Turnover, age and sex ratios of kestrels (Falco tinnunculus) in south Scotland

This paper examines the composition and turnover of a population of European kestrels Falco tinnunculus L. in the Southern Uplands of Scotland. Turnover was generally high, with most birds staying in the area for only one summer or winter. The rate at which birds arrived or left was highest in autumn and spring, and was independent of population size. During winter, breeding males were more likely to stay on their territories than females, and males that did so were more likely to retain their partners the following year. Breeding success was associated with a greater likelihood of return the following year, except in first-year females which were unlikely to return anyway. The sex ratio was biased toward males in winter, especially in poor vole years when there were also few first-year birds present. The study confirmed the high rate of turnover reported elsewhere in small raptors, and further indicated that the composition and turnover of the population were related to food supply and seasonal patterns of migration.     

Iris heterochromia: variations in form, age changes, sex dimorphism]

On a sample of n = 25,346 individuals from Vienna (10,855 males, 14,491 females) the iris pigmentation has been typed by the author. In this sample 65 cases of different types of heterochromia were found. The frequency of the occurrence of the different types of this anomaly could be calculated for the first time. Neglecting age, sex, and type of heterochromia the total frequency amounts to 0.256 (males: 0.157; females: 0.37) %. The variants of heterochromia very from cases of total heterochromia to those of various size; in addition to it a number of special types could be observed. The localization of the heterochrome parts of the iris shows certain variations; mostly, however, it is seen in the lower half of the iris. The nasal part is concerned in only one case; the temporal region never. Thus, the partial heterochromia is characteristic by a marked dependency of its localization. The colour of heterochromia varies from 2 a-14 according to the Martin-Schultz standard set of coloured eyes. However, No. 9 (ca. 50%) and No. 7 (ca. 20%) were the most frequent colours. The age variations are considerable. 5/6 of all heterochromias were found between the age from 2-19 years. Finally, a marked sexual dimorphism was observed, as in females heterochromia is much more frequent than in males.     

Metabolic and behavioral responses of American kestrels to food deprivation

• 1.1. The effect of short-term (79 hr) food deprivation at 27°C on body mass, locomotor activity, body temperature (T_b), and resting oxygen consumption was determined in eleven American kestrels (Falco sparverius).
• 2.2. The change in body mass during resting followed the relation, % mass remaining = 99 e^{0.07(days fasting)}. There was no significant difference in the rate of relative mass loss between males and females.
• 3.3. Locomotor activity, measured as perch hopping, was highly variable in both control and fasted birds and showed no correlation with stage of the fast, basal metabolic rate (BMR), or rate of mass loss during food deprivation.
• 4.4. Body temperatures of fasted birds declined continuously by 0.2–0.4°C per day from 39.3 to 38.3°C.
• 5.5. Both males and females responded to food deprivation with a decrease in metabolism. By the third night of fasting, BMR had declined 23.4% from 0.845 W (bird day)⁻¹ to 0.647 W (bird day)⁻¹. The observed reduction in BMR is 2.4 times that expected from a 1°C decline in T_b (assuming Q₁₀ = 2.5) indicating active suppression of metabolism.

     

Cognitive performance in rhesus monkeys varies by sex and prenatal androgen exposure

Men and women differ on performance and strategy on several spatial tasks. Rodents display similar sex differences, and manipulations of early hormone exposure alter the direction of these differences. However, most cognitive testing of nonhuman primates has utilized sample sizes too small to investigate sexually differentiated behaviors. This study presents an investigation of sex differences and the effects of prenatal androgen on spatial memory and strategy use in rhesus monkeys. Monkeys prenatally exposed to vehicle, testosterone, or the androgen receptor blocker flutamide performed a search task in which 5 of 12 goal boxes contained food rewards. Spatial consistency and the presence of local landmarks were varied. Performance when both spatial and marker cues were available did not differ by sex or prenatal treatment. Contrary to predictions, females easily solved the task when local markers were removed, and their performance outscored males. Although eliminating spatial consistency and requiring subjects to use local markers impaired performance by all monkeys, females continued to locate correct goal boxes at higher than chance levels and scored better than males. Blocking prenatal androgen exposure in males improved use of local markers. These findings suggest that the tendency to attend to landmarks and to use them in solving spatial problems is typical of females across many species, including rodents, humans, and rhesus monkeys. In rhesus monkeys and rodents, developmental androgen eliminates this specialization. However, these results are the only known example of better performance of females than males when salient markers are removed.     

Women's genital sexual arousal to oral versus penetrative heterosexual sex varies with menstrual cycle phase at first exposure

Reproductive-aged women show increased interest in sexual activity during the fertile phase of the menstrual cycle that can motivate sexual behavior and thereby increase the likelihood of conception. We examined whether women demonstrated greater sexual responses (subjective and genital sexual arousal) to penetrative versus oral sexual activities during the fertile versus non-fertile phases of their cycles, and whether women's arousal responses were influenced by the phase during which they were first exposed to these sexual stimuli (e.g., Slob et al., 1991; Wallen and Rupp, 2010). Twenty-two androphilic women completed two identical sexual arousal assessments in which genital responses were measured with a vaginal photoplethysmograph and their feelings of sexual arousal were recorded. Women viewed an array of 90 s films varying by couple type (female–female, male–male, female–male) and sexual activity type (oral or penetrative), during the fertile (follicular) and non-fertile (luteal) phases of their menstrual cycle, with the order of cycle phase at the first testing session counter-balanced. Women tested first in the fertile phase showed significantly greater genital arousal to female–male penetrative versus oral sex in both testing sessions, whereas self-reports of sexual arousal were not affected by cycle phase or testing order. These results contribute to a growing body of research suggesting that fertility status at first exposure to sexual stimuli has a significant effect on subsequent sexual responses to sexual stimuli, and that this effect may differ for subjective versus genital sexual arousal.     

Nucleolus size varies with sex,ploidy and gene dosage in insects

The nucleolus constitutes a cytologically visible phenotype for ribosomal DNA (rDNA). Nucleolar size, as determined by silver staining, is a good indicator of cell proliferation rate and biosynthetic activity. Nevertheless, the relationship between rDNA content and sexual dimorphism for nucleolar size is not well documented. In the present study, the impact of sex and ploidy level on nucleolar size is investigated in three haplo/diploid and three diplo/diploid species of insect. Nucleolar sizes are found to be proportional to ploidy level in the haplo/diploid hymenopterans Trypoxylon albitarse and Nasonia vitripennis. Conversely, in the ant Messor barbarus, nucleolar sizes are larger in haploid males (winged) than diploid females (apterous). Among the diplo/diploid species, evidence for gene dosage compensation on nucleolar activity is suggested by the absence of sex differences in Drosophila simulans, a species in which rDNA is limited to the X chromosome. By contrast, in the grasshopper Stenobothrus festivus, another species with rRNA genes restricted to the X chromosome, the size of the nucleolus is significantly larger in females than in males. Additionally, in the grasshopper Chorthippus parallelus, where rDNA is distributed evenly on several autosomes of males and females, the females also show larger nucleoli than males. In both grasshopper species, the magnitude of the female/male ratio for nucleolus area is very similar to the body size ratio, suggesting that body size, as well as sex, ploidy, gene dosage and physiological activity, may be an important determinant of nucleolus area.     

Facial movement varies by sex and is related to attractiveness

Facial movement has received little attention in studies of human attractiveness, yet dynamic displays are an important aspect of courtship in many species. This experiment investigated whether facial movement could be used to identify sex, and whether the ease of identification was associated with attractiveness. We removed shape cues to sex by applying movement from individual faces to a standardised facial model. Participants were able to distinguish between male and female animations of this model at levels above chance. Furthermore, there was a positive association between ease of sex identification and attractiveness for female, but not male, faces. Analysis of facial movement suggested several behaviours that are more frequent in women than men (blinking, tilting, nodding, shaking, and amount of movement). Although some of these behaviours may be cues to sex identification, none alone was directly linked to attractiveness. Our findings suggest that feminine motion is attractive in female faces, but sexually recognisable movement has no clear influence on male attractiveness, in agreement with work on static faces employing composite images.     

Yolk testosterone varies with sex in eggs of the lizard,Anolis carolinensis

In the green anole (Anolis carolinensis), a lizard with genotypic sex determination, yolk testosterone (T) concentration is greater in male-producing than female-producing eggs at oviposition, but the source and potential effects were not clear from previous studies. If yolk T levels are also sex-specific before eggs are laid, a period during which embryonic steroidogenesis is unlikely, it would strongly suggest that the difference in yolk T is maternally derived. We collected yolk samples from eggs shelling within the oviducts of anesthetized females, and then allowed these females to lay the eggs naturally. Eggs were incubated to hatching to determine sex morphologically, and yolk T concentrations were analyzed by radioimmunoassay. As is the case just after they are laid, yolk T is higher in male than female oviductal eggs. To our knowledge, this is the earliest sex difference reported for any yolk steroid. We suggest that maternally derived yolk T levels could influence sex by differentially affecting male- and female-inducing sperm, because fertilization occurs after yolk deposition and ovulation, while the egg is in the oviduct. Our results, together with those of an increasing number of studies, suggest that a relationship between hormones and vertebrate sex determination may be more widespread than generally appreciated.     

Behavioural reactivity of the Korean native Jindo dog varies with coat colour

This study aimed to compare the behavioural reactivity of Jindo dogs with two different coat colours. Fawn (16 males, 15 females; mean age ± S.D. = 7.2 ± 2.1 years) and white (10 males, 10 females; mean age ± S.D. = 6.9 ± 2.1 years) Jindo dogs were exposed to a set of behavioural tests. All of the dogs were videotaped during the testing period to allow further analysis. The intensity of social, aggressive, fearful, and submissive reactivity and the frequency of urination as a scent-marking behaviour were scored on a scale running from 0 to 4 points. For each dog, each variable was defined as the average of the scores of nine behaviour tests. Then, the behavioural reactivities of Jindo dogs of each coat colour were compared. The results suggested that Jindo dogs of fawn coat colour exhibited a significantly lower intensity of fearful and submissive reactivity than those of white coat colour. In addition, fawn Jindo dogs produced scent-marking behaviour significantly more frequently. The results of the present study may provide useful information for scientific researchers, potential owners and breeders of Jindo dogs.     

Seasonal shifts in sex ratios of fledgling American kestrels (Falco sparverius paulus): The Early Bird Hypothesis

We document a seasonal shift in the sex ratios of broods produced by resident southeastern American kestrels (Falco sparverius paulus) breeding in nest boxes in Florida. Early in the breeding season, most biased broods were biased towards males, whereas later in the season, most biased broods were biased towards females. Computer-simulated broods subjected to sex-biased egg and/or nestling mortality demonstrate that it is possible that differential mortality produced the pattern of bias that we observed. However, these simulations do not exclude the possibility that female kestrels were manipulating the primary sex ratio of the broods. We present evidence that this sex ratio shift is adaptive: for males we detected breeding as yearlings, all had fledged early the previous season. No such relationship between season and the probability of breeding as a yearling was found for females. We propose the Early Bird Hypothesis as the ecological basis for the advantage of fledg ing early in males. We hypothesize that pre-emptive competition among post-fledging, dispersing males for breeding sites confers an advantage to males fledged early in the season. This hypothesis may explain why a non-migratory population of the Eurasian kestrel (F. tinnunculus) and non-migratory American kestrels breeding in Florida (F. s. paulus) exhibit this seasonal shift in sex ratios, whereas migratory American kestrels (F. s. sparverius) breeding in Saskatchewan, Canada, do not. We discuss the relevance of the Early Bird Hypothesis for other animal species.     

Voluntary muscle activation varies with age and muscle group.

The consistency and the number of attempts required to achieve maximal voluntary muscle activation have not been documented and compared between young and old adults. Furthermore, few studies have contrasted activation between functional pairs of muscle groups, and no study has tested upper limb muscles. The purpose of this study was to measure and compare voluntary muscle activation of the elbow flexors and extensors in young and old men over two separate test sessions. With the method of twitch interpolation to measure activation, six young (24 +/- 1 yr) and six old (83 +/- 4 yr) men performed five maximal voluntary contractions (MVC) during each session for each muscle group. Elbow flexion and extension MVC was less (43 and 47%, respectively) in the old men, yet the best maximal voluntary muscle activation was similar between age groups. However, when all 10 attempts at MVC were compared, the mean activation scores were slightly less (approximately 5%) in the elbow extensors but were approximately 11% less (P < 0.001) in the elbow flexors of old men, compared with young men. During the second session, there was a significant improvement of 13% (P < 0.005) in mean elbow flexor activation in the old men. There were no session differences for either muscle group for the young men. The results indicate that, for aged men, elbow flexor maximal activation is achieved less frequently compared with elbow extensors, and thus mean activation for elbow flexors is less than for elbow extensors. However, if sufficient attempts are provided, the best effort for the old men is not different from that of the young men for either muscle group.     

Translation elongation rate varies among organs and decreases with age

There has been a surge of interest towards targeting protein synthesis to treat diseases and extend lifespan. Despite the progress, few options are available to assess translation in live animals, as their complexity limits the repertoire of experimental tools to monitor and manipulate processes within organs and individual cells. It this study, we developed a labeling-free method for measuring organ- and cell-type-specific translation elongation rates in vivo. It is based on time-resolved delivery of translation initiation and elongation inhibitors in live animals followed by ribosome profiling. It also reports translation initiation sites in an organ-specific manner. Using this method, we found that the elongation rates differ more than 50% among mouse organs and determined them to be 6.8, 5.0 and 4.3 amino acids per second for liver, kidney, and skeletal muscle, respectively. We further found that the elongation rate is reduced by 20% between young adulthood and mid-life. Thus, translation, a major metabolic process in cells, is tightly regulated at the level of elongation of nascent polypeptide chains.     

Sex-specific associations between reproductive output and hematozoan parasites of American kestrels

Parasites have the potential to decrease reproductive output of hosts by competing for nutrients or forcing hosts to invest in immune function. Conversely, reproductive output may affect parasite loads if hosts allocate resources to reproduction such that allocation to immune function is compromised. Both hypotheses implicitly have a temporal component, so we sampled parasites both before and after egg laying to examine the relationship between reproductive output (indexed using a combined measure of clutch size, egg volume, and initiation date) and blood parasite loads of American kestrels (Falco sparverius). Parasite loads measured prior to egg laying had no adverse effects on subsequent reproductive output. Females that previously had large reproductive outputs subsequently had lower parasite intensities than those whose outputs were smaller, suggesting that females were capable of allocating energy to both forming clutches and reducing parasite loads. Because male kestrels provide most of their mate's energetic needs before, during, and after egg laying, mate choice by females may have consequences for their parasite loads. Females choosing high-quality mates may not only have increased reproductive output, but may also obtain sufficient resources from their mates to enable them to reduce their parasite burdens. Males whose mates had large reproductive outputs were more likely to subsequently be parasitized and have more intense infections. For individual males sampled both before and after egg laying, those whose mates had larger reproductive outputs were also more likely to become parasitized, or remain parasitized, between sampling periods. Increased parasite loads of males may be one mechanism by which the costs of reproduction are paid.     

Incidence of age related macular degeneration in correlation with age, sex and occupation

This study assesses the relation between age related macular degeneration (ARMD) and age, sex and occupation. It is designed as a retrospective study conducted on patients presenting to the Eye Polyclinic "Dr. L. Pavicevi?", Rijeka, Croatia, during the years 1995, 2000 and 2005, and included total of 6617 patients. The number of patients diagnosed with ARMD, their age and sex distribution, as well as the correlation between occupation type (indoor/outdoor) and the incidence of ARMD were analyzed. The results of our study show that the incidence of ARMD is slightly increased in female vs. male, strongly age related, as expected, and significantly increased in patients with outdoor type of occupation. Besides, an increasing trend of incidence is noted.     

Prebreeding survival of Roseate Terns Sterna dougallii varies with sex,hatching order and hatching date

Unequal sex ratios can reduce the productivity of animal populations and are especially prevalent among endangered species. A cohort of 333 Roseate Tern Sterna dougallii chicks at a site where the adult sex ratio was skewed towards females was sexed at hatching and followed through fledging and return to the breeding area, and subsequently during adulthood. The entire regional metapopulation was sampled for returning birds. Prebreeding survival (from fledging to age 3 years) was lower in males than in females, but only among B‐chicks (second in hatching order). Prebreeding survival also declined with hatching date. The proportion of females in this cohort increased from 54.6% at hatching to 56.2% at fledging and to an estimated 58.0% among survivors at age 3 years. This was more than sufficient to explain the degree of skew in the sex ratio of the adult population, but changes in this degree of skew during the study period make it difficult to identify the influence of a single cohort of recruits. Many studies of prebreeding survival in other bird species have identified effects of sex, hatching order or hatching date, but no previous study has tested for effects of all three factors simultaneously.     

Digit ratio varies with sex, egg order and strength of mate preference in zebra finches

The steroid environment encountered by developing vertebrates has important organizational effects on physiology and behaviour that persist throughout an organism's lifetime. Optimal allocation of maternal steroids to zygotes may be difficult to achieve because of the sexually antagonistic effects of steroids; thus, for example, a hormone environment beneficial to a developing male may be much less beneficial to a developing female. Research into the important topic of how mothers might adaptively adjust steroid titres experienced by particular young has been constrained by the difficulty of measuring the steroid environment experienced by the embryo at critical times in development. A potential approach to this problem has been suggested by research on variation in digit ratios in humans, where the ratio of the length of the second and fourth digits reflects the steroid environment experienced by the foetus; notably, digit 4 lengthens in response to androgens. In light of the conservative nature of homeobox genes regulating early development in tetrapods, we questioned whether a sex difference in digit ratio exists in a passerine bird, the zebra finch, Taeniopygia guttata castanotis, and whether observed variation in the ratio is consistent with the previously reported pattern that androgen allocation to zebra finch egg yolk declines across laying order. We established an aviary population of outbred, wild-type zebra finches, and allowed them to breed freely. Hatchlings were marked to correspond to their egg order, and their digit ratios were measured after birds reached adulthood. We found that digit ratio increased across egg order, which is consistent with a pattern of decreasing androgen allocation. Moreover, digit ratios differed between the sexes. We also investigated whether variation in digit ratio among adult females predicted variation in their performance in mate-choice tests. Digit ratio accounted for almost 50% of the variance in strength of female preference for an attractive male trait: specifically, females with higher (presumably less 'androgenized') ratios had stronger preferences for attractive males. Digit ratio may prove to be an extremely useful tool for addressing a wide range of questions about vertebrate differentiation and behaviour.     

Environmental sex determination in a reptile varies seasonally and with yolk hormones

Most hypotheses that have been put forward in order to explain the persistence of environmental sex determination (ESD) in reptiles assume a relatively fixed association of sex with temperature-induced phenotype and no maternal influence on offspring sex. Here we demonstrate the association of maternally derived yolk hormone levels with the offspring sex ratio and describe two new aspects of temperature-dependent sex determination (TSD), i.e. seasonal variation in both thermal response and yolk steroid levels. Eggs from painted turtles (Chrysemys picta) were incubated at 28 degrees C. The hatchling sex ratio at 28 degrees C (i.e. the phenotypic reaction norm for sex at 28 degrees C) shifted seasonally from ca. 72% male to ca. 76% female. Yolk oestradiol (E2) increased seasonally while testosterone (T) decreased. The proportion of males in a clutch decreased as E2 levels increased and the E2:T ratio increased. These new findings are discussed in relation to heritability and adaptive explanations for the persistence of ESD in reptiles. Maternally derived yolk hormones may provide a mechanism for the seasonal shift in the sex ratio which in turn may help explain the persistence of ESD in reptiles. They may also explain those clutches of other reptiles with TSD that fail to yield only males at maximally masculinizing conditions.