Reproductive strategies in Latrodectus revivensis (Araneae; Theridiidae): functional morphology and sexual cannibalism [Elektronische Ressource] / vorgelegt von Bettina Berendonck

. . Seeboorapha

Sujets

• Biologie

Informations

• Publié par: heinrich-heine-universitat_dusseldorf
• Publié le: 01 janvier 2003
• Nombre de lectures: 42
• Langue: Deutsch
• Poids de l'ouvrage: 9 Mo

Extrait

Reproductive strategies in Latrodectus revivensis (Araneae;
Theridiidae): functional morphology and sexual cannibalism






I n a u g u r a l - D i s s e r t a t i o n

zur
Erlangung des Doktorgrades der
Mathematisch-Naturwissenschaftlichen Fakultät
der Heinrich-Heine-Universität Düsseldorf





vorgelegt von


Bettina Berendonck
aus: Duisburg




Düsseldorf 2003

































Gedruckt mit der Genehmigung der
Mathematisch-Naturwissenschaftlichen Fakultät
der Heinrich-Heine-Universität Düsseldorf



Referent: Prof. Dr. Hartmut Greven

Korreferent: Prof. Dr. Klaus Lunau


Tag der mündlichen Prüfung: 05. Juni 2003
2
Contents
1. Introduction.......................................................................................... 5
2. Material and Methods........................................................................ 12
2. 1. Animals...........12
2. 2. Mating experiments in the laboratory...............................................................12
2. 3. Statistics ..........................................................................14
2. 4. Light microscopy (LM)....................................................14
2. 5. Scanning electron microscopy (SEM) ..............................................................15
2. 6. Transmission electron microscopy (TEM)........................16
2. 7. Photography and Videography .........................................................................16
3. Results................................. 17
3. 1. The female.......17
3. 1. 1. The epigynum ..........................................................................................17
3. 1. 2. The spermatheca......................19
3. 1. 2. 1. The cuticle........................20
3. 1. 2. 2. The epithelium .................................................................................21
3. 1. 3. The uterus ................................................................................................25
3. 1. 4. Hemolymph and nervous supply..............................27
3. 2. The male..........................................................................................................28
3. 2. 1. Pedipalp...28
3. 2. 2. Tarsus of leg I ..........................................................................................30
3. 2. 3. Mouth region...........................31
3. 3. Female and male interactions ...........................................................................32
3. 3. 1. Relation in size and variation in genital and somatic characters ................32
3. 3. 2. Courtship and copulation..........34
3. 3. 2. 1. Behavioural elements .......................................................................34
3. 3. 2. 2. Phases of courtship...........36
3. 3. 2. 3. Copulation and postcopulatory events...............39
3. 3. 3. Spermatozoa and secretion .......................................................................40
3. 3. 4. Position of the inserted embolus and broken embolus tips ........................42
3. 3. 5. Data from the field ...................................................................................43
3. 3. 6. Data from the laboratory matings.............................44
3
4. Discussion ........................................................................................... 48
4. 1. The female.......................................48
4. 1. 1. The epigynum ..........................................................48
4. 1. 2. The spermatheca......................................................51
4. 1. 2. 1 The cuticle.........................52
4. 1. 2. 2. The epithelium .................................................54
4. 1. 3. The uterus ................................................................................................57
4. 2. The male..........60
4. 3. Female and male interactions ...........................................................................64
4. 3. 1. Relation in size and variation in genital and somatic characters ................64
4. 3. 2. Courtship .................................................................................................65
4. 3. 3. Spermatozoa and secretion.......71
4. 3. 4. Mating plugs............................77
4. 3. 4. 1. Embolus and embolus tips in Latrodectus revivensis ........................77
4. 3. 4. 2. Mating plugs in Araneae...................................................................79
4. 3. 5. Female remating probability in the field ...................................................84
4. 4. Sexual cannibalism ..........................................................85
4. 4. 1. Sexual cannibalism in Latrodectus revivensis...........85
4. 4. 2. Sexual cannibalism in Araneae.................................................................90
5. Summary .......................................................... 111
6. References......................................................... 114
7. Figures .............................................................. 132
7. 1. Abbreviations................................132
7. 2. Figures...........................................133









4
1. Introduction
Over the last decades, numerous empirical and experimental studies have shown that
sexual conflict arising from divergent interests in reproduction by male and females is a
decisive force in the evolution of male and female reproductive strategies (Trivers 1972;
Dawkins 1976; Parker 1979; Andersson & Iwasa 1996; Stockley 1997; Chapman et al.
2003). Since Darwin (1871), it is generally believed that a male should try to increase
his reproductive success by mating with numerous females to fertilise a maximum
number of eggs (Bateman 1948; Trivers 1972). Thus, selection will favour traits that
avoid sperm competition, e. g. by reducing the probability that their sperm will overlap
spatially and/or temporally with those stored from previous males and by reducing the
probability that the female(s) will remate with rival males (Simmons 2001). A female,
in contrast, is expected to maximise mate ‘quality’ by choosing the best possible mate
(Bateman 1948; Andersson 1994; Birkhead & Møller 1998). Female choice might be
direct (discrimination between individual males) or indirect (restriction of an
individual’s set of potential copulation partners) (Wiley & Poston 1996). Additionally,
direct and indirect choice can occur during the precopulatory, postcopulatory but
prefertilisation and postfertilisation stages of reproduction (Cunningham & Birkhead
1998). The mating preferences of the female might be favoured indirectly (genetically
by the Fisher process (sexy sons) (Fisher 1930) and/or the good genes process (handicap
principle) (Zahavi 1975; but see Kokko et al. 2002) or directly (e.g. nuptial gifts,
parental care, fewer parasites etc.) by sexual selection (Chapman et al. 2003). In the last
decades additional benefits for female fitness from multiple matings with different
males, beside receiving sufficient amounts of viable sperm, have been suggested (e.g.
‘avoiding genetically incompatible sperm’, Zeh & Zeh 1996, 1997; Jennions 1997;
‘genetic diversity‘ and ‘genetic benefits’, see Yasui 1998 for references; ‘bet-hedging
strategy’ Watson 1998; ‘insurance against first male’s infertility’, Schneider & Elgar
1998; ‘inbreeding avoidance’, Tregenza & Wedell 2002; see reviews Keller & Reeve
1998; Jennions & Petrie 2000; Arnqvist & Nilsson 2000; Zeh & Zeh 2001). However,
the intersexual conflict is reflected by the different strategies by which males or females
try to maximise their reproductive success. These strategies involve the evolution of
various morphological, physiological and behavioural characteristics (Thornhill &
Alcock 1983; Smith 1984; Birkhead and Møller 1998).
5
Sexual cannibalism by the large females of their tiny mates in black widow
spiders represents one of the best-known examples showing that the reproductive
interests of females and males do not necessarily coincide. However, spiders in general
provide a large potential for conflict over mating, since males are generally able to mate
more than once and females can store sperm over long periods (Austad 1984; Elgar
1998; Schneider & Lubin 1998). Additionally, females frequently mate with more than
one male (Jackson et al. 1981). For example, Watson (1998) was able to show that mate
number and mate size were positively related to offspring growth rates and the size of
the offspring in Neriene litigiosa (Linyphiidae).
In species where the female mates more than once, sperm priority patterns have
important implications for the mating behaviour of both sexes. According to their gross
reproductive anatomy araneomorphs can be roughly divided into tw