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1.
Katarzyna Wojczulanis-Jakubas Dariusz Jakubas Julien Foucher Joanna Dziarska-Pałac Hubert Dugué 《Die Naturwissenschaften》2013,100(11):1095-1098
Relatively little attention has been paid to sex differences in the migration of birds in autumn. We studied the autumn migration strategy of molecularly sexed males and females in the globally threatened aquatic warbler Acrocephalus paludicola. We captured 176 birds at a stopover site in the Loire estuary at Donges, France. The median date for the passage of adults was 8 days earlier in males than females, although the timing of migration in first-year males and females was similar. This indicates that males, who are without parental duties, can start their migration earlier than females and first-year birds. Adults were significantly heavier than immature birds but did not have higher fat scores. In both age categories, more males (two to three times more) were captured. However, various factors (including tape-luring) can affect observed sex ratio. 相似文献
2.
We analyzed the relationships among spleen size, body condition (measured as kidney fat), and larval counts of the nematode
Elaphostrongylus cervi in red deer (Cervus elaphus). The aim was to investigate the interaction between host body condition and intensity of infection with parasites. As red
deer are highly polygynous, we also tested whether these relationships varied with sex and age of the hosts. Kidney fat and
spleen size were positively correlated in subadults (2–3 years old) and adults (>3 years old), but not in calves (<1 year
old) or yearlings (1–2 years old). Spleen size was negatively associated with nematode load in subadult females and in adult
males. These two age classes are potentially the most nutritionally stressed, as subadult hinds are still growing and often
engaging in rearing their first calf, and adult stags were sampled just after the rut, which is recognized as a substantial
energy drain in this age–sex class, as they compete to hold females during the mating season. Body condition related negatively
to parasite count only in adult males. In the context of red deer life history, these findings suggest that spleen size is
dependent on body condition and that it could be affected by variation in resource partitioning among immune defense, growth,
and reproductive effort in red deer. For the first time in a wild mammal, the spleen mass is shown to be positively related
to body condition and negatively related to parasite infection. We conclude that elucidating whether spleen mass reflects
immune defense investment or a measure of general body condition should contribute to understanding topical issues in mammal
ecology. 相似文献
3.
The migration strategies of birds may vary strongly between species and also between age and/or sex groups. We studied the autumn migration and body condition of molecularly sexed Reed Warblers Acrocephalus scirpaceus and Sedge Warblers Acrocephalus schoenobaenus (211 and 208 ind., respectively) at a stopover site on Lake Druzno, Northern Poland, in 2008. Immature male Reed Warblers were caught significantly later than females (median dates 9 days later), but in the Sedge Warbler, both sexes of immatures migrated at about the same time. Adult males and females of both species did not differ in their time of migration. Adult and immature males of both species were larger (wing length and body mass) than females. In both species, fat reserves were similar in both sexes of both age classes. Adults of both sexes of Reed and Sedge Warbler were generally caught earlier than immatures. In both species, the body mass and fat reserves of immatures were generally less than in adults. The autumn protogyny of immature Reed Warblers may allow smaller females to limit competition with bigger males during migration and at the wintering grounds. In the Sedge Warbler, which tends to match its migration to peak of occurrence of superabundant food at stopover sites, both sexes gain an advantage from migrating at the same time. Since part of the measured wing length variation in both species was explained by sex differences, temporal trends in wing length recorded at stopover sites should be interpreted with caution. 相似文献
4.
Dugatkin LA 《Die Naturwissenschaften》2007,94(8):651-656
Using female mate choice copying as a rudimentary form of cultural transmission, this study provides evidence that social
environment during development has a significant effect on the tendency to use culturally acquired information. Groups of
newborn guppies (Poecilia reticulata) were raised for 35 days in 1 of 5 “developmental environments”. Groups of 15 newborns were raised in pools with no adults
(treatment 1), both adult male and female guppies (treatments 2 and 3), only adult females (treatment 4) or only adult males
(treatment 5). Mature females raised in treatments 1 and 2, but not treatments 3, 4, and 5, copied the mate choice of others.
Treatments 1 and 2 correspond to social structures that guppies experience during their development in the wild. Newborn guppies
swim together in shoals (analogous to treatment 1). As they mature, juveniles join schools of adult males and females (analogous
to treatments 2). At no time during the normal developmental process are juveniles found with males, but only unreceptive
females (as was the case for long periods in treatment 3) or in the presence of adults of only one sex (analogous to treatments
4 and 5). As such, normal developmental environments prime guppies for cultural transmission, while unnatural environments
fail to do so. 相似文献
5.
Under complementary sex determination (CSD), females of Hymenoptera arise from diploid, fertilized eggs and males from haploid,
unfertilized eggs. Incidentally, fertilized eggs that inherit two identical alleles at the CSD locus will develop into diploid
males. Diploid males are usually unviable or sterile. In a few species, however, they produce diploid sperm and father a triploid
female progeny. Diploid males have been reported in a number of social Hymenoptera, but the occurrence of triploid females
has hardly ever been documented. Here, we report the presence of triploid females, diploid males, and diploid sperm (produced
by diploid males and stored in queen spermathecae) in the ant Tapinoma erraticum. Moreover, we show variations in the frequency of triploids among female castes: Triploid females are more frequent among
workers than virgin queens; they are absent among mated, reproductive queens. The frequency of triploid workers also varies
between populations and between nests within populations. 相似文献
6.
Cremer S D'Ettorre P Drijfhout FP Sledge MF Turillazzi S Heinze J 《Die Naturwissenschaften》2008,95(11):1101-1105
Winged and wingless males coexist in the ant Cardiocondyla obscurior. Wingless (“ergatoid”) males never leave their maternal colony and fight remorselessly among each other for the access to
emerging females. The peaceful winged males disperse after about 10 days, but beforehand also mate in the nest. In the first
5 days of their life, winged males perform a chemical female mimicry that protects them against attack and even makes them
sexually attractive to ergatoid males. When older, the chemical profile of winged males no longer matches that of virgin females;
nevertheless, they are still tolerated, which so far has been puzzling. Contrasting this general pattern, we have identified
a single aberrant colony in which all winged males were attacked and killed by the ergatoid males. A comparative analysis
of the morphology and chemical profile of these untypical attacked winged males and the tolerated males from several normal
colonies revealed that normal old males are still performing some chemical mimicry to the virgin queens, though less perfect
than in their young ages. The anomalous attacked winged males, on the other hand, had a very different odour to the females.
Our study thus exemplifies that the analysis of rare malfunctioning can add valuable insight on functioning under normal conditions
and allows the conclusion that older winged males from normal colonies of the ant C. obscurior are guarded through an imperfect chemical female mimicry, still close enough to protect against attacks by the wingless fighters
yet dissimilar enough not to elicit their sexual interest. 相似文献
7.
This paper examines the phenology and biometrics of Bluethroats staging in the Eilat region. This is of special interest because
of the extreme conditions with which this temperate zone breeding species has to contend because Eilat is a desert habitat
and is the last green area before the crossing of the deserts in autumn or after it in spring. Data were collected during
20 spring and 18 autumn migration seasons in the years 1984–2003, and a total of 7,464 Bluethroat were recorded. The number
of trapped birds was much higher in autumn than in spring. The majority of Bluethroats caught in both the autumn and spring
migrations were juveniles. We found differences in sex ratio in the individual age classes only in the autumn wherein among
both adults and juveniles, males were in greater numbers. We also found significant differences in the dates of ringed birds
from different sex–age classes in the spring and in autumn migrations. In spring, males from both age classes were caught
earlier than females. In autumn, adult birds arrived earlier than juveniles. We think that it is important to identify and
conserve the high quality stopover habitats such as Eilat wherein not only Bluethroats have been shown to stopover but also
several hundred other species. 相似文献
8.
Kraaijeveld K Reumer BM Mouton L Kremer N Vavre F van Alphen JJ 《Die Naturwissenschaften》2011,98(3):175-180
Wolbachia is a maternally inherited bacterium that manipulates the reproduction of its host. Recent studies have shown that male-killing
strains can induce cytoplasmic incompatibility (CI) when introgressed into a resistant host. Phylogenetic studies suggest
that transitions between CI and other Wolbachia phenotypes have also occurred frequently, raising the possibility that latent CI may be widespread among Wolbachia. Here, we investigate whether a parthenogenesis-inducing Wolbachia strain can also induce CI. Parthenogenetic females of the parasitoid wasp Asobara japonica regularly produce a small number of males that may be either infected or not. Uninfected males were further obtained through
removal of the Wolbachia using antibiotics and from a naturally uninfected strain. Uninfected females that had mated with infected males produced
a slightly, but significantly more male-biased sex ratio than uninfected females that had mated with uninfected males. This
effect was strongest in females that mated with males that had a relatively high Wolbachia titer. Quantitative PCR indicated that infected males did not show higher ratios of nuclear versus mitochondrial DNA content.
Wolbachia therefore does not cause diploidization of cells in infected males. While these results are consistent with CI, other alternatives
such as production of abnormal sperm by infected males cannot be completely ruled out. Overall, the effect was very small
(9%), suggesting that if CI is involved it may have degenerated through the accumulation of mutations. 相似文献
9.
Martina Trinkel 《Die Naturwissenschaften》2013,100(4):345-353
Large carnivores are threatened by habitat loss, declining prey populations and direct persecution. Pride dynamics of eight lion prides in the centre of the Etosha National Park, Namibia are described during a 16-year study. Since the beginning of the 1980s, the number of adult and subadult lions declined continuously to two third of its initial population size, and reached a new equilibrium in the 1990s. Pride sizes decreased from 6.3 adult females in 1989 to 2.8 lionesses in 1997. While the number of adult females declined continuously, the number of adult males, subadult females and subadult males remained constant over the years. A severe drought period, lasting for more than 20 years, led to declining prey populations inside the lions’ territory. Besides declining prey populations, conflict with humans at the border of Etosha puts substantial pressure onto the lion population: 82 % of all known lion mortalities were caused by humans, and most of these consisted of adult females (28 %) and subadult males (29 %). I postulate that the considerable decline in the lion population is a response to declining prey populations, and although the human predator conflict is severe, it does not seem to limit the size of Etosha’s lion population. 相似文献
10.
Microplitis croceipes (Hymenoptera: Braconidae) is a larval parasitoid of Helicoverpa/Heliothis spp. In the course of mass rearing of M. croceipes, we found that females oviposited in the conspecific adults in rearing cages. When 20 pairs of inexperienced females and
males or of experienced females and males were reared in a cage, the males lived for 14–15 days and the females for 18–20 days
on average. At their death, 37–42% of the males and 50–57% of the females contained conspecific eggs or first instar larvae
in their abdominal cavity. When two of inexperienced females met on a host-infested leaf of soybean, they attempted to sting
each other. Of the attacked females, 30% contained a conspecific egg laid in their abdomen. In abdominal cavity of the adults
parasitized by a conspecific female, the majority of the parasitoid eggs laid disappeared within 1 day after oviposition.
Only 10–30% of the parasitoid eggs laid in conspecific adults hatched 3–4 days after oviposition, but those larvae never molted
to second instar. When the adults were stung by one or two conspecific females, their subsequent longevity was significantly
shorter than that for the control adults. Oviposition in conspecific adults may be prevalent in other parasitic wasps that
quickly oviposit without intensive host examination, and have cuticle and size of abdomen to be stung by conspeicifcs. 相似文献
11.
接种丛枝菌根真菌对雌雄美洲黑杨吸收铅镉的影响 总被引:2,自引:0,他引:2
以雌雄美洲黑杨(Populus deltoides)为研究对象,砂培条件下,研究接种丛枝菌根真菌(Glomus intraradices)对受Pb污染(200 mg·kg-1)、Cd污染(10 mg·kg-1)及复合污染的雌雄美洲黑杨Pb和Cd的富集与分配特征的影响,关注Pb/Cd复合污染独特的环境效应.结果表明:1未接种丛枝菌根真菌条件下,与单一污染相比,复合污染增加了美洲黑杨雄株叶、粗根、细根Pb和Cd含量;复合污染增加了雌株叶片中Pb和Cd含量,却降低了粗根和细根中Pb和Cd含量;复合污染条件下雄株Pb和Cd向地上部分器官的迁移率分别增加135%和78%,雌株则分别增加52%和18%.2复合污染条件下,接种丛枝菌根真菌引起雄株Pb和Cd富集系数分别增加87%和6%,雌株则分别增加171%和65%;雄株Pb和Cd向地上部分器官的迁移率降低65%和69%,雌株则分别降低59%和53%.3Pb污染条件下,接种丛枝菌根真菌的雌雄之间Pb积累量没有显著差异;Cd污染条件下,接种丛枝菌根真菌的雄株总Cd积累量是雌株的1.7倍;复合污染条件下,接种丛枝菌根真菌的雌株Pb和Cd总积累量分别是雄株的1.3和1.2倍.本研究表明,接种G.intraradices能提高美洲黑杨的Pb和Cd积累能力,对于不同污染条件下,应根据实际情况选择合适的杨树性别进行造林和生态修复. 相似文献
12.
Previous studies on arthropods showed that seasonality and parity in breeding considerably impact the direction of sex differences in immunocompetence, and it has been suggested that life span and the time window available for breeding play key roles in shaping sex-differences in immunity. One proposed mechanism behind this phenomenon is differential investment into life history traits in sexes. Here, we tested whether in a seasonally breeding semelparous arthropod sexes differ in their immunocompetence, predicting that females would show weaker immune response than males. We compared encapsulation efficiency (a well-established and widely used method for assessing immunocompetence) of freshly matured, virgin males and females of the lycosid spider Pardosa agrestis (Westring, 1861). On average, males mounted stronger immune response than females and the extent of encapsulation was positively associated with prosoma length in males, but not in females. Also, time until maturation was positively related to the extent of encapsulation in both sexes, but did not significantly affect adult prosoma length. We propose that sex-difference in encapsulation is likely shaped by combined effects of relatively higher costs of reproduction in females, narrow time window of reproductive activity, and the absence of trade-off between current and future reproduction. 相似文献
13.
Monogeny, the production of unisexual broods by individual females, has been recognized for nearly 80?years. The genetic nature of gall midges' sex determination predicts an equal numbers of male-producing and female-producing females in the populations such that the overall sex ratio is expected to be nearly 1:1. However, observations of some strictly monogenous populations with biased sex ratio, mainly toward females, have raised the question of whether gall midges are able to adjust their offspring sex ratio in response to changes in environmental conditions, and some authors have even considered sex ratio regulation as a strong force in the course of the evolution of monogeny. In this paper, first, by studying the sex ratio variations of the predatory gall midge, Aphidoletes aphidimyza within a generation, we showed that adult males emerge up to 1?day earlier and have shorter life span than females (less than 4?days and up to 6?days, respectively). Although, the sex ratio of A. aphidimyza at the time of emergence was nearly 1:1 (52.41?% males), a simple population simulation indicated that the differential mortality of sexes can lead to a female-biased sex ratio estimation (57.88?% females) under random sampling in the natural environments. Our results imply that the primary sex ratio of monogenous gall midges is nearly 1:1 and that the arrhenogenic/thelygenic gall midges are not able to alter the number of their male/female progenies in response to changes in environmental conditions. 相似文献
14.
Masahiko Tanahashi Kôhei Kubota Norihisa Matsushita Katsumi Togashi 《Die Naturwissenschaften》2010,97(3):311-317
Most wood-feeding insects need an association with microbes to utilize wood as food, and some have special organs to store
and convey the microbes. We report here the discovery of the microbe-storage organ (mycangium) in stag beetles (Coleoptera:
Lucanidae), which develop in decayed wood. The mycangium, which was discovered in the abdomen, is present in all adult females
of 22 lucanid species examined in this study, but absent in adult males. By contrast, adult insects of both sexes of selected
Passalidae, Geotrupidae, and Scarabaeidae, which are related to Lucanidae, lacked mycangia similar to those of the lucanid
species. Yeast-like microbes were isolated from the mycangium of five lucanid species. DNA sequence analyses indicate that
the microbes are closely related to the xylose-fermenting yeasts Pichia stipitis, Pichia segobiensis, or Pichia sp. known from the gut of a passalid species. 相似文献
15.
Increased egg estradiol concentration feminizes digit ratios of male pheasants (<Emphasis Type="Italic">Phasianus colchicus</Emphasis>) 总被引:1,自引:0,他引:1
The length ratio between individual digits differs between males and females in humans, other mammals, lizards, and one bird
species. Sexual dimorphism in digit ratios and variation among individuals of the same sex may depend on differential exposure
to androgens and estrogens during embryonic life. Organizational effects of sex hormones could cause the observed correlations
between digit ratios and diverse phenotypic traits in humans. However, no study has investigated experimentally the effect
of prenatal estrogens on digit ratios. We analyzed the effect of estradiol injection in ring-necked pheasant (Phasianus colchicus) eggs on digit ratios. Males from control eggs had higher ratios between the second or third and the fourth digit of the
right foot compared to females. Estradiol-treated eggs produced males with lower (feminized) right foot second to fourth digit
ratio. Thus, we provided the first experimental evidence that prenatal exposure to physiologically high estrogen levels affects
bird digit ratios. 相似文献
16.
In animals where males engage in signalling interactions, females might evaluate male–male contests to inform their reproductive choices. We used interactive playback to engage territorial male black-capped chickadees (Poecile atricapillus) of known dominance status in countersinging contests with an aggressive or submissive opponent. Previous analysis of these data showed that high-ranking males who received aggressive playback were more likely to be cuckolded. Here we describe the particular reproductive decisions of females whose partners received aggressive versus submissive playback. The proportion of extra-pair young per brood was higher for females paired to high-ranking males that received aggressive playback compared to submissive playback, and similar to levels in broods of females paired to low-ranking males. We found no strong predictors of whether high-ranking subjects lost paternity following aggressive playback. Females usually preferred extra-pair sires with high dominance status. When females had extra-pair fertilizations with low-ranking males, females chose males who had received submissive playback. We conclude that females mated to aggressive-playback, high-ranking males pursued mixed mating strategies similar to those of females mated to low-ranking males. Our results support the idea that male performance in song contests may influence multiple aspects of female reproductive choices. 相似文献
17.
Melissa S. Gerald James Ayala Angelina Ruíz-Lambides Corri Waitt Alexander Weiss 《Die Naturwissenschaften》2010,97(1):89-96
Several primate species show sexual dichromatism with males displaying conspicuous coloration of the pelage or skin. Studies
of scrotal coloration in male vervet monkeys (Chlorocebus aethiops) suggest that it is an important intrasexual signal, with relatively dark, colourful males dominating paler males. To date,
no studies have examined the influence of male colour on intersexual social interactions in vervet monkeys. The primary goal
of the present study was to evaluate whether female vervet monkeys attend to male coloration. We experimentally introduced
females, housed with either “pale” or “dark” males, to stimulus males whose scrota were pale, dark, or pale but painted to
look dark. Overall, during introductions, females did not differ in time spent directing affiliative behaviour toward pale,
dark, and painted males; however, females, permanently housed with dark males, spent significantly more time directing affiliative
behaviour toward pale than painted males. When the stimulus male was pale, affiliative exchanges between males and females
were longer than when the stimulus male was painted. Home male colour was not related to female-initiated aggression. Home
male colour was also not related to male-initiated aggression, although painted stimulus males were more likely to initiate
aggression than pale stimulus males. These findings lead us to conclude that females pay attention to male coloration, but
do not bias their interactions toward males solely on the basis of natural male coloration. 相似文献
18.
It has been proposed that blue-green egg colours have evolved as a post-mating signal of female quality, selected by males
allocating their parental effort in response to the strength of this signal. We tested two main assumptions of the sexually
selected egg coloration hypothesis: (1) whether the intensity of eggshell blue-green chroma (BGC) reflects female quality;
and (2) whether males make their decisions on the level of parental care that they provide according to the intensity of eggshell
BGC. As a model species, we chose the facultatively polygynous great reed warbler (Acrocephalus arundinaceus). In this species, females simultaneously paired with the same male, compete for his nest attendance and could benefit from
signalling their quality through egg coloration. However, we found no association between the variation in eggshell BGC and
the measures of female quality (physical condition, mean egg volume and age). Moreover, great reed warbler males did not adjust
their investment (as measured in terms of nest defence against a brood parasite) in relation to the eggshell BGC. We conclude
that blue-green egg coloration in this open-nesting passerine is unlikely to have a signalling function. Rather, the large
colour variation among clutches of individual females may depend on yearly fluctuations in environmental conditions. 相似文献
19.
Differential migration has been extensively reported in spring, but less so in autumn, particularly in relation to sex in monomorphic bird species. Here, we analysed the autumn passage of a monomorphic, globally threatened passerine, the Aquatic Warbler Acrocephalus paludicola throughout Western Europe, with regard to age and sex. We showed that, overall, adults migrated earlier than first-year birds, and males migrated earlier than females during the autumn migration. This may be caused by an overall social dominance of adults over immatures, and differentiated migration strategy of males and females. In addition, we found male-skewed sex proportions, with a tendency to an equalised ratio in more southern stopover sites. This may indicate a male bias in the global population or different migration strategies of the sexes. Differential migration may cause the age and sex classes to be exposed differently to various threats affecting demographic structure of the species. 相似文献
20.
The relevance of the integration of preimaginal and eclosion experiences on the subsequent habitat preferences and mate finding
by the adult has been rarely tested in holometabolous insects. In this work, the effect of larval and early adult experiences
on the behavioural responses of adult males of the aphid parasitoid, Aphidius ervi, towards volatiles from the host–plant complex (HPC) and from conspecific females were evaluated. Two experience factors
were considered: host diet (normal diet=ND; artificial diet=AD), and eclosion, i.e. extraction or non-extraction of the parasitoid
larva from the parasitised aphid (extracted=EX; non-extracted=NE). Thus, four treatments were set up: ND/NE, ND/EX, AD/NE
and AD/EX. Glass Y-tube olfactometers were used to investigate the responses of adult A. ervi males to the odour sources used. Males from the ND/NE treatment showed a shorter latency to the first choice of olfactometer
arms, displayed a marked preference towards the HPC olfactometer arm, and spent more time in the HPC arm than males from the
other treatments. Only the interaction of host diet and eclosion experiences proved to be relevant in explaining the differences
in latency to first choice, time spent in olfactometers arms, and behaviours displayed in the olfactometer arms. These results
show the importance of the integration of larval and eclosion experiences in the development of stereotyped responses of the
adults. This process may involve memory retention from the preimaginal and emergence period, but further research is needed
to disentangle the contribution of each stage. The response to conspecific females was much less affected by the treatments
in relation to first arm choice and times in olfactometer arms, suggesting a pheromone-mediated behaviour, even though a prompter
and more intense wing fanning courtship behaviour was registered in the ND/NE males compared to males from the AD/NE treatment.
These results show that sexual behaviours are less affected by early experiences than behaviours related with finding a HPC
for foraging or oviposition. Taken together, our results demonstrate for first time that larval and eclosion experiences affect
in a differential way the early responses of the adult towards environment-derived cues and mate related cues. 相似文献