Alternative reproductive tactics and their consequences in the ant genus Cardiocondyla [Elektronische Ressource] / Alexandra Schrempf

Schrempf Alexandra

Informations

• Publié par: universitat_regensburg
• Publié le: 01 janvier 2006
• Nombre de lectures: 7
• Langue: English

Extrait

Alternative reproductive tactics
and their consequences in the ant genus
Cardiocondyla















Alexandra Schrempf
Oktober 2005





Alternative reproductive tactics
and their consequences in the ant genus
Cardiocondyla



DISSERTATION ZUR ERLANGUNG DES DOKTORGRADES DER NATURWISSENSCHAFTEN
(DR. RER. NAT.) DER NATURWISSENSCHAFTLICHEN FAKULTÄT III –
BIOLOGIE UND VORKLINISCHE MEDIZIN DER UNIVERSITÄT REGENSBURG














vorgelegt von
Alexandra Schrempf aus Ergoldsbach
10/2005


























Promotionsgesuch eingereicht am: 29.09.2005
Die Arbeit wurde angeleitet von Prof. Dr. J. Heinze
Prüfungsausschuss: Vorsitzender: Prof. Dr. S. Schneuwly
1. Prüfer: Prof. Dr. J. Heinze
2. Prüfer: Dr. J. Korb
3. Prüfer: Prof. Dr. P. Poschlod

CONTENTS
TABLE OF CONTENTS


GENERAL INTRODUCTION ..................................................................................................... 1

CHAPTER 1: Proximate mechanisms of male morph determination in the ant
Cardiocondyla obscurior ..................................................................................... 12
Introduction ............................................................................................................................. 14
Materials and Methods ............................................................................................................ 15
Results ..................................................................................................................................... 17
Discussion ............................................................................................................................... 21

CHAPTER 2: Alternative reproductive tactics in males of the ant Cardiocondyla
obscurior .............................................................................................................. 24
Introduction 26
Materials and Methods 27
Results ..................................................................................................................................... 30
Discussion ............................................................................................................................... 35

CHAPTER 3: Back to one: consequences of secondary monogyny in an ant with
polygynous ancestors .......................................................................................... 39
Introduction ............................................................................................................................. 41
Materials and Methods ............................................................................................................ 42
Results 44
Discussion 48

CHAPTER 4: Inbreeding and local mate competition in the ant Cardiocondyla
batesii .................................................................................................................. 51
Introduction 53
Materials and Methods 54
Results ..................................................................................................................................... 58
Discussion ............................................................................................................................... 63

CHAPTER 5: Exclusion of complementary sex determination, inbreeding depression
and sex ratio adaptation in the ant Cardiocondyla obscurior ............................. 68
Introduction ............................................................................................................................. 70
Materials and Methods ............................................................................................................ 71
Results ..................................................................................................................................... 74
Discussion ............................................................................................................................... 80

CHAPTER 6: Sexual cooperation: mating increases longevity in ant queens............................ 86
Introduction ............................................................................................................................. 88
Materials and Methods ............................................................................................................ 89
Results and Discussion 89
CONTENTS


GENERAL DISCUSSION.......................................................................................................... 94

SUMMARY .............................................................................................................................. 101

ZUSAMMENFASSUNG 103

ACKNOWLEDGEMENTS ...................................................................................................... 105

REFERENCES.......................................................................................................................... 106








































GENERAL INTRODUCTION 1
GENERAL INTRODUCTION

“One of the greatest problems facing Darwin´s (1859) theory of evolution by natural selection
concerned conspicuous male traits, (….). These and other extravagant male characters would
seem to reduce survival, and so should be opposed by ordinary natural selection” (Andersson,
1994).
To solve the problem, Darwin (1871) developed his theory of sexual selection as a
special case of natural selection, of which a key aspect is the competition between males over
access to females, which can increase the variance in the reproductive success of individual
males and thus the opportunity for sexual selection. As a consequence, alternative reproductive
behaviours of males can evolve, for example, small, weak or young males that have low
competitive abilities do better using completely different tactics. Frequently used alternatives
are "sneaking" matings without paying the cost of fighting, or, mimicking females to avoid
being attacked by territorial males (Andersson, 1994; Neff, 2001; Shuster and Wade, 1991a;
Shuster and Wade, 2003).
The expression of alternative reproductive tactics is known from a variety of taxa,
including mammals, fish, birds and arthropods (for reviews see Alcock, 1998; Andersson, 1994;
Austad, 1984; Brockmann, 2001; Dominey, 1984; Gadgil, 1972; Neff, 2001). They are often
accompanied by morphological correlated traits such as the development of weapons (e.g.
mandibles in the coleopteran Dendrobias mandibularis, Goldsmith, 1987, forelegs in the thrips
Hoplothrips pedicularis, Crespi, 1986, and cerci in the earwig Forficula auricularia, Eberhard
and Gutierrez, 1991; see also below), and can be either genetically or environmentally
determined.
In case of genetic polymorphism, the fitness of the different phenotypes is expected to
be on average equal, otherwise, the most successful genotype would spread and replace the
others (Dominey, 1984; Gadgil, 1972; Gross, 1996). The different strategies can be maintained
for example due to environmental heterogeneity, accompanied by the occupation of different
niches (Dominey, 1984). Most often, however, they are maintained by negative frequency
dependent selection (Gadgil, 1972; Gross, 1996; Maynard Smith, 1982). Thus, male fitness
depends on the frequency of rival male types, and each morph has a fitness advantage when
rare (Alonzo and Warner, 2000; Henson and Warner, 1997). However, such alternative
strategies are rare in nature but do exist e.g. in fish (Zimmerer and Kallman, 1989), a bird (Lank
et al., 1995), lizards (Sinervo and Lively, 1996; Zamudio and Sinervo, 2000) and the marine
isopod Paracerceis sculpta. In the latter, three phenotypes correlate with three alleles at a single
GENERAL INTRODUCTION 2
autosomal locus. Big fighter males occur alongside of intermediate-sized males which mimic
females and also, alongside of small males which "sneak" matings (Shuster and Wade, 1991b).
Conversely, alternative tactics within a conditional strategy are frequent in nature
(Gross, 1996). Under the conditional strategy, individuals are genetically monomorphic. Theory
predicts that the “decision", which tactic is expressed, is dependent on the status of the
individual and will result in higher fitness for the individual (Gross, 1996). Individuals naturally
differ in their status, e.g. because of environmental influences or because they differ in their
developmental stages. The fitness