Mating History Research Articles

An Experimental Study on the Effects of Predation Risk and Feeding Regime on the Mating Behavior of the Water Strider

Influence du risque du a la presence de predateurs et a au jeune subit sur le taux d'accouplement et sur sa duree

Use of ev loci as a measure of inbreeding in domestic fowls.

1. The endogenous avian leukosis virus (ev) loci present in 9 lines of domestic fowls have been partially characterised and the average heterozygosity of the loci in each line calculated. 2. Using these data an estimate of the coefficient of inbreeding of the lines was derived; this estimate of the extent of inbreeding is compared with the mating history of the lines. 3. This method provides the first means of directly assessing the degree of inbreeding of fowl lines: assumptions implicit in the method are discussed.

Physical and behavioural factors affecting the sexual “attractiveness” of the ewe

In the first of 2 experiments, groups of 6 oestrous ewes that had been assigned to one of 3 mating treatments were presented to 10 rams and ranked for sexual “attractiveness”. Two ewes in each group were new, unmated and were recently in oestrus ( U), another 2 were new and had been mated by some other ram just before the test for ewe “attractiveness” ( D), and the remaining 2 ewes in each group had been mated by the ram being used in the test for ewe “attractiveness” just prior to the test ( S). In the second experiment, 6 oestrous ewes, 3 with 12 months' wool (woolly) and 3 which had been shorn 5 days before the experiment (shorn) were ranked for sexual “attractiveness” by the 10 rams. This was repeated 1 week later with a second group of 6 oestrous ewes (Groups 1 and 2). The results of Experiment 1 showed that there was no overall significant difference between the sexual “attractiveness” of different kinds of ewes (mean ranks of “attractiveness”: U=3.3, S=4.3, D=3.0). In paired comparisons, ewes mated by a different ram were more “attractive” than those mated by the same ram ( S v. D, P <0.05), but there was no significant difference between other combinations. In Experiment 2, woolly ewes were found to be more sexually “attractive” than shorn ewes (mean ranks of ”attractiveness”: Group 1, woolly 2.6 v. shorn 4.5; Group 2, woolly 2.4 v. shorn 4.7). It was concluded that the sexual “attractiveness” of a ewe to a ram is independent of whether she has been previously exposed to the ram or her immediate mating history. Also, some of the components of a ewe's sexual “attractiveness” may be associated with her wool, since woolly ewes were more “attractive” than shorn ewes.

THE MATING STATUS OF SPRUCE BUDWORM MALES, CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA: TORTRICIDAE), CAUGHT IN PHEROMONE-BAITED TRAPS

The mating status of recently-mated male spruce budworm moths, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae), caught in traps baited with five different treatments was indexed. During two sampling periods at two test sites both virgin and mated C. fumiferana males were trapped. Significantly more unmated males were captured early in the flight season. There was no significant difference between the proportion of mated and unmated males caught near the end of the flight season. Within sampling periods and sites there were not significant differences among treatments in the proportion of mated males captured nor were these proportions significantly different within sampling periods and between sites. Within sites and between sampling periods the proportion of mated males captured was significantly different, with more mated males being trapped during the later sampling period. The four lepidopteran species for which methodologies have been developed for indexing male mating status are compared with respect to the nature and behaviour of the colored ejaculatory duct fluids that are used as markers of mating history. Current limitations of the method are discussed and possible solutions to these are suggested.

The Natural Selection of Sexual Cannibalism

Sexual cannibalism, in which a male is eaten by his mate following copulation, is expected to convey a selective advantage to the male under certain conditions. As shown quantitatively in our model the phenomenon is expected when (1) a male can mate only a few times in his lifetime and (2) the cannibalism significantly increases the number and/or viability of eggs fertilized by his own sperm. The expected number of male matings appears to be the more important of these two conditions. The few available observations of sexual cannibalism in several species of arthropods agree qualitatively with the predictions of our model. The same parameters of the model also explain why sexual cannibalism is generally rare among vertebrates. Phenomena selecting for sexual cannibalism appear more closely related to paternal investment strategies than to ecological factors associated with other forms of cannibalism. Because few field studies of invertebrates have followed the mating history of marked males, we cannot test...

Anopheles stephensi (Diptera: Culicidae): changes in male mating competence and reproductive system morphology associated with aging and mating.

Laboratory observations on the mating behavior of the Khano-Harni ( KH ) strain of Anopheles stephensi indicated that females and males become sexually mature by their 2nd night of life. Some females (10%, n = 67) mated on their night of emergence when crossed with 3-day-old males. At 28–30 °C maximum male mating activity occurred between 3 and 7 days of age. Comparisons between the percentage of laboratoryadapted KH females inseminated by KH males and wild-caught ( WC ) males indicated that little change in group mating occurs during colonization, while the ability of males to mate singly improves with laboratory selection. Dissections of KH males of known age and mating history indicated that the number of spermatocysts decrease and the proportion of the testes occupied by the sperm reservoir increases with age, while the quantity of spermatozoa present in the sperm reservoir and postgonadal system and the degree of repleteness of the male accessory glands with secretory material decreases with successive matings. The male reproductive system was found to rejuvenate after mating, with the replenishment of male accessory gland substance in the accessory glands and spermatozoa in the sperm reservoir and postgonadal system. Males that multiplymated during an abbreviated interval took longer to rejuvenate their reproductive systems than did males mating once. Morphological changes associated with age and mating were used to develop a method to determine age and the reproductive history of male An. stephensi

Sex pheromone emission by female Stegobium paniceum (L.) (Coleoptera: Anobiidae) in relation to reproductive maturation and oviposition

AbstractPheromone emission by female Stegobium paniceum (L.) was tested in the laboratory by measuring responses of males to filter paper discs that had been exposed to standardised air flow over females in a simple apparatus. Results indicated that although ether-extractable pheromone is present at eclosion, emission of pheromone is not appreciable until day 2 or 3 and does not reach a maximum until day 3 or 4. After mating, pheromone emission oscillates markedly for reasons not fully understood. Ovary maturation was monitored by dissection of females 0–5 days old; the first mature oocytes were found in the calyces on day 3. Synchrony between reproductive maturation and pheromone emission was thereby demonstrated. Copulatory behaviour and oviposition in relation to female mating history were studied. Virgin females produce a few infertile eggs during the latter part of their adult life; mated females produce far more, much earlier, but fecundity is reduced when a female is kept with another beetle, particularly a male. The significance of multiple mating was not ascertained since neither fecundity nor fertility was increased.

Further studies on the effect of aging and mating history of males on cytoplasmic incompatibility inCulex pipiens fatigans

Previously reported effects of aging and mating history in causing partial loss of cytoplasmic incompatibility in males of Paris cytoplasmic type, have been shown also to occur in males with Delhi and Hamburg cytoplasmic types. It was unexpectedly found that increasing the ratio of females to males at the first mating did not lead to enhancement of the level of partial compatibility when the males were re-mated. The effect of aging is discussed in relation to the use of cytoplasmic incompatibility integrated with chromosomal abnormalities, for genetic control.

Partial loss of cytoplasmic incompatibility with age in males ofCulex fatigans

The cytoplasms of Paris and Delhi strains of Culex fatigans have been reported to be bi-directionally incompatible. However, in the present study it is shown that with increasing age males with Paris cytoplasm show an increasing degree of partial compatibility with Delhi females. A male history of previous mating seems a contributory effect in enhancing the degree of partial compatibility. The relevance of partial compatibility to genetic control of C. fatigans is discussed.

PRE-MATING SEXUAL ACTIVITY OF GYPSY MOTH MALES IN SMALL PLOT FIELD TESTS (LYMANTRIA (= PORTHETRIA) DISPAR (L.): LYMANTRIIDAE)

AbstractPre-mating behavior of male gypsy moths was investigated in 0.2 ha circular plots containing from 0 to 72 virgin females/plot in untreated areas and in areas treated with an aerial application of 20 g/ha microencapsulated disparlure. Male moths in both treated and untreated plots oriented initially to trees, not directly to females. Mating was disrupted in treated plots but males continued search behavior. No anemotactic behavior was evident in either treated plots or untreated plots with females. In untreated plots, male moths were not caught on sticky panels (panels suspended at 2, 4, and 6 m) higher than pheromone baited traps set at 2 m. In treated plots, equal number of males were caught at all panel heights and in baited traps at 2 m. Previous mating and pheromone exposure histories of males did not affect the response of these males to traps baited with 4–5 mg of disparlure in untreated plots. In a test of the relative attractiveness of a cotton wick and a new laminated bait dispenser in Johnson traps, traps baited with the laminated dispenser had a greater male moth catch/male contact to trap than the traps baited with the cotton wick. Not all males contacting the Johnson trap were caught. A mode of action for disparlure as a disruptive agent in the long range sexual communication system of gypsy moth is proposed.

A contact sex pheromone and some response parameters in lycosid spiders

The sexual response of male Schizocosa crassipalpis (Emerton), S. avida (Walckenaer), Pardosa moesta Banks, and P. saxatilis (Hentz) to filter paper discs previously exposed to females was studied in the laboratory. Evidence indicates that the females secrete a nonvolatile substance which the males receive through contact chemoreception and which excites them sexually. Attempts to demonstrate an olfactory cue in the sexual response were unsuccessful. The substance was found to be species specific except in S. crassipalpis. It was produced by adult females regardless of age or mating history. Male response was similarly not affected. The substance was active for about 4 weeks. It was labile to treatment with ether or benzene and could not be extracted with either solvent. The sites of its secretion and perception have not been ascertained.

Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle

Natural Selection, the Costs of Reproduction, and a Refinement of Lack's Principle

Contribucion al conocimiento biologico del calmar argentino, Illex illecebrosus argentinus: De Castellanos Zulma J. A., 1964. Inst. Biol. Mar., Mar del Plata, Bol., No. 8: 34 pp

Male blue crabs, Callinectes sapidus Rathbun, transfer sperm and seminal fluid to their mates. The quantity of both of these components can vary, and may be particularly reduced in the ejaculate of males that have recently mated. While the potential consequences for fitness of receiving less sperm are obvious, the same is not true of seminal fluid; its role in the blue crab, other than as a sperm plug, is not known. We documented the changes in seminal fluid over time following controlled matings in the laboratory. By allowing males to mate repeatedly in quick succession, we were able to manipulate both the amount of sperm and of seminal fluid that females received. We measured the initial amount of seminal fluid and sperm transferred, and followed the number and viability of sperm, and condition of the spermathecal organs and ovaries, in cohorts of females held for various times post-mating. Females whose mates had mated recently received only about 33% as much ejaculate as those whose mates had full sperm stores. Sperm viability was unaffected, and regardless of male mating history, sperm number declined nearly 50% prior to brood production. We found that all seminal fluid is gone by 5 weeks post-mating, making it unlikely that it plays a role during long-term storage of sperm. The amount of ejaculate was independent of the size of the mate. The spermathecal organs themselves lose 86% of their mass prior to brood production, and this allowed us to develop a staging system for spermathecal condition that was useful for estimating reproductive timing in a field population in North Carolina. Essentially all field-caught females had mated, but sperm viability, sperm number, and ejaculate weight varied with season.

X-ray induced mutability in male germ cells of Drosophila melanogaster

From the time the Drosophila melanogaster male is less than an hour old, sperm are continuously maturing, becoming motile, and entering the seminal vesicle, regardless of sexual activity. When a male, at any stage in its life history, is exposed to X-rays, all existing germ-cell stages are simultaneously irradiated. After irradiation, sperm will be sequentially produced by the male more or less in order of their stage of maturation at the time of irradiation, the first sperm samples being comprised of germ cells that were most mature at the time of irradiation. As the time interval between irradiation and the initial mating increases, the sperm samples consist of ever less homogeneous mixtures of cells that were at varying stages of maturity at the time of irradiation. If the male mates at a regulated pace after irradiation, sperm samples can be obtained that enable one to measure separately, and with reasonable accuracy, the mutability of mature sperm, intermediate and late spermatid stages, and early spermatids. Even so, unless each male in an experiment mates the same number of times each day, sampling of the various stages will become more and more asynchronous, as some males will produce sperm derived from stages quite different from those sampled at the same time from other males in the same experimental group. Then, if mutation frequencies are collected in terms of days after irradiation, they will not accurately reflect the mutability of any particular germ cell stage. When appropriate experimental procedures are followed, the mutability of mature, motile sperm is found to be as high, or higher, in male irradiations as in irradiations of inseminated females. The sex-linked recessive lethal mutation frequency characteristic of mature, motile sperm approaches 4% per 1000 R. Immotile sperm stages (intermediate and late spermatids) have a much lower mutability, less than 2% per 1000 R. Early spermatids again have a high mutability, probably exceeding that of motile sperm. The actual mutation frequency encountered at any time following irradiation reflects the proportion of the various kinds of irradiated germ cells in the sperm sample assayed. The precise proportion in any given sperm sample will be related to the age of the male at the time of irradiation, his previous mating history, the length of time that has elapsed between the irradiation and mating, and the number of inseminations that have ensued since the irradiation. The inherent mutability of male germ cells can be correlated with their physiological state at the time of irradiation. Thus, rapidly differentiating early spermatids are highly mutable and radiosensitive. Later, after the major structural modifications of the cell have been accomplished, the immotile intermediate and late spermatids exhibit a low mutability. Finally, in the terminal step in their differentiation the spermatids acquire motility, thereby becoming transformed into functional spermatozoa whose mutability is simultaneously reset to a high level.

An adaptive change in an inbred mouse strain maintained in a cold environment.

A STRAIN of A2Gmice (Mus musculusL.), maintained for a number of generations in a room kept at −3° C., has progressively improved in ability to cope with the cold. The mice were obtained from Glaxo Laboratories, and had a long history of sib mating. When the breeding was begun in the cold environment, a parallel colony was started at 21° C. (controls). Members of a single litter were used to start the two colonies: one pair was kept at 21° C. and the other transferred to −3° C. These initial pairs were the parents of the first generation of mice studied. All subsequent breeding pairs too were litter mates, and were selected at random at the age of 5 weeks. Reproductive performance was recorded to the age of 28 weeks. There were few barren pairs in the cold, and only one after the fourth generation. One control pair, in the fourth generation, failed to produce young. The methods used, and some of the physiological changes in the mice kept in the cold, have already been described1–3,5.