In this research I address the phenomenon of female fans’ fascination with online boys’ love fiction in China, and the discussion centers on the questions of why these women are interested in the boys’ love theme, why they prefer boys’ love to traditional heterosexual romance, and how they define and identify with male–male relationships in the boys’ love fiction. Through focusing research on a popular Chinese online-fiction website for women (www.jjwxc.net), I use historical review, online observations, and content analysis of online boys’ love fiction to collect data on my research questions. Understanding female fans’ expectation of and attitudes towards love and romance and analyzing the content of boys’ love fiction allow for a comprehension of the interactions of gender, sexuality, identity, and culture in shaping these women’s practice and choice of boys’ love genre in China. / text

This theses focuses on olfactory and visual components of mate choice in grey partridge. The aim is to evaluate the importance of melanin-based ornametnation and olfaction in mate choice and to explain the role of sexual selection in the evolution of secondary ornamentation in this socially monogamous galliform bird. To do that several experiments were conducted to (1) assess the ability of individuals to recognize conspecific odour and (2) to estimate the significance of melanin based feather ornamentation in male-male and male-female interactions. In some experiments I manipulated the expression (size) of feather maleanin- based ornamentation while in others I used birds forced to pair randomly to find out how the size of ornament and similarity in ornament expression between males and females (assortative pairing) affects reproductive success and investments (egg hatchability and number of eggs laid).

Ainda que existam diversos registros de formas extremas de dimorfismo sexual, a função do alongado quarto par de pernas nos machos de muitas espécies de opiliões permanece desconhecida. Neste estudo, testamos quatro previsões sobre a hipótese de que a seleção sexual está direcionando o alongamento do quarto par de pernas nos machos de Longiperna zonata e Promitobates ornatus: (1) o coeficiente alométrico do comprimento do fêmur IV em machos será maior do que o das fêmeas; (2) machos com pernas IV mais compridas vão residir próximos a grupos de fêmeas; (3) machos envolvidos em interações agressivas terão fêmures mais compridos do que o tamanho médio da população; (4) a diferença de tamanho de perna entre os oponentes será menor do que a diferença esperada entre pares de machos escolhidos ao acaso na população. Como o previsto, o coeficiente alométrico do fêmur IV foi significativamente maior em machos do que em fêmeas nas duas espécies. O comprimento do fêmur IV está positivamente relacionado à chance de um macho ser encontrado próximo a um grupo de fêmeas. Finalmente, a média do comprimento do fêmur IV dos machos envolvidos em brigas foi significativamente maior que a de machos selecionados ao acaso da população. Adicionalmente, a média da diferença de tamanho entre pares de machos que brigaram foi significativamente menor que a média da diferença de tamanho de perna entre pares de machos selecionados ao acaso na população. Assim, a seleção sexual na forma de competição entre machos parece estar direcionando o dimorfismo sexual extremo no comprimento do fêmur nessas duas espécies de opiliões. / Although there are many reports of extreme forms of sexual dimorphism in harvestmen, the function of the elongated fourth pair of legs in males of many species remains unknown. We tested four predictions to address the hypothesis that sexual selection is driving the enlargement of the fourth pair of legs in males of Longiperna zonata and Promitobates ornatus: (1) the allometric coefficient of femur IV length in males will be higher than in females; (2) males with longer legs IV will reside closer to groups of females; (3) males involved in aggressive interactions will have longer femur IV than the population average size; (4) the size difference between contenders will be smaller than the difference expected between randomly chosen pairs of males in the population. As predicted, the allometric coefficient of femur IV length was significantly higher in males than in females of both species. Femur IV length was positively related to the chance of a male being found close to a group of females. Finally, the mean femur IV length of the males involved in fights was significantly larger than the mean of random samples of males from the population, and the average difference between male contenders was smaller than the average random expected difference of the population. Therefore, sexual selection in the form of male-male competition seems to be driving the extreme sexual dimorphism in femur length in these species.

A wide variety of factors are predicted to influence the intensity and outcome of agonistic interactions in animals, including the resource holding potential of the opponents and the nature and value of the resource over which the individuals are competing. Field crickets (Orthoptera: Gryllidae) have been used extensively as model organisms with which to study animal contests, but relatively few studies have examined the effect of mandible size or structure, or the level of contact with females on the intensity and outcome of agonistic interactions. To do so was the aim of the present thesis, using Gryllus bimaculatus as the study species. The first finding of this study was that there is a significant degree of sexual dimorphism for anterior components of the anatomy in G. bimaculatus. The mandibles, head and pronotum of male crickets were all relatively larger than those of females. This indicates that these traits may be acted upon by intrasexual selection. In many animal species that show sexual dimorphism, a trade-off in development sees enhanced weapon growth at the expense of testes size, but no such relationship was seen in this species. A comparison of the mandible structure of males that either won or lost at flaring and or wrestling showed that a relatively wider mandible span was a significant predictor of success during mandible displays. It was also found that specific components of tooth structure, namely the length of the incisor and length to distal tip, were significantly associated with victory at the jaw flaring stage. This is the first time that mandible shape has been shown to affect fight outcome in the Gryllidae, and also the first confirmed identification of a visual cue component of fighting behaviour. Despite the effectiveness of their weapons in fighting, body mass is a primary predictor of victory in combat between G. bimaculatus males, with the greater the degree of asymmetry in weight the more likely the heavier fighter will win. However, a study of fighting behaviour between asymmetrically matched opponents found that even males who were out-weighed by 40% were still likely to escalate the fight to grappling. Furthermore, males who were able to fend off their larger opponent in their first clash were significantly more likely to win their overall encounter. This hyper-aggressive response may therefore represent an adaptive mechanism to extreme odds and is worthy of further study. Female contact is known to be a significant promoter of male aggression and fighting enthusiasm, and mate guarding aggression is well documented in G. bimaculatus. A recreation of two contradictory studies, including one which concluded that mating makes males lose fights, highlighted that female contact after spermatophore transfer can overcome the loser effect and cause a male to re-engage with a previously dominant opponent. Fighting behaviour in this species is therefore highly flexible and factors affecting the outcome of contests are complex. There is much scope for further studies on this topic.

Darwinian sexual selection predicts that males with the most extravagant secondary sexual traits suffer elevated mortality. Although correlative evidence has generally not borne this idea out, recent research, including a field cricket study, showed that investment in sexually selected traits is costly to survival. I investigated male survival, ornamentation (song) and mating success in a North American grylline, Gryllus pennsylvanicus, to test the generality of previous work and highlight the importance of ecology differences to resource allocation. As the calling songs of older male G. pennsylvanicus are highly attractive to females, in Chapter 2 I tested whether male age correlated with calling song and found a weak but statistically significant correlation, thus leaving open the possibility that choosy females use an age-based indicator mechanism. In Chapter 3, I tested the condition dependence of male survival and calling effort. In contrast to previous work, I found that high condition males both called more and lived longer than low condition males, although there was no trade-off between survival and calling effort. The substantial condition dependence of calling effort suggests that calling effort is under strong directional selection. In Chapter 4 I tested whether female mating preferences resulted in strong selection on male calling effort. I also tested for the condition dependence of female mating preferences. I found that female choosiness was condition-dependent, but the rank of preferred male songs (preference function) was not. Both low and high condition females preferred high calling effort over low calling effort song. In Chapter 5 I tested for evidence of nonlinear selection on male survival that might explain the nonlinear pattern of male investment in survival seen in Chapter 3 (i.e. male survival leveled-off with increasing condition). I found that socially experienced females, but not virgin and naive females, exerted linear selection on male age. I discuss these and the other results of my thesis in the context of previous work on field crickets and condition-dependent ornamentation. Finally, Appendix A reports results that confirm ancient Chinese cultural knowledge that large headed male crickets are more successful in male-male combat.

Darwinian sexual selection predicts that males with the most extravagant secondary sexual traits suffer elevated mortality. Although correlative evidence has generally not borne this idea out, recent research, including a field cricket study, showed that investment in sexually selected traits is costly to survival. I investigated male survival, ornamentation (song) and mating success in a North American grylline, Gryllus pennsylvanicus, to test the generality of previous work and highlight the importance of ecology differences to resource allocation. As the calling songs of older male G. pennsylvanicus are highly attractive to females, in Chapter 2 I tested whether male age correlated with calling song and found a weak but statistically significant correlation, thus leaving open the possibility that choosy females use an age-based indicator mechanism. In Chapter 3, I tested the condition dependence of male survival and calling effort. In contrast to previous work, I found that high condition males both called more and lived longer than low condition males, although there was no trade-off between survival and calling effort. The substantial condition dependence of calling effort suggests that calling effort is under strong directional selection. In Chapter 4 I tested whether female mating preferences resulted in strong selection on male calling effort. I also tested for the condition dependence of female mating preferences. I found that female choosiness was condition-dependent, but the rank of preferred male songs (preference function) was not. Both low and high condition females preferred high calling effort over low calling effort song. In Chapter 5 I tested for evidence of nonlinear selection on male survival that might explain the nonlinear pattern of male investment in survival seen in Chapter 3 (i.e. male survival leveled-off with increasing condition). I found that socially experienced females, but not virgin and naive females, exerted linear selection on male age. I discuss these and the other results of my thesis in the context of previous work on field crickets and condition-dependent ornamentation. Finally, Appendix A reports results that confirm ancient Chinese cultural knowledge that large headed male crickets are more successful in male-male combat.

Ainda que existam diversos registros de formas extremas de dimorfismo sexual, a função do alongado quarto par de pernas nos machos de muitas espécies de opiliões permanece desconhecida. Neste estudo, testamos quatro previsões sobre a hipótese de que a seleção sexual está direcionando o alongamento do quarto par de pernas nos machos de Longiperna zonata e Promitobates ornatus: (1) o coeficiente alométrico do comprimento do fêmur IV em machos será maior do que o das fêmeas; (2) machos com pernas IV mais compridas vão residir próximos a grupos de fêmeas; (3) machos envolvidos em interações agressivas terão fêmures mais compridos do que o tamanho médio da população; (4) a diferença de tamanho de perna entre os oponentes será menor do que a diferença esperada entre pares de machos escolhidos ao acaso na população. Como o previsto, o coeficiente alométrico do fêmur IV foi significativamente maior em machos do que em fêmeas nas duas espécies. O comprimento do fêmur IV está positivamente relacionado à chance de um macho ser encontrado próximo a um grupo de fêmeas. Finalmente, a média do comprimento do fêmur IV dos machos envolvidos em brigas foi significativamente maior que a de machos selecionados ao acaso da população. Adicionalmente, a média da diferença de tamanho entre pares de machos que brigaram foi significativamente menor que a média da diferença de tamanho de perna entre pares de machos selecionados ao acaso na população. Assim, a seleção sexual na forma de competição entre machos parece estar direcionando o dimorfismo sexual extremo no comprimento do fêmur nessas duas espécies de opiliões. / Although there are many reports of extreme forms of sexual dimorphism in harvestmen, the function of the elongated fourth pair of legs in males of many species remains unknown. We tested four predictions to address the hypothesis that sexual selection is driving the enlargement of the fourth pair of legs in males of Longiperna zonata and Promitobates ornatus: (1) the allometric coefficient of femur IV length in males will be higher than in females; (2) males with longer legs IV will reside closer to groups of females; (3) males involved in aggressive interactions will have longer femur IV than the population average size; (4) the size difference between contenders will be smaller than the difference expected between randomly chosen pairs of males in the population. As predicted, the allometric coefficient of femur IV length was significantly higher in males than in females of both species. Femur IV length was positively related to the chance of a male being found close to a group of females. Finally, the mean femur IV length of the males involved in fights was significantly larger than the mean of random samples of males from the population, and the average difference between male contenders was smaller than the average random expected difference of the population. Therefore, sexual selection in the form of male-male competition seems to be driving the extreme sexual dimorphism in femur length in these species.

I used annual killifish Nothobranchius orthonotus to investigate two separate questions related to behavioural aspects of their life history. The first study focused on spatial cognitive ability of two N. orthonotus populations that originated from temporary pools that varied in their expected duration due to differences in annual precipitation patterns (dry and humid region). Test of cognition was based on the ability to learn to find food in a dichotomous test. It was assumed that learning ability differs between populations when tested in young and old age along with their difference in captive lifespan. Additionally, association between cognitive ability and other life history traits was tested. It was found that: (1) there was no difference in the ability to learn spatial task between populations; (2) both populations had similar lifespan with no cognitive decay in older age, and older fish from dry region population had committed even less errors in the learning task than they did as young fish; (3) fish were able to effectively learn the task but (4) solitary fish had lower learning ability than group-reared fish; (5) longer- living fish were quicker learners; (6) high resting metabolic rate was associated with more effective learning; (7) hesitant fish found the food reward in learning task...

A critical mechanism underpinning current biological diversity is the extent to which one species mates with, or avoids mating with, another. However, little is known about the factors that mediate hybridisation, especially during the initial and rarely observed stages of secondary contact when interspecific interactions have not responded to selection. In particular, whilst hybridisation is ultimately a behavioural phenomenon, the role of behaviour in mediating hybridisation and how it is influenced by environmental and circumstantial factors is rarely investigated. Recently introduced species provide us with unequalled opportunities to study these factors. In this thesis I examine the role of behavioural mechanisms, in particular male-male competition and mate choice, in mediating mating patterns between two genetically and phenotypically distinct lineages of European wall lizard (Podarcis muralis) that have come into recent secondary contact through human introductions. In Chapter Two, I investigated how sexual selection during allopatry is responsible for creating stark differences in phenotypic traits such as body size and weapon performance evident in the two lineages today, ultimately explaining the strong biases in dominance during territorial disputes between males. However, I also show that even given this asymmetry in male competitive ability, the extent to which it extrapolates into greater access to females in naturalistic, outdoor enclosures depends strongly on the spatial clustering of basking sites, a critically important resource for many ectotherms. In contrast to initial predictions suggested by asymmetries in male competition outlined in the previous chapter, in Chapter Three I show that both paternity and courtship behaviour was strongly assortative in the outdoor enclosures. Further investigation through staged experiments on olfactory mate choice, mating trials and analyses on specific behavioural data obtained in an enclosure experiment, I show that lineage based dominance actually contributes to assortative mating patterns in conjunction with weak conspecific male choice. In contrast, female choice seems to play no role in mediating the mating patterns observed between the two lineages. In Chapter Four I had the rare opportunity to examine the morphological and behavioural factors that predict why animals should hybridise in the first place, using the data obtained in the enclosure experiment above. I found that hybridisation was particularly common between small individuals of the larger lineage and large individuals of the smaller lineage; a result that corroborates the mechanisms determining the assortative patterns uncovered in Chapter Three. Additionally, hybridisation rates were particularly high in less dominant individuals, which I suggest is due to subordinate males having reduced opportunities for courting conspecific females due to male-male competition, requiring them to become less ‘choosy’ and therefore more likely to mate with heterospecifics. Finally, secondary contact cannot occur without at least one lineage coming into a new environment, and yet relatively little attention is paid to how this environmental change can affect the signals involved in intraspecific communication and mate choice. In Chapter Five I show that a change in the amount of time male lizards spend thermoregulating (a likely consequence of arriving in a new environment) significantly changes the chemical composition of their scent marks. However, whilst female lizards were able to detect these effects, they did not seem to base their mating decisions on them. Nevertheless, this result raises interesting questions about the potential function and consequences of this plasticity, and highlights the importance of considering plasticity in chemical communication in heterogeneous environments. Overall, this thesis shows the critically important role of behaviour in mediating intra- and interspecific mating patterns during recent secondary contact. In particular, it highlights how the direction and extent of hybridisation and competition are influenced by the degree to which differing morphological and behavioural phenotypes interact over a heterogeneous environment, particularly during the initial stage of secondary contact when mate choice has not had the chance to respond to the selective pressures of hybridisation.

The availability of reproductive sites is a major factor shaping the behavior of males and females in species with resource-based mating systems. Using a meta-analytic approach, we tested five predictions directly or indirectly derived from the mating system theory. We expected that reproductive site limitation would lead to: (1) intense male-male competition for resource possession; (2) high variance in male reproductive success, generating high values of opportunity for sexual selection; (3) high intensity of selection on male traits related to resource possession; (4) high sperm competition risk; and (5) low quality of paternal care. We compiled information from observational and experimental studies that compared the reproductive behavior of individuals of the same species under low and high reproductive site limitation. We found that, when reproductive sites are limited, there is a slight increase in male-male competition, with higher rates of nest takeover and agonistic interactions, and a slight increase in the selection gradient on male traits, with successful males tending to be larger than unsuccessful males. Reproductive site limitation has no consistent effect on the opportunity for sexual selection and on the sperm competition risk. However, territorial males invest more in gonads and lose less paternity when reproductive sites are limited. There is also no clear effect of reproductive site limitation on the quality of paternal care, but few studies have addressed this subject. Taken together, our findings indicate that predictions on how reproductive site limitation affects several aspects of resource-based mating systems have weak empirical support. These predictions do not consider the plasticity in the mating tactics of males and females, which make them too simplistic. Moreover, since the original proposition of the mating system theory, our understanding of sperm competition increased a lot. We now know that accurate predictions on the intensity and direction of sexual selection should take into account both pre- and post-copulatory processes. Finally, the interplay between sexual selection and parental care is complex, and the original framework of mating system theory does not provide sufficient elements to derive clear and taxonomically broad predictions / A disponibilidade de sítios reprodutivos influencia tanto o comportamento de machos quanto de fêmeas em espécies cujo sistema de acasalamento depende da defesa de recursos. Usando uma abordagem meta-analítica, testamos cinco previsões direta ou indiretamente relacionadas à teoria de sistemas de acasalamento. Esperávamos que a limitação de sítios reprodutivos promoveria: (1) aumento na competição masculina pela posse de recursos; (2) aumento na variância do sucesso reprodutivo dos machos, gerando valores alto de oportunidade para a seleção sexual; (3) aumento da intensidade da seleção sobre características masculinas relacionadas à posse de recursos; (4) aumento no risco de competição espermática e (5) diminuição da qualidade do cuidado paternal. Compilamos informações de estudos observacionais e experimentais que compararam o comportamento reprodutivo de indivíduos da mesma espécie em situação de alta e baixa disponibilidade de sítios reprodutivos. Encontramos que, quando os sítios reprodutivos são escassos, há um ligeiro aumento na competição masculina, com maiores taxas de roubo de ninhos e interações agonísticas, e um ligeiro aumento no gradiente de seleção sobre características masculinas, com machos bem sucedidos tendendo a ser maiores do que machos mal sucedidos em monopolizar recursos. A disponibilidade de sítios reprodutivos não teve nenhum efeito consistente sobre a oportunidade para a seleção sexual e o risco de competição espermática. Entretanto, machos territoriais investiram mais em gônadas e perderam menos paternidade quando os sítios reprodutivos eram escassos. Não encontramos nenhum efeito da disponibilidade de sítios reprodutivos sobre a qualidade do cuidado paternal. Em conjunto, nossos resultados indicam que as previsões sobre como a disponibilidade de sítios reprodutivos influencia diversos aspectos de sistemas de acasalamento baseados na defesa de recursos têm fraco respaldo empírico. Tais previsões não consideram a plasticidade nas táticas de acasalamento de machos e fêmeas, tornando-as demasiadamente simplistas. Adicionalmente, desde a formulação original da teoria de sistemas de acasalamento, nossa compreensão sobre competição espermática aumentou. Sabemos atualmente que previsões acuradas sobre a intensidade e direção da seleção sexual devem levar em consideração processos pré- e pós-copulatórios. Finalmente, a interconexão entre seleção sexual e cuidado parental é complexa e a teoria original de sistemas de acasalamento não provê elementos suficientes para a construção de previsões claras e de amplo escopo taxonômico