larger brains in hummingbird skulls. / Ocampo, Diego; Barrantes, Gilbert; Uy, J. Albert.

In: Ecology and Evolution, 01.01.2018.

Research output: Contribution to journalArticle

@article{1f65d1bdd6c746bbabad5221358cbbfa,
title = "Morphological adaptations for relatively larger brains in hummingbird skulls",
abstract = "A common allometric pattern called Haller's Rule states that small species have relatively larger brains and eyes than larger species of the same taxonomic group. This pattern imposes drastic structural changes and energetic costs on small species to produce and maintain a disproportionate amount of nervous tissue. Indeed, several studies have shown the significant metabolic costs of having relatively larger brains; however, little is known about the structural constraints and adaptations required for housing these relatively larger brains and eyes. Because hummingbirds include the smallest birds, they are ideal for exploring how small species evolve morphological adaptations for housing relatively larger brain and eyes. We here present results from a comparative study of hummingbirds and show that the smallest species have the lowest levels of ossification, the most compact braincases, and relatively larger eye sockets, but lower eye/head proportion, than larger species. In contrast to Passerines, skull ossification in hummingbirds correlates with body and brain size but not with age. Correlation of these skull traits with body size might represent adaptations to facilitate housing relatively larger brain and eyes, rather than just heterochronic effects related to change in body size. These structural changes in skull traits allow small animals to accommodate disproportionately larger brains and eyes without further increasing overall head size.",
keywords = "braincase, eye socket size, Haller's rule, relative brain size, skull ossification",
author = "Diego Ocampo and Gilbert Barrantes and Uy, {J. Albert}",
year = "2018",
month = "1",
day = "1",
doi = "10.1002/ece3.4513",
language = "English (US)",
journal = "Ecology and Evolution",
issn = "2045-7758",
publisher = "John Wiley and Sons Ltd",

}

TY - JOUR

T1 - Morphological adaptations for relatively larger brains in hummingbird skulls

AU - Ocampo, Diego

AU - Barrantes, Gilbert

AU - Uy, J. Albert

PY - 2018/1/1

Y1 - 2018/1/1

N2 - A common allometric pattern called Haller's Rule states that small species have relatively larger brains and eyes than larger species of the same taxonomic group. This pattern imposes drastic structural changes and energetic costs on small species to produce and maintain a disproportionate amount of nervous tissue. Indeed, several studies have shown the significant metabolic costs of having relatively larger brains; however, little is known about the structural constraints and adaptations required for housing these relatively larger brains and eyes. Because hummingbirds include the smallest birds, they are ideal for exploring how small species evolve morphological adaptations for housing relatively larger brain and eyes. We here present results from a comparative study of hummingbirds and show that the smallest species have the lowest levels of ossification, the most compact braincases, and relatively larger eye sockets, but lower eye/head proportion, than larger species. In contrast to Passerines, skull ossification in hummingbirds correlates with body and brain size but not with age. Correlation of these skull traits with body size might represent adaptations to facilitate housing relatively larger brain and eyes, rather than just heterochronic effects related to change in body size. These structural changes in skull traits allow small animals to accommodate disproportionately larger brains and eyes without further increasing overall head size.

AB - A common allometric pattern called Haller's Rule states that small species have relatively larger brains and eyes than larger species of the same taxonomic group. This pattern imposes drastic structural changes and energetic costs on small species to produce and maintain a disproportionate amount of nervous tissue. Indeed, several studies have shown the significant metabolic costs of having relatively larger brains; however, little is known about the structural constraints and adaptations required for housing these relatively larger brains and eyes. Because hummingbirds include the smallest birds, they are ideal for exploring how small species evolve morphological adaptations for housing relatively larger brain and eyes. We here present results from a comparative study of hummingbirds and show that the smallest species have the lowest levels of ossification, the most compact braincases, and relatively larger eye sockets, but lower eye/head proportion, than larger species. In contrast to Passerines, skull ossification in hummingbirds correlates with body and brain size but not with age. Correlation of these skull traits with body size might represent adaptations to facilitate housing relatively larger brain and eyes, rather than just heterochronic effects related to change in body size. These structural changes in skull traits allow small animals to accommodate disproportionately larger brains and eyes without further increasing overall head size.

KW - braincase

KW - eye socket size

KW - Haller's rule

KW - relative brain size

KW - skull ossification

UR - http://www.scopus.com/inward/record.url?scp=85053938124&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85053938124&partnerID=8YFLogxK

U2 - 10.1002/ece3.4513

DO - 10.1002/ece3.4513

M3 - Article

AN - SCOPUS:85053938124

JO - Ecology and Evolution

JF - Ecology and Evolution

SN - 2045-7758

ER -