Previous Mating Research Articles

The Effects of Age and Previous Mating Experience on Pre- and Post-copulatory Mate Choice in Female House Crickets (Acheta domesticus L.)

Although females’ mating preferences are influenced by male characteristics, there are a number of factors intrinsic to females and unrelated to male phenotype that can modulate female choice. We assessed the effects of age and mating experience on mechanisms of pre- and post-copulatory mate choice in female house crickets, Acheta domesticus L., by randomly assigning males to females, but independently varying the age and number of previous matings of females at the time of experimental matings. Latency to mating, a measure of a female’s pre-copulatory preference, was influenced by female age at the time of mating, with older females mating sooner than younger females. The reduced selectivity of older females appears consistent with life-history theory, which predicts that the reproductive value of females should decline with age. The length of time that females retained the spermatophore after mating, a measure of a female’s post-copulatory mating preference, was not influenced by female age at the time of mating, the number of previous matings, or any interaction between the two main effects. Contrary to previous reports, male mass had no effect on either the latency to mating or female retention of the spermatophore in A. domesticus. We conclude that female age and mating experience can moderate female selectivity, but that their impact varies according to the mechanism by which females favor particular sires.

Reproductive strategies of Aphidius ervi Haliday (Hymenoptera: Aphidiidae)

Hymenopteran parasitoids are usually arrhenotokous parthenogenetic, where females arise from fertilized and males from unfertilized eggs. Therefore, the reproductive fitness of females is a function of egg production and furthermore affected by mating, whereas that of males is mainly determined by the number of daughters they father. Aphidius ervi Haliday is a quasi-gregarious parasitoid of a number of aphid pests on economically important crops such as legumes and cereals. Females are monandrous whereas males are polygynous. Here, we tested how parental age at mating and male mating history affected mating success, fecundity and daughter production in this species. Once-mated males perform significantly better than naïve males with regard to mating success, suggesting that males learn from previous matings. The fecundity of virgin females is not significantly different from that of mated females regardless of parental age at mating and male mating history, indicating that mating does not stimulate egg production or contribute to female nutrient supply. Males can replenish sperm supply after mating, implying that they are at least moderately synspermatogenic. Preference for young over old mates for mating by both sexes may be explained by the fact that aging of both sexes contributes to the reduction of daughter production. Rather than sperm depletion, the reduced daughter production may be attributed to diminishing sperm viability and mobility in aging males and increasing constraints in fertilization process in aging females. Our results also show that female age has a stronger impact on the production of daughters, suggesting that fertilization process in females is more sensitive to aging than sperm vigor in males.

Evidence of mate choice copying in Norway rats, Rattus norvegicus

In the literature, nonindependent mate choice of females is frequently referred to as ‘mate choice copying’. The label seems particularly appropriate when the probability that a focal female will mate with a male increases after she has watched him engage in sexual behaviour with another female. However, the classic definition of mate choice copying requires only that a male’s attractiveness to a female change following his acceptance or rejection by another female regardless of whether such alteration in a female’s response results from seeing him mate or from some other process. Here, we provide evidence that female Norway rats prefer to affiliate with a male that has recently engaged in sexual activity, even when they did not observe the male’s previous mating. Furthermore, when we provided oestrous females with access to two males tethered some distance apart, the male that had recently copulated also mounted and achieved intromission and ejaculation sooner and more frequently than the male that had not recently copulated. We also provide evidence that increased attractiveness of male rats that had recently copulated was mediated by olfactory cues, and that female rats tended to affiliate with males that had engaged in sexual activity but not with males that had spent time with anoestrous females.

Relative size influences gender role in the freshwater hermaphroditic snail, Helisoma trivolvis

Simultaneous hermaphrodites have the unique challenge of allocating their available resources to egg and sperm production and behaviorally to a male and/or female mating role. Models that address the influence of body size on sex allocation predict that larger individuals should allocate proportionally more resources to female than male function and that this should translate into corresponding behavioral preferences during mating. We investigated the relationship between size and gender role in the hermaphroditic freshwater snail Helisoma trivolvis. We hypothesized that when 2 H. trivolvis mate, the larger would assume the female role and the smaller the male role. We also predicted that reciprocal mating would be more likely when partners were similar in size. We measured 180 snails, paired them, and observed their sex roles during copulation. The size difference between snails neither influenced the latency to copulation nor predicted whether mating was unilateral or reciprocal. In unilateral matings, the smaller snail acted as the male significantly more often than the larger snail. In order to test the hypothesis that increased activity of smaller snails influences gender role, we also measured movement rates in snails of various sizes but found no relationship between size and activity. These experiments indicate that in H. trivolvis body size does influence gender role in unilateral matings, and enable us to rule out activity as a direct determinant of male gender role. Whether snails mate reciprocally or not may depend on other factors such as previous mating history, time of isolation, or age.

Multiple mating affects offspring size in the opisthobranch Chelidonura sandrana

Offspring size can have pervasive effects throughout the life history stages of many marine invertebrates. Although maternal offspring investment is largely determined by the environmental conditions experienced by the mother, egg size might additionally vary in response to the number and quality of previous mating partners. Positive effects of mating multiply with several different males (polyandry) have been confirmed for a variety of species, whereas such investigations are lacking for marine invertebrates. Here we differentiated between the effects of ejaculate amount (repeatedly mated) and ejaculate diversity (polyandry) on maternal offspring investment in the simultaneously hermaphroditic sea slug Chelidonura sandrana. We found that focal “females” mated with four different “males” produced significantly larger egg capsules and larger veligers, while focal “females” mated four times with the same “male” suffered from reduced mid-term fecundity. We found no effect of veliger size on veliger survival. Our results show that female mating patterns are an important addition to understanding the variation in offspring size in internally fertilizing marine invertebrates.

Sequential mate choice in decorated crickets: females use a fixed internal threshold in pre- and postcopulatory choice

In nature, female crickets often encounter males sequentially, choosing whether to mate with each male they find rather than selecting the most attractive male from a pool of available mates. Upon encountering a male, a female may base her decision to mate on a particular internal threshold or on a relative standard that takes into account the attractiveness of her previous mates. Here, we test whether the attractiveness of a female's previous mating partner influences her behaviour with respect to a second mate in the decorated cricket Gryllodes sigillatus. We measured both pre- and postcopulatory female mate choice as well as the effect that postcopulatory mating guarding by males had on females' postcopulatory behaviour. We showed that in both their first and second matings, pre- and postcopulatory mate choice are congruent, as females prefer to mate with, and accept more sperm from, attractive males. However, the outcome of pre- and postcopulatory choice does not depend on the attractiveness of a female's previous mate, suggesting that females employ a single standard upon which their mating decisions are based.

Context-dependent risk tolerance of the bicolour damselfish: courtship in the presence of fish and egg predators

Reproductive behaviours such as courting, copulation, parental care and mate guarding often entail a cost of increased predation risk, either to the individual itself or to the offspring under its care. Because of this, males of several species reduce courting effort in the presence of a predator. The degree to which reproduction is curtailed may depend upon the magnitude of potential benefits as well as the current and previous reproductive success of the male. We presented male bicolour damselfish, Stegastes partitus, with females in the presence and absence of fish and egg predators and tracked the realized fecundity of the males over the course of a spawning cycle to evaluate the degree to which courting reductions depend on the size of the female being courted, the type of predator involved and the previous and current mating success. We found that males increased courting towards larger females and that this courting was reduced in the presence of a fish or an egg predator for small females but not for large ones. We found no relationship between courting reduction and either past or current reproductive success for the fish or egg predator treatments, respectively. Our results demonstrate that male S. partitus do show context-dependent courting behaviour and seem to balance risk and reward in courting decisions.

MALE SCORPIONFLIES ASSESS THE AMOUNT OF RIVAL SPERM TRANSFERRED BY FEMALES' PREVIOUS MATES

Theory predicts that when sperm compete numerically, selection will favor males who vary the number of sperm they transfer with the immediate level of sperm competition. In this study, I measured male mating investment in response to both female mating status (virgin vs. mated) and the number of foreign sperm stored by females in a previous mating in the scorpionfly Panorpa cognata. Female sperm storage was manipulated by interrupting copulations at different time points. Female mating status did not significantly influence male mating investment, but resource-limited males invested strategically in relation to the amount of sperm stored by females in a previous mating. I found continuously decreasing male investment in response to increasing amounts of competing sperm. These results demonstrate an unprecedented male ability to assess the number of sperm stored by females. As a result, males are capable of an extraordinarily fine-tuned reaction to the intensity of sperm competition.

Seed production, germinability and seedling growth for a bird-pollinated shrub in fragments of kwongan in south-west Australia

In this study we investigate the effect of population size on the proportion of flowers that produce a fruit (fruit set), the number of seeds per fruit (seed set), seed germinability, seedling mortality and growth in a range of population fragments for the bird-pollinated mixed mating system shrub Calothamnus quadrifidus R. Br. (Myrtaceae). We found no significant linear relationship ( p < 0.05) between population fragment size and fruit set in any of the three years reproduction was studied. In contrast, we found a very strong positive correlation between the number of seeds produced per fruit and increasing population fragment size for each of the three years. We found no significant linear relationships between population fragment size and seed germination, or seedling growth and mortality. The most plausible explanation for the decline in seed set is increased inbreeding in smaller populations. Although a previous mating system analysis with allozymes did not reflect the above, we present evidence from other lines of inquiry to indicate that inbreeding does increase in smaller populations, but is masked by post-zygotic lethal systems that eliminate genetically incompetent homozygous embryos. We found no evidence that highly mobile pollinators transporting pollen among fragments rescue small fragments from inbreeding. We discuss the implications of our findings for the conservation of plant diversity in fragments of species rich Mediterranean climate shrublands.

Do female leopard geckos (Eublepharis macularius) discriminate between previous mates and novel males?

Females in numerous taxa engage in mating with more than one male within a breeding season, usually to gain direct or indirect benefits from their male partners. Although effort has been directed towards the benefits females derive from multiple mating, we have less information as to decisions females make when choosing to mate with more than one male and if her decision is contingent upon previous mating experience with a male. In some instances, females must decide whether or not to mate with a previous mate or a novel male, the outcome of which would have ramifications on the acquisition of direct and indirect benefits. In this study, we tested whether female leopard geckos, Eublepharis macularius, would forgo mating with a previous male partner in favor of a novel male. We found no difference in a female's willingness to copulate with a previous mate versus a novel male. However, we found that smaller females initiated copulation termination with a previous mate whereas larger females allowed males to terminate copulations. This pattern was not exhibited when smaller females were paired with novel partners. Thus, smaller females appear to discriminate between previous mates and novel males, favoring novel males as mates.

Mate preferences in female canaries (Serinus canaria) within a breeding season

Divorce and remating in birds can be described as strategies used to enhance reproductive success. Mate switching often occurs because pairs failed to brood at least one chick during the previous breeding season. In the present study, we evaluated the influence of reproductive success on female preferences in domesticated canaries (Serinus canaria). For that purpose, females previously paired and having reared young were placed in a choice test situation: They were allowed to choose between their previous mate and a familiar male (a male neighbor during the breeding period). During these choice tests, females tended to stay near their previous mate longer than near a male neighbor when their reproductive success was “good” (at least two chicks). On the other hand, females with “poor” reproductive success (one chick) did not show a preference for their previous mate. Furthermore, in the present study, we observed that during choice tests males reacted to the presence of their previous mate in a particular way, by gathering nest material. This behavior was more scarcely observed in neighbor males which, on the contrary, sang significantly more than previous mates did.

Independent effects of familiarity and mating preferences for ornamental traits on mating decisions in guppies

The avoidance of familiar individuals as mates can act to maximize the benefits of polyandry or might help to minimize inbreeding in small or highly philopatric populations. As previous mates are also familiar, the effects of familiarity and mating history can often be confounded. Here, we disentangle these effects on mating decisions in the guppy, Poecilia reticulata, and examine their influence on sexual selection. In 3 experiments, males and females were 1) able to mate, 2) had visual and olfactory contact, or 3) had visual contact only. Familiarity was successfully acquired via visual cues, and females were in all cases more likely to mate with unfamiliar than with familiar males, indicating that familiarity is a more important determinant of mating outcome than mating history. Males did not court unfamiliar females any more than familiar females and did not differentially allocate sperm. Familiarity did not alter the strength of sexual selection on male coloration: we found overall positive selection for bright, large males. Female preferences for unfamiliar males and ornamental traits may therefore be largely independent. Key words: mate choice, mating history, polymorphism, polyandry, sexual selection, sperm competition. [Behav Ecol]

Impact of male mating history on the postmating resumption of sexual receptivity and lifetime reproductive success in Choristoneura rosaceana females

Abstract The first objective of the present study is to test the hypothesis that the decrease in the number of eupyrene spermatozoa in the spermatheca is directly associated with the resumption of sexual receptivity in female moths, an aspect that has not been examined in previous studies. The obliquebanded leafroller, Choristoneura rosaceana, is used and females mated with previously mated males have a shorter refractory period than those mated with virgins. This difference is associated with a faster rate of movement of sperm from the spermatheca. Overall, the length of the female refractory period coincides with the mean time required for the number of eupyrene sperm in the spermatheca to drop to approximately 3000, regardless of male mating history. Although such a decline in sperm numbers may be a factor responsible for the resumption of sexual receptivity, this is clearly not the only one because more than 40% of females remate even though sperm numbers in the spermatheca are well above this threshold. Virgin males do not vary the mass or the content of their ejaculate as a function of the female's reproductive status and this may increase the risk of sperm competition if the female is previously mated. The second objective of this study is to examine the effect of previous male mating history on female reproductive potential. Females mated with previously mated males have a significantly lower fecundity than those mated with virgin males. However, in all treatments, remating increases both female longevity and lifetime fecundity. There is also a significant effect of female mass on the length of the refractory period and on lifetime fecundity, with large females resuming sexual receptivity sooner and laying more eggs than small ones, regardless of male mating history.

Do female bank voles (Clethrionomys glareolus) mate multiply to improve on previous mates?

Contrary to classical sexual selection theories, females of many taxa mate with multiple males during one reproductive cycle. In this study, we conducted an experiment on the “trade-up hypothesis”, which proposes that females remate if a subsequently encountered male is potentially superior to previous mates to maximize the genetic quality of their offspring. We presented bank vole females (Clethrionomys glareolus) sequentially with two males of known dominance rank in different orders, i.e., either first subordinate and second dominant, first dominant and second subordinate, or two males that were equal in dominance (high ranking) and observed their mating behavior. We found that 92% of the females mated multiply and did not base their remating decision on male social status. Therefore, polyandry cannot be explained by the “trade-up hypothesis” based on dominance rank in this species. However, we found that dominant males sired significantly more offspring than subordinate males. This varied according to mating order: dominant males sired more offspring when they were second than when they were first. Moreover, litter sizes were significantly smaller when the dominant male was first (smallest relative success of dominant males) compared to litter sizes when mating order was reversed or both males equal in status. Our results suggest that even though multimale mating includes males that are of poorer quality and thus potentially decreases the fitness of offspring, most of a female’s offspring are sired by dominant males. Whether this is due to cryptic female choice, sperm competition, or a combination of both, remains to be tested.

Reproductive Behavior of the Japanese Spineless Cuttlefish Sepiella japonica

The reproductive behavior of the Japanese spineless cuttlefish Sepiella japonica was observed in a tank. The males competed for females before egg-laying and then formed pairs with females. The male then initiated mating by pouncing on the female head, and maintained the male superior head-to-head position during the mating. Before ejaculation, the male moved his right (non-hectocotylized) arm IV under the ventral portion of the female buccal membrane, resulting in the dropping of parts of spermatangia placed there during previous matings. After the sperm removal behavior, the male held spermatophores ejected through his funnel with the base of hectocotylized left arm IV and transferred them to the female buccal area. The spermatophore transfer occurred only once during each mating. The female laid an egg capsule at average intervals of 1.5 min and produced from 36 to more than 408 egg capsules in succession during a single egg-laying bout. Our results also suggested one female produced nearly 200 fertilized eggs without additional mating, implying that the female have potential capacity to store and use active sperm properly. The male continued to guard the spawning female after mating (range=41.8-430.1 min), and repeated matings occurred at an average interval of 70.8 min during the mate guarding. Although the time spent on the sperm removal in S. japonica was shorter than in other sperm-removing cuttlefishes, the shorter sperm removal duration may be compensated by the post-copulatory mate guarding and repeated matings in this species.

How we know I: strange dreams

How we know I: strange dreams

Evolution and ecology of Calopterygidae (Zygoptera: Odonata): status of knowledge and research perspectives

We review the studies of evolution and ecology in the Calopterygidae. Adults are easily distinguished for their pigmented wings and territorial behaviour. Three genera have been well studied: Hetaerina, Calopteryx and Mnais. Larvae develop in riverine aquatic environments. Selection operates at this stage to produce large muscle mass for adults. The adult spends some days until sexually ready. During this time, it feeds extensively to produce muscle fat for egg production and flight. However, gregarine parasites may ingest the fat reserves. Males may use two mating tactics or strategies that may be genetically (Mnais) or environmentally (Calopteryx and Hetaerina) determined: territoriality and nonterritoriality. In Mnais, these strategies appear balanced in fitness terms. Males of Calopteryx, Mnais and Phaon show a precopulatory courtship that is not the case for Hetaerina. Male wing pigmentation seems to signal how good the male is to deal immunologically with parasites to females during the male courtship. During copulation, males displace the sperm the female has stored in the storage organs from previous matings. There is an enormous variation in male sperm displacement mechanisms and ability, and in genitalic morphology in both sexes. This variation possibly results from a coevolutionary game between the sexes to control stored sperm. After copulation, males guard females apparently to avoid that other males take the female in copulation. Our review suggests sources for research in this family.

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.

Deer antlers: a zoological curiosity or the key to understanding organ regeneration in mammals?

Many organisms are able to regenerate lost or damaged body parts that are structural and functional replicates of the original. Eventually these become fully integrated into pre-existing tissues. However, with the exception of deer, mammals have lost this ability. Each spring deer shed antlers that were used for fighting and display during the previous mating season. Their loss is triggered by a fall in circulating testosterone levels, a hormonal change that is linked to an increase in day length. A complex 'blastema-like' structure or 'antler-bud' then forms; however, unlike the regenerative process in the newt, most evidence (albeit indirect) suggests that this does not involve reversal of the differentiated state but is stem cell based. The subsequent re-growth of antlers during the spring and summer months is spectacular and represents one of the fastest rates of organogenesis in the animal kingdom. Longitudinal growth involves endochondral ossification in the tip of each antler branch and bone growth around the antler shaft is by intramembranous ossification. As androgen concentrations rise in late summer, longitudinal growth stops, the skin (velvet) covering the antler is lost and antlers are 'polished' in preparation for the mating season. Although the timing of the antler growth cycle is clearly closely linked to circulating testosterone, oestrogen may be a key cellular regulator, as it is in the skeleton of other male mammals. We still know very little about the molecular machinery required for antler regeneration, although there is evidence that developmental signalling pathways with pleiotropic functions are important and that novel 'antler-specific' molecules may not exist. Identifying these pathways and factors, deciphering their interactions and how they are regulated by environmental cues could have an important impact on human health if this knowledge is applied to the engineering of new human tissues and organs.

Females use self-referent cues to avoid mating with previous mates

Females of many species mate repeatedly throughout their lives, often with many different males (polyandry). Females can secure genetic benefits by maximizing their diversity of mating partners, and might be expected, therefore, to forego matings with previous partners in favour of novel males. Indeed, a female preference for novel mating partners has been shown in several taxa, but the mechanism by which females distinguish between novel males and previous mates remains unknown. We show that female crickets (Gryllodes sigillatus) mark males with their own unique chemical signatures during mating, enabling females to recognize prior mates in subsequent encounters and to avoid remating with them. Because self-referent chemosensory cues provide females with a simple, but reliable mechanism of identifying individuals with whom they have mated without requiring any special cognitive ability, they may be a widespread means by which females across a broad range of animal mating systems maximize the genetic benefits of polyandry.