Phylogenetic approaches for studying competition in mammals
Author(s)
Cooper, Natalie
Type
Thesis
Abstract
Interspecific competition is often proposed to shape mammalian evolution. Many
studies use trait and distribution data on extant species, but this ignores temporal aspects
of competition. Phylogeny provides a framework for integrating present-day data with
clade histories.
Here, I use phylogenetic comparative methods and present-day data to investigate the
role of competition in the evolution of four mammalian clades: New World leaf-nosed
bats (Phyllostomidae), New World monkeys (Platyrrhini), Australasian possums
(Phalangeriformes), and ground squirrels (Marmotini). I ask four specific questions: (1)
Do community phylogenies, and/or the traits of community members, show patterns
expected under competition? (2) Is there evidence of competition in the relationship
among species’ trait differences, phylogenetic differences and patterns of coexistence?
(3) Does the intensity of competition affect rates of morphological evolution? (4) Are
the tempo and/or mode of mammalian body size evolution influenced by competition?
I found evidence for competition in monkeys and squirrels, but not bats or possums.
Competition did not influence rates of morphological evolution; instead body mass was
the most important correlate across the groups. Across all mammals, the best-supported
model of body size evolution corresponded to a scenario in which mammals
experienced a relatively early burst of morphological evolution, followed by a
slowdown in rate as competition for niches increased. In addition, around 60% of the
variation in the tempo of body-mass evolution was explained by just a few predictors.
In conclusion, I find some support for competition shaping mammalian evolution.
However, there is evidence that the importance of other processes may outweigh the
effects of competition in some groups. Further study and methodological improvements
are required to fully understand the relative role of competition in evolution. The
methods developed in this thesis provide a useful starting point for such studies.
studies use trait and distribution data on extant species, but this ignores temporal aspects
of competition. Phylogeny provides a framework for integrating present-day data with
clade histories.
Here, I use phylogenetic comparative methods and present-day data to investigate the
role of competition in the evolution of four mammalian clades: New World leaf-nosed
bats (Phyllostomidae), New World monkeys (Platyrrhini), Australasian possums
(Phalangeriformes), and ground squirrels (Marmotini). I ask four specific questions: (1)
Do community phylogenies, and/or the traits of community members, show patterns
expected under competition? (2) Is there evidence of competition in the relationship
among species’ trait differences, phylogenetic differences and patterns of coexistence?
(3) Does the intensity of competition affect rates of morphological evolution? (4) Are
the tempo and/or mode of mammalian body size evolution influenced by competition?
I found evidence for competition in monkeys and squirrels, but not bats or possums.
Competition did not influence rates of morphological evolution; instead body mass was
the most important correlate across the groups. Across all mammals, the best-supported
model of body size evolution corresponded to a scenario in which mammals
experienced a relatively early burst of morphological evolution, followed by a
slowdown in rate as competition for niches increased. In addition, around 60% of the
variation in the tempo of body-mass evolution was explained by just a few predictors.
In conclusion, I find some support for competition shaping mammalian evolution.
However, there is evidence that the importance of other processes may outweigh the
effects of competition in some groups. Further study and methodological improvements
are required to fully understand the relative role of competition in evolution. The
methods developed in this thesis provide a useful starting point for such studies.
Date Issued
2009-04
Date Awarded
2009-04
Advisor
Jones, Kate
Purvis, Andy
Sponsor
NERC and Institute of Zoology
Creator
Cooper, Natalie
Grant Number
NER/S/A/2005/13577
Publisher Department
Division of Biology, Department of Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)