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opencc-by-4.0Aug 2015View details →

Figure 1. A in The green June beetle (Cotinis nitida) (Coleoptera: Scarabaeidae): local variation in the beetle's major avian predators and in the competition for mates

Figure 1. A stack of males piled up on the back of a receptive female. Note that the top male is facing in a different direction from the others and that he has everted his aedeagus, a sign of his strong sexual motivation.

Fig. 3 in Mating compatibility and competitiveness between wild and laboratory strains of Eldana saccharina (Lepidoptera: Pyralidae) afer radiation treatment

Fig. 3. The mean number of Eldana saccharina matings in a pair-wise comparison between non-irradiated laboratory adults and irradiated laboratory adults showing a significant 2-way interaction between time of night and location of trials. Data were pooled across the entire observation period to obtain total matings irrespective of cross type. Error bars denote 95% confidence limits.

Fig. 4 in Mating compatibility and competitiveness between wild and laboratory strains of Eldana saccharina (Lepidoptera: Pyralidae) afer radiation treatment

Fig. 4. The mean number of matings in a pair-wise comparison between irradiated laboratory reared and non-irradiated wild Eldana saccharina adults showing a significant 3-way interaction across time of night, type of cross and location of trials. The expected possible mating combinations/cross types were: (i) irradiated laboratory female and irradiated laboratory male (Sf x Sm); (ii) irradiated laboratory female and non-irradiated wild male (Sf x Wm); (iii) non-irradiated wild female and irradiated laboratory male (Wf x Sm); and/or (iv) non-irradiated wild female and non-irradiated wild male (Wf x Wm).

Fig. 2 in Mating compatibility and competitiveness between wild and laboratory strains of Eldana saccharina (Lepidoptera: Pyralidae) afer radiation treatment

Fig. 2. The mean number of matings in a pair-wise comparison between non-irradiated and irradiated laboratory reared Eldana saccharina adults. The expected possible mating combinations were: (i) non-irradiated laboratory female and non-irradiated laboratory male (Lf x Lm); (ii) non-irradiated laboratory female and irradiated laboratory male (Lf x Sm); (iii) irradiated laboratory female and non-irradiated laboratory male (Sf x Lm); and/or (iv) irradiated laboratory female and irradiated laboratory male (Sf x Sm).

Fig. 1 in Mating compatibility and competitiveness between wild and laboratory strains of Eldana saccharina (Lepidoptera: Pyralidae) afer radiation treatment

Fig. 1. The mean number of matings in a pair-wise comparison between non-irradiated laboratory and wild Eldana saccharina adults showing a significant 3-way interaction across time of night, type of cross and location of trials. The expected possible mating combinations were: (i) non-irradiated laboratory female and nonirradiated laboratory male (Lf x Lm); (ii) non-irradiated laboratory female and non-irradiated wild male (Lf x Wm); (iii) non-irradiated wild female and non-irradiated laboratory male (Wf x Lm); and/or (iv) non-irradiated wild female and non-irradiated wild male (Wf x Wm).

opencc-by-4.0Aug 2005View details →

Figure 3. A in The scramble competition mating system of the sphecid wasp Palmodes praestans (Kohl)

Figure 3. A male (marked with a white dot on the thorax) mounted on a female of Palmodes praestans during a period when the pair was not copulating.

opencc-by-4.0Aug 2005View details →

Figure 1 in The scramble competition mating system of the sphecid wasp Palmodes praestans (Kohl)

Figure 1. The total number of records of males of Palmodes praestans seen patrolling in an area roughly 15×40 m in the Usery Mountains, Arizona on two mornings in April 2004. Each sample was made over a 10-min period beginning at the time shown on the x-axis.

opencc-by-4.0Aug 2005View details →

Figure 2 in The scramble competition mating system of the sphecid wasp Palmodes praestans (Kohl)

Figure 2. The number of times each of 17 different males was seen again within the observation site where he was captured initially and marked.

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Data from: The role of male body size in mating success and male-male competition in a false widow spider

In many animals, body size is correlated with reproductive success. Selection sometimes generates striking differences in body size between males and females (i.e., sexual size dimorphism, SSD). SSD is common in spiders (Araneae), and is typically explained by selection for larger, more fecund females, and rapidly maturing, and consequently smaller males. Within a species males and females also often vary in body size. In the false widow spider (Steatoda grossa), females are larger than males and males trade off body size for rapid development and early maturation. Moreover, males exhibit considerable variation in body size, suggesting that under certain conditions there may be advantages to large size. Here, we tested the role of male body size on mating success under non-competitive and competitive mating conditions (i.e., male-male competition) in S. grossa. We found that body size did not influence mating success or copulation duration under non-competitive conditions, but that larger males were more successful at obtaining access to females under competitive mating conditions. Additionally, we found that total copulation duration was significantly lower when a rival male was present. Our results show a large male advantage under male-male competition, which we suggest may contribute to the high variation in male body size observed in S. grossa. We further suggest that the reduced copulation duration observed under competitive mating conditions may have potential ramifications for male and female reproductive success, and discuss how patterns of selection acting on male body size might limit the extent of SSD in this species.

opencc-zeroAug 2023View details →

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Data from: The role of male body size in mating success and male-male competition in a false widow spider

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publicAug 2023View details →

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Data from: Mating competition among females: testing the distinction between natural and sexual selection in an insect

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publicNov 2024View details →

opencc-zeroSep 2020View details →

Experimentally induced intrasexual mating competition and sex-specific evolution in female and male nematodes

Sexual dimorphism in life history traits and their trade-offs is widespread among sexually reproducing animals, and is strongly influenced by the differences in reproductive strategies between the sexes. We investigated how intrasexual competition (pre- and postcopulatory) acted on specific life history traits, important to fitness, and their trade-offs in the outcrossing nematode Caenorhabditis remanei. Here, we imposed strong sex-specific selection through experimental evolution with increased potential for intrasexual competition by skewing the adult sex ratio towards either males or females (1:10 or 10:1) over 30 generations, and subsequently measured the phenotypic response to selection in three traits related to fitness; body size, fecundity and tolerance to heat stress. We observed a stronger response to selection in females for body size and peak fitness, suggesting that females may experience stronger net selection and potentially harbour higher amounts of standing genetic variance compared to males. Our study highlights the importance of investigating direct and indirect effects of intrasexual competition in both sexes in order to capture sex-specific responses and understand the evolution of sexual dimorphism in traits expressed by both sexes.

opencc-zeroNov 2020View details →

Competition for pollination and isolation from mates differentially impact four stages of pollination in a model grassland perennial

1. Species that persist in small populations isolated by habitat destruction may experience reproductive failure. Self-incompatible plants face dual threats of mate-limitation and competition with co-flowering plants for pollination services. Such competition may lower pollinator visitation, increase heterospecific pollen transfer, and reduce the likelihood that a visit results in successful pollination. 2. To understand how isolation from mates and competition with co-flowering species contribute to reproductive failure in fragmented habitat, we conducted an observational study of a tallgrass prairie perennial, Echinacea angustifolia. We quantified the isolation of focal individuals from mates, characterized species richness and counted inflorescences within 1m radius, observed pollinator visitation, collected pollinators, quantified pollen loads on pollinators and on Echinacea stigmas, and measured pollination success. Throughout the season, we sampled 223 focal plants. 3. We present evidence that both co-flowering species and isolation from mates substantially limit reproduction in Echinacea. As the flowering season progressed, the probability of pollinator visitation to focal plants decreased and evidence for pollen-limited reproduction increased. Pollinators were most likely to visit Echinacea plants from low-richness floral neighbourhoods with close potential mates, or plants from high-richness neighbourhoods with distant potential mates. Frequent visitation only increased pollination success in the former case, likely because Echinacea in high-richness floral neighbourhoods received low-quality visits. 4. Synthesis: In Echinacea, reproduction was limited by isolation from potential mates and the richness of co-flowering species. These aspects of the floral neighbourhood influenced pollinator visitation and pollination success, although conditions that predicted high visitation did not always lead to high pollination success. These results reveal how habitat modification and destruction, which influence floral neighbourhood and isolation from conspecific mates, can differentially affect various stages of reproductive biology in self-incompatible plants. Our results suggest that prairie conservation and restoration efforts that promote patches of greater floral diversity may improve reproductive outcomes in fragmented habitats.

opencc-zeroDec 2016View details →

Data from: Reproductive interference and fecundity affect competitive interactions of sibling species with low mating barriers: experimental and theoretical evidence

When allopatric species with incomplete prezygotic isolation come into secondary contact, the outcome of their interaction is not easily predicted. The parasitoid wasp Encarsia suzannae (iES), infected by Cardinium inducing cytoplasmic incompatibility (CI), and its sibling species E. gennaroi (EG), not infected by bacterial endosymbionts, may have diverged because of the complementary action of CI and asymmetric hybrid incompatibilities. Whereas postzygotic isolation is now complete due to sterility of F1 hybrid progeny, prezygotic isolation is still incipient. We set up laboratory population cage experiments to evaluate the outcome of the interaction between ES and EG in two pairwise combinations: iES vs. EG and cured ES (cES, where Cardinium was removed with antibiotics) vs. EG. We also built a theoretical model aimed at exploring the role of life history differences and asymmetric mating on competitive outcomes. In three of four cages in each treatment, ES dominated the interaction. We found evidence for reproductive interference, driven by asymmetric mating preferences, which gave a competitive edge to ES, the species that better discriminated against heterospecifics. However, we did not find the fecundity cost previously shown to be associated with Cardinium infection in iES. The model largely supported the experimental results. The finding of only a slight competitive edge of ES over EG in population cages suggests that in a more heterogeneous environment the species could coexist. This is supported by evidence that the two species coexist in sympatry, where preliminary data suggest reproductive character displacement may have reinforced postzygotic isolation.

opencc-zeroDec 2021View details →

Immigrant males' memory acts to reduce ranging overlap and mating competition in wild baboons

Mechanistic models suggest that information acquired by animals ("knowledge") could shape home range patterns and dynamics, and how neighbours share space. In social species this would suggest that immigrants could bring new knowledge into social groups, potentially affecting the dynamics of home range overlap. We tested this "immigrant knowledge hypothesis" in a wild population of chacma baboons (Papio ursinus). We used data collected between 2005 and 2013 on two neighbouring troops in Namibia, comprising GPS records of daily ranges, male natal origins, daily females' reproductive status, and a satellite index of vegetation growth. We found that when the ratio of fertile females to adult males in the focal troop increased (i.e. increasing inter-troop mating competition costs for focal troop males), the focal troop tended to overlap less with a neighbouring troop's home range only when the alpha male had immigrated from that neighbouring troop and so was "knowledgeable" about its home range. When the alpha male was "not knowledgeable" the reverse was observed, with troops showing greater overlap, most likely reflecting an influence of fertile females on ranging patterns. Our findings support the immigrant knowledge hypothesis of group ranging behaviour, and suggest that dispersal and spatial memory may sometimes act to increase rather than decrease spatial segregation between groups. Very few previous studies have reported an effect of mating competition on ranging dynamics in social species, perhaps because previous studies did not consider divergent adaptive interest among group members and how they can be solved through collective-decision processes.

opencc-zeroMay 2022View details →

Dataset for: Mating competition and adult sex ratio in wild Trinidadian guppies

Most experimental tests of mating systems theory have been conducted in the laboratory, using operational sex ratios (ratio of ready-to-mate male to ready-to-mate female) that are often not representative of natural conditions. Here, we first measured the range of adult sex ratio (proportion of adult males to adult females; ASR) in two populations of Trinidadian guppies (Poecilia reticulata) differing in ambient predation risk (high vs. low). We then explored, under semi-wild conditions, the effect of ASR (i.e. 0.17, 0.50, 0.83) on mating competition patterns in these populations. ASR in the wild was female-biased and did not significantly differ between the two populations. The range of ASR in our experiment was representative of natural ASRs. As expected, we observed an increase in intrasexual aggression rates in both sexes as the relative abundance of competitors increased. In support of the risky competition hypothesis, all measured behaviors had lower rates in a high vs. low predation-risk population, likely due to the costs of predation. In terms of mating tactics, a male-biased ASR did not lead males to favor forced mating over courtship, indicating that males did not compensate for the cost of competition by switching to a less costly alternative mating tactic. Overall, this study highlights the need for field experiments using natural ranges of ASRs to test the validity of mating systems theory in a more complex, ecologically relevant context.

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Improving the mating competitiveness of male Anastrepha ludens (Diptera: Tephritidae) fruit flies by adding two juvenile hormone analogues

Improving the mating competitiveness and survival of sterile males are direct means to increasing the effectiveness of the Sterile Insect Technique (SIT). Some insecticide growth regulators, such as the juvenile hormone analogue (JHA) Methoprene, have been used to improve the mating competitiveness of male tephritid flies by reducing their sexual maturation period. However, a decrease in the period of sexual maturation induces a reduction in survival. Here, we compared the effects of methoprene and Pyriproxyfen (PPF), another JHA, in Anastrepha ludens males. Pyriproxyfen is an insect growth regulator that exhibits higher disruption on insects’ methamorphosis than methoprene or than natural JH. . Both compounds were administered at two doses (0.05 and 0.1%) via the male diet immediately after emergence. Our results show that both Pyriproxyfen and methoprene reduced male sexual maturation. However, PPF-treated males exhibited a shorter maturation period and obtained more matings at a given age than methoprene-treated males . No significant differences were observed between the two PPF doses tested (0.05 and 0.10 %). Male survival was equally accelerated by the two compounds. Our results demonstrate that PPF can be used as a tool to improve the mating performance of sterile males.

opencc-by-4.0Aug 2023View details →

opencc-zeroSep 2023View details →

Anisogamy does not always promote the evolution of mating competition traits in males

Anisogamy has evolved in most sexually reproducing multicellular organisms allowing the definition of the male and female sexes, producing small and large gametes. Anisogamy, as the initial sexual dimorphism, is a good starting point to understand the evolution of further sexual dimorphisms. For instance, it is generally accepted that anisogamy sets the stage for more intense mating competition in males than in females. We argue that this idea stems from a restrictive assumption on the conditions under which anisogamy evolved in the first place: the absence of sperm limitation (assuming that all female gametes are fertilized). Here, we relax this assumption and present a model that considers the coevolution of gamete size with a mating competition trait, starting in a population without dimorphism. We vary gamete density to produce different scenarios of gamete limitation. We show that, while at high gamete density the evolution of anisogamy always results in male investment in competition, gamete limitation at intermediate gamete densities allows for either females or males to invest more into mating competition. Our results thus suggest that anisogamy does not always promote mating competition among males. The conditions under which anisogamy evolves matter, as well as the competition trait.