Publications by authors named "Michael H Ferkin"

For males, the behaviour of rival conspecifics can provide vital information about finding reproductively available females, and which have high-quality phenotypes. While valuable, this information represents sperm competition risk and even the potential for rejection by females. Thus, males should show flexibility in signalling behaviours towards females based on social information acquired with emphasis on the context of that information.

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In rodents, defensive behaviors increase the chances of survival during a predator encounter. Observable rodent defensive behaviors have been shown to be influenced by the presence of predator odors and nearby environmental cues such as cover, odors from conspecifics and food availability. Our experiment tested whether a predator scent cue influenced refuge preference in meadow voles within a laboratory setting.

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For a scent mark to be informative it must provide a reliable, honest signal that allows individuals that detect it to predict fitness tradeoffs if they choose or not choose to respond to it. I argue that scent marks provide a great deal of information about the sender to receivers. The manner in which an animal uses this information to make decisions will depend on the context and manner in which it encounters these scent marks.

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Social monogamy, typically characterized by the formation of a pair bond, increased territorial defense, and often biparental care, has independently evolved multiple times in animals. Despite the independent evolutionary origins of monogamous mating systems, several homologous brain regions and neuropeptides and their receptors have been shown to play a conserved role in regulating social affiliation and parental care, but little is known about the neuromolecular mechanisms underlying monogamy on a genomic scale. Here, we compare neural transcriptomes of reproductive males in monogamous and nonmonogamous species pairs of mice, voles, parid songbirds, dendrobatid frogs, and species of cichlid fishes.

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This paper details how chemical communication is affected by ecological challenges such as finding mates. I list several conditions that affect the decision to attract mates, the decision to respond to the signals of potential mates and how the response depends on context. These mate-choice decisions and their outcomes will depend on the life history constraints placed on individuals such as their fecundity, sex, lifespan, opportunities to mate in the future and age at senescence.

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Two competing hypotheses have been used to explain species and sex differences in the effects of food availability on the sexual behavior of mammals. One hypothesis, the metabolic fuels hypothesis, posits that individuals, primarily females, forgo reproduction when faced with food deprivation and invest their limited resources in behaviors not associated with reproduction. The other hypothesis, the reproduction at all costs hypothesis, states that individuals, males and females, continue to reproduce or increase their reproductive behavior when faced with food deprivation.

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This article is part of a Special Issue "Chemosignals and Reproduction". Many terrestrial mammals must be able to distinguish between the myriad of scent marks they encounter in order for them to facilitate or deter direct interactions with their scent donors. I review studies that examine how rodents, mainly meadow voles (Microtus pennsylvanicus), respond when they encounter the scent marks of conspecifics and heterospecifics, and how context, as well as the age and condition of senders and receivers, affect their responses.

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Little is known about the occurrence of individual variation in sexual behavior and how maternal nutrition can affect this variation. We tested the hypothesis that male offspring of female meadow voles, , that were 30% food restricted (FR) during days 1-7 of lactation (FR 1-7), days 8-14 of lactation (FR 8-14), or late days 15-21 of lactation (FR 15-21) lactation show persistent, negative effects on their sexual behavior as adults relative to male offspring of females that were not food restricted. We measured three components of sexual behavior, attractivity, proceptivity and receptivity, beginning when the males were 98 days of age.

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Many terrestrial mammals will deposit scent marks and over-marks, the latter being the overlapping scent marks of two conspecifics. Studies have shown that male rodents that are exposed to the overlapping scent marks of two female conspecifics later spend more time investigating the mark of the top-scent female than that of the bottom-scent female. This suggests over-marking is a form of competition and that the top-scent female is more likely than the bottom-scent female to be chosen as a potential mate.

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In many species of small mammals, including meadow voles, , females come into postpartum estrus (PPE) within 12-24 h of giving birth, allowing them to mate and become pregnant while raising the current litter. PPE females show increases in attractivity, proceptivity, and receptivity, the three components of sexual behavior, relative to females not in PPE. Several studies have shown that food deprivation and restriction reduce attractivity, proceptivity, and receptivity of females not in PPE.

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Many nonhuman animals are capable of discriminating a group or entity containing more objects from one containing less of the same objects. The capacity for making judgments of numerousness may also allow individuals to discriminate between potential mates. Female meadow voles (Microtus pennsylvanicus) may use judgments of relative numerousness to distinguish between potential suitors by selecting males that signal their interest by depositing more scent marks relative to other males.

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An individual's nutritional status affects the manner in which same- and opposite-sex conspecifics respond to that individual, which may affect their fitness. Male meadow voles, Microtus pennsylvanicus, increase their sperm allocation if they encounter the scent mark of an unfamiliar male that is not nutritionally challenged. If, however, the scent mark comes from a male that has been food deprived for 24 hours, stud male voles do not increase their sperm allocation.

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Proceptive behaviours are used by animals to indicate interest in opposite-sex conspecifics. These behaviours can be affected by an individual's nutritional status. Two mutually exclusive hypotheses have been proposed to account for the effects of food availability on reproduction.

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Scent marking and over-marking are important forms of communication between the sexes for many terrestrial mammals. Over the course of three experiments, we determined whether the amount of time individuals investigate the scent marks of opposite-sex conspecifics is affected by four days of olfactory experience with those conspecifics. In experiment 1, female meadow voles, Microtus pennsylvanicus, spent more time investigating the scent mark of the novel male conspecific than that of the familiar male donor, whereas male voles spent similar amounts of time investigating the scent mark of the familiar female and a novel female conspecific.

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Models of age-related effects on behavior predict that among short-lived species younger adults are more attractive and attracted to opposite-sex conspecifics than are older adults, whereas the converse is predicted for long-lived species. Although most studies of age-related effects on behavior support these predictions, they are not supported by many studies of scent marking, a behavior used in mate attraction. Over-marking, a form of scent marking, is a tactic used by many terrestrial mammals to convey information about themselves to opposite-sex conspecifics.

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Sperm competition occurs when 2 or more males copulate with a particular female during the same reproductive cycle, and their sperm compete to fertilize the female's available eggs. One strategy that male voles use to assess the risk and intensity of sperm competition involves responding to the presence of scent marks of conspecific males found near a sexually receptive female. Previously, we have shown that if a male vole copulated with a female while he was in the presence of the odors of another male he increased his sperm investment relative to his investment if another male's odors were not present.

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Animals in a variety of taxa discriminate between a greater quantity and a lesser quantity of the same object, an ability that is referred to as relative numerousness judgment. For example, meadow voles can distinguish between areas containing more over-marks by one opposite-sex scent donor and fewer over-marks by another opposite-sex scent donor. Females appear to be able to make better discriminations between more or less over-marks than do males.

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Particular features of the signaling characteristics of the scent marks of temperate-zone, seasonally breeding mammals may reflect differences in their reproductive state and, hence, be variable. Consequently, an individual's perception of self may depend more on the condition independent than on the condition-dependent signaling characteristics of the scent marks. Yet, we do not know whether an individual responds to changes in the signaling characteristics of its own scent marks, such as those associated with changes in an individual's reproductive state.

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Some non-human animals may possess the ability to recall the "what", "where", and "when" of a single past event. We tested the hypothesis that male meadow voles possess the capacity to recall the "what", "where", and "when" of a single past event associated with mate selection in two experiments. Briefly, male voles were allowed to explore an apparatus that contained two chambers.

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For meadow voles, Microtus pennsylvanicus, seasonal differences exist in self-grooming and in odor preferences for conspecifics, two behaviors which facilitate sexual interactions in this species. Both behaviors are mediated by photoperiodically-induced changes in circulating gonadal steroid hormone titers which, in turn, can be transduced by the duration of the melatonin signal that a seasonally breeding animal receives. The goal of this study was to determine whether exogenous melatonin administration affects circulating gonadal steroid hormone titers in meadow voles, and whether it influences their odor preferences and self-grooming behavior to same- and opposite-sex conspecifics.

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Female mammals are particularly sensitive to changes in food availability. The mechanisms that affect sexual behavior and food intake are closely related to one another; chief among the mechanisms that control sexual behaviors in females is estradiol. In order to understand how food deprivation results in inhibition of sexual behavior (attractivity, proceptivity, and receptivity), we measured the effects of food deprivation on circulating concentrations of estradiol.

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In many species of small mammals, females undergo post-partum oestrus soon after delivering a litter, becoming pregnant while suckling the previous litter. Females raising two concurrent litters need to allocate many more resources to reproduction than females raising only one litter. Consequently, there may be differences between litters raised concurrently or singly.

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Many hypotheses have been put forth to account for differences in the amount of time that animals engage self-grooming when exposed to conspecifics or their odors, but most ignore the possibility that self-grooming may be associated with olfactory communication between groomers and conspecifics. As yet, we do not know the function of self-grooming and why animals do so when they encounter the odors of conspecifics. The present experiment tests the hypothesis that the amount of time that a meadow vole, Microtus pennsylvanicus, self-grooms is affected by the reproductive state of the odor donor and its own reproductive state.

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Self-grooming in response to the odors of conspecifics is a form of olfactory communication among meadow voles. The amount of time meadow voles spend self-grooming when they encounter the odors of conspecifics varies seasonally, with males targeting the odors of reproductively active females only during the breeding season. Other odor related behaviors in male voles such as odor preferences for conspecifics and the attractiveness of their odors to conspecifics vary seasonally as well.

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We provide a battery of screens that reflect the social and sexual behavior displayed by both captive and feral mice. Some screens focus on measuring aspects of chemical communication, providing information about whether or not mice will interact and if they do so, predict the nature of the interaction. Other screens measure direct interactions between target mice and same- and opposite-sex conspecifics, providing an indication of the social status and sexual responsiveness, respectively, of target mice.

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