Skip Navigation


Bioscience Horizons Advance Access originally published online on April 10, 2009
Bioscience Horizons 2009 2(2):164-171; doi:10.1093/biohorizons/hzp019
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrowOA All Versions of this Article:
2/2/164    most recent
hzp019v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Google Scholar
Right arrow Articles by Parker, D.
PubMed
Right arrow Articles by Parker, D.
Related Collections
Right arrow Animal Behaviour
Right arrow Biology
Right arrow Genetics
Right arrow Zoology
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© 2009 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Pre- and post-copulatory mate choice in Platygryllus primiformis: cryptic female choice and sexual conflict

Darren Parker*

University of Derby, Derby, UK

* Corresponding author: 45 Wild Street, Derby DE1 1GP, UK. Tel: +44 7929528965. Email: dazparker14{at}hotmail.com

Supervisor: Dr Karim Vahed, N610, University of Derby, Kedleston Road, Derby DE22 1GB, UK.


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 Funding
 References
 Author Biography 
 
The effect of sexual conflict upon mating systems is a controversial topic. The aim of this study was to determine whether post-copulatory choice by females (spermatophore removal) reinforces pre-copulatory choice with respect to male body size and fighting ability, and whether such post-copulatory female choice is influenced by post-copulatory mate guarding by males using Platygryllus primiformis (Orthoptera: Gryllidae; Gryllinae). A no-choice test was used to determine the attractiveness of males and spermatophore attachment time was recorded as a measure of cryptic female choice. Females maintained a pre-copulatory mate choice for large males that were more successful in fighting, shown by a shorter latency to copulation. Larger, males that were more successful in fighting were also preferred by post-copulatory cryptic female choice, shown by a longer spermatophore attachment time, reinforcing pre-copulatory mate choice. Males attempted to counter this selection by guarding females, which increased their spermatophore attachment time. Interestingly, spermatophore attachment time increased similarly for all sizes of male as a result of mate guarding, meaning that females maintained their original choice.

Key words: Platygryllus primiformis, mate choice, sexual conflict, cryptic female choice, male manipulation, sexually antagonistic coevolution


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Conclusion
 Funding
 References
 Author Biography 
 
In the animal kingdom, females are typically the choosy sex due to the effects of anisogamy.1, 2 Females prefer to mate with males which best increase their fitness and classically this is thought to be for larger males. However, some recent studies have shown that females of various taxa may mate indiscriminately or even actively discriminate against larger males.3–6

Active discrimination against larger males is likely to be the result of either a direct fitness cost to the female (e.g. increased the risk of injury)7 or a indirect (genetic) cost (e.g. large size genes may reduce fitness when in female offspring).8 Indiscriminate mate choice (in non-lekking species) may evolve for a number of reasons: to increase female survivorship if the costs generated by resisting a male are higher than by accepting mating,9 leading to the adoption of a convenience polyandry mating system,10 or to gain direct fitness benefits from males (e.g. from donation of a prey item (material benefit polyandry)).11 Indiscriminate mate choice seems particularly likely to evolve if females can subsequently bias paternity towards males with superior genes using post-copulatory mate choice, as this allows females to gain both from direct benefits (or reduced costs) and indirect genetic benefits by biasing paternity towards genetically desirable males.10

The majority of studies on Gryllid crickets (but not all),3 however, show that females prefer to mate with larger males.12–14 In many taxa, choice for large males is put down to one of two major explanations. The first is that females may gain more direct benefits from mating with larger males and thus by preferring to mate with larger males they will gain from an increase in fitness. This is unlikely to affect Gryllid mating systems, as males provide little nutritional resources to the female (Gryllid spermatophores are generally small, and thus consumption is unlikely to provide any increase in female fitness12, 13, 15 (but refer Wagner and Harper16 and Discussion section). The second explanation suggests that females gain from mating with larger males via indirect genetic benefits.12, 13, 17 Size is thought to be highly correlated with genotypic fitness, as it measures an individual's ability to withstand environmental pressures (from parasites, etc.). Individuals that are best able to deal with environmental pressures are able to allocate more recourses to growth and therefore are able to achieve a larger size.18 Thus, by selecting males who are large, a female is able to gain genes for her offspring which could then aid them to successfully withstand environmental pressures, enhancing the female's fitness.18, 19 A large size is also thought to secondarily increase the fitness of both sexes of offspring via increased egg production in females13 and greater access to females for males via enhanced fighting ability (rival displacement)3, 20 (the latter was tested by this study as it has not been demonstrated in the literature for Platygryllus primiformis (Prediction 1)). Thus, as genes for a large size may provide offspring with both increased environmental robustness18, 19 and increased reproductive success3, 13, 20 female P. primiformis are expected maintain a preference for large males who are more successful at fighting8 (Prediction 2).

Selection for purely indirect benefits, however, is a controversial issue,21 as it is often seen as a weak selective force in comparison to selection for direct benefits.22, 23 This means that if indirect benefits are opposed by a direct cost, selection should act to reduce the direct cost and not favour selection for indirect benefits (producing a convenience polyandry mating system).23 Investigation into this area is often confounded by direct benefits,24 however, Gryllid crickets such as P. primiformis remove this confounding influence as the direct costs to the female associated with choosing a male (reduced foraging,25 increased predation25, 26 and the signal itself27) are large with little chance of compensation via any nutritional benefits gained from mating12, 13, 15, 17 (but refer Wagner and Harper16). Thus, as there is a direct cost associated with choosing a male any pre-copulatory mate choice in P. primiformis will be maintained to gain from indirect benefits (despite the direct cost).17

Cryptic Female Choice
Cryptic female choice is a controversial topic28–30 due to the challenges of formally demonstrating its existence.12, 31 Gryllid crickets allow cryptic female choice to be demonstrated as the male's spermatophore is attached externally onto the female's ovipositor,13 meaning spermatophore attachment time (the length of time the spermatophore is attached to the females ovipositor) can be recorded. A greater spermatophore attachment time means increased paternity for the male as a greater amount of sperm is transferred to the spermatheca where it mixes randomly with stored sperm to generate a ‘fertilization set’ which the female then uses to fertilize her eggs (fair raffle system).13, 32 Thus, males with greater spermatophore attachment times gain a greater share of the fertilization set and thereby gain from increased reproductive success. As females can remove the spermatophore at any time, they can easily bias paternity towards certain male phenotypes,12, 14, 15, 33 most likely discriminating against smaller males (Prediction 3).

A further unresolved question is whether post-copulatory mate choice acts to reinforce pre-copulatory mate choice choice12, 13 or oppose it.34 One reason for reinforcing pre-copulatory mate choice may be to ‘double up’ choice to counter any male manipulation at either the pre-copulatory or post-copulatory mating stages. By ‘doubling up’ mate choice females are able to reduce the effects any male manipulation may have. In contrast, it is difficult to see why post-copulatory mate choice should oppose pre-copulatory mate choice9 (Prediction 4).

Males should attempt to oppose female post-copulatory choice by premature spermatophore removal by guarding the female (staying in close proximity after copulation and attacking the female if she attempts to move away/remove the males spermatophore)35 in order prolong spermatophore attachment (shown by a number of studies12, 14, 15, 33 but not all)36 (Prediction 5). An increase in the male's spermatophore attachment time due to mate guarding, however, may be a product of either male manipulation (where males prevent spermatophore removal by the female) or female choice (where females choose to extend spermatophore attachment time on the basis of the male's guarding behaviour (vigour hypothesis)). In the literature, there is support for both the vigour hypothesis15, 35, 37 (where preferred males (as determined from female spermatophore attachment times when the male is prevented from guarding) guard females most vigorously) and the alternative sexual conflict/male manipulation hypothesis,12, 38 (disfavoured males guard more vigorously, as they stand to lose most from cryptic female choice).12, 38 The two hypotheses can be resolved by observation of mate guarding behaviour (which males guard with most vigour (vigour was not recorded by this study, see12, 35 for details on the quantification of mate guarding vigour)) or by calculation of relative gains from increased attachment time as a result of guarding (as if guarding is manipulative, disfavoured males would be expected to gain more from mate guarding, but if females use mate guarding to assess a male's quality, favoured males should gain most from mate guarding)12 (Prediction 6).

This study investigated how pre- and post-copulatory sexual selection has shaped mating behaviour of P. primiformis (Orthoptera: Gryllidae; Gryllinae)39 by investigating female pre-copulatory mate choice, cryptic female choice, and possible male counter-adaptation to female choice. In addition, this investigation sheds light on a number of currently unresolved issues: if females choose large males, if cryptic female choice exists and if post-copulatory mate choice acts to reinforce pre-copulatory mate choice, all of which are currently contested in the literature.4, 10, 29

Predictions
The following predictions were tested by this study.

  1. Larger males will have a higher fighting success than smaller males.
  2. Males that are large and more successful at fighting will have a shorter latency to mating time.
  3. Spermatophore attachment time will be longer for larger, more successful males.
  4. Post-copulatory mate choice will enforce pre-copulatory mate choice.
  5. Spermatophore attachment times will be longer when a male is allowed to guard.
  6. Disfavoured males will gain relatively more benefits from mate guarding (via extension of spermatophore attachment time).


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Conclusion
 Funding
 References
 Author Biography 
 
Study Animals
The stock of P. primiformis in this study was taken from a maintained population at the University of Derby originally collected from Westville, Durban, Natal in South Africa (Lat: 29°49'60S, Lon: 30°55'60E).37 The colony of P. primiformis was maintained in semi-natural conditions (28°C, 12 h light: 12 h dark cycle, in plastic aquaria (30 cm x 20 cm x 15 cm) and fed on dried rat and rabbit pellets with the addition of vegetables (as a vitamin supplement).

Before all experiments, both male and female P. primiformis were mated once with a stock P. primiformis (stock males and females used were of similar size (0.32 ± 0.08 and 0.37 ± 0.07 g, respectively) to avoid any effects that variation in previous mate quality may have) in order to make sure males were sexually competent14, 40 and to better parallel the in vivo situation as females are unlikely to be virgins for the majority of copulations.13 It has also been demonstrated that virgin females behave differently on their first mating as insurance against a lack of other mating opportunities14, 36, 41 to the extent that males may skip part of their courtship.10 Thus, by using mated females, this study minimizes the risk of misunderstanding important aspects of P. primiformis' mating behaviour.10 This is particularly important for understanding male manipulative behaviour as on the first mating females will be less choosy10 and also leave the males spermatophore attached for longer36 meaning males will have less need to manipulate the female on the first copulation than on subsequent copulations.

Assessing Male Fighting Ability
Eighty males were used to assess male fighting ability, split randomly into 10 groups of 8 and then weighed. Males were then chilled for 15 min at 8–10°C allowing them to be marked easily on their pronotum using non-toxic enamel paint. Males were then left for 24 h to reacclimatize before experimentation.

Two males from a marked set of eight were then placed into a small container (15 cm x 8 cm x 6 cm) and left to fight. The winner was determined by the male that initiated three attacks in which the opponent retreated (the fighting behaviour in P. primiformis is highly ritualized (similar to Gryllus bimaculatus)20 with the winning male producing a victory song). The remaining six males were then paired and fought in the same way to produce four winners and four losers. The four winners were then paired up to fight and the same for the losers. Following the second fight, crickets with the same fight outcomes from the two fights were then placed together for a third fight, allowing the males to be placed into fighting classes based on number of fights won (3,2,1, or 0).3 The weight of the males in different fighting classes was then compared using one-way ANOVA to test Prediction 1. Pairing males with the same fight history controls for any order effects fight history may have had on a males fighting ability.42 The males used here to assess fighting ability were then subsequently used in mate trails (below).

Mate Trials
The P. primiformis used in this study were all of a similar age, as a number of studies have shown that female crickets prefer older males, regardless of size.18, 43 Before the beginning of the mate trials, each male was placed into a container with a mesh barrier which physically separated the male from the female (subsequently excluded from mate trials) but still allowed visual and chemical communication. This was to ensure each male had a spermatophore ready to transfer (indicated by the male stridulating) to ensure that none of the males used would be delayed in mating as a result. Female weight was standardised (0.34 ± 0.02 g) as males have been shown to exhibit mate choice for larger females in a number of Orthopteran taxa including G. bimaculatus44 and P. primiformis13 possibly related to the cost of spermatophore production.45 As this study is concerned with female choice, this variable was eliminated.

Pre-copulatory Choice
Seventy-four males that had been ranked into fighting classes (based on the number of fights won (3, 2, 1, 0) (above)) were used to investigate pre-copulatory choice. This was done by introducing a ranked male to a randomly selected stock female (0.34 ± 0.02 g) into a small container (15 cm x 8 cm x 6 cm) and recording the latency to mating time (from introduction to copulation) to test Prediction 2. Six males from the 80 used in the fighting trials (above) were not used to establish this relationship due to death (meaning only 74 of the males (10, 29, 26, and 9 males in fighting Classes 3, 2, 1, and 0, respectively) could be used to establish this relationship.

This study used latency to copulation as a measure of attractiveness, with short latency times indicating greater attractiveness. This method of assessing attractiveness is closer the situation faced by females in vivo46 than studies that determine female preference by presenting two males simultaneously47, 48 as male Gryllid crickets do not tolerate the presence of rivals.40, 46, 49

Post-copulatory Choice
Spermatophore attachment time was also measured after recording the latency to mating time for 50 of the males used in the pre-copulatory trials (above) (spermatophore attachment time was not recorded for three sets of males used in the pre-copulatory mate trails (above) due to time constraints) to test Predictions 3 and 4.

The male's presence was varied during this study, either removing the male directly after spermatophore transfer or leaving the male with the female until the spermatophore was detached, to test the effects of mate guarding (Predictions 5 and 6). Each male was used in each treatment only once with 24 h in-between to recover, females however were not reused. Whether a male was left to guard a female first or removed first was varied in each set of mating trials to counter any order effects (e.g. ageing of the males).25, 43

Statistical Analysis
All statistical analyses (Dunn-Sidac, one- and two-way ANOVAs) were performed using SPSS v16.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Conclusion
 Funding
 References
 Author Biography 
 
Fighting Ability of Male P. primiformis in Relation to Weight
Heavier males were found to have a higher fighting success (Fig. 1) supporting Prediction 1. One-way ANOVA showed this result was statistically significant (F3,76 = 139.59, P < 0.01).


Figure 1
View larger version (61K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Figure 1. Relationship of male weight (mean ± standard deviation) to the number of fights won, showing that heavier males were more likely to win fights. n = number of individual males in each treatment (total number of males used = 80).

 
Post hoc (Dunn-Sidac) analysis showed that the males' weights were significantly different in each fighting class (P < 0.01 in all instances), showing that a male's weight is an accurate predictor of his fighting success.

Attractiveness of Male P. primiformis as Determined by a No-choice Test
The most successful fighting males (those that won the most fights) were shown to have shorter ‘latency to mating’ times (Fig. 2) and thus considered to be more attractive to females (Prediction 2).3, 12 One-way ANOVA showed this relationship to be statistically significant (F3,70 = 170.75, P < 0.01).


Figure 2
View larger version (50K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Figure 2. Relationship between fighting class and latency to mating time (mean ± standard deviation) showing a shorter latency to mating times for more successful fighting males. n = number of individual males in each treatment. Total number of individual males used = 74.

 
Post hoc (Dunn-Sidac) analysis showed that there was a significant difference in latency to mating time between each fighting class (P < 0.01 in all instances).

Spermatophore Attachment Time in Relation to Male Fighting Ability and Mate Guarding
Females left spermatophores from males in higher fighting classes attached for longer (Prediction 3) (Fig. 3), reinforcing pre-copulatory mate choice (Prediction 4). This study also found that females left spermatophores attached for longer with a male present (Prediction 5) (Fig. 3). Two-way ANOVA showed both mate guarding (F1,92 = 451.42, P < 0.01) and fighting class (F3,92 = 20.27, P < 0.01) has a significant effect on spermatophore attachment time. Please note each male was used once in each treatment (guarding or not guarding) to ensure data was independent and comparable across the treatments (see Materials and Methods section for details).


Figure 3
View larger version (53K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Figure 3. Relationship of spermatophore attachment time (mean ± standard deviation) to both fighting class and male presence (after spermatophore attachment), showing a decrease in attachment time, with a decrease in fighting class and with male absence. n = number of males in each treatment (each male was used in each treatment once). Number of individual males and females used in trials = 50.

 
Dunn-Sidac analysis showed that there was only a significant difference in spermatophore attachment time between fighting Class 3 and the other classes (P < 0.01), with no significant difference between the other classes (P > 0.05). This trend was shown both when males were present or absent after spermatophore attachment, showing that the two factors (fighting class and male presence) are independent (interaction was found not to be statistically significant in the two-way ANOVA (F3,92 = 1.47, P = 0.23)).

This study also found no significant difference between fighting classes in the amount spermatophore attachment time increased as a result of mate guarding using one-way ANOVA (F3,46 = 1.78, P = 0.164); each class of male gained a similar increase in spermatophore attachment time as a result of guarding (Table 1). A significant difference was, however, found between fighting classes in the relative gain in spermatophore attachment time (per cent increase in attachment time) as a result of mate guarding using one-way ANOVA (F3,46 = 14.18, P < 0.01), with relative gains being significantly higher for less successful, smaller males (Table 1), providing support for Prediction 6. Please note each male was used once in each treatment (guarding or not guarding) to ensure data was independent and comparable (as above).


View this table:
[in this window]
[in a new window]

  		Table 1. Average increase in spermatophore attachment time as a result of mate guarding

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Conclusion
 Funding
 References
 Author Biography 
 
Male–Male Interactions
As predicted larger males won more fights3, 20 and can therefore potentially gain from increased access to females by exclusion of smaller rivals. Size is also likely to be highly correlated with genotypic fitness18, 19 and increased egg production in females13 which may account for why females maintain a strong selection for large males (below).8

Pre-copulatory Mate Choice
Males that were more successful at fighting had shorter latency to mating times, supporting the classic idea that females prefer to mate with larger males.13, 45, 50 This study also supports the idea that female preference for large males is maintained to gain from indirect genetic benefits, as it seems highly unlikely that females gain any direct benefits from mating, due to the small size of the males' spermatophore13 (if benefits are gained they are unlikely to compensate costs caused by the males' courtship,25–27, 51, 52 and frequently spermatophores were simply detached and left on the substrate rather than consumed). Thus, as females were shown to mate discriminately for no known direct benefits, the most plausible reason for female preference for large males in P. primiformis is to gain from indirect genetic benefits (but see below).

Pre-copulatory Sexual Conflict
Female choice for large males creates a selection pressure on smaller, disfavoured males to override a female's choice and manipulate the female into mating sub-optimally.53 This is supported by this study because if females were free to simply choose the best males, then males of a lower quality should have been ignored indefinitely (as females were not virgins).54 As even the smallest males were able to secure matings it suggests that female choice may be compromised by male manipulation, however further study is required to confirm this.

Problem of Indirect Benefits
As already stated females in this study are likely to be choosing males for indirect genetic benefits, however indirect benefits are seen as a weak selective pressure and thus easily opposed by direct fitness costs.22, 23, 38 As female crickets appear to suffer greatly from the effects of male courtship,37, 52, 55 incurring a number of direct fitness costs (e.g. reduced foraging25, increased risk of parasitism (particularly from phonotactic dipterans),51, 56 predation,25, 26 or simply by the signal itself27, 52), selection should act against the maintenance of pre-copulatory mate choice (favouring convenience polyandry).13

An explanation for why female P. primiformis maintain a pre-copulatory mate choice for indirect benefits is thought to be due to one of the following: (i) copulation with males is costly and thus females reduce direct costs by being selective, (ii) females gain direct benefits from mating with superior males, or (iii) the direct costs from mating are low.

The total cost of mating in P. primiformis was not quantified is this study nor available in the literature, however studies on similar species (e.g. G. bimaculatus)27 have shown that the largest cost associated with mating arises from courtship (rather than copulation or the ejaculate) suggesting that mate choice is not maintained to avoid mating costs. It is possible that females may gain direct benefits from larger males and not smaller males (benefits must differ between sizes of male otherwise a convenience polyandry system would be expected to evolve) from greater hatching success, however, where this is the case it is often as a result of larger males providing fertility benefits to females16, 57 which P. primiformis do not appear to provide,13 making it unlikely that females gain direct benefits from large males (although further study is still needed to confirm this). As this study was conducted in vitro, females and males were kept in close proximity during experiments meaning females could not escape from disfavoured males. If females were free to move away from disfavoured males (as in vivo), it is likely that costs of resisting disfavoured males would be greatly reduced. Thus, this study suggests that P. primiformis females select large males for indirect benefits, despite possible direct costs however these are likely to be much reduced in vivo.

Post-copulatory Mate Choice
Males that were more successful at fighting were shown to have longer spermatophore attachment times both in the presence and absence of a guarding male,12–14, 37 and thus are likely to gain from increased paternity.32, 58 This shows that females can bias paternity using premature spermatophore removal,12, 14, 15, 33 and in doing so amplify pre-copulatory mate choice.12, 13 There does not appear to be any direct costs or benefits to the female associated with spermatophore attachment time in Gryllid crickets, either from the transfer of the full ejaculate27 or premature spermatophore removal (e.g. via reduced clutch hatching success,13 although this may play a role in other species)16 supporting the idea that female choice is for indirect benefits (although further work is needed to confirm this).

Post-copulatory Sexual Conflict
In absence of a mate guard, only the largest males that had been the most successful at fighting (Class 3) had a significantly increased spermatophore attachment time, showing that females discriminate highly against smaller males, creating a selection pressure on disfavoured males to oppose female choice. This study showed that mate guarding increased spermatophore attachment time and thus appears to represent a male counter-adaptation to cryptic female choice.12, 14, 15, 33 There are two hypotheses suggested for how this behaviour influences the female to prolong the attachment of the spermatophore, the vigour hypothesis or sexual conflict hypothesis (see Introduction section), and this study supports the latter. This is because smaller males gained relatively more from mate guarding (703% increase in spermatophore attachment time compared 154% for the largest males, despite the fact that absolute increase in attachment time is similar for all males), contrary to what would be expected if females used mate guarding to further assess a male's quality.12, 38 Mate guarding intensity (the amount of mate guarding behaviours (e.g. body judders)35 preformed over a particular time period) is also predicted to be higher in smaller males which could be confirmed by quantification of mate guarding intensity (as has been demonstrated in Teleogryllus commodus).12

As mate guarding was found to increase spermatophore attachment time by a similar amount for all classes of male it appears that female P. primiformis may have evolved resistance to the males' counter-adaptation. The reasons for suspecting this is that although males do actively guard females, they do not seem to be able to prevent spermatophore removal. Often when the female attempts to remove the male's spermatophore it goes unheeded, and on the occasions when it is challenged (by aggressive attack from the male) the spermatophore is often removed anyway (usually by female rubbing her ovipositor on the substrate). This shows that males do not directly affect the females' choice of when to remove the spermatophore. This disagrees with several other studies, which show that males can actively prevent females from removing their spermatophore,12, 35, 36 however the mate guarding behaviour for P. Primiformis has not been detailed in the literature and so may they be unique in this respect. Males may still gain benefits from guarding, despite not altering the female's choice, by preventing rival males from mating with the female (rival exclusion)36, 55, 59 or possibly from the opportunity to remate with the female (spermatophore renewal).36, 59

Thus, even though males transfer more sperm by mate guarding, females are still able to bias paternity towards attractive males. Males continue to guard females, as females discriminate highly against males that to do not guard and also may gain from other routes (rival exclusion or spermatophore renewal).


   Conclusion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
Funding
 References
 Author Biography 
 
In conclusion, this study showed that female P. primiformis prefer to mate with larger, males that were more successful at fighting. This choice is reinforced by post-copulatory mate choice whereby females left the spermatophores from larger males attached for significantly longer (demonstrating cryptic female choice).

Mate guarding was shown to increase spermatophore attachment time and appears to have evolved due to conflict over spermatophore attachment times (as the optimal spermatophore attachment time for males is longer than that of non-virgin females)10 rather than a way for a females to assess a male's vigour as a basis to extend his spermatophore attachment time. Thus, mate guarding in P. primiformis appears to represent a male manipulation to increase paternity (via increased spermatophore attachment time) by opposing female choice. Females appear to have evolved resistance to the male's manipulation however, as although spermatophore attachment times were increased by mate guarding, it was by a similar amount for all sizes of male, meaning females retained their original choice.35


   Funding
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 Funding
References
 Author Biography 
 
This work was funded by the University of Derby.


   Acknowledgements
 
I would like to thank my supervisor, Karim Vahed, for providing guidance during this project. I would also like to thank Karim Vahed, Natalie Welden, and Jamie Langton for providing useful discussion and Lisa Williams for proof reading earlier drafts. Finally, I would like to thank Jane Barker for her invaluable contribution in rearing the crickets used in this experiment, without which, none of this would have been possible.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 Funding
 References
Author Biography 
 

  1. Kokko H, Jennions MD, Brooks R. Unifying and testing models of sexual selection. Annu Rev Ecol Evol Syst (2006) 37:43–66.[CrossRef]
  2. Trivers RL. Parental investment and sexual selection. In: Sexual Selection and the Descent of Man—Campbell BG, ed. (1972) Chicago: Aldine. 136–179.
  3. Shackleton MA, Jennions MD, Hunt J. Fighting success and attractiveness as predictors of male mating success in the black field cricket, Teleogryllus commodus: the effectiveness of no-choice tests. Behav Ecol Sociobiol (2005) 58:1–8.[CrossRef][Web of Science]
  4. Qvarnstrom A, Forsgren E. Should females prefer dominant males? Trends Ecol Evol (1998) 13:498–501.[CrossRef]
  5. Wong BBM. Superior fighters make mediocre fathers in the Pacific blue-eye fish. Anim Behav (2004) 67:583–590.[CrossRef][Web of Science]
  6. Bonduriansky R, Rowe L. Interactions among mechanisms of sexual selection on male body size and head shape in a sexually dimorphic fly. Evolution (2003) 57:2046–2053.[Web of Science][Medline]
  7. Watson PJ, Arnqvist G, Stallmann RR. Sexual conflict and the energetic costs of mating and mate choice in water striders. Am Nat (1998) 151:46–58.[CrossRef][Web of Science][Medline]
  8. Chippindale AK, Gibson JR, Rice WR. Negative genetic correlation for adult fitness between sexes reveals ontogenetic conflict in Drosophila. Proc Natl Acad Sci USA (2001) 98:1671–1675.[Abstract/Free Full Text]
  9. Arnqvist G, Rowe L. Sexual Conflict (2005) Princeton: Princeton University Press.
  10. Eberhard WG. Female Control: Sexual Selection by Cryptic Female Choice (1996) Princeton: Princeton University Press.
  11. Brown WD. Female remating and the intensity of female choice in black-horned tree crickets, Oecanthus nigricornis. Behav Ecol (1997) 8:66–74.[Abstract/Free Full Text]
  12. Bussiere LF, Hunt J, Jennions MD, et al. Sexual conflict and cryptic female choice in the black field cricket, Teleogryllus commodus. Evolution (2006) 60:792–800.[Web of Science][Medline]
  13. Bateman PW. Assortative mating by both sexes in the cricket Platygryllus primiformis. In: Trans Am Entomol Soc (1998) 124. Orthoptera: Gryllidae; Gryllinae. 63–68.
  14. Bateman PW, Gilson LN, Ferguson JWH. Male size and sequential mate preference in the cricket Gryllus bimaculatus. Anim Behav (2001) 61:631–637.[CrossRef][Web of Science]
  15. Simmons LW. Female choice in the field cricket Gryllus bimaculatus (De Geer). Anim Behav (1986) 34:1463–1470.[CrossRef][Web of Science]
  16. Wagner WE, Harper CJ. Female life span and fertility are increased by the ejaculates of preferred males. Evolution (2003) 57:2054–2066.[Web of Science][Medline]
  17. Head ML, Hunt J, Jennions MD, et al. The indirect benefits of mating with attractive males outweigh the direct costs. PloS Biol (2005) 3:289–294.[CrossRef][Web of Science]
  18. Zuk M. Parasite load, body size, and age of wild-caught male field crickets (Orthoptera, Gryllidae)—effects on sexual selection. Evolution (1988) 42:969–976.[CrossRef][Web of Science]
  19. Rantala MJ, Kortet R. Male dominance and immunocompetence in a field cricket. Behav Ecol (2004) 15:187–510.[Abstract/Free Full Text]
  20. Hofmann HA, Schildberger K. Assessment of strength and willingness to fight during aggressive encounters in crickets. Anim Behav (2001) 62:337–348.[CrossRef][Web of Science]
  21. Kotiaho JS, Puurtinen M. Mate choice for indirect genetic benefits: scrutiny of the current paradigm. Funct Ecol (2007) 21:638–644.[CrossRef]
  22. Kirkpatrick M. Good genes and direct selection in evolution of mating preferences. Evolution (1996) 50:2125–2140.[CrossRef][Web of Science]
  23. Kirkpatrick M, Barton NH. The strength of indirect selection on female mating preferences. Proc Natl Acad Sci USA (1997) 94:1282–1286.[Abstract/Free Full Text]
  24. Iyengar VK, Reeve HK, Eisner T. Paternal inheritance of a female moth's mating preference. Nature (2002) 419:830–832.[CrossRef][Medline]
  25. Zuk M, Kolluru GR. Exploitation of sexual signals by predators and parasitoids. Q Rev Biol (1998) 73:415–438.[CrossRef]
  26. Robert D, Amoroso J, Hoy RR. The evolutionary convergence of hearing in a parasitoid fly and its cricket host. Science (1992) 258:1135–1137.[Abstract/Free Full Text]
  27. Bateman PW, Ferguson JWH, Yetman CA. Courtship and copulation, but not ejaculates, reduce the longevity of female field crickets (Gryllus bimaculatus). J Zool (2006) 268:341–346.[CrossRef][Web of Science]
  28. Birkhead TR. Defining and demonstrating postcopulatory female choice—Again. Evolution (2000) 54:1057–1060.[Web of Science][Medline]
  29. Eberhard WG. Criteria for demonstrating postcopulatory female choice. Evolution (2000) 54:1047–1050.[Web of Science][Medline]
  30. Kempenaers B, Foerster K, Questiau S, et al. Distinguishing between female sperm choice versus male sperm competition: a comment on Birkhead. Evolution (2000) 54:1050–1052.[Web of Science][Medline]
  31. Birkhead TR. Cryptic female choice: criteria for establishing female sperm choice. Evolution (1998) 52:1212–1218.[CrossRef][Web of Science]
  32. Parker GA. Sperm competition games—raffles and roles. Proc R Soc Lond B Biol Sci (1990) 242:120–126.[Abstract/Free Full Text]
  33. Fleischman RR, Sakaluk SK. No direct or indirect benefits to cryptic female choice in house crickets (Acheta domesticus). Behav Ecol (2004) 15:793–798.[Abstract/Free Full Text]
  34. Danielsson I. Antagonistic pre- and post-copulatory sexual selection on male body size in a water strider (Gerris lacustris). Proc R Soc Lond B Biol Sci. 268:77–81.
  35. Simmons LW. Postcopulatory guarding, female choice and the levels of gregarine infections in the field cricket, Gryllus bimaculatus. Behav Ecol Sociobiol (1990) 26:403–407.[Web of Science]
  36. Wynn H, Vahed K. Male Gryllus bimaculatus guard females to delay them from mating with rival males and to obtain repeated copulations. J Insect Behav (2004) 17:53–66.[CrossRef][Web of Science]
  37. Hockham LR, Vahed K. The function of mate guarding in a field cricket (Orthoptera: Gryllidae; Teleogryllus natalensis Otte and Cade). J Insect Behav (1997) 10:247–256.[CrossRef][Web of Science]
  38. Chapman T, Arnqvist G, Bangham J, et al. Sexual conflict. Trends Ecol Evol (2003) 18:41–47.[CrossRef]
  39. Otte D, Cade W. African crickets (Gryllidae). 4. The genus Platygryllus from eastern and southern Africa (Gryllinae, Gryllini). Proc Acad Nat Sci Philadelphia (1984) 136:45–66.
  40. Simmons LW. Male size, mating potential and lifetime reproductive success in the field cricket, Gryllus bimaculatus (De Geer). Anim Behav (1988) 36:372–379.[CrossRef][Web of Science]
  41. Ono T, Hayakawa F, Matsuura Y, et al. Reproductive biology and function of multiple mating in the mating system of a tree cricket, Truljalia hibinonis (Orthoptera, Podoscritinae). J Insect Behav (1995) 8:813–824.[CrossRef][Web of Science]
  42. Khazraie K, Campan M. The role of prior agonistic experience in dominance relationships in male crickets Gryllus bimaculatus. In: Behav Process (1999) 44. Orthoptera: Gryllidae. 341–348.[CrossRef][Web of Science]
  43. Simmons LW. Correlates of male quality in the field cricket, Gryllus campestris L: age, size, and symmetry determine pairing success in field populations. Behav Ecol (1995) 6:376–381.[Abstract/Free Full Text]
  44. Bateman PW, Fleming PA. Males are selective too: mating, but not courtship, with sequential females influences choosiness in male field crickets (Gryllus bimaculatus). Behav Ecol Sociobiol (2006) 59:577–581.[CrossRef][Web of Science]
  45. Bonduriansky R. The evolution of male mate choice in insects: a synthesis of ideas and evidence. Biol Rev (2001) 76:305–339.[Medline]
  46. Ivy TM, Sakaluk SK. Sequential mate choice in decorated crickets: females use a fixed internal threshold in pre- and postcopulatory choice. Anim Behav (2007) 74:1065–1072.[CrossRef][Web of Science]
  47. Rantala MJ, Kortet R. Courtship song and immune function in the field cricket Gryllus bimaculatus. Biol J Linn Soc (2003) 79:503–510.[CrossRef][Web of Science]
  48. Wagner WE, Reiser MG. The importance of calling song and courtship song in female mate choice in the variable field cricket. Anim Behav (2000) 59:1219–1226.[CrossRef][Web of Science][Medline]
  49. Campbell DJ. Resolution of spatial complexity in a field sample of singing crickets Teleogryllus commodus (Walker) (Gryllidae)—a nearest-neighbor analysis. Anim Behav (1990) 39:1051–1057.[CrossRef][Web of Science]
  50. Cordero C, Eberhard WG. Female choice of sexually antagonistic male adaptations: a critical review of some current research. J Evol Biol (2003) 16:1–6.[CrossRef][Web of Science][Medline]
  51. Lehmann GUC, Lehmann AW. Potential lifetime reproductive success of male bushcrickets parasitized by a phonotactic fly. Anim Behav (2006) 71:1103–1110.[CrossRef][Web of Science]
  52. Bateman PW, Verburgt L, Ferguson JWH. Exposure to male song increases rate of egg development in the cricket Gryllodes sigillatus. Afr Zool (2005) 40:323–326.
  53. Rowe L, Cameron E, Day T. Escalation, retreat, and female indifference as alternative outcomes of sexually antagonistic coevolution. Am Nat (2005) 165:S5–S18.[CrossRef][Web of Science][Medline]
  54. Eberhard WG. The function of female resistance behavior: intromission by male coercion vs. female cooperation in sepsid flies (Diptera: Sepsidae). Rev Biol Trop (2002) 50:485–505.[Web of Science][Medline]
  55. Sakaluk SK. Postcopulatory mate guarding in decorated crickets. Anim Behav (1991) 41:207–216.[CrossRef][Web of Science]
  56. Lehmann GUC. Review of biogeography, host range and evolution of acoustic hunting in Ormiini (Insecta, Diptera, Tachinidae), parasitoids of night-calling bushcrickets and crickets (Insecta, Orthoptera, Ensifera). Zool Anz (2003) 242:107–120.[CrossRef]
  57. Wagner WE, Basolo AL. The relative importance of different direct benefits in the mate choices of a field cricket. Evolution (2007) 61:617–622.[CrossRef][Web of Science][Medline]
  58. Parker GA., Simmons LW. A model of constant random sperm displacement during mating—evidence from Scatophaga. Proc R Soc Lond B Biol Sci (1991) 246:107–115.[Abstract/Free Full Text]
  59. Bateman PW, MacFadyen DN. Mate guarding in the cricket Gryllodes sigillatus: influence of multiple potential partners. Ethology (1999) 105:949–957.[CrossRef][Web of Science]

   Author Biography 
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Conclusion
 Funding
 References
 Author Biography 
 
    Darren Parker recently graduated from the University of Derby with a first-class Honours degree in Biology, receiving the Institute of Biology (IOB) Award for Best Student Performance. During his final year project Darren became particularly interested in the effects of sexual conflict on the evolution of Gryllid mating systems. He is currently undertaking a post as a research assistant at the University of Derby with his final year project tutor, Dr Karim Vahed, investigating several aspects of Orthopteran behavioral ecology. In the future, Darren hopes to pursue Master's Degree in an evolutionary discipline before moving on to a PhD.
Submitted on 30 September 2008; accepted on 18 December 2008


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrowOA All Versions of this Article:
2/2/164    most recent
hzp019v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Google Scholar
Right arrow Articles by Parker, D.
PubMed
Right arrow Articles by Parker, D.
Related Collections
Right arrow Animal Behaviour
Right arrow Biology
Right arrow Genetics
Right arrow Zoology
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?