The effects of body size, ownership and sex-ratio on the precopulatory mate guarding of Caprella penantis (Crustacea: Amphipoda)

2009 ◽  
Vol 90 (2) ◽  
pp. 275-279 ◽  
Author(s):  
Fumio Takeshita ◽  
Yasuhisa Henmi
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Laboratory Experiments ◽  
Mate Guarding ◽  
Operational Sex Ratio ◽  
Receptive Female ◽  
Type I ◽  
Male Body ◽  
Precopulatory Mate Guarding ◽  
Secondary Factor

Precopulatory mate guarding behaviour of the skeleton shrimp Caprella penantis is described. Moreover, the effects of body size, ownership and sex-ratio on mate guarding were examined experimentally in the laboratory. In the field population, the operational sex-ratio was male-biased. Guarding pairs, which were collected from the field, continued guarding for an average of 350 minutes in the laboratory, indicating that the normal guarding duration is approximately 10 hours. In this species, two guarding types were found: Type O and Type I-like. In Type O guarding, the male would fold the female into a horseshoe shape, whilst the male held the female parallel to him in Type I-like guarding. In the laboratory experiments, male body size was the most important factor affecting competition for a receptive female; ownership was the secondary factor. Guarding duration was prolonged when the sex-ratio was male-biased. Thus, the precopulatory mate guarding behaviour of C. penantis is influenced by several factors, such as body size, ownership and sex-ratio.

scholarly journals Brood Sex Ratios are Related to Male Size but not to Attractiveness in Common Yellowthroats (Geothlypis Trichas)

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 176-184 ◽  
Author(s):  
Betsy Abroe ◽  
Julia C. Garvin ◽  
Marc C. Pedersen ◽  
Linda A. Whittingham ◽  
Peter O. Dunn
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Reproductive Value ◽  
Male Body ◽  
Male Size ◽  
Common Yellowthroat ◽  
Geothlypis Trichas ◽  
The Common ◽  
Fitness Benefits ◽  
Male Ornament

Abstract When the reproductive value of sons differs from that of daughters, selection will favor broods biased toward the sex that can provide greater fitness benefits. In species where female choice is based on male ornamentation, females mated to highly ornamented males may experience a reproductive advantage by skewing the brood sex ratio toward sons. In the Common Yellowthroat (Geothlypis trichas), males with larger black facial masks are more likely to gain a social mate and sire extrapair young and, as a result, have increased seasonal reproductive success. Females mated to larger-masked males could benefit if they produced more sons. Given that larger- masked males are preferred as extrapair sires, females may also benefit by producing more extrapair sons. We tested these hypotheses during a five-year study of Common Yellowthroats in Wisconsin. Contrary to our predictions, females did not produce more sons when mated to males with larger masks, and extrapair young were not more likely to be male. However, sons were more likely to be sired by males with longer tarsi, which suggests that females may respond to male body size rather than to male ornament size. El Cociente de Sexos en las Nidadas Está Relacionado con el Tamaño de los Machos pero no con el Atractivo en Geothlypis trichas

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

Behaviour ◽  
2001 ◽  
Vol 138 (10) ◽  
pp. 1303-1318 ◽  
Author(s):  
Murray Itzkowitz ◽  
Anna Ludlow ◽  
David Baird
Keyword(s):  
Body Size ◽  
Laboratory Experiments ◽  
Female Preference ◽  
Male Reproductive Success ◽  
Male Mating ◽  
Male Body ◽  
Male Mating Success ◽  
Substrate Type ◽  
Sandy Substrate ◽  
Cyprinodon Bifasciatus

AbstractSummary 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.

Mate Guarding in Male Sand Lizards (Lacerta Agilis)

Behaviour ◽  
1996 ◽  
Vol 133 (5-6) ◽  
pp. 367-386 ◽  
Author(s):  
Annica Gullberg ◽  
Mats Olsson ◽  
Hakan Tegelström
Keyword(s):  
Laboratory Experiments ◽  
Mate Guarding ◽  
Operational Sex Ratio ◽  
Sexually Active ◽  
Museum Collection ◽  
Male Size ◽  
Female Age ◽  
In The Wild ◽  
Mate Acquisition ◽  
Lacerta Agilis

AbstractWe investigated factors that may determine mate guarding tactics in male sand lizards. In a sample of lizards from a museum collection, larger males had larger testis, but in laboratory experiments and in a natural population larger males did not sire more offspring. Males with long inter-copulatory intervals were more successful in sperm competition than males with short inter-copulatory intervals. In the wild, the operational sex ratio (OSR, No of receptive females/No of sexually active males) declined throughout the mating season. Mean duration of mate guardings was unaffected by OSR, time to ovulation, female age and mass, and clutch size. Larger males guarded females longer and were more likely to mate guard a female of similar age. Larger males had more partners but there was no correlation between male size or guarding time and the proportion of young that males sired in clutches from females mated with several partners. Males with more partners were more successful at siring offspring in clutches from females that mated with more than one partner. We suggest that fitter males are better at both mate acquisition and have more competitive sperm.

Proximate mechanisms responsible for random mating by size in the Himalayan toad Duttaphrynus himalayanus

2020 ◽  
pp. 1-13
Author(s):  
Lixia Zhang ◽  
Yongsun Sheng ◽  
Xiangyu Yuan ◽  
Fei Yu ◽  
Xueting Zhong ◽  
...  
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Female Body ◽  
Random Mating ◽  
Apparent Size ◽  
Operational Sex Ratio ◽  
Female Body Size ◽  
Short Period ◽  
Significant Difference ◽  
Duttaphrynus Himalayanus

Abstract Exploring the mechanisms that affect mating pattern with respect to body size has implications for understanding the evolution of sexual selection. Theory predicts that the absence of a relationship between female body size and fecundity, unbiased operational sex ratio, and a short breeding season will lead to random mating by body size in anuran amphibians. We tested these predictions in the Himalayan toad Duttaphrynus himalayanus inhabiting southeastern Tibet. Our study did not detect any correlation between female body size and number of eggs laid, nor was there a significant difference in the sex ratio of toads captured from the breeding site. In addition, the toads were reproductive for only a short period, from late April to early May (typical of an explosively breeding species). As expected, we detected a weak but not significant relationship between body size of amplexing males and females. Our results revealed no apparent size-assortative pairing in the study population of the Himalayan toad and may contribute to an increasing body of literature on mating patterns in relation to body size in animals with indeterminate growth.

Mating Tactics in the Tropical Millipede Alloporus Uncinatus (Diplopoda: Spirostreptidae)

Behaviour ◽  
1993 ◽  
Vol 124 (1-2) ◽  
pp. 45-56 ◽  
Author(s):  
Steven R. Telford ◽  
J. Mark Dangerfield
Keyword(s):  
Sex Ratio ◽  
Mating System ◽  
Sperm Competition ◽  
Breeding Season ◽  
Female Choice ◽  
Laboratory Experiments ◽  
Mating Behaviour ◽  
Operational Sex Ratio ◽  
Mating Tactics ◽  
Mate Acquisition

AbstractField and laboratory observations of mating behaviour in a population of the tropical millipede Alloporus uncinatus were carried out over one breeding season. Males obtained mates through random encounters and by forming triplet associations with copula pairs. The occurrence of triplet associations in the field was coincident with a highly male biased operational sex ratio. Mate acquisition by males was apparently stochastic and direct physical competition did not occur. In laboratory experiments mating was size-selective probably as a consequence of female choice. We consider the possibility that sperm competition has contributed to the evolution of the mating system in this species.

Seahorses Exhibit Conventional Sex Roles in Mating Competition, Despite Male Pregnancy

Behaviour ◽  
1994 ◽  
Vol 128 (1-2) ◽  
pp. 135-151 ◽  
Author(s):  
Amanda C.J. Vincent
Keyword(s):  
Sex Ratio ◽  
Sex Roles ◽  
Laboratory Experiments ◽  
Sex Role ◽  
Male Reproduction ◽  
Operational Sex Ratio ◽  
Mating Competition ◽  
Male Pregnancy ◽  
The Impact

AbstractIn seahorses, only males undergo a pregnancy. It had been tacitly and explicitly assumed that seahorses were sex role reversed (that females competed more intensely than males for access to mates), on the basis that male pregnancy so limited male reproduction as to produce a female-biased operational sex ratio (OSR). However, this supposition had never been investigated. The laboratory experiments in this paper demonstrate that, contrary to expectations, seahorses exhibit conventional sex roles: male seahorses compete more intensely than females for access to mates, on both the first and final days of courtship. Competing males are more active than competing females in those courtship and competitive behaviours common to both sexes, and only males exhibit uniquely competitive behaviours (wrestling and snapping). Males which succeeded in copulating are heavier than their rivals and copulating seahorses of both sexes generally are more active in courtship and competition than are their unsuccessful rivals. The finding that seahorses maintain conventional sex roles requires us to reconsider the impact of male pregnancy on the OSR.

Does perceived sex ratio influence intrasexual competitiveness in women?

2020 ◽  
Author(s):  
Thomas Richardson
Keyword(s):  
Sex Ratio ◽  
Statistical Power ◽  
Sex Ratios ◽  
Facial Attractiveness ◽  
Single Women ◽  
Operational Sex Ratio ◽  
Type I ◽  
Double Blind ◽  
Future Career ◽  
Biased Sex Ratio

The operational sex ratio has been shown to influence a variety of behaviours in humans and non-human animals, particularly relating to intrasexual competition. One way females compete for mates is by derogating other women’s attractiveness. Recent studies have shown that priming participants with different sex ratios can induce sex ratio effects on behaviour. In a pre-registered, double blind experiment, 71 single women came to the lab twice and were primed with either a favourable (many men) or unfavourable (few men) sex ratio. I assessed whether unfavourable sex ratios increased self reported intrasexual competitiveness, as well as competitor derogation in the form of decreased ratings of female facial attractiveness and kindness. I also assessed whether they expressed less choosiness by rating male faces as more attractive. I tested whether any sex ratio effects are weaker for more attractive women. Finally, I attempted to replicate previous work suggesting that a male biased sex ratio increases women's preference for their future career over their future family. Despite having higher statistical power than most previous studies of this type, I did not find evidence for any of the hypothesised effects and failed to replicate 2 previous findings. The data indicated that the sex ratio manipulation likely did not work.

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