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1.
Males of the aphid hyperparasitoid Dendrocerus carpenteri (Curtis) were attracted by a sex pheromone released by conspecific females. The intensity of this cue, and thus female attractiveness,
depended both on the female's mating status and her age. Only virgin females younger than 2 h were consistently recognized
as mates by foraging males. Male age did not influence foraging and mating success. Empty mummies, from which females had
emerged within the previous 10 min were attractive to males and examined intensively. Rain reduced the searching success of
males, although the host plant Vicia faba provided sheltered places. Wind did not reduce mating success but prevented both sexes from leaving the host plant. Since
the time of female attractiveness seems to be very limited, wind may have an enormous effect on the mating success of D. carpenteri in the field and thus on the population dynamics of this species.
Received: 5 October 1998 / Accepted: 16 December 1998 相似文献
2.
Germ line transposition rates of the retrotransposon copia were directly measured in males and females of an inbred Drosophila melanogaster line, 2b3, which is highly polymorphic for copia insertion sites. The elevated germ line transposition rate of copia in this line (3–8 × 10−3 per generation per element) is confined to males, with transposition in females being undetectable under the conditions of
the experiment but at most 50-fold lower than the rate for males. To determine the molecular basis of this effect, copia RNA levels were measured in whole bodies and germ lines of male and female flies of both the unstable 2b3 line and a stable
line, Oregon RC-iso, which shows normal rates of copia transposition. Both male and female 2b3 flies contain much more copia RNA than flies of the stable line. However, 2b3 male germinal tissues contain much higher levels of copia RNA than the equivalent female tissues. The highest copia expression is detected in maturing primary spermatocytes. Our data show that high rates of germ line copia transposition are restricted to males by tissue-specific control of RNA levels and suggest that transposition of copia only occurs in fly tissues containing more than a relatively high threshold level of copia RNA.
Received: 8 October 1996 / Accepted: 7 January 1997 相似文献
3.
J. Stout J. Hao P. Kim D. Mbungu M. Bronsert S. Slikkers J. Maier D. Kim K. Bacchus G. Atkins 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1998,182(5):635-645
Juvenile hormone III (JHIII), when applied to the abdomen of 1-day-old female Acheta domesticus (in quantities that would create JHIII titers in the hemolymph that were within the range measured in females of this species)
caused a significant decrease in phonotactic thresholds (Fig. 1). Removal of the corpora allata from 5-day-old females with
low phonotactic thresholds caused significantly increased phonotactic thresholds 2–5 days later. After a temporary increase
(24 h) of, on average, about 25 dB, the phonotactic thresholds drop to about 10 dB above preallatectomy levels (Fig. 2), but
remain significantly higher than controls. Application of JHIII to allatectomized females, with a mean increase in thresholds
of 20 dB, results in significantly decreased thresholds (mean of about 20 dB) over the next 6 h (Fig. 3). Exposure to males
1 week before the imaginal molt causes the phonotactic thresholds of postimaginal females to drop 1–2 days significantly earlier
than controls (Fig. 4). One- and 3-day-old females, phonotactically tested only once, exhibit lower thresholds in the early
morning than they do in the late afternoon (Fig. 5). Five-day-old females do not exhibit such a diurnal rhythm. Phonotactically
testing females more than once a day significantly influences their phonotactic thresholds (Figs. 6, 7). In 1-day-old females,
with high (above 70 dB) phonotactic thresholds, the threshold of their L1 auditory interneurons can be 30 dB or more below
their phonotactic threshold (Fig. 8). In females with phonotactic thresholds of 70 dB or lower, the L1 threshold is within
10 dB of their phonotactic threshold. Both JHIII and allatectomy influence phonotactic and L1 thresholds in a similar manner.
Accepted: 29 September 1997 相似文献
4.
In species where males and females interact during mating, the role of females in sexual selection cannot always be demonstrated unambiguously. Here we present a model system to study female choice for mates. Orchesella cinca is a soil-dwelling hexapod with indirect sperm transfer. Females and males do not interact physically for reproduction. We gave females the choice between spermatophores produced by two different males. Paternity analysis based on microsatellite variation revealed that offspring in one clutch were sired by one male only. Direct observations showed that after a female has taken up a spermatophore, the female's receptivity to further spermatophore uptake seem to end. Our results imply that the female is in full control of paternity. 相似文献
5.
Some key aspects of the reproductive strategy of the brown trout (Salmo trutta fario L.) in the Yadong River, Tibet, including spawning season, age at sexual maturity, fecundity and egg size, have been studied.
The majority of the samples were less than 215 mm and age ranged from 1 to 4 in both sexes, indicating that the majority of
the fish were younger and the pressure by overfishing was high. The spawning periodicity was determined to be between the
end of October and January, mainly in November and December. The ratio of male to female brown trout population (1.29:1 with
P > 0.05) suggested no sex significant differences, although males were significantly more abundant than females in October
(P < 0.0001) on monthly basis. Age and size of males and females at maturity was different and males matured earlier than females.
Fecundity was markedly correlated with their body weight (P < 0.001, r = 0.9255), standard length (P < 0.01, r = 0.8879), and gonad weight (P < 0.001, r = 0.9366). The mean size of mature eggs in the spawning season was: 4.0 ± 0.45 mm and tended to increase along with the female
spawners size (P < 0.001, r = 0.9641). Further researches about the brown trout population in the Yadong River should be conducted on issues such as
artificial reproduction, culture, conservation, management, and restocking. 相似文献
6.
Saleh Mohammad Adnan Iffat Farhana Polychronis Rempoulakis Phillip W. Taylor 《Journal of Applied Entomology》2020,144(6):500-508
Pre-release dietary treatment with methoprene, a juvenile hormone analogue, decreases the age at which male Queensland fruit flies mature and hence may decrease the post-release delay until released sterile flies participate in sterile insect technique (SIT) programmes. However, if matings of young methoprene-treated males are not effective at inducing sexual inhibition in their mates, then this treatment may not enhance SIT. The present study investigates efficacy of matings of methoprene-treated males at inducing sexual inhibition in their mates. Methoprene incorporated into a diet of sugar and yeast hydrolysate (w/w 3:1) for 48 hr after emergence resulted in significantly increased male mating propensity when flies were <10 days of age, but not when older, and longer copulations. Copula latency did not vary with methoprene treatment but did decrease with age. The matings of young methoprene-treated males were effective at inducing sexual inhibition in their mates, matching the efficacy of untreated mature males. Regardless of treatment, females had reduced tendency to remate if their first mate was 15 days of age than if their first mate was younger (6, 8 days) or older (20, 25, 30 days). Females mated by methoprene-treated males that did remate tended to remate later in the day than females mated by untreated males. Also, second copula durations of females first mated by a 6- to 10-day-old male were shorter if the male was methoprene treated. These patterns in remating females may indicate greater efficacy of the initial mating of methoprene-treated males. Overall, we find that the additional matings of young methoprene-treated male Queensland fruit flies are effective at inducing sexual inhibition in their mates. This finding supports the incorporation of methoprene into pre-release diet for SIT. 相似文献
7.
The study was conducted to investigate the effects of dietary maternal selenomethionine or sodium selenite supplementation
on performance and selenium status of broiler breeders and their next generation. Two hundred and forty 39-week-old Lingnan
yellow broiler breeders were allocated randomly into two treatments, each of which included three replicates of 40 birds.
Pretreatment period was 2 weeks, and the experiment lasted 8 weeks. The groups were fed the same basal diet supplemented with
0.30 mg selenium/kg of sodium selenite or selenomethionine. After incubation, 180 chicks from the same parental treatment
group were randomly divided into three replicates, with 60 birds per replicate. All the offspring were fed the same diet containing
0.04 mg selenium/kg, and the experiment also lasted 8 weeks. Birth rate was greater (p < 0.05) in hens fed with selenomethionine than that in hens fed with sodium selenite. The selenium concentration in serum,
liver, kidney, and breast muscle of broiler breeders, selenium deposition in the yolk, and albumen and tissues' (liver, kidney,
breast muscle) selenium concentrations of 1-day-old chicks were significantly (p < 0.01) increased by maternal selenomethionine supplementation compared with maternal sodium selenite supplementation. The
antioxidant status of 1-day-old chicks was greatly improved by maternal selenomethionine intake in comparison with maternal
sodium selenite intake and was evidenced by the increased glutathione peroxidase activity in breast muscle (p < 0.05), superoxide dismutase activity in breast muscle and kidney (p < 0.05), glutathione concentration in kidney (p < 0.01), total antioxidant capability in breast muscle and liver (p < 0.05), and decreased malondialdehyde concentration in liver and pancreas (p < 0.05) of 1-day-old chicks. Feed utilization was better (p < 0.05), and mortality was lower (p < 0.05) in the progeny from hens fed with selenomethionine throughout the 8-week growing period compared with those from
hens fed with sodium selenite. In summary, we concluded that maternal selenomethionine supplementation increased birth rate
and Se deposition in serum and tissues of broiler breeders as well as in egg yolk and egg albumen more than maternal sodium
selenite supplementation. Furthermore, maternal selenomethionine intake was also superior to maternal sodium selenite intake
in improving the tissues Se deposition and antioxidant status of 1-day-old chicks and increasing the performance of the progeny
during 8 weeks of post-hatch life. 相似文献
8.
This study examines how Choristoneura rosaceana male quality, as determined by larval diet, age and mating history, affects the reproductive success of both sexes. While the size of the spermatophore produced at first mating increased linearly with male age, the frequency of mating was significantly higher for middle-aged males (2–4 days old) than younger (0–2 days old) or older (6–8 days old) individuals, when both sexes were fed on artificial diet. However, the duration of copulation was longer in couples with older than younger males. The observed age-related changes in spermatophore size had no significant effect on female longevity, fecundity or fertility, suggesting no direct relationship between male investment and spermatophore size under these experimental conditions. Different larval food sources (artificial diet, maple and hazelnut) did not affect the proportion of 2-day-old virgin males that mated; however, the proportion that remated was significantly higher for males reared on high-quality food (maple and artificial diet) than those on hazelnut, a poorer food source. There was a 5-fold decline in spermatophore size between the first and second matings on all diets, but female reproductive output was reduced by only 25%. In contrast, while the first spermatophore produced by males on hazelnut was 1.5 times smaller than those produced on maple and artificial diet, the fecundity of their mates was 40% less than those mated with high-quality virgin males. These results provide additional support to the idea that spermatophore size is not a valuable indicator of male quality. Most tethered females placed in the field during the first flight period mated with virgin males (based on the size of the spermatophore), suggesting that female choice exists in this species. These results are discussed in relation to the incidence of polyandry in naturally occurring populations of Choristoneura and the potential use of size and/or chemical cues by females to assess male quality. 相似文献
9.
Animals of many species prefer some partners over others. Discriminating among potential mates causes strong sexual selection
that shapes characters and behaviors. In bushcrickets the sexes shows different latencies to remate due to differences in
investment in production of the nuptial gift by males and the induced refractory period in females. We conducted experiments
with the Australian bushcricket Kawanaphila mirla to test the variation in male mating success by female choice.
Male remating intervals under unlimited access to food and mates were around two days, whereas most females did not remate
within 12 days. Males had therefore a much shorter “time-out” from mating than females. The adult sex ratio from field samples
was near to 1:1. Consequently, the OSR was male-biased with more males than females ready to mate. This male-biased OSR led
to mating competition in males and choosiness in females. In a field enclosure with unlimited supply of receptive females
the number of matings varied widely between males, with twenty percent of males neglected by the females. The number of matings
within this enclosure was neither related to male size nor to song characters, recorded previously in the lab. However, the
number of matings by individual males was positively correlated to the size of their spermatophore producing accessory gland.
Females appear to prefer males with a large nutritive donation, thereby receiving a direct fitness benefit. 相似文献
10.
Male katydids (Orthoptera: Tettigoniidae) invest in offspring through nutrients provided in a large spermatophore. Previous research with Requena verticalishad shown that almost all of the investment of males mating with recently mated (4 days previously) females is in eggs fertilized by the female's previous mate. Thus males are predicted to discriminate against such females as mates. In experiments placing males with both a virgin and a female mated 4–5 days previously, virgin females obtained almost all matings. Although male discrimination of mates was noted in the experiments, there was no evidence that such discrimination was against nonvirgins in both this experiment and one in which a single virgin or mated female was placed with a male. Instead, the results suggest that the differential mating was a result of interfemale competition. The mating advantage held by virgin females over nonvirgins appeared to be lost once the latter had oviposited. Finally, there was no evidence from both single- and paired-female experiments that males preferred larger females as mates. 相似文献
11.
Blaszkowska J 《Cell biology and toxicology》2008,24(3):213-224
Chymotrypsin inhibitor isolated from Ascaris suum (ACHI) was tested for the induction of dominant lethal mutations in male mice. Dominant lethal effects of ACHI for the main
stages of germ cell development were analyzed by mating at specific time points after dosing. Two groups of adult BALB/c males
received 24 or 40 mg per kilogram body weight (BW) per day intraperitoneal (IP) injection of ACHI in sterile phosphate-buffered
saline (PBS) for five consecutive days (subacute exposure). Males from a third group were administered single IP injections
of ACHI—60 mg/kg BW (acute exposure). The control group received concurrent injections of PBS for five successive days. After
the last dose, each male was mated with two untreated females. For fractionated examination with regard to successive germ
cell stages (spermatozoa, spermatids, spermatocytes, spermatogonia), every second week, two other untreated virgin females
were placed with each male for mating. The uteri of the females were inspected on the 15th day of gestation, and preimplantation
loss and postimplantation loss determined from dominant lethal parameters. Exposure of mice germ cells to ACHI did not impair
mating activity of males. Fertility index was reduced (P < 0.05) only for females mated at the third week with males exposed to the highest dose of ACHI. In the females bred to ACHI-treated
males, significant (P < 0.05) increase in preimplantation loss was observed at postinjection weeks 1 (reflecting exposure to spermatozoa after
single treatment and to spermatozoa or late spermatids after subacute dosing) and 3 (reflecting exposure to mid and early
spermatids for acute dosing and to mid and early spermatids or late spermatocytes following acute treatment), regardless of
dose and length of exposure to the inhibitor. At the 60-mg/kg-BW group, a significant increase of this parameter was also
noted at week 5 (reflecting exposure to early spermatocytes). During mating days 15–21, a significant (P < 0.05) increase in postimplantation loss and dominant lethal effects were observed for all doses of ACHI. Acute ACHI exposure
5 weeks prior to mating resulted in dominant lethal effects in early spermatocytes. These preliminary data suggest that ACHI
induces dominant lethal mutations at postmeiotic and meiotic stages of spermatogenesis, but spermatids are the most sensitive
cell stage to the effect of ACHI. These results show that ACHI may be one of the factors causing disturbances in spermatogenesis
leading to a reduction of host reproductive success. 相似文献
12.
Jianguo Lai Bo Chen Hsiaopei Mok Guochun Zhang Chongyang Ren Ning Liao 《Journal of cellular and molecular medicine》2020,24(16):9145-9153
Accumulating evidence revealed that autophagy played vital roles in breast cancer (BC) progression. Thus, the aim of this study was to investigate the prognostic value of autophagy‐related genes (ARGs) and develop a ARG‐based model to evaluate 5‐year overall survival (OS) in BC patients. We acquired ARG expression profiling in a large BC cohort (N = 1007) from The Cancer Genome Atlas (TCGA) database. The correlation between ARGs and OS was confirmed by the LASSO and Cox regression analyses. A predictive model was established based on independent prognostic variables. Thus, time‐dependent receiver operating curve (ROC), calibration plot, decision curve and subgroup analysis were conducted to determine the predictive performance of ARG‐based model. Four ARGs (ATG4A, IFNG, NRG1 and SERPINA1) were identified using the LASSO and multivariate Cox regression analyses. A ARG‐based model was constructed based on the four ARGs and two clinicopathological risk factors (age and TNM stage), dividing patients into high‐risk and low‐risk groups. The 5‐year OS of patients in the low‐risk group was higher than that in the high‐risk group (P < 0.0001). Time‐dependent ROC at 5 years indicated that the four ARG–based tool had better prognostic accuracy than TNM stage in the training cohort (AUC: 0.731 vs 0.640, P < 0.01) and validation cohort (AUC: 0.804 vs 0.671, P < 0.01). The mutation frequencies of the four ARGs (ATG4A, IFNG, NRG1 and SERPINA1) were 0.9%, 2.8%, 8% and 1.3%, respectively. We built and verified a novel four ARG–based nomogram, a credible approach to predict 5‐year OS in BC, which can assist oncologists in determining effective therapeutic strategies. 相似文献
13.
The growth rate, reproductive aspects, and natural mortality of chimaeras and ratfish are poorly known. In this study, life-history
parameters for cockfish Callorhinchus callorhynchus (Holocephali—Callorhinchidae) are estimated, which is an important fish resource exploited in Chile. Specimens were sampled
from the artisanal fishery captures, from November 2006 to November 2007. The standard length (SL) of males fluctuated between
20 and 62 cm, and between 21 and 70 cm for females. Von Bertalanffy growth parameters were estimated through length-frequency
data analysis using MULTIFAN. The length-weight relationship and von Bertalanffy growth parameters were significantly different
for males and females, as well as the length at 50% maturity. For males a model with 5 age-classes was the best, with asymptotic
length L
∞ = 52 cm SL, growth coefficient K = 0.473 yr−1, and age at length zero t
0 = −0.690 yrs. For females the best model was represented by 10 age-classes (L
∞ = 70.3 cm SL, K = 0.193 yr−1, t
0 = −1.158 yrs) in the length-frequency data sets. Length at 50% maturity of males was estimated in 43.7 cm SL, and in 50.2 cm
SL for females. The natural mortality rate fluctuated between 0.42 and 0.82 yr−1 for males and between 0.12 and 0.37 yr−1 for females, depending upon the method used. It is concluded that C. callorhynchus is a species with life-history parameters significantly different between males and females, and such differences should
be taken into account in future population dynamics analysis. 相似文献
14.
Beob G. Kim Merlin D. Lindemann Gary L. Cromwell 《Biological trace element research》2010,133(2):181-196
We investigated the effects of supplemental chromium (Cr) as Cr (III) picolinate on pigs fed high-fat diets (HFD) in a 56-day
experiment. Thirty-two crossbred pigs (9.6 kg) were allotted to four treatments with four blocks and two pigs/pen. Treatments
included: (1) low-fat diet (fat < 3.5%; LFD) with no Cr, (2) HFD (fat > 30%) with no Cr, (3) HFD with 1,000 ppb Cr, and (4)
HFD with 2,000 ppb Cr. Pigs fed HFD gained weight faster, consumed less, and had lower feed:gain (p < 0.05). Pigs fed HFD had higher respiration rates than pigs fed LFD on d 41 (p < 0.05). Plasma insulin on d 14 linearly decreased with Cr (p = 0.05). Plasma cholesterol concentrations were higher in the pigs fed HFD than those fed LFD, but were largely unaffected
by supplemental Cr. Consumption of HFD resulted in greater carcass weight, perirenal fat, and backfat measures (p < 0.01) compared with the LFD group. Cr resulted in linear reductions of hot carcass weight (p = 0.08) and average backfat (p < 0.05). The effects of Cr on carcass fat measures were more pronounced in castrated males than in females. These results
indicate that Cr attenuates some effects of a HFD, mainly body fat accretion of pigs, and especially in castrated pigs. 相似文献
15.
Naoki Yagishita Yoshiaki Kai Atsushi Yamasaki Tetsuji Nakabo 《Ichthyological Research》2007,54(2):198-206
Morphological and genetic differences between red and yellow morphotypes of Sebastes owstoni were investigated, utilizing 277 males [84.0–194.3 mm in standard length (SL)] and 542 females (92.3–251.5 mm SL) from the
Sea of Japan. All males smaller than 120 mm SL were characterized by red body color. The frequency of specimens with yellow
body color thereafter increased gradually with SL, all specimens larger than 170 mm SL being yellow. The specimens with yellow
body color were observed throughout the year. All females smaller than 170 mm SL were characterized by red body color, the
frequency of specimens with yellow body color tending to slightly increase with SL. However, most females had red body color,
except for 16 specimens (177.7–241.5 mm SL) that were yellow, growth-related color change from red to yellow being uncommon.
Morphological analysis of 49 males (107.6–193.3 mm SL) and 68 females (108.7–241.5 mm SL) showed the head length, orbit diameter,
lower jaw length, and predorsal length to be relatively greater, but the distance between the pelvic and anal fins less, in
males. A discriminant analysis using Mahalanobis distances resulted in 100% correct assignment of specimens to sex, regardless
of SL and body color. In addition, no genetic differences were apparent between red and yellow individuals in mitochondrial
DNA sequence analyses from the threonine tRNA to the first half of the control region (498 bp). Accordingly, the differences
in body color, maximum size, and the five morphometric characters listed above were considered to represent sexual dimorphism.
That evidenced by body color was considered to appear after that shown by morphometric characters, some exceptions in the
former occurring in females. This is the first report of permanent sexual dimorphism in body color in Sebastes. 相似文献
16.
The proportion of mated females (M f) of the osmund sawfly, Strongylogaster osmundae, and the sex ratio of the eggs they deposited (r, proportion of males) were estimated in the wild by collecting egg masses. The proportion of mated females at oviposition varied from 0 to 1.0. M f was high (often 1.0) among the females that emerged after hibernation, and lower in the subsequent generations. Mated females of the hibernated generation deposited equal numbers of eggs of both sexes. Mated females of the first and subsequent generations produced more female than male eggs. These results qualitatively agreed with the prediction provided by an evolutionarily stable strategy (ESS) model (if M f < 1 then r < 0.5). However, the quantitative prediction provided by the model [M f (1 − r) = 0.5] was not always observed in the wild, especially where the population density and M f were high. The value of r was often lower than the predicted one. The following simple hypothesis was tested by experimentation: “Females that encounter males frequently estimate the proportion of mated females to be high and deposit eggs with a 1:1 sex ratio.” However, results did not support this hypothesis. Females that copulated soon after emergence and were courted by males two or more times did not show a higher offspring sex ratio than those which mated 1 or 2 days after emergence and experienced no other sexual encounter. Another mechanism for determination of r is suggested, and the reason why the population sex ratio of sawflies is often female-biased (r < 0.5) is discussed. 相似文献
17.
Schizopygopsis younghusbandi younghusbandi is an endemic species whose distribution is restricted to the middle reaches of the Yarlung Zangbo River, being one of the
most important commercial fishes in this area. Age and growth of 606 specimens captured between October 2002 and April 2005
were studied. The range in standard length (L) was 65.7–387.3 mm and total weight (W) was 3.3–772.0 g. The relationship between
L and W was W = 0.000909L2.2493 for males and W = 0.000259L2.4781 for females. Age, determined from anal scales and lapillus otoliths, ranged from 3 to 18 years. The parameters of von Bertalanffy
growth functions, estimated by back-calculated length, were L¥ = 442.7mm LL_\infty = 442.7mm\;L, k = 0.0738 year−1 and t
0
= −1.4 year for males, and L¥ = 471.4mm LL_\infty = 471.4mm\;L, k = 0.0789 year−1 and t
0 = 0.2 year for females. Males and females exhibited statistically significant differences in growth. χ
2-test indicated that von Bertalanffy growth functions could well describe the growth of S. y. younghusbandi. The longevities were 39.2 and 38.2 years for males and females, respectively. Growth inflexion points were 10.2 and 12.0 years
for males and females, respectively, but 84.8% of the captures were at the smaller ages. So conservation and management schemes
for this population should be considered urgently. In addition, we found that populations from the upstream of the Lhasa River,
the downstream of the Lhasa River and the middle reaches of the Yarlung Zangbo River showed statistically significant differences
in growth patterns. 相似文献
18.
Deficiencies in Cu, Se, and Zn impair one or more biochemical functions, and excess are associated with toxicity. Baseline
studies on the Ghanaian population are scanty. The study was undertaken to determine whether significant rural/urban differences
in the serum levels of Cu, Se, and Zn did exist. Forty males/60 females from rural and 50 males/50 females from urban Ghanaian
communities were sampled. Serum Cu, Se, and Zn were determined using flame atomic absorption spectrometry. Cu level for rural
and urban subjects was 997 ± 333 and 979 ± 290 μg/L, respectively (p = 0.68). However, Cu levels were significantly higher in the rural females (1,063 ± 367 μg/L) than the rural males (898 ± 249 μg/L;
p = 0.0085). Se levels for rural/urban subjects were 97 ± 36 and 87 ± 31 μg/L, respectively (p = 0.03). Zn levels in the rural/urban subjects were 312 ± 218 and 150 ± 102 μg/L, respectively (p = 0.002). Additionally, Zn was significantly higher in rural females (428 ± 204 μg/L) than the urban females (166 ± 103 μg/L;
p = 0.0002). Finally, Zn was significantly higher in rural females (428 ± 204 μg/L) than males (172 ± 116 μg/L; p = 0.0028). In conclusion, Cu, Se, and Zn were higher in the rural group compared to the urban group, and the generally low
Zn levels were confirmed in another cohort follow-up study. 相似文献
19.
Seasonal Variation in Mate Choice of Photinus ignitus Fireflies 总被引:2,自引:1,他引:1
Christopher K. Cratsley & Sara M. Lewis† 《Ethology : formerly Zeitschrift fur Tierpsychologie》2005,111(1):89-100
Mate choice by either sex may vary with changes in the associated costs and benefits, determined by factors such as the availability of potential mates and variation in mate quality. We examined seasonal variation in operational sex ratio, courtship behavior, spermatophore mass, egg count, and the relationship between morphological traits and mating success in Photinus ignitus fireflies to determine if mate choice in either sex varied with the availability and relative reproductive investment of fertilizable females and sexually active males. Successfully mating males had larger lanterns than unsuccessful males when the operational sex ratio was male‐biased. In addition, female responsiveness to male signals increased as the number of courting males decreased, and male spermatophore mass decreased with body size across the mating season. Successfully mating females had larger body mass than unsuccessful females. Female body mass predicted egg count and female rejection by males increased as the season progressed and female size decreased. These results suggest that both male and female P. ignitus exhibit mate choice, and that such choice is influenced by seasonal variation in the abundance and quality of potential mates. 相似文献
20.
The aim of this study was to describe growth, determine age at sexual maturity and investigate the condition of bearded seals
(Erignathus barbatus) collected in the fjords of Spitsbergen, Svalbard, Norway. Morphometric data, teeth and sex organs were collected from 110
animals. Age was determined by reading the cementum layers in hard longitudinal sections of canine teeth. Sexual maturity
in males was determined according to the size of the testes and bacula. Females were defined as being sexually mature according
to findings of mature follicles or corpora lutea/albicantia. Von Bertalanffy growth curves were applied to both standard length and body mass, and asymptotic values for males and females
were 231.1 ± 11.4 cm and 269.9 ± 26.2 kg, and 233.1 ± 7.5 cm and 275.3 ± 47.8 kg, respectively. Maximum recorded lengths and
masses were 254 cm and 313 kg in males and 242 cm and 358 kg in females. All males older than 6 years were found to have been
sexually mature. Females were found to attain sexual maturity at about 90% of the asymptotic length, corresponding to an age
of 5 years. In males a significant decrease in condition was observed from June to August, with a subsequent increase in September.
In adult females, condition decreased from May to June and increased again from June to September. The conditional changes
seen are likely to be due to the extra energetic cost and reduced food intake associated with reproduction, lactation and
molt.
Accepted: 28 July 1998 相似文献