Female Preference For Large Males Research Articles

Mismatch between calf paternity and observed copulations between male and female reindeer: Multiple mating in a polygynous ungulate?

In polygynous systems, such as that exhibited by reindeer Rangifer tarandus, mate choice can be difficult to disentangle from male intrasexual competition because male behavior may constrain female choice. Multiple mating may provide an avenue for female mate choice, though it is difficult to identify using behavioral estimators alone. Molecular techniques address this issue by affording ecologists an opportunity to reassess mating systems from a genetic perspective. We assessed the frequency and possible explanations for multiple mating in reindeer using a genetic approach to determine the success of observed copulations in a semi-domesticated herd in Kaamanen, Finland. Behavioral and genetic data were synthesized with population characteristics over a 7-year period to test the hypothesis that, if present, polyandry in reindeer is driven by sexual harassment from sub-dominant males. We observed multiple mating in 42% of females, with as many as 60% exhibiting multiple mating in certain years. We found no evidence that multiple mating resulted from sexual harassment by sub-dominant males, suggesting that it is likely a deliberate strategy among females. Conversion rate of copulations into paternities varied with male size, with smaller males more likely to experience mismatch than larger males. Female preference for larger males persisted despite the occurrence of multiple mating, possibly suggesting a mechanism for cryptic post-copulatory selection. We suggest further research to delineate the possible influence of cryptic post-copulatory selection and multiple mating to defend against infertility in exhausted males.

Quasi-experimental determination of a mass standard in the forest millipede <em>Centrobolus inscriptus</em>

Sexual size dimorphism (SSD) in the diplopod species Centrobolus inscriptus has a positive correlation with body size. Intraspecific intersexual variation in mass was calculated twice in this species (males: 2.48 ± 0.57g; 2.00 ± 0.22g; females: 2.27 ± 0.28g; 2.61 ± 0.42g) and data sets tested for SSD. Males differed significantly from females in body mass (students t-test: t=9.38, d.f.=95, p<0.05). This was again found in the larger sample where males and females differed significantly from each other in mass (Wilcoxon matched pairs test: T= 554, n = 88, P = 0.00). When the two data sets were pooled and the mean’s compared, a difference was found (t=2.3162, n=273; p=0.020918). It was found males were lighter and have higher reproductive success through female preference for larger males when there was Size assortative mating behaviour. Conformity to the mass standard in sexual selection was suggested. Millipedes may influence concentrations of soil elements through sex‐specific difference.

Male size does not correlate with fertilization success in two bufonid toads that show size-assortative mating

Abstract We examined sexual size dimorphism (SSD), mating pattern, fertilization efficiency and female reproductive traits in two bufonid toads (Bufo gargarizans and Duttaphrynus melanostictus) to test the idea that importance of male body size for egg fertilization success depends on the mating pattern. Female-biased SSD was evident only in D. melanostictus. Female B. gar-garizans laid fewer larger eggs nearly three months earlier than did female D. melanostictus. Fertilization efficiencies on average were higher in B. gargarizans (95%) than in D. melanostictus (91%). Though differing in the degree of SSD, body size, breeding season, clutch size, egg size and fertilization efficiency, the two toads were similar in four aspects: (1) both showed size-assortative mating; (2) females did not tradeoff egg size against egg number; (3) male size, clutch size and clutch dry mass were greater in male-larger than in female-larger pairs after accounting for female snout-vent length (SVL); and (4) the ratio of male to female SVL did not affect fertilization efficiency. Our data show that: (1) a female preference for large males is likely not important in terms of egg fertilization success; (2) a male preference for large females is likely important because larger females are more fecund; and (3) size-assortative mating arises from a male preference for large females. Our study demonstrates that male size is not always important for egg fertilization success in anurans that show size-assortative mating.

Mate preference in the neotropical freshwater crab Aegla longirostri (Decapoda: Anomura): does the size matter?

This study analyzed sexual selection in Aegla longirostri through one of the mechanisms that can alter species’ evolution: mate choice. Y maze experiments were performed by placing a male or a receptive female (chooser) in the center of the maze; and two other individuals were placed each in a different corridor, according to the chooser: a receptive and an immature female, or two males that differed in size, respectively. The third corridor remained empty, and the choosers could walk among the branches of the maze. The results showed that only females spent more time in the corridors harboring a large male. Moreover, females had higher rates of movement in the corridors harboring males. Thus, female preference for larger males may be one factor that prompted the evolution of sexual dimorphism in this species.

Females of a tree cricket prefer larger males but not the lower frequency male calls that indicate large body size

In the tree cricket Oecanthus henryi, females are attracted by male calls and can choose between males. To make a case for female choice based on male calls, it is necessary to examine male call variation in the field and identify repeatable call features that are reliable indicators of male size or symmetry. Female preference for these reliable call features and the underlying assumption behind this choice, female preference for larger males, also need to be examined. We found that females did prefer larger males during mating, as revealed by the longer mating durations and longer spermatophore retention times. We then examined the correlation between acoustic and morphological features and the repeatability of male calls in the field across two temporal scales, within and across nights. We found that carrier frequency was a reliable indicator of male size, with larger males calling at lower frequencies at a given temperature. Simultaneous playback of male calls differing in frequency, spanning the entire range of natural variation at a given temperature, revealed a lack of female preference for low carrier frequencies. The contrasting results between the phonotaxis and mating experiments may be because females are incapable of discriminating small differences in frequency or because the change in call carrier frequency with temperature renders this cue unreliable in tree crickets. (C) 2012 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Discrimination of conspecifics’ chemicals may allow Spanish terrapins to find better partners and avoid competitors

Chemosensory discrimination of sex and other individual traits based on pheromones occurs in many reptiles. However, the use of chemoreception in turtle social behaviour is poorly known. We examined the role of chemical signals in intraspecific communication of Spanish terrapins, Mauremys leprosa, during the breeding season. Chemical cues released by terrapins in the water might inform on sex and other individual characteristics, such as size, body condition or health state, which are important in sexual selection processes. To test this hypothesis, we compared the time spent by turtles in water pools containing chemical stimuli obtained from different conspecifics. Behavioural responses showed that turtles were able to detect and discriminate chemical cues released by conspecifics, and to modify their use of space in response to these cues alone. Males preferred water pools with chemicals of females with greater immune responses, while females preferred water pools with odours of larger males. Preferences for water used by better potential partners could increase mating opportunities with these partners, which would increase offspring fitness. Female preference for large males could also be a mechanism of protection from harassment by small males. On the other hand, males avoided water pools with chemicals of heavier, or relatively heavier, males and preferred water with chemicals of smaller, or relatively smaller, males. Chemosensory assessment of body size may allow males to minimize the risk of costly aggressive interactions with other males. Selection of water pools based on chemical cues of conspecifics may allow terrapins to optimize their mate searching while avoiding competitors.

Rapid assessment of female preference for male size predicts subsequent choice of spawning partner in a socially monogamous cichlid fish

Although size-assortative mating in convict cichlids, Amatitliana nigrofasciata, is supposed to result from mutual mating preference for larger individuals, female choice in relation to male size remains ambiguous. We revisited the evidence for directional preference for larger males in female convict cichlids using a classical two-way choice apparatus in which each female could decide to spend time in front of a small male or a large one. We found evidence for female preference for large males, as assessed from association preference during a 4-hour period following encounter. Furthermore, females decided to spawn in front of the initially preferred male more often than expected by chance. Our results thus confirm the existence of a directional preference for large males in female convict cichlids, and indicate that association preference measured over a short period of time can provide a quick and reliable proxy for reproductive preference in this species.

How female size and male displays influence mate preference in a swordtail

Building a complete model of animal behaviour requires knowing both the internal and external factors that influence behaviour. As recent genomic and neural studies begin to establish the northern swordtail, Xiphophorus nigrensis, as a model for proximate explorations of female mate preference, it is important to recognize the complexity of other factors that can drive variation in female preference. In this study, we determined how different experiential and social factors correlate with interindividual variation in female mate preference: female body size, sexual experience and male behavioural displays. We found a significant positive correlation between female size and female preference for large males, as well as a significant relationship between male activity and female preference. We also demonstrate that copulating at least once may be sufficient to increase preference for large males. Our identification of these relationships emphasizes the multiple and diverse types of mechanisms that can influence variation in female mate preference and encourage their consideration in future studies when trying to assess why and how females choose males.

Influence of size- and sex-biased harvesting on reproduction of the coconut crab Birgus latro

Larger individuals of many biological resources are more likely to be caught than smaller ones. However, larger individuals can contribute disproportionately to reproduction through sexual selection. Therefore, it is likely that size-selective harvesting of larger individuals can lead to a decline in the reproductive output. Populations of the coconut crab Birgus latro have been severely depleted in most habitats due to overharvesting. Thus, to understand the harvesting pattern and determine its impacts on coconut crab reproduction, we investigated the size and sex of crabs that are marketed for consumption. The harvested population structure and the relationship between male body size and mating success were determined using market research, field investigations, and lab- oratory experiments. The harvesting pattern was sex- and body size-biased, in which larger males (>40 mm thoracic length) were exclusively taken. Sex ratio was skewed significantly toward females and mean male size decreased in the harvested population. Most female coconut crabs were esti- mated to mate only with males that are larger than or approximately equal to themselves in body size, implying female preference for larger males as mates. The present large male-selective harvesting could lead to depletion of the resource through reduced reproductive output brought about by reduced probability of encountering potential mates. Therefore, we recommend male-only harvest- ing with slot size limits as an effective management measure for coconut crabs.

Sociality, Mate Choice, and Timing of Mating in American Bison (Bison bison): Effects of Large Males

AbstractWe studied group size, composition, and mating activities in American bison (Bison bison) during rut on the Delta Junction Bison Range in interior Alaska, USA, in 1996 and 1997. Our purpose was to determine the effects of large males (≥5 yr old) on mating and associated activities. Groups with large males were larger than those containing smaller males. Most groups of bison were mixed‐sex (90%), but large males occurred in only one‐half of all groups. Moreover, females in groups with large males were more likely to copulate than those in groups with smaller males, indicating a female preference for large males. Nevertheless, our results are consistent with large males seeking out adult females for mating rather than vice versa. Mating peaked in mid‐August during both the study years and was highly synchronous. Scent marking was coincident with mating, an outcome consistent with a hypothesis of such behavior triggering ovulation. Scent marking by large male bison occurred in both male–male and male–female contexts, but was associated most often with sexual activities. No differences in group size occurred with changes in weather or among vegetation types occupied by bison. Group size of bison, however, was larger with increasing distance from the forest edge, which likely was a response to predation risk in this predator‐rich environment.

Strategic egg allocation in the zebra fish, Danio rerio

Females across a range of taxa have been shown to differentially allocate their reproductive resources according to the attractiveness of their mate. Previous studies demonstrated a female preference for larger males in the zebra fish but have so far failed to uncover a size-mediated difference in male mating success, possibly due to the effects of male-male competition. By controlling for male-male competition in the present study, we show that females strategically allocate their reproductive resources (i.e., eggs) toward larger males. When females were mated sequentially with a large and small male, they released a greater number of eggs to the second male when he was large than when he was small. Furthermore, there was also a trend for females to release a greater proportion of their eggs to the first male when he was large. Across females, the total number of eggs laid by each female increased with the average standard length of the male pair, whereas the number of eggs laid to the second male also increased with his standard length. This study represents one of the first attempts at identifying differential allocation in a resource-free egg scatterer and suggests that female preferences may play a greater role in the reproductive success of males in this species than previously envisaged.

The large-male advantage in brown antechinuses: female choice, male dominance, and delayed male death

Male-biased dimorphism in body size is usually attributed to sexual selection acting on males, through either male competition or female choice. Brown antechinuses (Antechinus stuartii) are sexually dimorphic in size, and heavier males are known to sire more offspring in the wild. We investigated four possible mechanisms that might explain this large-male reproductive advantage. We tested if there is a female preference for large males, a female preference for dominant males, if larger males compete more effectively for mates, and if there is a survival advantage for large males during the mating season. We established nesting groups of males in captivity and conducted mate choice trials in which males from nesting groups either could or could not interact. We assessed male dominance rank and recorded survival times after mating. Females did not prefer larger males directly. The results suggest that the other three mechanisms of sexual selection tested account for the large-male advantage: large males competed more successfully for mates, so were socially dominant; females rejected subordinates (males they saw losing twice in contests to previous mates); and dominant males survived for longer after their first mating. Females judged male rank based on direct observation of male competitive interactions at the time of mating and apparently could not distinguish rank from male scent. Effects of size and dominance on male reproductive success are not confounded by age because male antechinuses are semelparous.

Female preference for large males in sailfin mollies, Poecilia latipinna : the importance of predation pressure and reproductive status

We examined the effect of predation risk on female association patterns in the live-bearing sailfin molly (Poecilia latipinna). We tested two classes of females, with and without the risk of predation by a green sunfish (Lepomis cyanellus): (1) postpartum females (maintained with males until visibly gravid, then isolated and tested within 24-48 h of dropping a brood); and (2) non-postpartum females (different females, isolated from males for >50 days). When there was no apparent risk of predation, postpartum females showed a significant preference for large over small males, whereas non- postpartum females showed no size preference at all. When there was an apparent risk of predation, postpartum females maintained their preference for larger males and non-postpartum females continued to show no preference for large or small males. These results suggest that reproductive status (receptivity) plays a greater role in mate preference than predation risk. For postpartum females, the cost of not choosing a preferred mate may outweigh the potential cost of predation. Non-postpartum females either do not benefit from mating or are being indecisive about mating and thus are less likely to be choosy whether or not a predator is present.

Females produce larger eggs for large males in a paternal mouthbrooding fish

When individuals receive different returns from their reproductive investment dependent on mate quality, they are expected to invest more when breeding with higher quality mates. A number of studies over the past decade have shown that females may alter their reproductive effort depending on the quality/attractiveness of their mate. However, to date, despite extensive work on parental investment, such a differential allocation has not been demonstrated in fish. Indeed, so far only two studies from any taxon have suggested that females alter the quality of individual offspring according to the quality/attractiveness of their mate. The banggai cardinal fish is an obligate paternal mouth brooder where females lay few large eggs. It has previously been shown that male size determines clutch weight irrespective of female size in this species. In this study, I investigated whether females perform more courtship displays towards larger males and whether females allocate their reproductive effort depending on the size of their mate by experimentally assigning females to either large or small males. I found that females displayed more towards larger males, thereby suggesting a female preference for larger males. Further, females produced heavier eggs and heavier clutches but not more eggs when paired with large males. My experiments show that females in this species adjust their offspring weight and, thus, presumably offspring quality according to the size of their mate.

MALE MATING SUCCESS AND FEMALE PREFERENCE FOR MULTIPLE TRAITS IN THE TWOLINE PUPFISH (CYPRINODON BIFASCIATUS)

Abstract Summary Using the twoline pupfish (Cyprinodon bifasciatus), a species with a resource-based polygynous breeding system, we examined male mating success in the wild, and we experimentally investigated effects of male body size and substrate type on female association patterns in the laboratory. Our purpose was to (a) identify the traits contributing to male reproductive success in the field, (b) measure preferences for each trait independently in the laboratory, and (c) determine the relative importance of each trait. Field observations revealed that substrate type was the main determinant of male reproductive success: males defending territories on rocks mated significantly more often than males defending territories on silt or sand. Laboratory experiments supported the field data, and revealed that the female preference for substrate type was independent of male body size effects. When given a choice between two males matched for size but differing in the type of substrates they were defending, females preferred the male on the rocky substrate over the male on the sandy substrate. Laboratory experiments also revealed a female preference for larger males when substrate type was held constant. Finally, when females were presented with a choice between a large male on a sandy substrate and a small male on a rocky substrate, no clear preference emerged. We provide several interpretations for this result, and we argue that both traits may be strong predictors of the male's competitive ability.

Female fifteen-spined sticklebacks prefer better fathers

We studied how male fifteen-spined sticklebacks,Spinachia spinachia, vary in paternal competence, whether males advertise their competence and whether females prefer better fathers. In this species the male alone provides care for the offspring through nest building, fanning, cleaning and protecting the eggs. We found no female preference for larger males. Instead, females preferred males that during the subsequent paternal phase fanned their nests in shorter fanning bouts. Such males enjoyed a significantly higher hatching success because they fanned more often than males with longer fanning bouts. Males that fanned for short bouts during the paternal phase were also able to increase their fin beat rate. Frequent fanning and high fin beat rates may improve the flow of oxygen to the eggs. Beat rate may be a condition-dependent trait, because males that lost more weight were unable to increase their fin beat rate. During courtship, males perform behaviours such as displacement fanning and body shaking. Females preferred males showing more frequent body shakes during courtship. Body shake frequency correlated positively with hatching success, and negatively with mean fanning bout duration during the paternal phase. The results indicate that femaleS.spinachiashow a preference for direct benefits in terms of better paternal care, and that males may signal this ability to females by shaking their body during courtship.

Mate Choice by Chemical Cues in Western Redback (Plethodon vehiculum) and Dunn's (P. dunni) Salamanders

AbstractWestern redback and Dunn's salamanders (Plethodon vehiculum and Plethodon dunni, respectively) can distinguish between potential mates by using chemical cues. In laboratory choice tests, adult males of both species showed significant discrimination between chemical cues of gravid females over non‐gravid females of equal body size. Furthermore, males of both species differentiated the odour of paired gravid females that differed by ≅ 5 mm snout‐vent length (SVL). Given that clutch size is related to female body size in these species, adult males may be able to distinguish between females via cues that signal potentially high female reproductive success. In choice tests, P. vehiculum females did not discriminate between two relatively large males that differed by ≅ 5 mm SVL. However, females of P. vehiculum did discriminate between two relatively small males that differed by the same amount. Apparently, P. vehiculum females ranked males by both absolute and relative body size using chemical cues. This pattern could reflect a female preference for large males or that females avoid mating with the smallest males.

Female mate choice in the non-territorial lizard Ameiva plei (Teiidae)

Mate choice by females has been documented in a variety of taxa. Female mate choice in species lacking male resource control or paternal care might occur if preferred males provide protection from harassment. Female mate choice was investigated in a natural population of the non-territorial lizard Ameiva plei (Teiidae). Consort pairs were allowed to form naturally. Consort males were significantly larger than non-consort males. After removal of consort males, the “abandoned” female's reaction to the first male who approached her was recorded. Females rejected all small males. Female preference for large males was significantly higher than preference for small males. Large males may be better equipped to guard the females from harassment and behavior of large males is less harassing than behavior of small males, thereby affording the female increased foraging time.

Maximizing male reproductive success in the broad-headed skink (Eumeces laticeps): preliminary evidence for mate guarding, size-assortative pairing, and opportunistic extra-pair mating

AbstractSeveral lines of evidence suggest that male Eumeces laticeps may increase reproductive success by 1) mating with larger females to increase clutch size, 2) mate guarding to be present during the female's receptive period and/or prevent sperm competition, and 3) engaging in extra-pair copulations. Clutch size increases with female body size, establishing a potential advantage of male preference for large female mates. Mate association lasts up to 8 days and possibly longer, with a mean of nearly 5 days. Males may remain with females during a major portion of the mating season, which preliminary data suggest lasts about two weeks, suggesting that mate-guarding may reduce the level of polygyny. Tethered introductions of intruder males to consort pairs showed that consort males use aggressive behavior to exclude other males from the vicinity of females. Eumeces laticeps exhibits strong positive size-assortative pairing, suggesting the possible importance of male choice of large mates. Female preference for large males could account for this relationship, but only if large females prefer the largest possible males within the acceptable size range and aggressively exclude other females from preferred males. Females are sometimes aggressive to each other, especially near nest sites, but aggression is suppressed by males, as shown by tethered introduction of females to consort pairs. Size-assortative pairing may be based in part on male preference if males can prevent larger females from aggressively excluding smaller ones. In addition to preferentially guarding large females, males not currently guarding mate with any females not large enough to deter them aggressively. A field observation of an extra-pair copulation, responses by consort males to introduced females, and the lack of size preference in the absence of consorts suggest that males may engage opportunistically in extra-pair copulations to increase reproductive success and are not then choosy about female size.

Sperm competition or sperm selection: no evidence for female influence over paternity in yellow dung flies Scatophaga stercoraria

Recent studies of non-random paternity have suggested that sperm selection by females may influence male fertilization success. Here we argue that the problems originally encountered in partitioning variation in non-random mating between male competition and female choice are even more pertinent to interpreting patterns of non-random paternity because of intense sperm competition between males. We describe an experiment with the yellow dung fly, Scatophaga stercoraria, designed to partition variance in the proportion of offspring sired by the second male, P 2, between males and females, and to control for sperm competition. Large males were shown to have a higher P 2 than small males but P 2 was independent of the size of the female’s first mate. This result might suggest an absolute female preference for large males via sperm selection. However, large males have a higher constant rate of sperm transfer and displacement. After controlling for this effect of sperm competition, large males did not achieve higher paternity than small males. We argue that a knowledge of the mechanism of sperm competition is essential so that male effects can be controlled before conclusions are made regarding the influence of sperm selection by females in generating non-random paternity.