The impact of overgrazing on reptile diversity and population dynamics of Pedioplanis l. lineoocellata in the southern Kalahari, South Africa [Elektronische Ressource] / von Bernd Wasiolka

Bernd Wasiolka

Informations

• Publié par: universitat_potsdam
• Publié le: 01 janvier 2007
• Nombre de lectures: 33
• Langue: English
• Poids de l'ouvrage: 3 Mo

Extrait

Bernd Wasiolka


The impact of overgrazing on reptile diversity
and population dynamics of Pedioplanis l.
lineoocellata in the southern KalahariDieses Werk ist unter einem Creative Commons Lizenzvertrag lizenziert:
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Elektronisch veröffentlicht auf dem
Publikationsserver der Universität Potsdam:
http://opus.kobv.de/ubp/volltexte/2008/1661/
urn:nbn:de:kobv:517-opus-16611
[http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-16611] Institut für Biochemie und Biologie
Arbeitsgruppe Vegetationsökologie und Naturschutz





Impact of overgrazing on reptile diversity and population
dynamics of Pedioplanis l. lineoocellata in
the southern Kalahari, South Africa







Dissertation
zur Erlangung des akademischen Grades
"doctor rerum naturalium"
(Dr. rer. nat.)
in der Wissenschaftsdisziplin " Ökologie"








eingereicht an der
Mathematisch-Naturwissenschaftlichen Fakultät
der Universität Potsdam



von
Bernd Wasiolka






Potsdam, den 31.08.2007 Table of Contents

Preface 1
General Introduction 2

Chapter 1
Effects of habitat degradation on regional reptile diversity 8
1. Abstract 9
2. Introduction 10
3. Methods 11
3.1. Study area and period 11
3.2. Reptile survey 12
3.3. Vegetation 13
3.4. Prey availability
3.5. Habitat preference 13
3.6. Data analyses 13
4. Results 15
4.1 Vegetation survey 15
4.2 Reptile 16
4.3 Prey availability 18
4.4 Habitat preference 19
5. Discusion 22
5.1. Thermoregulation 22
5.2. Predation risk 23
5.3. Resource availability 23
5.4. Habitat preference 24
i5.5. Conclusions 25
6. References 26

Link tochapter two 31

Chapter 2
Impact of overgrazing: Behavioural responses of the
lizard Pedioplanis l. lineoocellata 32

1. Abstract 33
2. Introduction 34
3. Methods 35
3.1. Study area and period 35
3.2. Vegetation survey 36
3.3. Behavioural observations 37
3.4. Prey abundance 38
3.5. Data analyses
4. Result 39
5. Discusion 40
6. References 44

Link to chapter three 48
iiChapter 3
Space use of the Spotted Sand Lizard (Pedioplanis l. lineoocellata)
under different degradation states 49

1. Abstract 50
2. Introduction 51
3. Methods 52
3.1. Study area 52
3.2. Habitat selection 53
3.3. Radio tracking
3.4. Daily movement distances 55
3.5. Home range size 55
3.6. Microhabitat preference 56
3.7. Statistical analyses 56
4. Results 57
4.1 Daily movement distances 57
4.2 Home range size 58
4.3 Microhabitat preference 59
5. Discusion 60
5.1. Daily movement distances 61
5.2. Home range size 61
5.3. Microhabitat preference 62
5.4. Conclusions 63
6. References 64

Link to chapter four 68
iiiChapter 4
Consequences of habitat degradation for the population
dynamics of the lizard Pedioplanis l. lineoocellata
in the southern Kalahari 69

1. Abstract 70
2. Introduction 71
3. Methods 72
3.1. Study area 72
3.2. Capture-Mark-Recapture 72
3.3. Trap design 73
3.4. Size class 74
3.5. Population size 75
3.6. Survival rate
3.7 Sex ratio 75
3.8. Fecundity 76
3.9. Predation risk 76
3.10 Condition
3.11 Statistical analyses 76
4. Results 77
4.1 Size clas 77
4.2 Population size 78
4.3 Survival rate 81
4.4 Sex ratio 82
4.5 Fecundity 83
4.6 Predation risk 83
iv4.7 Condition 84
5. Discusion 85
6. References 88

General Discussion and conclusions 92
Zusammenfassung 97
Danksagung 100
Ehrenwörtliche Erklärung 101
v Preface
Preface

The aim of my PhD-thesis is to analyse the impact of overgrazing caused by
intensive land use on the reptile community in the southern Kalahari and to
understand the effect of changing habitats on population dynamics of the lizard
Pedioplanis lineoocellata lineoocellata. My thesis consists of four major chapters
which can be read independently, since every single chapter focus on a specific part
of the influence of overgrazing on reptiles. Owing to the cumulative form of my thesis,
some parts (e.g. methods) overlap to some extent. The first three chapters are
submitted to scientific journals in cooperation with co-authors and the fourth chapter
is in preparation. Because of the idea to submit all chapters to scientific journals my
thesis has been written in the first person plural. Co-authors include my thesis
advisor Prof. Dr. Florian Jeltsch, my thesis co-advisor Dr. Joh Henschel and Dr. Niels
Blaum, who has been partners of fruitful discussion. Nonetheless, all findings
presented here resulted from work that has been done independently by me.
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