Mate‐sampling costs and sexy sons

Costly female mating preferences for purely Fisherian male traits (i.e. sexual ornaments that are genetically uncorrelated with inherent viability) are not expected to persist at equilibrium. The indirect benefit of producing ‘sexy sons’ (Fisher process) disappears: in some models, the male trait becomes fixed; in others, a range of male trait values persist, but a larger trait confers no net fitness advantage because it lowers survival. Insufficient indirect selection to counter the direct cost of producing fewer offspring means that preferences are lost. The only well‐cited exception assumes biased mutation on male traits. The above findings generally assume constant direct selection against female preferences (i.e. fixed costs). We show that if mate‐sampling costs are instead derived based on an explicit account of how females acquire mates, an initially costly mating preference can coevolve with a male trait so that both persist in the presence or absence of biased mutation. Our models predict that empirically detecting selection at equilibrium will be difficult, even if selection was responsible for the location of the current equilibrium. In general, it appears useful to integrate mate sampling theory with models of genetic consequences of mating preferences: being explicit about the process by which individuals select mates can alter equilibria.     

The Effect of Timing of Female Vibrational Reply on Male Signalling and Searching Behaviour in the Leafhopper Aphrodes makarovi

Sexual communication in animals often involves duetting characterized by a coordinated reciprocal exchange of acoustic signals. We used playback experiments to study the role of timing of a female reply in the species-specific duet structure in the leafhopper Aphrodes makarovi (Hemiptera: Cicadellidae). In leafhoppers, mate recognition and location is mediated exclusively by species- and sex-specific substrate-borne vibrational signals and a female signal emitted in reply to male advertisement calls is essential for recognition and successful location of the female. In A. makarovi, males have to initiate each exchange of vibrational signals between partners, and in a duet the beginning of a female reply overlaps the end of the male advertisement call. Results of playback treatments in which female replies were delayed and did not overlap with the male call revealed that in order to trigger an appropriate behavioural response of the male, female reply has to appear in a period less than 400 ms after the end of the initiating male call. Results also suggest that males are not able to detect a female reply while calling, since female reply that did not continue after the end of male call triggered male behaviour similar to behaviour observed in the absence of female reply. Together, our results show that vibrational duets are tightly coordinated and that the species-specific duet structure plays an important role in mate recognition in location processes.     

The Influence of Age on the Behaviour of Carcinoma of the Breast

A consecutive series of 1530 patients with carcinoma of the breast has been reviewed to study the influence of age and marital status on the disease.The risk of developing breast cancer increases with age, though a peak may be reached at 75 years. The risk of developing a tumour of advanced clinical stage at presentation apparently increases with age. Local recurrence rates and mortality rates are similar at all ages. It is concluded that the therapy required is similar in all age groups.The increased risk of developing breast cancer in “never married” women is in the postmenopausal period. Survival rates and the distribution of the various presenting clinical stages are similar in both single and married patients.Though ageing and marital status have an initiating effect on breast cancer, they do not have a continuing effect on the established disease.     

The Disruption Hypothesis Does Not Explain Mate‐Choice Copying in the Guppy (Poecilia reticulata)

In some species, female mate choice is non‐independent as, under certain circumstances, females may copy the mate choice of other nearby females. One standard experimental protocol used to test for mate‐choice copying is the mate‐choice ‘reversal’ protocol. In this protocol, a focal female is allowed to choose between two males as potential mates and then is presented with an opportunity to see another female (i.e. the model female) choose the male that she did not initially choose. The focal is subsequently allowed to again choose between the same set of males. An observed reversal of her initial choice in this second preference test has been previously interpreted as evidence for mate‐choice copying. Alternatively, it has recently been proposed that environmental events, such as seeing the mate choice of nearby females that occur within the visual field of a female actively engaged in mate assessment, may ‘disrupt’ her decision‐making behavior and consequently alter the consistency of her mating preference, and may thus cause mate‐choice reversals. The disruption hypothesis predicts that if a model female is placed near the male that the focal female initially chose, the latter's mate preference would be disrupted and she would subsequently and consistently prefer the male that she initially rejected. Here we examined whether the disruption hypothesis explains mate‐choice copying in the guppy (Poecilia reticulata). Our results do not support this hypothesis, but rather provide further support for mate‐choice copying in the guppy.     

Mate‐choice copying: A fitness‐enhancing behavior that evolves by indirect selection

A spatially explicit, individual‐based simulation model is used to study the spread of an allele for mate‐choice copying (MCC) through horizontal cultural transmission when female innate preferences do or do not coevolve with a male viability‐increasing trait. Evolution of MCC is unlikely when innate female preferences coevolve with the trait, as copier females cannot express a higher preference than noncopier females for high‐fitness males. However, if a genetic polymorphism for innate preference persists in the population, MCC can evolve by indirect selection through hitchhiking: the copying allele hitchhikes on the male trait. MCC can be an adaptive behavior—that is, a behavior that increases a population's average fitness relative to populations without MCC—even though the copying allele itself may be neutral or mildly deleterious.     

Mate‐choice copying by females: the advantages of a prudent strategy

Mate choice by females may be influenced by both advertizing traits of males, and behaviour of other females. Here, a simple genetic and behavioural model studies the advantages of mate‐choice copying. From a genetic point of view, a female preferring to copy others’ mate choice adopts a prudent strategy, because her offspring will inherit the same alleles from their father as the other young in the population. The model predicts that a female should copy others’ mate‐choice, unless she encounters a relatively more attractive male than the one she has observed mating, and the attractiveness of the male reflects his genotype. For low or moderate reliability of male signalling, mate‐copying is always predicted, even if the newcoming male is more attractive than the first male. This effect is attenuated, however, when the number of females that have already chosen the first male increases.     

Paternity Loss in Relation to Male Age, Territorial Behaviour and Stress in the Pied Flycatcher

For sexual selection to operate in monogamous species, males of poor quality in some factor like age, ornamentation, condition or aggressiveness, should lose paternity compared with higher quality males. We tested this idea in an Iberian population of pied flycatchers ( Ficedula hypoleuca ). Microsatellite analysis of 67 broods revealed moderate levels of extra-pair paternity (22.4% of broods, 7.5% of young). In a sample of 58 broods for which the caring male was identified, a higher paternity loss was associated with younger males, males that were less aggressive during territorial intrusion tests performed before the commencement of laying, and with males that showed higher levels of corticosterone metabolites in faecal samples collected at the end of the nestling period. Plumage darkness, forehead patch size and condition were not related to paternity loss. Paternity loss is more related to behavioural or physiological traits than to morphological ones in this population.     

The Effects of Inbreeding on Male Courtship Behaviour and Coloration in Guppies

Despite an extensive literature on inbreeding depression in a variety of traits, relatively little is known about the effects of inbreeding on patterns of sexual behaviour. In this study, we use the guppy Poecilia reticulata to investigate the influence of parental relatedness (full‐sib. vs. unrelated matings) on sexual behaviour and colour pattern variation in adult male offspring. Our results revealed that one generation of full‐sibling mating resulted in a strong decline in male sexual motivation (courtship intensity and following behaviour) and mating success (number of successful copulations and insemination success – as estimated by the frequency of post‐copulatory jerks after mating), but we detected no significant influence of inbreeding on colour pattern variation. Our finding that sexual ornamentation (colour) did not show similar inbreeding depression to courtship behaviour may be due to differences in the genetic basis of these traits. Our findings indicate that courtship can be a sensitive indicator of genetic stress and add to an emerging picture that sexually selected traits can be severely affected by inbreeding depression.     

Mate‐searching behavior in the invasive German wasp,Vespula germanica,in Patagonia

In order to increase the probability of reproduction, social insects can adopt various mate‐finding strategies, such as increasing densities of males at specific locations, and/or visual and chemical cues that attract the opposite sex. In field and laboratory studies we investigated strategies used by the invasive eusocial wasp Vespula germanica (Fabricius) (Hymenoptera: Vespidae). In tethered flight assays, we established contrasting flight patterns in females and males that may partly explain how related individuals distribute spatially during the mating period. We also determined experimentally, in the field and in the laboratory via olfactometer assays, that gynes produce airborne pheromonal cues that attract drones and are important during mate location. Our field trials also suggest that visual cues play a role in mate location. We conclude that in addition to aspects of the social biology of the species, an efficient mate‐location strategy can partly explain the invasion success of the species. Tools to mitigate the damage caused by yellowjackets may be developed by focusing on reproductive castes, in addition to workers.     

Searching Behaviour and Direction Finding of Differently Motivated Displaced Honeybees—an ‘Etho-psychological’ Study of Release Behaviour

Bees were captured as they left from or arrived at a feeding place (F), or took off from the hive (H) (leave-F, arrive-F, and leave-H, respectively). They were displaced and released (one or more times) at initially unfamiliar sites. In some tests, sight conditions prior to release were restricted. Searching behaviour performed prior to leaving the release site was recorded as well as the final vanishing bearing (VB). The VBs obtained are distributed in one or more clusters, depending on the type of experiment. As a rule, one of the peaks coincides with the compass bearing that bees would have selected had they not been displaced. Another peak is in accordance with a ‘fleeing’ course in the direction of the hive, probably initiated by the stress situation caused by the experimental manipulations. Prior to selecting the final course, leave-H bees searched longer than did leave-F or arrive-F bees, first-time flyers searched longer than repeaters and bees limited to sky-vision searched longer than bees with free sight. There is a significant positive correlation between searching behaviour and scatter of vanishing bearings. Function and origins of the searching behaviour, as well as the effects of sight conditions and of repeated releases, are discussed.     

Influence of Age on the Fatty Acid Composition of Breast and Thigh Muscles of Male Turkeys

Large White male turkeys were sacrificed at 4-week intervals from 4 to 28 weeks of age to study the fatty acid distribution in lipid of breast and thigh muscles. A total of 70 turkeys were sampled for this experiment.

Fatty acid distribution varied with advancing maturity and between muscle types. The most abundant fatty acids in the tissues were those with carbon chain lengths of 15:0, 16:0, 18:0, 18:1, 18:2, 20:4 and 24:0. Thigh muscle contained significantly more linoleate (18:2) than did breast. Larger proportions of pentadecanoic (15:0), arachidonic (20:4) and lignoceric (24:0), however, appeared in breast. Indications of minor fatty acids appeared on the chromatograms, but their low concentrations made their estimation and identification difficult.     

The Influence of State‐Ownership on Eco‐Innovations in Russian Manufacturing Firms

This paper studies drivers for eco‐innovation in Russian manufacturing firms on a sample of 2,212 innovative firms, of which over 600 introduced eco‐innovations. The companies in our sample specifically mention environmental regulation as a reason for engaging in eco‐innovations. Furthermore, we show that those firms who engage in eco‐innovations are motivated even stronger by the desire to increase resource efficiency. Companies under state ownership are especially prone to a higher likelihood to invest. We conclude that regulations are mostly relevant to the late comers who are obliged to follow minimum standards. On the other hand, the state uses its controlling influence to press companies under their control to exceed these minimum standards. Thus, we argue, state ownership does indeed have an influence on both the likelihood to eco‐innovate and on the levels of spending. Eco‐innovative state‐owned companies are only prone to invest in eco‐innovations, if they get additional money.     

Influence of Age and Prior Experience on Territorial Behavior and the Costs of Defense in Male Collared Lizards

In polygynous species where males maintain strong interseasonal philopatry to the same breeding territories, older individuals have prior experience defending their areas, whereas younger individuals are defending a territory for the first time. Theoretical and empirical studies predict that under such conditions the cumulative costs of defense may be lower for older experienced males as a consequence of familiarity with environmental and/or social conditions in their particular local habitats. We used quantitative data from focal observational studies and introduction experiments to test the hypothesis that older collared lizard males (Crotaphytus collaris) with prior territorial experience (3 yr+ males) acquire larger territories allowing them to court more, different females, with greater frequency without incurring higher defense costs. Consistent with this hypothesis, 3 yr+ males controlled significantly larger territories and courted more females, without having significantly higher rates of territory patrol, frequencies of advertisement display, or aggressive interactions with same‐sex competitors. Moreover, the intensity of responses to size‐ and age/experience‐matched tethered intruders by 3 yr+ males was lower than that by 2 yr males in their first season of territory defense. Our results support the hypothesis that age/prior occupancy of territories lowers defense costs allowing males to defend larger areas and increase opportunities to court females, perhaps increasing mating opportunities. By contrast, 2 yr males may need to respond more aggressively to intruders because their ownership of territories is tenuous as a consequence of shorter territory occupancy.     

Trans-Generational Influence of Human Disturbances in Japanese Quail: Egg Quality Influences Male Social and Sexual Behaviour

In many bird species prenatal exposure to yolk androgens of maternal origin has been found to influence offspring behavioural phenotype. In contrast to altricial birds, far less is known about maternal effects in precocial birds. In a previous experiment we found that female quail ( Coturnix japonica ) that were not previously habituated to humans (NH) produced eggs with less androgens (testosterone, androstenedione) and more progesterone when exposed to human disturbances than females habituated to humans (H). Here, we analysed social motivation and sexual behaviour of the male offspring of NH and H females. Classical behavioural test procedures were applied including separation, runway, partner choice and female encounter tests. As chicks, offspring of the NH females spent more time far from conspecifics than offspring of the H females. As adults, the same NH males showed less crowing and courtship behaviour (ritual preening) in female encounter tests than H males. Thus, maternal environment and egg quality may be key factors in the emergence of individual variability of appetitive behaviour, such as social proximity and courtship behaviour. Human disturbance of the mother seems to have triggered trans-generational effects resulting in consistently reduced social and sexual motivation in offspring until adulthood.     

The Curious Feminist: Searching for Women in a New Age of Empire

The Curious Feminist: Searching for Women in. New Age of Empire . Cynthia Enloe. Berkeley: University of California Press, 2004. 367 pp.     

Searching for Food or Hosts: The Influence of Parasitoids Behavior on Host–Parasitoid Dynamics

A host–parasitoid system with overlapping generations is considered. The dynamics of the system is described by differential equations with a control parameter describing the behavior of the parasitoids. The control parameter models how the parasitoids split their time between searching for hosts and searching for non-host food. The choice of the control parameter is based on the assumption that each parasitoid maximizes the instantaneous growth rate of the number of copies of its genotype. It is shown that optimal individual behavior of parasitoids, with respect to time sharing between hosts and food searching, may have a stabilizing effect on the host–parasitoid dynamics.     

The Impact of Adult Vitamin D Deficiency on Behaviour and Brain Function in Male Sprague-Dawley Rats

Background

Vitamin D deficiency is common in the adult population, and this has been linked to depression and cognitive outcomes in clinical populations. The aim of this study was to investigate the effects of adult vitamin D (AVD) deficiency on behavioural tasks of relevance to neuropsychiatric disorders in male Sprague-Dawley rats.

Methods

Ten-week old male Sprague-Dawley rats were fed a control or vitamin D deficient diet for 6 weeks prior to, and during behavioural testing. We first examined a range of behavioural domains including locomotion, exploration, anxiety, social behaviour, learned helplessness, sensorimotor gating, and nociception. We then assessed locomotor response to the psychomimetic drugs, amphetamine and MK-801. Attention and vigilance were assessed using the 5 choice serial reaction time task (5C-SRT) and the 5 choice continuous performance task (5C-CPT) and, in a separate cohort, working memory was assessed using the delay match to sample (DMTS) task. We also examined excitatory and inhibitory neurotransmitters in prefrontal cortex and striatum.

Results

AVD-deficient rats were deficient in vitamin D₃ (<10 nM) and had normal calcium and phosphate levels after 8–10 weeks on the diet. Overall, AVD deficiency was not associated with an altered phenotype across the range of behavioural domains tested. On the 5C-SRT AVD-deficient rats made more premature responses and more head entries during longer inter-trial intervals (ITI) than control rats. On the 5C-CPT AVD-deficient rats took longer to make false alarm (FA) responses than control rats. AVD-deficient rats had increases in baseline GABA levels and the ratio of DOPAC/HVA within the striatum.

Conclusions

AVD-deficient rats exhibited no major impairments in any of the behavioural domains tested. Impairments in premature responses in AVD-deficient rats may indicate that these animals have specific alterations in striatal systems governing compulsive or reward-seeking behaviour.     

Scent‐Marking Behaviour in a Pack of Free‐Ranging Domestic Dogs

Most mammals scent‐mark, and a variety of hypotheses have been put forward to explain this behaviour. Most of our knowledge about scent marking in domestic dogs comes from studies carried out on laboratory or companion dogs, while few studies have been carried out on free‐ranging dogs. Here, we explored the functional significance of different scent‐marking behavioural patterns in a pack of free‐ranging domestic dogs by testing two non‐exclusive hypotheses: the indirect territorial defence and the dominance/threat hypotheses. Through direct observation, we recorded the locations of dog scent marks (urination, defecation and ground scratching) and information regarding the identity and posture of the marking animal. We found evidence that markings are used by dogs to form a ‘property line’ and to threaten rivals during agonistic conflicts. Both males and females utilized scent marking to assert dominance and probably to relocate food or maintain possession over it. Raised‐leg urination and ground scratching probably play a role in olfactory and visual communication in both males and females. Urinations released by females, especially through flexed‐leg posture, may also convey information about their reproductive state. Finally, our observations suggest that defecation does not play an essential role in olfactory communication among free‐ranging dogs and that standing and squat postures are associated with normal excretion. Our results suggest that many of the proposed functions of marking behaviours are not mutually exclusive, and all should be explored through detailed field and laboratory studies.     

Influence of the Queen on Worker Behaviour and Queen Recognition Behaviour in Ants

We investigated the influence of the queen on worker behaviour in ants and their queen recognition behaviour. Queenless and queenright homo- and hetero-specific groups were created using three Myr-micinae species (Manica rubida, Myrmica rubra and Myrmica ruginodis). In homospecific groups, the presence of a queen contributed to an increase in the brood care, which had an effect on all other tasks of the group. In heterospecific groups, the presence of a queen led workers to care more for the conspecific brood. The queen appears to be a factor in the maintenance of both behavioural characteristics of the workers and the organization of the colony. The absence of the queen revealed some behavioural differences between species compared and populations that did not occur in queenright groups. Attractiveness tests were also conducted on these colonies. In homospecific queenright groups, workers were attracted both by unfamiliar conspecific and allospecific queens, but they were attracted more by the former. Therefore, queens appear to emit volatile pheromones which have a non-species-specific and a species-specific attractant effect. In heterospecific groups, workers were attracted more by an unfamiliar queen of the familiar species (even if allospecific) than by an unfamiliar conspecific queen, suggesting the importance of early social experience for the discrimination behaviour of adults.