Preferences of female American goldfinches (Carduelis tristis) for natural and artificial male traits

We conducted two experiments to determine mating preferencesof female American goldfinches (Carduelis tristis). In the firstexperiment, females were allowed to choose among four naturallyvarying males. In the second, females chose among four maleswearing either orange, blue, yellow, or no color bands. In experiment1, females performed more courtship with males that had significantlybrighter bills and were brighter overall. In experiment 2, femalespreferred males wearing orange bands over unhanded males. Blue-bandedmales ranked second and yellow third, but neither was preferredsignificantly more often than the unbanded males. A female'spreference for a particular band color was weakly associatedwith her own bill and plumage measures; females with brighterthroat feathers and yellower bills preferred orange bands toblue bands. The results suggest that female preferences fororange and yellow may be functional and that females may alsohave aesthetic preferences.     

Energy relations of winter roost-site utilization by American goldfinches (Carduelis tristis)

Summary American goldfinches (Carduelis tristis) were observed roosting in Colorado blue spruce (Picea pungens), which comprised part of a mixed stand of conifers. Their winter roost-sites were distally situated among the most densely-needled branches on the leeward sides of these trees. Heated and unheated taxidermic goldfinch mounts were placed within these sites and at the same height in an adjacent clearing. The radiative and convective characteristics of these locations were monitored simultaneously and compared to predicted power requirements of live goldfinches (based on laboratory calibration of heated mounts) and operative temperatures (T _e ; based on body temperatures of unheated mounts). The winter roost-sites significantly reduced radiative and convective heat exchanges between goldfinches and the environment. Based on body composition data for winter goldfinches, all but two birds sampled could endure a 15-h roost period at average overnight T _e 's as low as-40°C. In contrast, if these birds were prevented from feeding the following day, only 30% could survive the imposition of a 39-h fast at average T _e 's of-2°C. Winter roost-site selection may be more constrained by thermoregulatory considerations in small birds than in larger species.     

The influence of carotenoid acquisition and utilization on the maintenance of species-typical plumage pigmentation in male American goldfinches (Carduelis tristis) and northern cardinals (Cardinalis cardinalis).

Birds display a tremendous variety of carotenoid-based colors in their plumage, but the mechanisms underlying interspecific variability in carotenoid pigmentation remain poorly understood. Because vertebrates cannot synthesize carotenoids de novo, access to pigments in the diet is one proximate factor that may shape species differences in carotenoid-based plumage coloration. However, some birds metabolize ingested carotenoids and deposit pigments that differ in color from their dietary precursors, indicating that metabolic capabilities may also contribute to the diversity of plumage colors we see in nature. In this study, we investigated how the acquisition and utilization of carotenoids influence the maintenance of species-typical plumage pigmentation in male American goldfinches (Carduelis tristis) and northern cardinals (Cardinalis cardinalis). We supplemented the diet of captive goldfinches with red carotenoids to determine whether males, which are typically yellow in color, were capable of growing red plumage. We also deprived cardinals of red dietary pigments to determine whether they could manufacture red carotenoids from yellow precursors to grow species-typical red plumage. We found that American goldfinches were able to deposit novel pigments in their plumage and develop a striking orange appearance. Thus, dietary access to pigments plays a role in determining the degree to which goldfinches express carotenoid-based plumage coloration. We also found that northern cardinals grew pale red feathers in the absence of red dietary pigments, indicating that their ability to metabolize yellow carotenoids in the diet contributes to the bright red plumage that they display.     

On the function of female ornaments: male bluethroats prefer colourful females

Female ornaments in animals with conventional sex roles have traditionally been considered non-functional, being merely a genetically correlated response to selection for male ornamentation. Alternatively, female ornaments may be influenced by selection acting directly on the females, either through female–female competition or male choice. We tested the latter hypothesis in mate choice experiments with bluethroats (Luscinia s. svecica), a passerine bird in which females vary considerably in coloration of an ornamental throat patch. In outdoor aviaries placed in prime breeding habitat, males were allowed to choose between a colourful and a drab female. We found that males associated more with, and performed more sexual behaviours towards, colourful females. Female coloration was not age-related, but correlated significantly with body mass and tarsus length. Thus, we have demonstrated both a male preference for female ornamentation, and a relationship between ornament expression and female body size, which may be indicative of quality. Our results refute the correlated response hypothesis and support the hypothesis that female ornamentation is sexually selected.     

Proteome analysis of separated male and female gametocytes reveals novel sex-specific Plasmodium biology

Gametocytes, the precursor cells of malaria-parasite gametes, circulate in the blood and are responsible for transmission from host to mosquito vector. The individual proteomes of male and female gametocytes were analyzed using mass spectrometry, following separation by flow sorting of transgenic parasites expressing green fluorescent protein, in a sex-specific manner. Promoter tagging in transgenic parasites confirmed the designation of stage and sex specificity of the proteins. The male proteome contained 36% (236 of 650) male-specific and the female proteome 19% (101 of 541) female-specific proteins, but they share only 69 proteins, emphasizing the diverged features of the sexes. Of all the malaria life-cycle stages analyzed, the male gametocyte has the most distinct proteome, containing many proteins involved in flagellar-based motility and rapid genome replication. By identification of gender-specific protein kinases and phosphatases and using targeted gene disruption of two kinases, new sex-specific regulatory pathways were defined.     

Nutrients affect allocation to male and female function in Abutilon theophrasti (Malvaceae)

In a pair of similar experiments, we examined the effects of varying substrate nutrient levels on several measures of male and female function in Abutilon theophrasti (Malvaceae). In the first trial, plants adjusted allocation to female function at several levels: number of flowers initiated, locule number, percentage of fruits matured, and percentage of ovules matured. In the second trial, plants were much larger, opened more flowers, and matured more fruit (in total but not on a percentage basis). However, in response to nutrient level, plants adjusted maternal investment at fewer levels than in the first trial. Seed mass varied between, but not within, trials. Little to no adjustment was seen in male characters within either trial, although flower number differed within trials and stamen number differed between trials. The lack of adjustment of paternal investment may be due to the fact that A. theophrasti is primarily an autogamous species. Between the two trials, growing conditions, primarily light intensity, varied and plants adjusted their allocation to reproduction differently, indicating plasticity in this trait.     

The cause of correlations between nightly numbers of male and female barking treefrogs (Hyla gratiosa) attending choruses

The number of males displaying in a lek or chorus each day isoften positively correlated with the number of females visitingor mating in the aggregation. I tested hypotheses that mightexplain such correlations in a study of the barking treefrog(Hyla gratiosa). Experimental reduction of the number of callingmales did not reduce female visitation, ruling out the hypothesisthat such correlations are owing to female preference for, orpassive attraction to, larger choruses. Separate regressionof the numbers of males and females on 13 environmental variablesexplained 45–74% of the variance in the nightly numbersof males and females. Partial regression coefficients for mostof the 13 variables were not significantly different betweenthe sexes, and the relative importance of variables in explainingvariation in the numbers of individuals was similar for bothsexes. These results support the hypothesis that positive correlationsbetween nightly numbers of males and females are owing to asimilar response by both sexes to the same environmental variables.Thus, it appears that the intense sounds emanating from chorusesof H. gratiosa do not function in long-range communication andmay instead be an epiphenomenon of intense, short-range vocalcompetition for females.     

The function of female and male ornaments in the Inca Tern: evidence for links between ornament expression and both adult condition and reproductive performance

Inca Terns Larosterna inca are medium-size seabirds that breed along the Peruvian and Chilean coast. They are monogamous and both sexes incubate and contribute to chick provisioning. The sexes are similar in appearance and have elaborate ornaments, including a long white moustache of feathers and fleshy yellow wattles. In this paper we report the differences in ornamentation between sexes and examine whether the trait predicts body condition, reproductive performance or chick quality in either sex. The ornaments were similar in size and coloration between the sexes, except for the wattle length, the difference in which can be due to greater head length in males. Moustache length was the most reliable signal of body condition in both sexes. Moreover, there was a significant relationship between the moustache length and reproductive category of adults (non-breeder, unsuccessful breeder, or one or two chicks fledged). Both asymptotic chick body mass and the T-cell mediated response of chicks (a measure of immunocompetence) were related to the moustache length of male and female adults. These results provide support for the role of ornaments in mutual signalling of condition in this species. Female and male ornaments predict body condition, reproductive performance and chick quality, as predicted by sexual selection models.     

禁食时间对雌性长爪沙鼠免疫功能的影响

动物的免疫系统是防御细菌、病毒等病原体侵害的重要途径,对其生存很重要,而食物短缺是影响动物免疫的重要因素。前期研究发现,禁食3天可抑制雌性长爪沙鼠T细胞介导的免疫功能,而禁食时长可能在影响动物免疫中起重要作用。为此,本实验主要测定不同的禁食时间如何影响雌性长爪沙鼠的免疫功能,该问题的解决有助于理解它们在野外面临食物短缺时的生存状况。将55只成年雌鼠随机分为8组,分别禁食1 d、2 d 、3 d和自由取食,每种处理又分别注射磷酸缓冲液和植物血凝素（PHA）。结果发现,随禁食时间的延长,PHA反应（指示T细胞介导的免疫功能）逐渐受到抑制,胸腺和脾脏逐渐萎缩,表明禁食时间对长爪沙鼠的免疫功能影响显著。同样,随饥饿时间增加,长爪沙鼠的体脂、血糖和血清瘦素水平逐渐下降,并且与PHA反应呈正相关,但白细胞总数和皮质酮水平不受禁食时间的影响。结果表明,禁食时间长短能显著影响雌性长爪沙鼠的免疫功能,随禁食时间的延长,长爪沙鼠T细胞介导的免疫功能逐渐受抑制,这可能与体脂和葡萄糖含量下降有关,血清瘦素逐渐降低也可能是其免疫受抑制的原因。     

Novel function of the skin in calcium metabolism in female and male chickens (Gallus domesticus)

To study the role of the skin in differential calcium metabolism in White Leghorn chickens, we compared the composition of suction blister fluid (SBF) collected from cutaneous blisters with blood and serum in female and male animals in various physiological states. As an estimate for interstitial fluid (IF), SBF was used as a determinant of local cutaneous metabolism. Sample collection was carried out under ketamine–xylazine anesthesia. Eight chickens of both sexes were raised freely in similar environmental conditions and fed with similar food during their growth from juvenile to sexually mature and fully adult state. SBF, blood and serum were examined for concentrations of ionized Ca²⁺, Na⁺ and K⁺ with ion-selective electrodes (ISEs), and osmolalities by freezing point osmometry. pH and total protein content were also assessed. Our results showed that SBF of chickens is calcium-poor at the juvenile state and that it draws more Ca²⁺ in adult males than laying females of the same age. Interestingly, Ca²⁺ accumulation was observed also in females after laying had ceased. There was a positive correlation between blood and SBF Ca²⁺ in females but a negative one in males. In general, it was found that SBF of chickens was rich in Na⁺ and K⁺, was hypertonic compared to serum at the juvenile state and had a protein content of 36–47% of that in serum. Different from mammals, SBF in adult chickens was alkaline with the mean values of 8.7 ± 0.14 in females and 8.8 ± 0.06 in males. Age- and sex-related variability in cutaneous Ca²⁺ concentrations in chickens, and the differences of SBF composition between that of mammals point to a novel role of skin functions in avians. Possible functions of the skin as a dynamic calcium source balancing the free circulating Ca²⁺ levels and, also, as an excretory organ for Ca²⁺ are discussed.     

Superoxide dismutase as modulator of immune function in American white shrimp (Litopenaeus vannamei)

The immunomodulatory action of superoxide dismutase (SOD) and its possible use as an indicator of immune responses in American white shrimp (Litopenaeus vannamei) were studied. Juvenile shrimp were immersed in aerated beta-glucan and sulfated polysaccharide solutions for 6 h. SOD activity in haemocytes and muscle was quantified to evaluate whether beta-glucan and sulfated polysaccharide induce immunostimulatory activity. Haemocytes and muscle showed similar increased levels of SOD activity (1.5- and 1.4-fold that of control, respectively). Total haemocyte count decreased within the first 24 h after challenge with immunostimulants, but total haemocyte count and total soluble haemocyte protein increased over normal values after 48-120 h. Single immunostimulation with beta-glucan and sulfated polysaccharide is sufficient to generate an increase in the antioxidant activity of L. vannamei SOD.     

Analysis of recombination rate in female and male gametogenesis in pearl millet (Pennisetum glaucum) using RFLP markers

Sex as a factor affecting recovered recombination in plant gametes was investigated in pearl millet, Pennisetum glaucum, by using reciprocal three-way crosses [(AxB)xCvCx(A x B)]. The two populations were mapped at 42 loci pre-selected to cover the majority of the genome. No differences in recombination distances were observed at the whole-genome level and only a few individual linkage intervals were found to differ, all in favour of increased recombination through the male. Distorted segregations found in the three-way crosses provide evidence of post-gametic selection for particular gene(s) or chromosome regions. The significance of these results for the design of pearl millet breeding programmes and inheritance experiments, as well as for other experimental strategies, is discussed.     

Relation between average daily metabolic rate and resting metabolic rate of the mongolian gerbil (Meriones unguiculatus)

Summary Some early reports have claimed that the Mongolian gerbil is a diurnal rodent, but we found it to be active both night and day, being more active at night. A circadian rhythm was found both in locomotory activity under laboratory conditions and in average daily metabolic rate (ADMR).The ADMR of the Mongolian gerbil observed at 20° C in our study was 2.921 ml O₂/g·h which was near the value expected from Grodzinski's equation (ADMR=19.94 W^-0.50).Both ADMR and RMR were found to be negatively correlated with ambient temperature, with the slope of the regression line for ADMR being less than that for RMR. These two lines intersected at 20° C, lower below 20° C.According to Grodzinski, the ADMR is usually lower than RMR, but in our study the ADMR was found to be lower than the RMR only below 20° C, which suggests that the ambient temperature acts differently on ADMR and RMR. The temperature-dependent variation of both ADMR and RMR as well as their differences should be taken into account in the estimation of the productivity of animal population.     

Development of distylous flowers and investment of biomass in male and female function in Palicourea padifolia (Rubiaceae)

Knowledge of developmental pathways for achieving differences in style and anther heights, in concert with those of ancillary features accompanied with data in regard to biomass investment to male and female function, provide an excellent opportunity for examining the developmental correlations between primary and ancillary floral traits so as to understand the evolution of heterostyly. The ontogenetic relationships between bud length and anther height and between bud length and style height, and between bud length versus bud width, anther length, and number of pollen grains per anther for long-styled (LS) and short-styled (SS) morphs of P. PADIFOLIA are described. We also described the ontogenetic biomass allocation to male and female function and to corolla with elongation of buds harvested at regular intervals. We observed an early termination of stylar growth in SS buds, whereas LS styles steadily increased in size. Morph differences for relative growth rates were significant for anther height, anther length, and pollen number but not for bud width. Bud width and anther length had a negative allometric relationship with bud elongation. The relationship between bud length and number of pollen grains per anther was positive and morph differences in pollen number were detected at later stages of development. An increase in corolla mass involved a disproportionate allocation to the female function in SS flowers and male allocation was similar for the two morphs over the course of development. Our results are consistent with theoretical and empirical data for distylous species with an approach herkogamous ancestor, and with the more general hypothesis of ontogenetic lability of heterostyly, in which morph differences in style and anther heights are achieved in various ways. Variations observed in sexual investment between floral morphs suggest differences in sex expression during flower development.