Behavioral Ecology Advance Access originally published online on December 8, 2004
Behavioral Ecology 2005 16(2):461-466; doi:10.1093/beheco/ari013
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Sequential mate encounters: female but not male body size influences female remating behavior
a Institut für Tierzucht und Genetik, Veterinärmedizinische Universität Wien, Josef Baumann Gasse 1, A-1210 Wien, Austria, and b Department of Neuroethology, Institute of Zoology, University of Bonn, Endenicher Allee 11-13, D-53115 Bonn, Germany
Address correspondence to G. Uhl. E-mail: g.uhl{at}uni-bonn.de.
Received 26 March 2004; revised 22 October 2004; accepted 25 October 2004.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Whether and how individuals choose sequentially among mates is an important but largely neglected aspect in sexual selection studies. Here, we explore female remating behavior in the cellar spider Pholcus phalangioides. We focus on body size as one of the most important traits involved in mate choice. Large and small females (n = 216) were double mated with large or small males in all eight possible combinations. All females copulated when virgin, but only 82% accepted a second male. The chance of a female remating was not significantly predicted by the body size of the second or first male or by the size difference between the two. In contrast, a previous study demonstrated a male size effect in that larger males monopolized females until egg laying when two males of different sizes were present. We suggest that sequential encounters are more common under natural conditions than male monopolization of females because estimates of concurrent multiple paternity together with observations in a natural population do not favor mate guarding as the predominant mating strategy in this species. It follows from our study that the intensity of sexual selection on male size may be greatly overestimated when using a competitive laboratory setting for a species in which females generally encounter mates in a sequential fashion. Female remating probability was significantly predicted by female size, with large females remating with higher probability than small females. Thus, when mating with large females, males may gain higher fertilization success through increased female fecundity but also face a higher sperm competition risk.
Key words: Araneae, body size, fecundity, mate choice, mate rejection, sexual selection.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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One of the most obvious mechanisms through which sexual selection acts is mate choice. Discrimination among potential partners is advantageous, despite the costs individuals incur from discrimination because it can lead to increased offspring production, viability, or offspring mating success (Andersson, 1994
). The focus of much recent research has been to determine the traits that females use when discriminating among males (Jennions and Petrie, 1997, 2000). Such decision-making processes are mostly studied using simultaneous choice experiments, where a female is presented with a pair of males that differ phenotypically. However, it has been doubted whether simultaneous encounters reflect the natural situation. Except for some lekking and swarm-mating species, or those with resource defense polygyny, potential mates are more likely to encounter each other sequentially (Gabor and Halliday, 1997; Janetos, 1980; Real, 1990, 1991). There are at least two ways in which females can successively choose among males; either they can assess the current male's phenotype against some kind of internal standard and mate if the phenotypic expression of the male trait exceeds a certain threshold level or they can compare successive mates with one another and only mate if the phenotypic "quality" of the actual mate is higher (Janetos, 1980; Real, 1990, 1991). Empirical studies have demonstrated that females are more likely to mate with attractive males without direct comparison (e.g., Bensch and Hasselquist, 1992; Houde, 1987; Moore AJ and Moore PJ, 1988; Zuk et al., 1990) or that females sample information from several males prior to mating (e.g., Choudhury and Black, 1993; Dale et al., 1990, 1992). Moreover, the few studies explicitly investigating sequential female mating decisions showed that females can assess a male against some trait or combination of traits of the previous male(s) she encountered (Bateman et al., 2001; Pitcher et al., 2003; Rasa, 1997; Savalli and Fox, 1998; Zeh et al., 1998; for a review, see Gibson and Langen, 1996). Generally, female choice criteria should also vary with her reproductive state, with virgin females being less choosy than mated females (Halliday, 1983).
Studies have demonstrated that one of the most important traits involved in mate choice is an individual's body size. This is because body size is highly correlated with various fitness traits (Andersson, 1994; Johnstone, 1995). Large male body size predicts, for example, a male's fighting ability during male-male contests and leads to a higher mating success or mating frequency in many species (Johnstone, 1995). Body size has also been shown to reflect male condition and other life-history traits (Johnstone, 1995). As a result, females can benefit from preferring larger, and thus more competitive, attractive, or viable males to sire their offspring. On the other hand, offspring number, offspring size, or survival can increase with female body size (Honek, 1993; Stearns, 1992), suggesting that male mate choice is of fundamental importance in the evolution of animal mating systems (for reviews, see Bondurianski, 2001; Gwynne, 1991; Wedell et al., 2002). Male preference for larger, more fecund females can lead to different female mating rates and thus result in different risks or intensities of sperm competition among female phenotypes (Parker et al., 1996). Further, if males prefer fecund females and male-male competition or female choice favors large males, a size-assortative mating pattern can arise with pairs of similiar size mating with higher probability, as prevalent in various taxa (for a review, see Crespi, 1989).
The cellar spider Pholcus phalangioides (Fuesslin) is well suited to examine the effects of body size in sequential mate choice. Laboratory studies showed that virgin females nearly always copulate but female receptivity significantly decreases after the first mating (Schäfer and Uhl, 2002; Uhl, 1994). A marked decrease in sexual receptivity after the first copulation is common in insects (Ringo, 1996) and spiders (Elgar, 1998). One explanation for this phenomenon is that after having secured enough sperm to fertilize their eggs, females become choosier to increase "offspring quality" by mating with high "quality males." Especially in species with last-male sperm precedence, a female's remating behavior greatly reduces the previous male's reproductive success (Halliday, 1983). The cellar spider P. phalangioides exhibits a marked last-male sperm precedence (median P2 = 89%), despite much shorter copulations in second males, which can be explained by a sperm removal mechanism (Schäfer and Uhl, 2002). Also, males cannot force females to copulate as copulation is only possible when the female assumes a horizontal body posture. This allows the male to secure a sclerotized hook on the female's genital plate with two cheliceral apophyses and hence to insert his secondary copulatory organs (Uhl et al., 1995). Unreceptive females show aggressive behavior toward males or simply escape.
Size seems to play an important role in sexual selection because large males can monopolize access to females under laboratory contest conditions (Schaefer and Uhl, 2003). In addition, female choice for larger males may lead to larger offspring with higher reproductive success because body size exhibits additive genetic variation as well as condition-dependent variation, as indicated by significant genotype-by-environment interactions (Uhl et al., 2004). Female body size, on the other hand, is highly correlated with fecundity in terms of clutch size and hatching success (Uhl, 1998). Under natural conditions, larger more fecund females are visited more frequently by males than smaller females (Uhl, 1998), and larger females show higher degrees of multiple paternity in a single egg sac compared to smaller females (Schulz J and Uhl G, in preparation). Thus, higher attractiveness seems to translate into a higher mating rate.
In the present study, we explore the role of male and female body size on female remating behavior in P. phalangioides. We chose a sequential setting in which females could not directly compare between males and males could not physically interact because this setup seems to represent the predominant encounter mode in natural populations. In contrast, previous studies on mate choice used a simultaneous setting with two or more potential partners present at the same time, often without knowledge of the natural encounter mode. We asked whether the size of the present or past mating partner affects female remating behavior and whether larger females remate with higher probability. Our experimental setup further allows to test whether females prefer to mate with males of similar size.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Collection and size measurements
Juvenile spiders were collected in spring 2001 from a large population in Bonn, Germany. In the laboratory they were kept in individual transparent polyvinyl chloride boxes at room temperature and under natural light and were reared on a diet of flightless Drosophila and Lucilia ssp. Drosophila were reared on a nutrient-rich medium according to Mayntz and Toft (2001)
. After the spiders' final molt, the length of the patella plus the tibia of the first leg was measured to the nearest 0.01 mm. This measure is highly and isometrically correlated with prosoma length and width in males and females (Uhl, 1994) and hence was used as an index of body size. All individuals were measured two times independently. Measurements were highly repeatable (males: r = .980, N = 872; females: r = .979, N = 544), and the mean of the two measures was used as size measure. Males were significantly larger than females (mean additive length of patella and tibia: males = 10.96 ± 0.88 mm; females = 10.79 ± 0.88 mm; t = 3.59, df = 142, p < .001). Body size of both sexes fitted a normal distribution (Kolmogorov-Smirnov test, males: Z = 0.95, p = .32, N = 872; females: Z = 0.50, p = .97, N = 544).
Mating experiments
In order to investigate the effects of male and female body size on sequential mate choice we used a successive double-mating design with eight different size combinations (Table 1). We used spiders of the upper and lower 25% of the size distributions and classified them as large and small. Within the two size classes, individuals were randomly chosen for the mating trials. Virgin females were transferred to transparent mating containers (17 x 9 x 6 cm) at least 1 day prior to the mating trial. Each female was mated with two males in succession with an interval of 1–4 h between the first and the second mating, similar to the procedure used in an earlier study (Schäfer and Uhl, 2002). All males were used in a single mating trial only.
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During mating trials we recorded how long a male took to start courting the females (courtship latency) and the interval between the onsets of courtship activity and copulation (mating latency). Higher latencies were expected to reflect a lower motivation to mate. During copulation, males move their copulatory organs, the pedipalps, in a rhythmic, twisting manner (Uhl et al., 1995
). These pedipalp movements (PPMs), rather than copulation duration, are a good predictor of paternity (Schäfer and Uhl, 2002) and their frequency correlates positively with the amount of sperm transferred (Uhl, unpublished data). In order to evaluate whether female remating probability depends on the amount of sperm transferred by the first male, we recorded the number of PPMs during the first mating.
Statistical analyses
We performed a multiple logistic regression to test for effects of male and female body size (categorical variables) on female remating behavior. We created interaction terms between the male and female size to test for relative size effects on remating behavior. The interaction term between first and second male size was created to test for experience-dependent remating. We included the copulatory behavior of the previous male (number of PPMs) as it may potentially influence female's remating decisions. Parameters were entered en bloc, and the robustness of the results was assessed using both forward selection and backward elimination of variables, with an inclusion probability of variables set to p = .05 and an exclusion probability set to p = .1.
Because the parameters "courtship latency" and "mating latency" did not meet the assumption of normality, we used a nonparametric two-way ANOVA (Scheirer-Ray Hare extension of the Kruskal-Wallis test according to Sokal and Rohlf 1995) to test for effects of size on both parameters. Statistical analyses were performed using the computer software SPSS 10.0 (Noru
is, 2000). All significance levels were two tailed with 
set to 0.05.
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Size-related courtship
Courtship latency did not differ significantly between first and second matings (first matings: median = 6.3 min, interquartile range [IQ] = 1–15.67 min; second matings: median = 4.1 min, IQ = 0.65–14.6 min; U test: Z = –1.72, p = .086, N1 = 215, N2 = 215). Body size of males and females did not significantly influence courtship latency in first matings. In second matings, however, courtship latency was lower in larger females than in smaller ones. Neither second male size nor the interaction between the sexes had any effect on courtship latency (Table 2).
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Mating latency was slightly lower in second compared to first matings (first matings: median = 2.68 min, IQ = 1.56–6.80 min; second matings: median = 2.00 min, IQ = 0.98–6.73 min; U test: Z = –2.00, p = .045, N1 = 213, N2 = 173). Body size of males and females did not significantly influence mating latency in first matings (Table 2). In second matings, mating latency was also not affected by female size but was lower when males were large. There was no significant interaction between the sexes in the latency to mate. There was no significant correlation between courtship latency and mating latency in first and second matings (Spearman rank correlations, all p > .196). Likewise, there was no correlation between the first and second matings of females in either courtship latency or mating latency (Spearman rank correlations, all p > .70).
Size-related female remating
When virgin, 100% of the females mated, but the remating probability of already mated females dropped to 81.9% (Table 1). Courtship latency of the second male did not significantly influence female remating (U test: Z = –0.966, p = .334, N1 = 37, N2 = 178). Multiple logistic regression showed that first male's copulatory behavior did not significantly influence female remating behavior (Table 3). The size of first or second males had no significant impact on female remating probability (Table 3). The interaction term between first and second male size was close to significance (Table 3).
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2 = 22.19, df = 7, p = .002)Female body size was the main predictor for female remating probability: larger females remated with higher probability than smaller ones irrespective of male size (Table 3). This effect was corroborated when using backward elimination and forward selection procedures (both p < .001). The interaction between the first male size and female size was close to significance using a backward regression model (–2 log likelihood ratio = 3.700, df = 1, p = .0544), which resulted from smaller females remating with lower probability after experience with a large male (Table 1).
To increase statistical power we performed a multiple logistic regression on a reduced set of variables in which male-female interactions as well as male copulatory behavior were excluded. Again, first male size, second male size, or the interaction between the two did not have any significant effect on female remating probability (first male size: B = 0.321 ± 0.202, 95% confidence intervals (CI) for eB = 0.928–2.049, p = .112; second male size: B = 0.080 ± 0.202, CI = 0.729–1.609, p = .694; first male x second male size: B = 0.305 ± 0.202, CI = 0.913–2.017, p = .131), whereas the positive effect of female size on remating probability was corroborated (B = –0.706 ± 0.224, CI = 0.318–0.766, p = .002).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Effect of male size on female remating behavior
Virgin female P. phalangioides accepted any male they encountered first but once mated they showed a drop in receptivity to 82%, averaged over all treatments. However, female receptivity was not significantly related to male body size. Female acceptance of a second male did not depend on his size, on the size of the previous male, or on the relative size difference between the successive males, even though body size in P. phalangioides shows both additive and condition-dependent genetic variation (Uhl et al., 2004
), and large males achieve higher mating success in a competitive laboratory setting (Schaefer and Uhl, 2003), suggesting a fitness advantage for females that mate with larger males. Our finding is opposed to other studies on insects and spiders, in which it was shown that females choose to mate with larger or heavier males (Andersson, 1994; for spiders, see Maklakov et al., 2003; Masumoto, 1999; Riechert and Johns, 2003; Singer and Riechert, 1995; Watson, 1991). There are at least three explanations for the lack of a significant effect of male size on female remating behavior. First, it is possible that female cellar spiders may only be able to discriminate among differently sized males by direct comparison. However, it is questionable why a simultaneous mode of choice should be favored and a sequential mode should not be favored, given that male residency in the close vicinity of a female was found to last only a maximum of half a day in a natural population, limiting the opportunity for direct comparison (Uhl, 1998). Second, female choice according to male size may not result in a significant fitness advantage because benefits are too low or are counterbalanced by some other costs. Viability selection due to a higher energy demand of larger individuals may significantly constrain fitness of larger individuals in an environment in which food is limited, although the empirical evidence available is scarce (Blanckenhorn, 2000). Alternatively, there may be a trade-off between benefits and costs of female choice. Female sticklebacks (Gasterosteus aculeatus), for example, are highly selective in a sequential mate choice experiment when time and energy expenditure are low but selectivity decreases with increasing effort (Milinski and Bakker, 1992). Finally, sequential female choice based on male size may simply not have evolved, although it would be adaptive. For instance, in species with small effective population sizes, as generally seems to be the case in P. phalangioides (Schäfer et al., 2001), genetic drift can alter or prevent the evolution of female choice for male traits, even if the benefits of choice were moderate (see discussion in Pomiankowski and Iwasa, 1998). It has to be noted that we cannot fully exclude an effect of male size on female remating as some p values ranged around .1 (Table 2), but sample sizes are large enough to assume that potential effects must be small.
Male size effects and the mating scheme
Our study demonstrates that the intensity of sexual selection on male body size strongly depends on the mating scheme. In our sequential setting we found no significant effect of male size on female remating. However, when two males competed directly over access to a single female, the larger and more dominant male achieved almost exclusive mating success (Schaefer and Uhl, 2003). Thus, male size seems to be strongly selected for by male-male competition, not by direct female choice. Moreover, the remating probability of 82% derived from our sequential mating scheme is much higher than that derived from a competitive setting, in which only 5.2% of females remated during the average period of 8 days until oviposition (Schaefer and Uhl, 2003). The difference between the two studies suggests that the intensity of selection on male size in natural populations will strongly depend on the probability that males encounter a female simultaneously or not and on the benefit from monopolizing a female versus finding another one. However, residency time of males close to females was generally low in a natural population (Uhl, 1998), suggesting that monopolization does not play an important role. Moreover, recent data on the degree of multiple paternity in a natural population of cellar spiders showed that (1) 83.3% of the broods are sired by more than one male and (2) the average number of sires per brood is 2.5 (Schulz J and Uhl G, unpublished). In the present study, remating frequency was 82%. The correspondence between the data on the probability of multiple paternity in a natural population and our present results suggests that under natural conditions sequential encounters play a more important role than direct male-male competition and monopolization of the female. Consequently, our data imply that the intensity of sexual selection on male size within natural populations is probably much weaker than suggested by experimental data on male-male competition.
Effects of female size on remating behavior
The main predictor for female remating probability in our study was female body size, with large females remating with higher probability than small females. This correlation has been reported for several taxa under natural (e.g., Bergström et al., 2002; Gage, 1998), as well as under experimental conditions (e.g., Bergström et al., 2002; Gage, 1998; Rowe and Arnqvist, 1996). Theoretically, a correlation can result from male mate choice for larger more fecund females or from different mating optima of different female phenotypes. Male mate choice in terms of rejecting matings with less fecund females has been documented for species in which mating entails substantial costs in males, for example, species whose males provide nuptial gifts or paternal care (e.g., Gwynne, 1981; Wang and Millar, 1997). For P. phalangioides we doubt that male mate rejection could influence remating probabilities because copulation seems to entail few costs, given the small duration of second matings during which males perform only few PPMs (Schäfer and Uhl, 2002) and given that males who mate can expect high fertilization success due to last-male sperm precedence (Schäfer and Uhl, 2002) and moderate natural female mating rates (Schulz J and Uhl G, unpublished). Moreover, all males used in our study courted a given female irrespective of her size.
Higher remating rates of larger females may also occur when large more fecund females suffer from higher harassment rates compared to smaller females (Rowe and Arnqvist, 1996; Trexler et al., 1997; Watson et al., 1997). Under natural conditions, male P. phalangioides are found with higher probability in the vicinity of larger females, suggesting higher attractiveness and thus possibly higher harassment rates (Uhl, 1998). In our present study, courtship latencies were lower with large females than with small females in second matings, suggesting that indeed male choice may play a role in the probability of female remating.
Size-related mating optima may also originate from higher mating costs for small females. In our experiment, we observed extrusion of hemolymph from the female genital cavity during copulation in three cases exclusively involving small females, suggesting that they are more likely to suffer from injury by male genital structures during copulation. As the size of genital structures of both sexes are correlated with overall body size (Uhl, 1994), costs due to mechanical problems between different-sized mating partners may be substantial, leading to injury in extreme cases. Virgin females of both size classes mated readily with either large or small males, suggesting that the benefits of securing sperm override the risk of injury. However, in mated females, small females tended to remate with lower probability after experience with a large male as the interaction between female size and first male size on remating probability was close to significance (Table 2). We suggest that occasional injury in matings with large males may lead to the optimal mating frequency being lower for small compared to large females. Overall, there was no indication of assortative mating by size in first and second matings.
Larger females may be more likely to mate because they require more sperm to fill their sperm stores. Although the size of the sperm storage organs is positively related to female size in P. phalangioides (Uhl, 1994), females that experienced little sperm transfer (i.e., few PPMs) during the first mating did not remate with higher probability (Table 2). Females thus do not seem to remate on the basis of the amount of sperm stored in their spermatheca.
The design used in this study does not allow for a clear discrimination between intrinsic size-dependent female propensity to remate and higher attractiveness of larger females to males. Irrespective of the causes of female size-related remating, the impact on male sperm allocation strategies should be immense. There is an increasing body of correlational evidence from diverse taxa that female fecundity has shaped male sperm allocation tactics, with males transferring larger ejaculates to larger females (Wedell et al., 2002). However, if large females remate with higher probability, sperm competition risk and intensity increases as well (Parker et al., 1996). Our results therefore strongly suggest that male sperm allocation tactics depend on the trade-off between female size-related fecundity and the risk of sperm competition.
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REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
|---|
Andersson M, 1994. Sexual selection. Princeton, New Jersey: Princeton University Press.
Bateman PW, Gilson LN, Ferguson JWH, 2001. Male size and sequential mate preference in the cricket Gryllus bimaclatus. Anim Behav 61:631–637.[CrossRef]
Bergström J, Wiklund C, Kaitala A, 2002. Natural variation in female mating frequency in a polyandrous butterfly: effects of size and age. Anim Behav 64:49–54.[CrossRef]
Bensch S, Hasselquist D, 1992. Evidence for active female choice in a polygynous warbler. Anim Behav 44:310–312.
Blanckenhorn WU, 2000. The evolution of body size: what keeps organisms small? Q Rev Biol 75:385–407.[CrossRef][Medline]
Bondurianski R, 2001. The evolution of male mate choice in insects: a synthesis of ideas and evidence. Biol Rev 76:305–339.[Medline]
Choudhury S, Black JM, 1993. Mate-selection behaviour and sampling strategies in geese. Anim Behav 46:747–757.[CrossRef][Web of Science]
Crespi BJ, 1989. Causes of assortative mating in arthropods. Anim Behav 38:980–1000.[CrossRef]
Dale S, Amundson T, Lifjeld JT, Slagsvold T, 1990. Mate sampling behaviour of female pied flycatchers: evidence for active mate choice. Behav Ecol Sociobiol 27:87–91.
Dale S, Rinden H, Slagsvold T, 1992. Competition for a mate restricts mate search of female pied flycatchers. Behav Ecol Sociobiol 30:165–176.[CrossRef][Web of Science]
Elgar MA, 1998. Sperm competition and sexual selection in spiders and other arachnids. In: Sperm competition and sexual selection (Birkhead TR, Moller AP, eds). San Diego, CA: Academic Press; 307–332.
Gabor CR, Halliday TR, 1997. Sequential mate choice by multiple mating smooth newts: females become more choosy. Behav Ecol 8:162–166.
Gage MJG, 1998. Influences of sex, size, and symmetry on ejaculate expenditure in a moth. Behav Ecol 9:592–597.
Gibson RM, Langen TA, 1996. How do animals choose their mates? Trends Ecol Evol 11:468–470.[CrossRef]
Gwynne DT, 1991. Sexual competition among females: what causes courtship-role reversal? Trends Ecol Evol 6:118–121.
Halliday TR, 1983. The study of mate choice. In: Mate choice (Bateson P, ed). Cambridge, MA: Cambridge University Press; 3–22.
Honek A, 1993. Intraspecific variation in body size and fecundity in insects: a general relationship. Oikos 66:483–492.[CrossRef][Web of Science]
Houde AE, 1987. Mate choice based upon naturally occurring color-pattern variation in a guppy population. Evolution 41:1–10.
Janetos AC, 1980. Strategies of female mate choice: a theoretical analysis. Behav Ecol Sociobiol 7:107–112.
Jennions MD, Petrie M, 1997. Variation in mate choice and mating preferences: a review of causes and consequences. Biol Rev 72:283–327.[Medline]
Jennions MD, Petrie M, 2000. Why do females mate multiply? A review of the genetic benefits. Biol Rev 75:21–61.[Medline]
Johnstone RA, 1995. Sexual selection, honest advertisement and the handicap principle: reviewing the evidence. Biol Rev 70:1–65.[Medline]
Maklakov AA, Bilde T, Lubin Y, 2003. Vibratory courtship in a web-building spider. Signalling quality or stimulating the female? Anim Behav 66:623–630.[CrossRef][Web of Science]
Masumoto T, 1999. Size assortative mating and reproductive success of the funnel-web spider, Agelena limbata. J Insect Behav 12:353–361.
Mayntz D, Toft S, 2001. Nutrient composition of the prey's diet affects growth and survivorship of a generalist predator. Oekologia 127:207–213.
Milinski M, Bakker TCM, 1992. Costs influence sequential mate choice in sticklebacks, Gasterosteus aculeatus. Proc R Soc Lond B 250:229–233.
Moore AJ, Moore PJ, 1988. Female strategy during mate choice: threshold assessment. Evolution 42:387–391.[CrossRef][Web of Science]
Noruis MJ, 2000. SPSS 10.0. Guide to data analysis. Englewood Cliffs, NJ: Prentice-Hall.
Parker GA, Ball MA, Stockley P, Gage MJG, 1996. Sperm competition games: assessment of sperm competition intensity by group spawner. Proc R Soc Lond B 263:1291–1297.
Pitcher TE, Neff BD, Roff FH, Rowe L, 2003. Multiple mating and sequential mate choice in guppies: females trade up. Proc R Soc Lond B 270:1623–1629.[Medline]
Pomiankowski A, Iwasa Y, 1998. Runaway ornament diversity caused by Fisherian sexual selection. Proc Natl Acad Sci U S A 95:5106–5111.
Rasa OAE, 1997. Female mate assessment tactics in a subsocial desert beetle: a test of Janetos' models. Ethol Ecol Evol 9:233–240.
Real LA, 1990. Search theory and mate choice. I. Models of single-sex discrimination. Am Nat 136:376–404.[CrossRef][Web of Science]
Real LA, 1991. Search theory and mate choice. II. Mutual interaction, assortative mating, and equilibrium variation in male and female fitness. Am Nat 138:901–917.[CrossRef][Web of Science]
Riechert SE, Johns PM, 2003. Do female spiders select heavier males for the genes for behavioural aggressiveness they offer their offspring? Evolution 57:1367–1373.[CrossRef][Web of Science][Medline]
Ringo J, 1996. Sexual receptivity in insects. Ann Rev Entomol 41:473–484.[Web of Science][Medline]
Rowe L, Arnqvist G, 1996. Analyses of the causal components of assortative mating in water striders. Behav Ecol Sociobiol 38:279–286.[CrossRef][Web of Science]
Savalli UM, Fox CW, 1998. Sexual selection and the fitness consequences of male body size in the seed beetle Stator limbatus. Anim Behav 55:473–483.[CrossRef][Web of Science][Medline]
Schäfer MA, Hille A, Uhl G, 2001. Geographical patterns of genetic subdivision in the cellar spider Pholcus phalangioides (Aranea). Heredity 86:94–102.[CrossRef][Web of Science][Medline]
Schäfer MA, Uhl G, 2002. Determinants of paternity success in the spider Pholcus phalangioides (Pholcidae: Araneae): the role of male and female mating behaviour. Behav Ecol Sociobiol 51:368–377.[CrossRef][Web of Science]
Schaefer D, Uhl G, 2003. Male competition over access to females in a spider with last-male sperm precedence. Ethology 109:385–400.[CrossRef][Web of Science]
Singer F, Riechert SE, 1995. Mating system and mating success of the desert spider Agelenopsis aperta. Behav Ecol Sociobiol 36:313–322.[CrossRef][Web of Science]
Sokal RR, Rohlf FJ, 1995. Biometry, 3rd ed. New York: Freeman.
Stearns SC, 1992. The evolution of life histories. Oxford: Oxford University Press.
Trexler JC, Travis J, Dinep A, 1997. Variation among populations of the sailfin molly in the rate of concurrent multiple paternity and its implications for mating-system evolution. Behav Ecol Sociobiol 40:297–305.[CrossRef][Web of Science]
Uhl G, 1994. Reproduktionsbiologie von Zitterspinnen (PhD dissertation). Freiburg i. Br.: University of Freiburg.
Uhl G, 1998. Mating behaviour in the cellar spider, Pholcus phalangioides, indicates sperm mixing. Anim Behav 56:1155–1159.[CrossRef][Web of Science][Medline]
Uhl G, Huber BA, Rose W, 1995. Male pedipalp morphology and copulatory mechanism in Pholcus phalangioides (Fuesslin, 1775) (Araneae, Pholcidae). Bull Br Arachnol Soc 10:1–9.
Uhl G, Schmitt S, Schäfer MA, Blanckenhorn WU, 2004. Food and sex specific growth strategies in a spider. Evol Ecol Res 6:523–540.
Wang Q, Millar JG, 1997. Reproductive behavior of Thyanta pallidovirens (Heteroptera: Pentatomidae). Ann Entmol Soc Am 90:380–388.
Watson PJ, 1991. Multiple paternity and first mate sperm precedence in the sierra dome spider, Linyphia litigiosa Keyserling (Linyphiidae). Anim Behav 41:135–148.[CrossRef][Web of Science]
Watson PJ, Arnqvist G, Stallmann RR, 1997. Sexual conflict and the energetic costs of mating and mate choice in water striders. Am Nat 151:46–58.[CrossRef][Web of Science]
Wedell N, Gage MJG, Parker GA, 2002. Sperm competition, male prudence and sperm limited females. Trends Ecol Evol 17:313–320.[CrossRef]
Zeh JA, Newcomer SD, Zeh DW, 1998. Proc Natl Acad Sci U S A 95:13732–13736.
Zuk M, Johnson K, Thornhill R, Ligon JD, 1990. Mechanisms of female choice in red jungle fowl. Evolution 44:477–485.[CrossRef][Web of Science]
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