Quality Of Mates Research Articles

Ecological crossovers of sexual signaling in a migratory bird.

Environmental shifts may induce sudden reversals in the relative quality or sexual attractiveness of mates (ecological crossovers) leading to non-directional sexual selection. Studies on such ecological crossovers induced by environmental shifts during the nonbreeding season are particularly rare. We studied the interactive effects between nonbreeding conditions and a male white wing patch on the breeding success of breeding pairs and the local survival of females in a migratory passerine population over a 32-year period. After dry winters, females paired with large-patched males were more likely to survive than those paired with small-patched males, and vice versa after moist winters. Moreover, after dry winters, large-patched males succeeded in attracting females that laid large clutches, while small-patched males bred with females that laid small clutches, and vice versa after moist winters. This phenomenon led to a difference in fledgling numbers only during years with dry winters and high precipitation during the breeding season. The selection on this male trait and its signaling value to females thus depended on a complex interaction between conditions both at the nonbreeding and breeding grounds. We show that it is important to consider conditions during the nonbreeding season when examining the effects of sexual ornaments on fitness.

Differential Allocation Revisited: When Should Mate Quality Affect Parental Investment?

Differential allocation (DA) is the adaptive adjustment of reproductive investment (up or down) according to partner quality. A lack of theoretical treatments has led to some confusion in the interpretation of DA in the empirical literature. We present a formal framework for DA that highlights the nature of reproductive benefits versus costs for females mated to males of different quality. Contrary to popular belief, analytical and stochastic dynamic models both show that additive benefits of male quality on offspring fitness have no effect on optimal levels of female investment and thus cannot produce DA. Instead, if offspring fitness is affected multiplicatively by male quality, or male quality affects the female cost function, DA is expected because of changes in the marginal benefits or costs of extra investment. Additive male quality effects on the female cost function can cause a novel form of weak DA, because reduced costs can slightly favor current over future reproduction. Combinations of these distinct effects in more realistic model scenarios can explain various patterns of positive and negative DA reported for different species and mating systems. Our model therefore sheds new light on the diversity of empirical results by providing a strong conceptual framework for the DA hypothesis.

Plumage Colouration and the Provisioning Behaviour of Male and Female Eastern Phoebes

Many factors, including nestling age, brood size, and mate quality, can influence the provisioning behaviour of adult birds. Mate quality may affect provisioning behaviour because high-quality individuals may be ‘good parents’ and provision at higher rates. Alternatively, individuals paired to high-quality mates may provision at higher rates because the benefits provided by such mates ( e.g. good genes) increase the likelihood of reproductive success. We examined variation in the plumage colour of male and female Eastern Phoebes ( Sayornis phoebe) and the possible relationship between such variation and provisioning behaviour. During the 2006–2007 breeding seasons, we captured, banded, and measured adult Eastern Phoebes and collected belly feathers for spectral analyses. We also videotaped nests to quantify provisioning behaviour. Male Eastern Phoebes were larger than females, but the plumage (belly feathers) of males and females did not differ in brightness, hue, and carotenoid chroma (all P ≥ 0.37). Females provisioned nestlings at higher rates than males ( P = 0.009), but we found no significant relationship between provisioning rates of males and females and plumage colour. However, relationships between female provisioning rates and the brightness and carotenoid chroma of their mates’ belly feathers approached significance ( P ≤ 0.08). The larger size of male Eastern Phoebes suggests there is male–male competition for access to resources ( e.g. nest sites and mates), with larger size conferring a selective advantage. However, the absence of intersexual differences in plumage colour suggests limited sexual selection driven by female choice for extra-pair partners. Differences in provisioning rates of males and females may be due to male uncertainty of paternity status or to intersexual differences in foraging behaviour. The relationship between female provisioning rates and male plumage quality suggests that females may invest more in reproduction if male Eastern Phoebes with brighter, carotenoid-rich belly plumage are better able to provide quality nest sites and territories or, perhaps, high-quality genes that can potentially enhance female fitness (differential-allocation hypothesis).

Quantity and quality of available mates alters female responsiveness but not investment in the Pacific field cricket, Teleogryllus oceanicus

An individuals’ experience with conspecific signaling during development can lead to variation in their mating signals and behavior later in life. It is unclear whether experience with sexual signals also alters receivers’ fitness through changes in investment in offspring. Male field crickets attract mates using a long-distance calling song. To determine how developmental experience with calling song quality and quantity alters mating responsiveness and fitness, we raised juvenile female Teleogryllus oceanicus in five acoustic environments. These environments mimicked two mate quantities (high and low) crossed with two mate qualities (high and low), and a silent control. At adulthood, we measured females’ responsiveness in phonotaxis trials. Following phonotaxis, females were offered opportunities to mate and lay eggs. We measured egg number and proportion hatching as components of fitness and reproductive investment. Corroborating previous research in this system, female crickets raised in silence approached a broadcast calling song nearly 45% faster than their counterparts reared hearing a high-quantity/high-quality combination of calling song. Additionally, females adjusted other aspects of phonotaxis behavior in response to the quantity, but not quality of song. We found no evidence that females adjusted mating rates or investment in offspring. Regardless of acoustic experience, females laid equivalent numbers of eggs that had equivalent hatching success. Our results show that female mating behavior responds to juvenile experience mimicking a lack of mating opportunities, but is less responsive to variation in mate quality. Furthermore, reproductive investment may be less plastic than mating behavior. Social experience can inform organisms about current environmental conditions and lead to changes in behavior. Existing work suggests that field crickets in the genus Teleogryllus change their mating behavior in response to acoustic environments that mimic varied mate availabilities and qualities. However, we do not know if females alter their investment in offspring under similar circumstances. Variable investment could speed evolutionary change when combined with behavioral plasticity. We found that although female mating behavior is sensitive to variation in acoustic experience, reproductive investment is not. The number of eggs laid and the percent hatching did not depend on acoustic experience. We discuss evolutionary explanations for these patterns, including the possibility that investment is less plastic than mating behavior.

Blown by the wind: the ecology of male courtship display behavior in orchid bees.

Many insects rely on chemical signals to transmit precise information on the location, identity, and quality of potential mates. Chemical signals are often broadcasted at sites with physical properties that maximize signal propagation and signal transmission. Male neotropical orchid bees (Euglossini) perch and display on vertical branches and tree trunks in the forest to expose volatile blends (perfumes) that they previously collected from their environment. Previous studies have shown that the chemical composition of perfume blends is highly differentiated even between closely related species. However, variation in behavioral components of perfume exposure and male display remain poorly understood. We conducted a four-year study on orchid bee display sites (8 species) in pacific Costa Rica, using field observations along with chemical analysis and cage experiments to assess display niche partitioning among sympatric species. We evaluated the influence of physical factors (terrain, wind, light) on the distribution of perch sites and on display behavior, and tested a prediction of the sex pheromone-analogue hypothesis, i.e., that displaying males have above-average quantities or qualities of acquired perfumes. Males of different species displayed in the same general area and sometimes in close proximity to each other, but partitioned the display niche by selecting different perch diameters, display heights, and by displaying at different times of the day. Most perch sites were located inside the forest on elevated ground, especially along ridges, where stronger winds may help disperse perfume signals. Furthermore, the angular position of displaying males on perches was narrowly determined by wind direction, with males being positioned on the downwind side of the perch, where they would be most conspicuous to conspecifics approaching on an odor trail. Although our results generally support the hypothesis that perfumes serve as pheromone analogues, we did not find differences in the perfume composition of males caught at display perches and males captured at chemical baits. This suggests that, while chemical communication is an integral part of orchid bee display, male display activity is not determined by the history of, and success in, volatile acquisition.

Breeding behavior of female white-tailed deer relative to conception: Evidence for female mate choice.

Female white‐tailed deer (Odocoileus virginianus) are thought to choose between two behavioral strategies to maximize the quality of potential mates: sit and wait, characterized by concentrating activity within a restricted area, and excursive behavior, characterized by increased activity and excursions outside the home range. As movement patterns may influence conception, our goal was to examine the patterns of female white‐tailed deer movements to evaluate which breeding strategy was employed. We equipped 36 female white‐tailed deer with GPS collars from August 2013 to December 2015. We found that movement rate and probability of activity were greatest near the peak of the breeding season, and we observed increases in both metrics during the 40 days prior to estimated conception. Peak size of home range and core area occurred in the days surrounding conception. We found that 11 deer performed an excursion, ranging from 43 days before until 36 days after conception, with the peak probability of being outside of an individual home range occurring 1 day prior to conception. Our results suggest that female white‐tailed deer may attempt to maximize the quality of their mates by advertising availability for breeding through excursive behaviors just prior to entering estrus.

Male and Female Soldier Beetles Relax Choice for Mate Quality Across Daily Courtship Periods

AbstractMutual mate choice occurs when members of each sex will reject some potential mates in efforts to encounter better prospects later. The decision to reject may represent the interaction between mate preferences, mate availability, and temporal constraints. Theory predicts that mutual mate choice will favor relaxed choosiness as mate availability and time for courtship decline. We explored mutual mate choice in the soldier beetle, Chauliognathus pennsylvanicus (Cantharidae), where courtship consisted of males attempting to secure evasive females. We employed field observations, laboratory experiments, and stochastic simulations to investigate the decline in choosiness over the daily courtship period, during which individuals can mate at most once. We found that reproductive success of males and females increases with mate size and mating frequency. Females biased copulations toward larger mates by attempting to evade suitors, while males biased copulations by releasing the smaller females they capture. However, late in the day males and females may increase reproductive success by accepting rather than rejecting lower quality mates to maintain high mating rates. Stochastic simulations indicated that reproductive success, the product of mating frequency and mean mate size, was maximized in males and females by incrementally reducing mate standards across daily courtship periods. In the field, large males who rejected small females early in the daily courtship period rarely did so later. Large females used less effective evasive maneuvers later in the courtship period, resulting in copulations with progressively smaller males. These results support models of mutual mate choice that predict that individuals of high quality will maximize reproductive success by relaxing choosiness as the courtship period wanes.

Mate choice in fruit flies is rational and adaptive

According to rational choice theory, beneficial preferences should lead individuals to sort available options into linear, transitive hierarchies, although the extent to which non-human animals behave rationally is unclear. Here we demonstrate that mate choice in the fruit fly Drosophila melanogaster results in the linear sorting of a set of diverse isogenic female lines, unambiguously demonstrating the hallmark of rational behaviour, transitivity. These rational choices are associated with direct benefits, enabling males to maximize offspring production. Furthermore, we demonstrate that female behaviours and cues act redundantly in mate detection and assessment, as rational mate choice largely persists when visual or chemical sensory modalities are impaired, but not when both are impaired. Transitivity in mate choice demonstrates that the quality of potential mates varies significantly among genotypes, and that males and females behave in such a way as to facilitate adaptive mate choice.

Mate quality and the temporal dynamics of breeding in a sex-role-reversed pipefish, S. typhle

The spatiotemporal dynamics of receptivity and breeding date, coupled with individual-level quality and attractiveness, are centrally important to mating system dynamics. These topics have been investigated in some detail in birds, but much less work has been devoted to other taxonomic groups, and almost no work has addressed spatiotemporal factors and individual quality in sex-role-reversed taxa. The broad-nosed pipefish, Syngnathus typhle, provides an excellent opportunity to investigate these ideas in a sex-role-reversed fish. Here, we addressed three questions related to mating dynamics in S. typhle: (1) Do higher-quality males arrive earlier on the breeding grounds and mate first? (2) Are early-breeding males in better condition than later-breeding males? And (3) do mating events involving higher-quality males produce better clutches than mating events involving lower-quality males? We collected data from a field study and a laboratory breeding experiment to address our hypotheses. Our results show that larger males mate earlier than smaller males and that pregnant males have higher measures of condition compared to non-pregnant males. Moreover, our laboratory results demonstrate that pairings between larger males and preferred females yielded more offspring than pairings involving smaller males. In summary, the spatiotemporal dynamics of S. typhle breeding patterns, combined with variation in individual quality, play an important role in shaping mating systems and should be incorporated in future analyses of mating behavior and sexual selection in this interesting sex-role-reversed pipefish. The breeding patterns of a species can fluctuate over time due to a number of factors, one of which is individual quality. Although the effects of both the timing of reproduction and female quality on mating systems have been studied in some species, they have been investigated primarily in isolation. Here, we demonstrate that individual quality and the timing of reproduction interact to affect reproductive success in a wild population of sex-role-reversed fish.

Sperm allocation in relation to female size in a semelparous salmonid.

To maximize reproductive success, males have to adaptively tailor their sperm expenditure in relation to the quality of potential mates because they require time to replenish their sperm supply for subsequent mating opportunities. Therefore, in mating contexts where males must choose among females in a short period of time, as is the case with semelparous species (which die after one intensely competitive short duration breeding season), selection on sperm allocation can be expected to be a powerful selective agent that shapes the male reproductive success. We quantitatively investigated sperm allocation patterns in chum salmon in relation to perceived female quality by developing a novel method for determining the amount of sperm allocated per ejaculate during spawning bouts. We examined the relationship between sperm expenditure and the body size of paired females (a proxy of egg number and egg quality) in the absence of male–male competition in an experimental channel. The estimated amount of sperm released per spawning event was positively correlated with the size of paired females. However, the number of spawning events a female participated in, which reduces the number of eggs she spawns in each subsequent bout, did not affect this relationship. These results provide support for predictions arising from the sperm allocation hypothesis, male salmon do economize their sperm expenditure in accordance with paired female body size as predicted for their first spawning event, but males overestimate or are unable to assess the quality of females beyond size and provide more sperm than they should in theory when paired with a female that spawned previously. Overall, the observed sperm allocation pattern in chum salmon appears to be adapted to maximize reproductive success assuming female size is an honest indicator of quality, although temporal changes in a female's quality during a reproductive season should be considered when examining sperm allocation strategies.

The mating consequences of rewarding vs. deceptive pollination systems: Is there a quantity–quality trade‐off?

AbstractPlant mating commonly involves quality–quantity trade‐offs. Such a trade‐off features explicitly in the cross‐promotion hypothesis for the evolution of pollination by deceit. According to this hypothesis, rewardlessness enhances mating quality by altering pollinator behavior in ways that reduce self‐pollination and increase outcrossing, thus compensating for the reduced pollen dispersal and seed production resulting from lack of reinforcement of pollinator visitation behavior. The high prevalence of rewardlessness in orchids suggests that deceit pollination conveys benefits that outweigh the fecundity advantages of reward production. We test the cross‐promotion hypothesis in Disa, an African orchid genus in which nectar rewards have evolved repeatedly from rewardless ancestors. To address this hypothesis directly, we quantified pollinator behavior and the associated dispersal of stained pollen for four nectar‐producing (N+) and 10 nectarless (N−) species. We also assessed more extensive, if less direct, evidence from a survey of lifetime pollination outcomes for 15 N+ and 32 N− species. Pollinators visited N+ species more frequently and visited 1.5 times more flowers per inflorescence than in N− species. In contrast, pollinators skipped more conspecific plants between visits to donor and recipient plants when visiting N− species than when visiting N+ species. Over floral lifetimes, both N− and N+ species exhibited similar overall pollen‐transfer efficiency (8.2%) and did not differ in the overall fractions of pollen involved in self‐pollination (26% of all pollen deposited), geitonogamy (82% of all self‐pollination), or export to other conspecific plants (74%). N+ species set more fruit per flower (68.8% vs. 48.8%), but equivalent fractions of ovules per fruit were fertilized and subsequently developed into seeds in N− and N+ species. These findings provide only limited evidence that deceit pollination enhances mating quality (nectar production causes more local mating in N+ species than in N− species). Contrary to the hypothesis, deceit does not generally affect pollinator‐mediated self‐pollination. The repeated evolution of nectar production from rewardless ancestors in Disa likely occurred under severe visit limitation, favoring nectar‐producing mutants with higher reproductive output. Given that we did not find any mating quality advantage for rewardlessness in Disa, its persistence in some lineages remains an evolutionary enigma.

Sex Differences in Preening Behaviour in the White StorkCiconia ciconia

ABSTRACT Preening is a type of feather maintenance behaviour in birds, that fulfils an important role in grooming. Preening may also be important for signalling quality of mates. Therefore we hypothesized that the frequency of preening may be related to sex and population density of White Stork Ciconia ciconia. We observed preening activity of 25 pairs in Western Poland at the beginning of incubation, when preening frequency is the highest. Birds were observed on the nest, because most preening behaviour occurs there. We found that being on the nest males spent proportionally more time on preening than females (on average 30% vs. 16%). Females spent more time preening when their mate was present at the nest. There was no significant relationship between preening frequency and indirect quality indicators (arrival date, laying date, hatching date, clutch size, brood size) nor between the distance to nearest neighbours and the time males and females spent on preening.

Machiavellianism, perceived quality of alternative mates, and resistance to mate guarding

Women higher on Machiavellianism may benefit from controlling their resistance to a partner's mate guarding behaviour. This may reduce the likelihood of relationship dissolution whilst retaining opportunities to engage in extra-pair relationships. Women (N=197) completed the Mach IV (Christie & Geis, 1970), Quality of Alternatives Scale (Rusbult, Martz, & Agnew, 1998), and the Resistance to Mate Guarding Scale (Cousins, Fugure, & Riggs, 2015). Women with higher levels of Machiavellianism displayed greater resistance to their partner's mate guarding. In particular, Machiavellianism predicted more frequent use of covert resistance and resisting control. Furthermore, women higher in Machiavellianism who perceived a high quality of alternative mates resisted their partner's public displays of affection. These findings further demonstrate the manner in which Machiavellianism influences behaviour in long-term romantic relationships.

Female active sampling of male paint on bowers predicts female uncertainty in mate choice

It can be difficult to assess the degree to which a female attends to an individual element of a multicomponent male courtship display. Quantifying behaviours where females actively sample a male display element (such as smelling or tasting a chemical signal) can provide detailed information about differences between females in their sampling behaviour and reliance on that element in making mate choice decisions. Bower ‘paint’ is a unique male sexual display trait found in satin bowerbirds, Ptilonorhynchus violaceus. Male bowerbirds masticate dried hoop pine (Araucaria cunninghamii) needles and apply this paste to the inside walls of their bowers. Female bowerbirds move among bowers of different males until they choose a mate. Recent mate searching experience and other factors appear to affect this process. Females visiting bowers taste the paint when they nip at the painted wall. Why females sample paint is unknown, but there is now strong evidence that female sampling of paint is important in mate selection. We tested the hypothesis that tasting is related to female uncertainty in mate choice. We found that a greater tendency of females to taste paint on bowers was associated with three measures of female mate choice uncertainty: (1) more frequent female visits to bowers, (2) mating with multiple males and (3) switching frequently among visited males. We suggest that high rates of tasting are predictive of female uncertainty in mate choice, perhaps due to some females initially having limited information about the quality of potential mates.

配偶选择中“听众效应”及鸣唱对雌性灰文鸟行为的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 配偶选择中“听众效应”及鸣唱对雌性灰文鸟行为的影响 DOI: 10.5846/stxb201501290238 作者: 作者单位: 辽宁大学生命科学院,辽宁大学生命科学院,辽宁大学生命科学院,辽宁大学生命科学院,辽宁大学生命科学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31100271） Effects of “audience effects” and song on female Padda oryzivora mate choice behavior Author: Affiliation: Department of Life Sciences, Liaoning University,,,,Department of Life Sciences, Liaoning University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:配偶选择是性选择研究核心问题之一。雌性通过选择高质量的雄性配偶获得直接利益，如资源、营养和保护等，也可以通过获得高质量雄性提高后代的适合度。配偶选择研究对于研究性选择机制和进化均具有重要意义。目前，对配偶选择的研究主要集中在影响配偶选择的因素及雌性"听众效应"中雄性-雄性竞争方面。鸣唱对配偶选择的影响和雄性"听众效应"中雌性-雌性竞争的研究对于探索鸟类配偶选择中信号交流、调整的方式及选择策略均具有重要意义。以灰文鸟为对象，研究了雄性鸣唱对雌性配偶选择的影响及雄性"听众效应"对雌性灰文鸟同性竞争行为的影响进行了探讨。实验一利用双向选择装置，以配偶鸣唱（求偶鸣唱或非求偶鸣唱）和非配偶鸣唱（求偶鸣唱或非求偶鸣唱）对雌鸟进行刺激，观察雌鸟对两端鸣唱的偏爱状况。实验二主要观察雌鸟之间在无听众、听众为熟悉的雄性和听众为配偶条件下的竞争行为。结果表明，雌性灰文鸟大多偏爱配偶鸣唱，相对于配偶的非求偶鸣唱更偏爱非配偶的求偶鸣唱。求偶鸣唱比非求偶鸣唱更具有吸引力，求偶鸣唱更能刺激雌性灰文鸟配偶选择的积极性，这种积极要付出更多的时间和资源，但雌鸟可以通过选择更高质量的雄性配偶获益。在配偶雄性作为听众条件下雌鸟攻击行为最高，显著高于熟悉雄性为听众的条件下，并且两者都显著高于无听众条件下雌鸟的攻击行为。雌性灰文鸟会基于不同"听众"而对雌-雌竞争行为做出适当调整。上述研究结果对于深入理解鸟类的性选择行为机制具有重要帮助作用。 Abstract:Mate choice is one of the most important aspects of sexual selection, and uncovering the mechanisms behind mate choice is a central issue in sexual selection studies. Females choose high-quality males as mates to obtain direct benefits such as resources, nutrition, and protection, and in doing so they acquire indirect genetic benefits for future generations. Further studies of female mate choice would improve our understanding of sexual selection and evolutionary processes. Song is one of the most important secondary sexual characteristics in birds and can reflect male territory quality and genetic and physiological status. Females can extract information about male quality by assessing their songs, and more complex songs are preferred over simple ones. Birds inhabit a communication network in which individuals can assess the quality of potential mates by visual and auditory observation of their interactions. In addition, individuals being observed may adjust their signaling behavior. Audience effects are defined as changes in signaling behavior of an individual engaged in an interaction due to the presence of an audience consisting of a conspecific witnessing the interaction. To date, studies of sexual selection have mainly focused on the driving factors of mate choice and on female audience effects on female-female competition. In contrast, there is limited knowledge about the effects of bird song on mate choice and about male audience effects on female-female competition. Here, we investigated the effects of male song on female mate choice and the male audience effect on female-female competition in Padda oryzivora. In the first part of the study, we used a two-way choice device and stimulated the female by courtship or other songs of a spouse and other males, and we observed female song preference. In the second part of the study, females were observed under three conditions: (a) in the absence of an audience, (b) in the presence of a familiar male, and (c) in the presence of a mate. Our results showed that female P. oryzivora preferred the spouse's song and preferred courtship songs of other males to the non-courtship song of their mates. The courtship song was more attractive than other songs, and its effects were much stronger in stimulating positive female mate choice. The courtship chirp caused a positive response in the female. Females expended more time and resources, but also benefited more, by selecting higher-quality mates. Female P. oryzivora were more aggressive in the presence than in the absence of a male and were more aggressive in the presence of the mate than in the presence of a familiar male. Females appropriately adjust female-female competition behavior when under the male audience effect; whether this is a result of males choosing mates by observing this competition remains to be examined, as does female-female competition in the wild. These results improve our understanding of the underlying mechanism of mate choice behavior in birds. 参考文献 相似文献 引证文献

Attendance, but not performance, predicts good genes in a lek-breeding treefrog

According to the good-genes hypothesis, females prefer males with costly displays because the costs are reliable indicators of genetic quality. In leks, mating costs result from a multiplicative interaction between the number of display performances (lek attendance) and the energetic expenditure associated with each display performance. If males differ in their allocation strategies between the 2 components of mating effort, the reliability of display performance as an indicator of genetic quality may be disrupted. Here, we investigate the association between male genetic quality and both lek attendance and display performance in the Italian treefrog, Hyla intermedia. We recorded lek attendance and display performance (nightly calling effort) during 2 breeding seasons, and we set up a breeding experiment to evaluate sire effects on 3 larval fitness-related traits (growth rate, age, and size at metamorphosis). Attendance and calling effort were positively correlated with each other and both with male mating success, providing no evidence for a performance-attendance trade-off at the population level. In the breeding experiment, we found some evidence for an effect of sire identity and attendance on growth rate and age at metamorphosis, but no evidence for an effect of sire calling effort. We conclude that female preference, by imposing high-quality standards for calling males, strengthens the role of endurance rivalry in male mating competition, indirectly favoring males of higher-than-average mating effort. Under this scenario, although male displays are unreliable indicators of mating quality, females nevertheless gain benefits because of the reduced risk of coming on low-quality males.

Influences on male reproductive success in long-lived Blanding’s Turtles (Emydoidea blandingii)

Knowing how the number and qualities of mates influence male reproductive success (RS) can help interpret mating-system dynamics that are important for conservation efforts. We combined parentage data (1999–2006) with data from a long-term life-history study (1953–2007) of Blanding’s Turtles (Emydoidea blandingii (Holbrook, 1838)) on the University of Michigan’s E.S. George Reserve to document the relative influence of mate number and quality on male RS. Blood samples were taken from >92% of resident adults and tissue samples were taken from 723 hatchlings from 92 nests of 54 females over eight nesting seasons. The incidence of multiple paternity averaged 41.6% (N = 77), was variable among years (minimum–maximum = 15.4%–55.6%), and was positively associated with female age, body size, and clutch size. Repeat paternity was observed in 69.9% of sequential clutches of the same female separated by 1–7 years. Male RS was variable (1–40 offspring) and was positively associated with the number of mates and clutches sired. The youngest male to sire offspring was 22 years old. Adult movements that result in encountering different mates and (or) the ability to use attributes (e.g., size or age) to identify high-quality mates have the potential to substantially increase RS.

Playing Smart: The Mating Game and Mating Intelligence

Current work investigated the extent to which mating intelligence was related to one’s own mate value as well as the value of one’s mate. We hypothesized that (1) mating intelligence is positively correlated with measures of self-perceived mate value, (2) greater mating intelligence is associated with greater partner mate value, (3) greater mating intelligence is associated with less mate settling, and according to Parental Investment Theory, females are predicted to have significantly higher mean mate value than males. Along with the adoption of the Mate Value Inventory and Mating Intelligence Scale, a method was developed to assess a more objective rating of self and partner’s physical attractiveness. A large sample (N > 500) was obtained for this study via internet survey. As predicted, mating intelligence appeared to be a valid predictor of one’s own value in the mating market, as well as the quality of mates that one can attract. High mating intelligence also corresponded to lower mate value discrepancy within a mateship. That is, high MI tended to go with a relatively small gap between the mate value of oneself and the mate value of ones partner, or less mate settling. Moreover, the positive relationship between objective and subjective ratings of self and partner’s physical attractiveness suggests that participants were able to judge themselves and their partners through the eyes of another. In all, evidence from the current work suggests that mating intelligence has important implications for individuals’ mating behavior within the mating market.

A male pheromone-mediated trade-off between female preferences for genetic compatibility and sexual attractiveness in rats

IntroductionChemosensory signals play a vital role in socio-sexual interactions of rodents. Females rely heavily on chemosensory signals to evaluate genetic similarity and quality of potential mates, but their olfactory preferences for these criteria often conflict in mate choice.ResultsUsing two inbred strains of rats, Brown Norway (BB) and Lewis (LL) and their F1 reciprocal hybrids (BL, BB♀ breed with LL♂; LB, LL♀ breed with BB♀) as genetic models, we found that the chemosensory preferences of BB and LL females between these 4 strains of rats could be predicted on the basis of genetic compatibility benefits, except that LL females exhibited incestuous preferences for male urine odor of LL rats over that of the BB strain and the F1 hybrids. Seven ketone components of major urine volatiles proved to be potential male pheromones and were enriched in LL males compared to BB males or the F1 hybrid males. We hypothesize that these ketones produced an extravagant male trait that attracts LL females, overriding compatibility traits. This conclusion was corroborated by adding three synthetic pheromone analogues, 4-heptanone, 2-heptanone and 9-hydroxy-2-nonanone of these 7 components, which resulted in equalization of the sexual attractiveness of BB male urine and LL male urine. Additionally, in the genetically diverse F2 hybrids (BL♀ breed with BL♂), the pheromones-enriched males could consistently attract the F2 females.ConclusionsWe suggest that the exaggerated male pheromones serve as a “sexual chemical ornament” to attract females, independent of genetic compatibility, whereas genetic dissimilarity could influence the preferences only when male pheromones varied on a small scale.

Mates of Competitive Females: The Relationships between Female Aggression, Mate Quality, and Parental Care

Though rarely mate-limited, females in a wide variety of species express traits commonly associated with mate competition in males. Recent research has shown that these competitive traits (ornaments, armaments, and intense aggression) often function in the context of female-female competition for nonsexual reproductive resources and are often positively related to reproductive success. Increased success could occur because competitive females acquire limited ecological resources (nest sites, territories, etc.) or because they pair with high quality males, that is, older, more ornamented, or more parental males. Further, males paired with aggressive/low care females may compensate by increasing their paternal efforts. Here, I examined patterns of social pairing and parental care in free-living dark-eyed juncos (Junco hyemalis), a biparental songbird. I found no detectable relationship between female competitive behavior (aggression) and male quality (age, size, or ornamentation) or male provisioning. Thus, neither of the mate choice hypotheses (females compete for males or males prefer aggressive females) was supported. Instead, these results suggest that females compete for nonsexual resources and mate quality is a secondary consideration. I also found a negative relationship between male and female provisioning rates, suggesting that partners adjust their level of parental effort in response to their partner’s efforts.