Male reproductive condition is the limiting factor of efficiency in the male effect during seasonal anestrus in female goats

Two experiments were conducted to determine whether the failure of males to induce sexual activity in goats during seasonal anestrus is due to unresponsiveness of females to male stimulus or insufficient stimulation from males. In the first study, one group of males (sexually inactive, SI; n = 4) was kept under natural photoperiod while the other (sexually active, SA; n = 4) was subjected to 2.5 mo of long days (16L:8D) and received 2 s.c. implants of melatonin. Two mo later, 2 different flocks of anovulatory goats previously separated from bucks were exposed to either SI (n = 34) or SA (n = 40) bucks. Progesterone assays and estrous behavior were used to determine ovarian and behavioral responses of the females to teasing. Of the goats exposed to SI males, only 2 ovulated, and none showed estrous behavior during the 35 days of the study. In contrast, all females (40 of 40) in contact with SA males ovulated and showed at least one estrous behavior during the first 11 days following male introduction (P < 0.001). Overall, 38 of 40 females stimulated with SA bucks were diagnosed pregnant at Day 35, according to progesterone assay (versus 0 in SI-treated group: P < 0.001). To control for a possible difference of responsiveness between flocks, the experiment was repeated 1 yr later using a single flock of goats divided into 2 groups. Again, over the first 14 days, 1 of 33 goats showed estrous behavior in the SI-treated group versus 27 of 33 in the SA-treated group (P < 0.001). Therefore, treating bucks with long days and melatonin increased their teasing capacity to induce sexual activity in females during anestrus. These results indicate that the absence of response to teasing at this time of the year is not due to female unresponsiveness, but to insufficient stimulation from the male.     

The effect of diet quality and wing morph on male and female reproductive investment in a nuptial feeding ground cricket

A common approach in the study of life-history trade-off evolution is to manipulate the nutrient content of diets during the life of an individual in order observe how the acquisition of resources influences the relationship between reproduction, lifespan and other life-history parameters such as dispersal. Here, we manipulate the quality of diet that replicate laboratory populations received as a thorough test of how diet quality influences the life-history trade-offs associated with reproductive investment in a nuptial feeding Australian ground cricket (Pteronemobius sp.). In this species, both males and females make significant contributions to the production of offspring, as males provide a nuptial gift by allowing females to chew on a modified tibial spur during copulation and feed directing on their haemolymph. Individuals also have two distinct wing morphs, a short-winged flightless morph and a long-winged morph that has the ability to disperse. By manipulating the quality of diet over seven generations, we found that the reproductive investment of males and females were affected differently by the diet quality treatment and wing morph of the individual. We discuss the broader implications of these findings including the differences in how males and females balance current and future reproductive effort in nuptial feeding insects, the changing nature of sexual selection when diets vary, and how the life-history trade-offs associated with the ability to disperse are expected to differ among populations.     

Beak colouration as a possible sexual ornament in gentoo penguins: sexual dichromatism and relationship to body condition

Gentoo penguins (Pygoscelis papua) have conspicuous red beak spots, the function of which is currently unknown. We hypothesized that beak spots might be sexual ornaments and investigated sexual dichromatism, assortative mating and the possible relationship between beak spot colouration and body condition. Beak colouration was measured with a portable spectroradiometer in 19 breeding pairs of gentoo penguin. Body mass and body mass relative to structural body size were used as estimates of body condition. We found that beak spots were sexually dichromatic, as they were more UV in males and more violet in females, but males and females did not mate assortatively in relation to beak spot colouration. Body condition was strongly related to red colouration in males, with individuals in good condition having redder beaks and individuals in poor condition more orange beaks. The beaks of males in good condition were also brighter. Body condition was not significantly related to beak spot colouration in females, so females might show red beak spots because of genetic correlation with the male trait. These results suggest that the red colour of the beak spot has the potential to be a secondary sexual character in males. Interpretation of the sexual dichromatism in the UV colour will require further knowledge of the capability of gentoo penguins to discriminate small differences in UV wavelengths. In any case, experimental manipulation of beak colouration will be needed to ascertain the role of this trait.     

Seasonal clutch size decline and individual variation in the timing of breeding are related to female body condition in a non-migratory species, the Upland Goose Chloephaga picta leucoptera

Several studies have shown that waterfowl females in good condition lay larger clutches and start egg-laying earlier in a breeding season. However, most of these studies lack corresponding data on individual condition and timing of breeding in different years. We analysed data on clutch size, egg size, hatching date and female body condition of a non-migratory species, the Upland Goose Chloephaga picta leucoptera, recorded in three seasons on New Island, Falkand Islands. We found a strong seasonal decline in both egg and clutch size. Egg size increased with clutch size. The mean egg volume and total clutch volume increased with female body condition and hatching date was earlier for females in higher body condition. Chicks hatched from nests with higher mean egg volume had higher early body condition. We also compared individual females between different study years and found that individual body condition showed a significant repeatability between years, whereas hatching date did not. While female aging did not systematically affect hatching date, females produced clutches that hatched earlier in years of higher body condition. We could thus show for the first time that the frequently reported negative relationship between female condition and hatching date also holds true on an individual basis. To our knowledge, this is the first study on seasonal clutch size decline in sheldgeese and one of a few in waterfowl comparing condition and timing of breeding within individuals between different years.     

Loudness of birdsong is related to the body size,syntax and phonology of passerine species

Songs of passerines are generally complex, long‐range acoustic signals, and are highly diverse across species. This diversity must nevertheless be shaped by the capabilities of the avian vocal physiology. For example, within species, loudness has been shown to trade‐off with aspects of song complexity. Here, I ask if such trade‐offs with loudness influenced the evolutionary diversification of song among passerines. Comparing perceived song loudness across > 140 European and North American species showed that loudness is positively related to body size and to singing with simple trilled syntax, and negatively related to aspects of syllable complexity. Syntax and syllable phonology together explained more variation than body size did, indicating that the acoustic design of songs is an important factor determining loudness. These results show for the first time that loudness covaries with, and possibly limits, song complexity across species, suggesting that a trade‐off with loudness shaped the evolutionary diversification of passerine song.     

Male contest investment changes with male body size but not female quality in the spider Nephila clavipes

Animals use rules to adjust their level of investment in a contest. We evaluate male strategies during contests over females in the golden orb-web spider Nephila clavipes. We tested whether male behaviour changes with female value, and found that contests were similar in intensity and outcome whether the female was a juvenile or adult, virgin or non-virgin, or whether one male had invested sperm in the female. We found evidence that males use a self-assessment strategy when deciding to withdraw from a contest. Loser body size and contestant size difference were correlated with a higher frequency of contest escalation, and fights involving two large males were more likely to escalate than a fight in which one male was small. A multiple regression showed that loser body size had a stronger effect on contest escalation than contestant body size difference. More importantly, the size of the winning male had no effect on contest escalation, a key prediction of a self-assessment strategy. In N. clavipes, body size is the primary factor that determines the outcome of male contests, and males do not appear to assess their opponent or the quality of the resource when deciding to withdraw from the fight.     

Parental investment and brood defence by made and female great skuas Catharacts skua: the influence of food supply, laying date, body size and body condition

This paper tests the predictions of parental investment theory and other hypotheses relating to variation in brood defence by examining aggression displayed by great skuas Catharacta skua towards intruders within their territories. Aggression serves the function of nest defence; hatching success of adults breeding in Shetland increased with aggression displayed during incubation, and the correlation between aggression and hatching success was apparent in three separate age classes. Adults displayed higher levels of aggression and greater parental investment in reproduction in years of poor food supply. This was not due to an increase in adults' expectations of future benefits of brood defence with increased investment. since hatching success was unaffected by food supply, and breeding success was lower in years of poor food supply. The observed increase in aggression therefore supports parental investment theory. Aggression increased with body condition index (in terms of mass corrected for body size) for females, but decreased with increasing body condition index for males. This probably reflects size-specific differences in the relative benefits of weight and manoeuvrability as means of promoting effective brood defence and reducing the risk of injury to parents. Aggression may also reflect adult quality, with body condition reflecting quality in opposite ways in males and females, as a result of their different roles during the breeding season.     

Antioxidant status in relation to age,condition, reproductive performance and pollution in three passerine species

Oxidative stress has been suggested as a mediator in life‐history trade‐off. By spending more resources on for example reproduction an organism might sacrifice its antioxidant defence. So far, most conclusions on trade‐offs between life‐history traits and oxidative stress have been drawn from laboratory studies using a few model species and there is a need for studies conducted in natural settings. We investigated associations between markers for antioxidant status (antioxidant enzyme activities and antioxidant levels), body condition, age and reproduction in three species of wild‐living passerines. The impact from an anthropogenic stressor (metal pollution) was also assessed. The three bird species showed interspecific variation in their SOD and CAT activities, indicating different pathways to eliminate radicals. The age of females affected both antioxidant status and the breeding performance, indicating the importance of age as a factor in life‐history studies. Old birds had lower levels of antioxidants/antioxidant enzyme activities and they produced larger broods/more successful broods, though the latter might be confounded by surviving females having increased fitness. Metal exposure had a negative impact on breeding, and improved breeding outcome was also associated with increased antioxidant defence, but metal exposure was not directly related to the oxidative status of birds, emphasizing that additional stressors might independently affect the same traits. Our results highlight that caution has to be taken when generalizing and extrapolating results to even closely related species. The results support the idea that there is a cost of reproduction, in terms of increased resources spent on antioxidant defence, though this should be confirmed with experimental studies.     

Variations in body weight, wing length and condition of Mallard Anas platyrhynchos platyrhynchos and their relationship to environmental changes

This paper describes the analysis of over 15,000 weights of Mallard caught for ringing at Borough Fen Decoy, Northamptonshire, during a 13 year period. Weights are corrected to give condition indices by using wing length to give an indication of body size. The weight of pectoral muscles varies with body weight but as the fat stores increase in weight the proportion of body weight made up of flight muscles decreases. Body weight corrected for size gives a better indication of the bird's condition (defined as its fitness for its present and future needs) than the relative weight of the pectoral muscles or the shape of the breast.
The relationships between food availability and weather, and condition are examined. Only occasionally can a drop in condition following hard weather be detected; the birds normally emigrate to the coast after a few days of adverse conditions. There is a relationship between the condition of Mallard in autumn and the amount of grain left on their stubble feeding grounds after harvest. The implications of variations in winter condition on survival and breeding success are briefly discussed.     

GhPSY,a phytoene synthase gene,is related to the red plant phenotype in upland cotton (Gossypium hirsutum L.)

Carotenoids are important accessory pigments in plants that are essential for photosynthesis. Phytoene synthase (PSY), a rate-controlling enzyme in the carotenoid biosynthesis pathway, has been widely characterized in rice, maize, and sorghum, but at present there are no reports describing this enzyme in cotton. In this study, GhPSY was identified as a candidate gene for the red plant phenotype via a combined strategy using: (1) molecular marker data for loci closely linked to R1; (2) the whole-genome scaffold sequence from Gossypium raimondii; (3) gene expression patterns in cotton accessions expressing the red plant and green plant phenotypes; and (4) the significant correlation between a single nucleotide polymorphisms (SNP) in GhPSY and leaf phenotypes of progeny in the (Sub16 × T586) F₂ segregating population. GhPSY was relatively highly expressed in leaves, and the protein was localized to the plastid where it appeared to be mostly attached to the surface of thylakoid membranes. GhPSY mRNA was expressed at a significantly higher level in T586 and SL1-7-1 red plants than TM-1 and Hai7124 green plants. SNP analysis in the GhPSY locus showed co-segregation with the red and green plant phenotypes in the (Sub16 × T586) F₂ segregating population. A phylogenetic analysis showed that GhPSY belongs to the PSY2 subfamily, which is related to photosynthesis in photosynthetic tissues. Using a reverse genetics approach based on Tobacco rattle virus-induced gene silencing, we showed that the knockdown of GhPSY caused a highly uniform bleaching of the red color in newly-emerged leaves in both T586 and SL1-7-1 plants with a red plant phenotype. These findings indicate that GhPSY is important for engineering the carotenoid metabolic pathway in pigment production.     

条纹短攀鲈的雄性个体大小、雌性偏好以及雄性之间的竞争

本研究考察了条纹短攀鲈(Trichopsis vittata)雄性个体的身体大小对雌性个体性偏好的影响以及对雄性之间竞争的影响。本研究设立了两种处理来研究雌性个体的性偏好以及雄性之间的竞争。在一种处理中,放入同样大小的雄性个体,而在另一种处理中,放入大小不同的雄性个体。结果表明,雄性个体的大小不影响雌性条纹短攀鲈的性偏好。在对雄性之间竞争的研究中,发现个体较大的个体获胜的次数比较多。在个体大小相同的处理中,雄性之间打斗的持续时间比另一种处理中的打斗持续时间长。对这两种处理中不同对抗行为的比较表明,个体大小相同处理组中的发声、咬、以及总体对抗行为发生得更为频繁。对个体大小不同处理组中的大、小个体的进一步观察也揭示出体型大的个体比体型小的个体有更多的追逐行为和更少的逃脱行为。这些结果表明,在雄性个体比雌性个体大的物种中,体型的性两型可能与雄性之间的竞争有关,而不是与雌性偏好有关。     

Steroid hormones in bluegill, a species with male alternative reproductive tactics including female mimicry

The proximate mechanisms underlying the evolution and maintenance of within-sex variation in mating behaviour are still poorly understood. Species characterized by alternative reproductive tactics provide ideal opportunities to investigate such mechanisms. Bluegill (Lepomis macrochirus) are noteworthy in this regard because they exhibit two distinct cuckolder (parasitic) morphs (called sneaker and satellite) in addition to the parental males that court females. Here we confirm previous findings that spawning cuckolder and parental males have significantly different levels of testosterone and 11-ketotestosterone. We also report, for the first time, that oestradiol and cortisol levels are higher in cuckolders than in parental males. The two cuckolder morphs did not differ in average levels of any of the four hormones. However, among satellite males which mimic females in appearance and behaviour, there was a strong negative relationship between oestradiol levels and body length, a surrogate for age. This finding suggests that for satellite males, oestradiol dependency of mating behaviour decreases with increasing mating experience. Although such decreased hormone dependence of mating behaviour has been reported in other taxa, our data represent the first suggestion of the relationship in fishes.     

Genetic diversity and the reproductive system in related species of antirrhinum

BACKGROUND AND AIMS: Seven related species of Antirrhinum (A. siculum, A. majus, A. latifolium, A. linkianum, A. litigiosum, A. cirrhigherum and A. tortuosum) were studied in order to compare levels of genetic variation and its partitioning in them, and to check relationships between genetic patterns and the reproductive system. METHODS: Eight hundred and fifty-one plants were screened for variability at 13 allozyme loci by means of horizontal starch gel electrophoresis. Parameters of genetic diversity and its partitioning, the inbreeding coefficient as well as an indirect estimate of gene flow based on the equation: Nm = (1 - G(ST))/4G(ST), were calculated. KEY RESULTS: Genetic variability in A. siculum was found to be the lowest known in the genus. Mean values of F(IT) and F(IS) were mostly positive and not significantly different from zero. Population differentiation (F(ST)) ranged between 6.1 in A. tortuosum and 17.6 in A. linkianum. The inbreeding coefficient within populations ranged between F(IS) = -0.5 in A. tortuosum and F(IS) = 1 in A. siculum. Estimates of gene flow ranged between Nm = 15 in A. majus (considered as very high) to Nm = 0.42 in A. siculum (considered as low). CONCLUSIONS: Correlation was found between levels of diversity and differentiation on one hand, and the reproductive system of the studied taxa on the other. Striking differences among species in the inbreeding coefficient (F(IS)) show different reproductive systems, which mostly support previous reports. Strategies for the conservation of A. siculum are recommended, such as preservation of natural populations as well as ex situ preservation of seeds from different populations.     

Differences in potential reproductive rates of male and female seahorses related to courtship roles

Dwarf seahorses, Hippocampus zosterae (Syngnathidae), are distinguished by extreme morphological specialization for paternal care, the formation of monogamous pair bonds and mating repeatedly over the course of a breeding season. To determine the potential reproductive rates of male and female dwarf seahorses, we measured (1) the maximum number of offspring produced per breeding cycle when sexually receptive mates were unlimited, and (2) the relative time each sex was unavailable for mating ('time out'). We paired sexually isolated males and females with sexually receptive partners and observed them from the day of introduction through to copulation, to determine the length of time it takes each sex to prepare to mate. We conducted additional experiments to determine the length of gestation, which when added to the time needed to prepare to mate and copulate gives an estimate of total reproductive cycle duration, T. We estimated potential reproductive rate by dividing the mean number of offspring produced per breeding cycle by the duration of the breeding cycle (T). We estimated reproductive 'time out' by identifying the period of time males and females were physiologically capable of mating ('time in', S) and subtracting time S from time T. When provided with sexually receptive partners, females took 2 days longer than males to complete courtship and copulation, but neither males nor females remated during gestation. Therefore, males could potentially produce 17% more offspring than females over the course of one breeding season. Females had reproductive 'times out' 1.2 times longer than did males, as they were only capable of mating during the 4 h directly preceding copulation. Thus, H. zosterae males have higher potential reproductive rates and shorter reproductive 'times out' compared with H. zosterae females. These results and previous work indicating that seahorses display traditional courtship roles support the prediction that the sex having the higher potential reproductive rate, or equivalently, the shorter 'time out', will compete more intensely for access to the opposite sex. Copyright 2000 The Association for the Study of Animal Behaviour.     

Pheromonal discriminations of sex,reproductive condition,and species by the lacertid lizard Podarcis hispanica

In some vertebrate taxa, pheromones provide important information about species, sex, reproductive condition, kinship, and even individual identity. Because they possess highly developed nasal chemosensory systems, lizards are capable of many chemical discriminations, but many aspects of their pheromonal communication remain poorly understood even in major families. We report that males of a lacertid lizard, Podarcis muralis, are capable of differential response to surface chemical cues from conspecific males and females, from gravid and nongravid females, and from conspecific females and females of the closely related sympatric congener, P. bocagei carbonelli. In 60 sec trials in which stimuli from the femoral, cloacal, lateral, and upper body surfaces were presented to males on cotton swabs, males tongue-flicked at significantly higher rates to stimuli from conspecific females than males, from conspecific nongravid than gravid females, and from conspecific than heterospecific females. Responses to stimuli from conspecific males did not differ from those to distilled water. Together with previous findings that males can distinguish between chemical cues from familiar and unfamiliar males, these findings suggest that pheromones provide male P. hispanica important information regarding the presence of sexual rivals and the reproductive condition of potential mates without visually encountering other lizards. A growing body of literature indicates that lacertids are capable of sophisticated pheromonal discriminations that may play important roles in their social behavior.     

Female reproductive strategies in orangutans,evidence for female choice and counterstrategies to infanticide in a species with frequent sexual coercion

Intersexual conflicts over mating can engender antagonistic coevolution of strategies, such as coercion by males and selective resistance by females. Orangutans are exceptional among mammals for their high levels of forced copulation. This has typically been viewed as an alternative mating tactic used by the competitively disadvantaged unflanged male morph, with little understanding of how female strategies may have shaped and responded to this behaviour. Here, we show that male morph is not by itself a good predictor of mating dynamics in wild Bornean orangutans but that female conception risk mediated the occurrence and quality of male–female interactions. Near ovulation, females mated cooperatively only with prime flanged males who they encountered at higher rates. When conception risk was low, willingness to associate and mate with non-prime males increased. Our results support the hypothesis that, together with concealed ovulation, facultative association is a mechanism of female choice in a species in which females can rarely avoid coercive mating attempts. Female resistance, which reduced copulation time, may provide an additional mechanism for mate selection. However, coercive factors were also important as prime males were frequently aggressive to females and females used mating strategies consistent with infanticide avoidance.     

Changes in female reproductive condition following male take-overs in a colony of hamadryas and hybrid baboons

This paper describes and discusses events observed in the Madrid colony of hamadryas and hybrid baboons, when a novel group of 3 adult males, 3 adult females and 1 unweaned infant was introduced to the resident colony comprising 12 adult females, 11 juveniles and 6 unweaned infants. Novel males took over resident adult females in any reproductive condition, and all acyclic females (i.e. lactating, pregnant and immature) exhibited a dramatic enhancement of sexual activity. Lactating females shortened their postpartum amenorrhoea periods and resumed oestrous cycles around day 14 following the introduction of the novel males, without infanticide occurring. Their return to breeding condition was not affected by the age of their current infant or the day they were taken over by the males. A female in an early stage of pregnancy aborted spontaneously and resumed oestrus on day 26. The other pregnant female significantly shortened her gestation time, delivered a viable infant on day 13, and resumed breeding activity 39 days post-partum (on day 52), while suckling her infant. A cycling female adopted and suckled a 74-day-old infant, continued showing oestrous cycles and conceived. Immature females reached menarche significantly earlier than expected and only then joined one of the newly established harem units. It is argued that the observed enhancement of sexual activity was not imposed by the males' aggressive behaviour but rather was a spontaneous female response to male novelty. This single causal factor was potent enough to override the role that nutrition and lactation normally play in the control of the females' reproductive activity. Differences in latency until the appearance of the response were probably due to the different constraints imposed by the female's current reproductive state. It was also hypothesized that when (a) sexual swellings are attractive to males, (b) novel males are especially active in the process of bonding with new females, and (c) males are important sources of coalitionary support, females might by developing sexual swellings compete more successfully against other females and attain a higher position in the female hierarchy of the newly established unit. This would have the ultimate effect of increasing their potential reproductive success. In several cases females did gain socially by coming into oestrus, but attained no immediate reproductive advantage.