Yukio Yasui

Kagawa University · Faculty of Agriculture

https://rdcu.be/c8Q9K Dispersal from birthplace is an effective strategy to cope up with unpredictable environmental change. In many animals, dispersal is carried out prior to mating and reproduction to avoid inbreeding. However, this also means that the dispersers must find mates in the new habitat. Phorytocarpais fimetorum (= former name Parasit...

Sexual reproduction requires mating partners and transmits only half of their genomes to an offspring1,2. However, because the sex-controlling allele is fixed at the first gametic sexual reproduction as isogamy (fusion between equal-sized gametes), the genome-dilution cost disappears3. In the traditional view1,2, derivative anisogamy (fertilization...

Sexual reproduction requires mating partners and transmits only half of their genomes to an offspring1,2. However, because the sex-controlling allele is fixed at the first gametic sexual reproduction as isogamy (fusion between equal-sized gametes), the genome-dilution cost disappears3. In the traditional view1,2, derivative anisogamy (fertilization...

The dispersal from birthplace is an effective strategy to cope with unpredictable environmental change. In many animals, dispersal is carried out prior to mating and reproduction to avoid inbreeding. However, this also means that the dispersers have to find mate at the new habitat. Parasitus fimetorum (Acari; Parasitidae) is a free-living predatory...

Dispersal from birthplace is an effective strategy to cope with unpredictable environmental change. In many animals, dispersal is carried out prior to mating and reproduction to avoid inbreeding. However, this also means that the dispersers must find mates in the new habitat. Phorytocarpais fimetorum (Acari; Parasitidae) (= former name Parasitus fi...

The evolution of gametic sex (meiosis and fertilization) and subsequent transition from isogamy (fusion between two equal-sized gametes) to anisogamy (dimorphism into eggs and sperm, namely, females and males) is one of the largest enigmas of evolutionary biology. Meiosis entails genome-dilution cost and anisogamy entails male-production cost. Desp...

Securing females is a crucial determinant of male fitness in many species. Mate-searching efficiency is often associated with increased mobility in males, but an increased investment in movement may reduce other fitness traits via potential trade-offs. In precopulatory sexual selection via female mate choice, the rate of encounter with females and...

In traditional theories, bet-hedging in evolutionary biology is defined as a trade-off between the within-generation arithmetic mean fitness (AMF) of a genotype and between-generation variance (BGV) in AMF across generations. The rationale of this definition is that a bet-hedger genotype suppresses the BGV to increase between-generation geometric m...

You can read this article at : https://onlinelibrary.wiley.com/share/author/3NH9ZFPFEHTNG4M2RUXB?target=10.1111/1440-1703.12296 -------------------------------------------------------------------------------------------------- In addition to unpredictable natural ephemeral wetlands (e.g., temporal pools after rainfall), artificial environments suc...

Theory shows that polyandry (mating with multiple males within a reproductive season) works as bet-hedging to increase the geometric mean fitness (GMF) of polyandrous genotype over generations and avoid extinction but it was rarely tested empirically. In this study, we distributed the eggs of Gryllus bimaculatus females mated with 1-4 males (mating...

Bet‐hedging via polyandry (spreading the extinction risk of the female's lineage over multiple males) may explain the evolution of female multiple mating, which is found in a wide range of animal and plant taxa. This hypothesis posits that females can increase their fitness via polyandrous mating when “unsuitable” males (i.e., males causing reprodu...

Females that mate with multiple males (polyandry) may reduce the risk that their eggs are fertilized by a single unsuitable male. About 25 years ago it was hypothesized that bet-hedging could function as a mechanism favoring the evolution of polyandry, but this idea is controversial because theory indicates that bet-hedging via polyandry can compen...

Polyandry (female multiple mating) has profound evolutionary and ecological implications. Despite considerable work devoted to understanding why females mate multiply, we currently lack convincing empirical evidence to explain the adaptive value of polyandry. Here, we provide a direct test of the controversial idea that bet-hedging functions as a r...

Polyandry (female multiple mating) has profound evolutionary and ecological implications. Despite considerable work devoted to understanding why females mate multiply, we currently lack convincing empirical evidence to explain the adaptive value of polyandry. Here, we provide a direct test of the controversial idea that bet-hedging functions as a r...

Hericia sanukiensis (Astigmata: Algophagidae) is a semi-aquatic mite inhabiting fermented sap flux of the Japanese sawtooth oak (Quercus acutissima) and utilizes Nitidulidae (Coleoptera) as the dispersal (phoretic) carrier. Although nitidulid beetles are commonly found in sap flux, the occurrence of H. sanukiensis has been extremely limited to a fe...

Hericia sanukiensis (Acari, Algophagidae) is a species of tree sap mite which has been newly discovered in the sap flux of oak trees (Quercus acutissima). In this study, we have clarified the life history of H. sanukiensis at the onset of sap exudation in spring, overwintering deutonymphs molt to tritonymphs as their molting is exacerbated by the s...

In many insect species with high levels of polyandry, females benefit directly from remating. The effects of remating on female fitness have generally been examined by comparing the fitness of females in multiple-mating and single-mating treatments. In this standard approach, females in the multiple-mating group that refuse to remate are often excl...

Female multiple mating (or polyandry) is considered to act as a genetic bet-hedging mechanism, by which females can reduce the assessment error in regard to mates’ genetic quality when only uncertain information is available. In spite of frequent verbal arguments, no theoretical examination has been carried out to determine the effectiveness of bet...

Effects of neem oil on mating and oviposition behaviour of C. chinensis grown on azuki bean under laboratory conditions were studied. Mating frequency, copulation duration, fecundity and survivorship of the next generation progenies were significantly decreased by neem oil. Mating frequency was always found to be lower in the oil-treated pair than...

In many animals, males can generally increase their fitness by mating with many mates, but females cannot produce more offspring than the number of their eggs. In spite of this restriction, females often mate with more than one male. In species without any male-provided resource benefits, females are thought to obtain some `genetic benefits' from m...

Females of the predatory mite Parasitus fimetorum (Gamasida; Parasitina) inhabiting animal manure indiscriminately copulate with many mates. The sperm competition between the males was estimated by electrophoresis of allozymes and the effects of multiple mating on female reproduction were investigated. When females were forced to mate only once, th...

To achieve higher fitness than monandrous females, polyandrous females must be able to allocate more fertilization to particular mates. Even if females cannot discriminate male genetic qualities before mating, they sometimes can actively choose a particular male’s sperm after multiple mating (e.g. by postcopulatory sperm selection or cryptic female...

Without Abstract

In a manure-inhabiting predatory mite, Macrocheles muscaedomesticae (Gamasida, Macrochelidae), when the female mates with two males, the first male takes nearly perfect fertilization priority (Yasui, 1988). The present study examined whether the first-male's sperm precedence is influenced by the copula-duration of the first and second males mating...

The author investigated the mechanism which elicits precopulatory mate guarding toward immature females in the male of manure-inhabiting miteMacrocheles muscaedomesticae (scopoli). The results of this study point to the following conclusions: (1) The existence of a sex attractant produced by the deutonymphal female is highly questionable. (2) Adult...

Adult male Macrocheles muscaedomesticae mite uses palps to recognize the pheromone on body surface of female deutonymph prior to molt.

The adult males of the manure-inhabiting predatory mite,Macrocheles muscaedomesticae, mounted on the backs of pharate female deutonymphs and guarded them from other males for several hours until female emergence and ensuing copulation. I assumed that an adaptive significance of such characteristic precopulatory mate guarding behavior was closely re...