Flight is the primary form of locomotion for many avian species and is enabled by allometric scaling of morphological features such as wingspan, flight muscle size, and bone tensile strength. Contrary to this, the evolution of flightlessness in birds displays a selection towards an increase in body size with a reduction in flight associated features. The aim of this chapter is to explore the Loss of Dispersibility hypothesis as a cause for flightlessness in island birds, with consideration of the Island Rule and the Size-Constraint hypothesis. With island species paired with closest mainland relatives, comparative analyses were conducted comparing the change in wing loading ratios, wing lengths, and mass. With paired t-tests and Major Axis linear regression modelling, the hypotheses of isometric or allometric scaling in each of the features were tested. An increase in wing-loading ratio was apparent for many island species, as well as an increase in both mass and wing length. However, the rate of increase between mass and wing length is disproportionate, with mass increasing at a greater rate than wing length. These trends reject the Loss of Dispersibility hypothesis in support of the Size-Constraint hypothesis while providing little evidence for the Island Rule.
Date of Award2021-04-29
PublisherTe Herenga Waka—Victoria University of Wellington
Rights LicenseAuthor Retains Copyright
Degree DisciplineEcology and Biodiversity
Degree GrantorTe Herenga Waka—Victoria University of Wellington
Degree NameMaster of Science
ANZSRC Type Of Activity codeSchool of Biological Sciences
Victoria University of Wellington Item TypeAwarded Research Masters Thesis
Alternative DescriptionA suite of ecological and environmental factors influence plant physiology, with morphology of a plant described by the allometric scaling of structural features abiding Corner’s Rule. The aim of this study is to examine three potentially influencing factors on the morphology of plants within the Coprosma genus: the triangular relationship of allometric scaling in leaf, petiole, and seed size, scaling relationships between reproductive structures of male and female flowers in diecious plants, as well as the effect of elevation on the applicability of Corner’s Rule on high altitude species. Each of the features across specimens representative of fifty Coprosma species within Te Papa’s herbarium collection were measured with callipers and analysed with correlations and regression modelling. The results show that Coprosma species abide Corner’s Rule of allometric scaling, however, no relationships were found between floral features of males and females, as well as no evidence for a significant impact of elevation on the applicability of Corner’s Rule on high altitude plants.
Victoria University of Wellington SchoolSchool of Biological Sciences