The dynamics of operational sex ratios and competition for mates

Kvarnemo, Charlotta; Ahnesjö, Ingrid

doi:10.1016/0169-5347(96)10056-2

Cited by 576 publications

(483 citation statements)

References 39 publications

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“…Similarly, this pattern led to the increase in observed male-male mount attempts during the male-biased OSR trial. Male-biased OSRs have been reported to influence the frequencies of both male sexual displays and male-male competition within other mating systems (Kvarnemo & Ahnesjo, 1996;Jirotkul, 1999;Huffard, 2005). Therefore, it is suggested that the limitation of available females in the male-biased OSR within the present study led to heightened male activity, resulting from increased male motivation to copulate.…”

Section: Discussionmentioning

confidence: 99%

“…Seawater was obtained from Cockburn Sound, WA where most of the animals were sourced, and water parameters we continuously maintained at 22 o C and between 34 -35 ppt salinity. Male and female containers were separated by an opaque divider, and activated carbon was used to neutralise odours in seawater before entering animals' individual containers to limit animals' awareness of any pre-existing OSR prior to trials (see Kvarnemo & Ahnesjo, 1996). Each animal was given an appropriately sized shell for use as a den, and animals were fed ad libitum with sections of prawn and occasional live crabs.…”

Section: Animal Acquisition and Maintenancementioning

confidence: 99%

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Nocturnal mating behaviour and dynamic male investment of copulation time in the southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae)

Morse

Zenger

McCormick

et al. 2015

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The southern blue-ringed octopus, Hapalochlaena maculosa (Hoyle, 1883) is a nocturnal species that exhibits a mating system in which females hold sperm from multiple males over a one to two month breeding window before laying a single egg clutch. Contrary to most studied animal mating systems where anisogamy exists, gamete package production is limited for both males and females of this species (~50 spermatophores/eggs). This presents an animal model for studying aspects of sperm competition and dynamic mate choice behaviours. The present study reports on the mating behaviour of H. maculosa observed under laboratory conditions using infrared closed-circuit television video footage. Rates of male copulation attempts increased with male size, while female receptivity to mating attempts increased with female size, resulting in larger animals of both sexes gaining more copulations and spending more time per day in copulation. There was some evidence of female preference of larger males, but no male preference of females based on measured morphological traits. Both sexes terminated copulations in equal frequencies but male-terminated copulations were significantly shorter in duration. Males were more likely to terminate copulation early with females they had previously mated with, however were less likely to do so if the female had recently mated with a different male. Among male-terminated copulations, males mated for longer with females that had previously mated with other males in the trial. Male-male mounts were as common as male-female mounts, suggesting that male H. maculosa are not able to discriminate the sex of conspecifics. These findings suggest male strategic allocation of spermatophores based female mating history is an important factor influencing mating behaviours of this species.ADDITIONAL KEYWORDS: mate choice -Octopus -operational sex ratio -sperm competition.

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Section: Discussionmentioning

confidence: 99%

Section: Animal Acquisition and Maintenancementioning

confidence: 99%

Nocturnal mating behaviour and dynamic male investment of copulation time in the southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae)

Morse

Zenger

McCormick

et al. 2015

Behav

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“…Fluctuations in the ASR are central to predicting the intensity of competition for mates and resources (3,4). However, there is little information available on how ASR-mediated changes in Population viability is maximized for adult male survival probabilities similar to the ones observed in wild populations from which the lizards originated (15).…”

Section: Discussionmentioning

confidence: 99%

“…adult sex ratio ͉ Lacerta vivipara ͉ male behavior ͉ population extinction ͉ sexual coercion T he adult sex ratio (ASR) is a central concept of population demography (1, 2) and a key factor of evolution under sexual selection (3,4). Recently, the issue of understanding the population consequences of ASR variation has attracted much attention from human demographers, who have become seriously concerned with the social challenges that face fast-growing populations with increasingly male-biased ASR, as in China and India (5).…”

mentioning

confidence: 99%

Sex ratio bias, male aggression, and population collapse in lizards

Galliard

Fitze

Ferrière

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

384

442

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The adult sex ratio (ASR) is a key parameter of the demography of human and other animal populations, yet the causes of variation in ASR, how individuals respond to this variation, and how their response feeds back into population dynamics remain poorly understood. A prevalent hypothesis is that ASR is regulated by intrasexual competition, which would cause more mortality or emigration in the sex of increasing frequency. Our experimental manipulation of populations of the common lizard (Lacerta vivipara) shows the opposite effect. Male mortality and emigration are not higher under male-biased ASR. Rather, an excess of adult males begets aggression toward adult females, whose survival and fecundity drop, along with their emigration rate. The ensuing prediction that adult male skew should be amplified and total population size should decline is supported by long-term data. Numerical projections show that this amplifying effect causes a major risk of population extinction. In general, such an ''evolutionary trap'' toward extinction threatens populations in which there is a substantial mating cost for females, and environmental changes or management practices skew the ASR toward males.adult sex ratio ͉ Lacerta vivipara ͉ male behavior ͉ population extinction ͉ sexual coercion

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“…gravid; receptive to mating; not receptive to mating). These parameters allowed us to calculate the proportion of individuals in reproductive 'time-in' condition (for males: non-moulting individuals; for females: non-moulting and non-gravid individuals receptive to mating; see Moreau & Rigaud 2000) and, therefore, to estimate the operational sex ratio (OSR): the ratio of males versus females actually able to reproduce (Kvarnemo & Ahnesjö 1996;Moreau & Rigaud 2000). The females were then dissected and DNA extracted from their gonads, to enable detection of Wolbachia parasites by PCR amplification of a part of the bacterial 16S rDNA (see Bouchon et al (1998) for methods and controls avoiding false negative results).…”

Section: (B) Evaluation Of Male MCmentioning

confidence: 99%

Variable male potential rate of reproduction: high male mating capacity as an adaptation to parasite–induced excess of females?

Moreau

Rigaud

2003

Proc. R. Soc. Lond. B

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Numerous animals are known to harbour intracytoplasmic symbionts that gain transmission to a new host generation via female eggs and not male sperm. Bacteria of the genus Wolbachia are a typical example. They infect a large range of arthropod species and manipulate host reproduction in several ways. In terrestrial isopods (woodlice), Wolbachia are responsible for converting males into females (feminization (F)) in some species, or for infertility in certain host crosses in other species (cytoplasmic incompatibility (CI)). Wolbachia with the F phenotype impose a strong excess of females on their host populations, while Wolbachia expressing CI do not. Here, we test the possibility that male mating capacity (MC) is correlated with Wolbachia-induced phenotype. We show that males of isopod hosts harbouring F Wolbachia possess a strong MC (i.e. are able to mate with several females in a short time), while those of species harbouring CI Wolbachia possess a weaker MC. This pattern may be explained either by the selection of high MC following the increase in female-biased sex ratios, or because the F phenotype would lead to population extinction in species where MC is not sufficiently high. This last hypotheses is nevertheless more constrained by population structure.

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The dynamics of operational sex ratios and competition for mates

Cited by 576 publications

References 39 publications

Nocturnal mating behaviour and dynamic male investment of copulation time in the southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae)

Nocturnal mating behaviour and dynamic male investment of copulation time in the southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae)

Sex ratio bias, male aggression, and population collapse in lizards

Variable male potential rate of reproduction: high male mating capacity as an adaptation to parasite–induced excess of females?

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