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Publié par | eberhard_karls_universitat_tubingen |
Publié le | 01 janvier 2010 |
Nombre de lectures | 28 |
Poids de l'ouvrage | 4 Mo |
Extrait
Morphological
evolution
through
integration:
quantitative
analysis
of
crani o‐mandibular
covariance
structures
in
extant
hominids
Dissertation
zur
Erlangung
des
Grades
eines
Doktors
der
Naturwissenschaften
der Geowissenschaftlichen Fakultät
der Eberhard Karls Universität Tübingen
vorgelegt
von
Nandini
Singh
aus
Neu
Delhi
(Indien)
2010
Tag
der
mündlichen
Prüfung:
Dekan:
Prof.
Dr.
Peter
Grathwohl
1.
Berichterstatter:
Prof.
Dr.
Katerina
Harvati
2.
Be richterstatter:
Prof.
Dr.
Jean ‐Jacques
Hublin
ii
Dedicatio n
To the two most important people in my life: my mother and sister,
… and to the memory of my father and grandfather.
iii
“I mean by this expression [correlated variation] that the whole organization is so
tied together during its growth and development, that when slight variations in any
one part occur, and are accumulated through natural selection, other parts become
modified. This is a very important subject, most imperfectly understood,
and no doubt wholly different classes of facts may be here easily confounded
together.” (Charles Darwin, “ The Origin of Species ”, Chapter V – Laws of variation
and correlated variation)
iv
v
Table of Contents
THESIS
SUMMARY
8
ZUSAMMENFASSUNG
12
PREFACE
17
INTRODUCTION
20
MORPHOLOGICAL
INTEGRA TION
IN
THE
HOMINID
SKULL
21
CANALISATION
AND
DEVE LOPMENTAL
STABILITY
25
“F UNCTIONAL
MATRIX
HYP OTHESIS ”:
CRANIUM
AND
MANDIBL E
27
RESEARCH GOAL AND OBJECTIVES
29
MATERIALS
33
METHODS
36
TRADITIONAL
MORPHOMET RICS
36
GEOMETRIC
MORPHOMETRI CS
38
SUPERIMPOSITION TECHNIQUES
39
THIN‐PLATE SPLINE: SHAPE DEFORMATION
40
EUCLIDEAN DISTANCE MATRIX ANALYSIS
41
MULTIVARIATE STATISTICS
42
SOFT WARE
PACKAGES
44
RESULTS
67
MANUSCRIPT
1:
CRANIAL
INTEGRATION
I N
H OMO,
PAN ,
GORILLA
AND
PONGO
67
MANUSCRIPT
2:
E VOLUTION
OF
COVARIAN CE
STRUCTURES
IN
THE
CRANIUM
OF
H OMO,
PAN ,
GORILLA
AND
PONGO
–
A
DEVELOPMENTAL
PER SPECTIVE
98
MANUSCRIPT
3:
COMPARATIVE
STUDY
OF
ONTOGENETIC
VARIATIO N
IN
H OMO
AND
PAN
MANDIBLES
127
FUTURE
PROJECTS
163
PROJECT
1:
PATTERNS
OF
MANDIBULA R
INTEGRATION
IN
PAN
AND
H OMO
163
PROJECT
2:
DEVELOPMENTAL
TRAJECT ORIES
IN
DIFFERENT
P ARTS
OF
THE
CRANIUM :
A
LOOK
AT
DEVELOPME NTAL
MODULARITY
166
PROJECT
3:
AN
ASSESSMENT
OF
DIRE CTIONAL
ASYMMETRY
IN
THE
CRANIUM
OF
GORILLA ,
PAN
AND
H OMO
168
REFERENCES
ERROR!
BOOKMARK
NOT
DEFINED.
ACKNOWLEDGEMENTS
188
vi
SUMMARY
Thesis summary
The primate skull is a functionally integrated and complex structure. The
skull is commonly divided into different functional units, such as the bones and
muscles that are involved in mastication, bones of the face, and the bones that house
the brain. However, each of the functional units must also function within the skull
as an integrated whole. This integration or covariation is reflected in structures
vary ing with change in other structures. Understanding the evolution of integrated
or covariance structures provides important insight into the underlying
mechanisms that generate phenotypic variability and variation. The main goal of
this thesis is to investigate covariance in the cranio ‐mandibular form of Pongo ,
Gorilla , Pan and Homo using quantitative methods such as landmark‐based 3D
geometric morphometrics. This thesis comprises thr ee individual studies that
address questions related to covariance ‐generating processes such as:
morphological integration, allometry, canalisation and developmental stability. T he
three studies collectively provide important insight into the underlying mechanisms
that generate phenotypic variability and variation in closely related hominid taxa.
Phenotypic variability is of particular interest to biological anthropologists
for several reasons one being that majority of the questions addressed in primate
evolution centre around morphological variation. The primate cranium is an
important source of information for biological anthropologists because it preserves
better in the fossil record than most other skeletal components. Due to the lack of
large fossil samples, closely related extant hominids have long been used as
analogues to better understand phenotypic changes related to developmental and
functional adaptations in fossil ho minids.
The first manuscript is a study of the patterns of morphological integration
between the face, basicranium and cranial vault in adult humans, chimpanzees,
bonobos, gorillas and oranugtans. Regions of the mammalian cranium differ in their
developmental origin and functional demands. Accordingly, we sub ‐divide the
8
SUMMARY
cranium into three functional components: (a) facial skeleton, including the
zygomatic processes, nasal, lacrimal and maxillary bones (b) cranial vault,
consisting of the frontal and parie tal bones and (c) basicranium, comprising the
non ‐squamous parts of the temporal and occipital bones. We choose to call these
modules “functionally” derived because they are loosely based on Moss’ “functional
matrix hypothesis” (Moss and Young, 1960); how ever, they are primarily
distinguished based on differential growth patterns. Patterns of integration can help
understand the structural relationship between morphological units, providing
important insight into how phenotypes can evolve or how they may be constrained.
The main goal of this study is to evaluate whether integration patterns vary across
these closely related hominid taxa. Results show that even though taxa exhibit
species ‐specific variation, particularly in interactions between the basicra nium and
other cranial regions, the overall pattern in wh