Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Biology

Date of Defense

1-5-2015

Graduate Advisor

Robert E. Ricklefs, Ph.D.

Committee

Bette A. Loiselle

Mark Westoby

Ivan Jimenez

John Bates

Abstract

The first part of this dissertation explores the evolution of two iconic groups of species through Australian climate space: the Meliphagidae, or honeyeaters, which are primarily nectar-feeding birds, and the Hakeinae, a section of the plant family Proteaceae. Both groups are inferred to have had their origins in Gondwanan rainforests that were widespread across Australia 45 million years ago and then diversified into more arid environments as the continent’s climate became more arid. Accordingly, dry environments are inhabited by closely related (phylogenetically clustered) sets of species, although, in contrast to the honeyeaters, Hakeinae communities are characterized by more localized diversification. The impressive and rapid Hakeinae diversification may have been driven by specialization onto a variety of highly weathered, nutrient-poor soil types on the ancient Australian landmass. The second part of this dissertation reviews a variety of methods to assess the phylogenetic structure of communities, such as local assemblages of honeyeaters and Hakeinae. Many published methods were found to be redundant, and some of the truly unique approaches do not measure what they purport to. Accordingly, only a small subset of phylogenetic community structure methods have merit. In the third part of the dissertation, observations on foraging by 74 of 75 Australian honeyeater species are used to explore patterns of community assembly. Australian honeyeater communities reflect both stochastic and deterministic processes. Co-occurring species exhibit substantial overlap in foraging niche space, in contrast to predictions from assembly theory based on competition. At the same time, species tend to occupy characteristic portions of niche space and available niche space is smaller in the arid regions of the continent. Within this smaller available niche space, arid-zone species tend to be more widely separated in niche space than species in more mesic environments.

Included in

Biology Commons

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