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1.
Mohammad Mahmudur Rahman Gary Owens Ravi Naidu 《Environmental geochemistry and health》2009,31(Z1):179-187
Chronic exposure to arsenic (As) causes significant human health effects, including various cancers and skin disorders. Naturally
elevated concentrations of As have been detected in the groundwater of Bangladesh. Dietary intake and drinking water are the
major routes of As exposure for humans. The objectives of this study were to measure As concentrations in rice grain collected
from households in As-affected villages of Bangladesh where groundwater is used for agricultural irrigation and to estimate
the daily intake of As consumed by the villagers from rice. The median and mean total As contents in 214 rice grain samples
were 131 and 143 μg/kg, respectively, with a range of 2–557 μg/kg (dry weight, dw). Arsenic concentrations in control rice
samples imported from Pakistan and India and on sale in Australian supermarkets were significantly lower (p < 0.001) than in rice from contaminated areas. Daily dietary intake of As from rice was 56.4 μg for adults (males and females)
while the total daily intake of As from rice and from drinking water was 888.4 and 706.4 μg for adult males and adult females,
respectively. From our study, it appears that the villagers are consuming a significant amount of As from rice and drinking
water. The results suggest that the communities in the villages studied are potentially at risk of suffering from arsenic-related
diseases. 相似文献
2.
A. Cornils S. B. Schnack-Schiel M. Böer M. Graeve U. Struck T. Al-Najjar C. Richter 《Marine Biology》2007,151(4):1261-1274
A total of 12 feeding experiments were conducted in the northern Gulf of Aqaba during spring (March/April) and autumn (September/October)
2002 at the Marine Science Station (MSS) in Aqaba. Females of three species of clausocalanids were selected: Clausocalanus
farrani, C. furcatus and Ctenocalanus vanus. Natural occurring particle (NOP) larger than 5 μm were investigated as food source. The ambient chlorophyll a concentration at sampling depth (∼70 m) ranged between 0.15 and 1.00 μg chl a l−1 and NOP concentrations ranged between 1.78 and 14.0 × 103 cells l−1 during the sampling periods. The division of particles into five size classes (5–10, 10–20, 20–50, 50–100 and >100 μm) revealed
that most of the particles were found in the size classes below 50 μm (81–98%), while most of the natural occurring carbon
(NOC) was concentrated in the size classes larger than 20 μm (70–95%). Ingestion rates were food density dependent rather
than size dependent ranging between 0.02 and 1.65 × 103 NOP ind−1 day−1 and 0.01 and 0.41 μg NOC ind−1 day−1, respectively, equivalent to a body carbon (BC) uptake between 0.4 and 51.8% BC day−1. The share of the size classes to the total ingestion resembled in most cases the size class composition of the natural particle
community. 相似文献
3.
An assessment of exposure to mercury in Changchun city has been undertaken. We estimated Hg exposure to members of the general population based on currently available information and our research. We also studied the Hg concentrations in scalp hair of adults. Adults have an estimated intake of all Hg species via all routes of 6.780 μg day−1 (excluding dental amalgam), which equates to an absorbed dose of 1.718 μg day−1. Fish consumption was the most important exposure route (12% of intake, 43% of absorbed dose). Furthermore, air, cereals and vegetables were important exposure routes, and these exposure were estimated for absorbed dosed at 0.296, 0.209 and 0.318 μg day−1, respectively. The mean Hg concentration in hair was 0.448 μg g−1 (range 0.092–10.463 μg g−1). Hg concentration in the hair of males was 0.422 μg g−1 (0.105–2.665 μg g−1), and was 0.474 μg g−1(0.092–10.463 μg g−1) in the hair of females. Neither place of residence nor age had any significant effect on hair Hg concentrations. 相似文献
4.
Paul R. D. Wright Robin Rattray Gerald Lalor Richard Hanson 《Environmental geochemistry and health》2010,32(6):567-581
Elevated concentrations of naturally occurring Cd have been found mainly in the bauxitic soils of central Jamaica at levels
up to 100–1,000 times higher than typical worldwide averages. Some food crops cultivated on these soils absorb significant
amounts of Cd. Autopsy studies of kidney Cd concentrations confirm elevated human exposure, and some long-term residents in
central Jamaica exceed the general population average by a factor of two. Diet studies have ascertained that a population
in central Jamaica is at risk of being exposed to Cd levels in excess of the Provisional Tolerable Weekly Intake (PTWI) set
by the WHO of 7 μgCd/kg bodyweight/week, and the EU TWI of 2.5 μgCd/kg bodyweight/week. Elevated levels of urine cadmium (U-Cd)
and beta-2 microglobulin (β2-MG) concentrations were confirmed with a strong correlation between soil Cd and the U-Cd. Also,
higher β2-MG concentrations (>200μg/g creatinine) were found in the population with U-Cd concentrations greater than 2.5μg/L.
While this identification is often taken to indicate impairment in the reabsorption capacity of the renal tubules leading
to renal disease, there is no evidence in the mortality records of enhanced deaths in central Jamaica compared with the general
population resulting from renal disease or diabetes related complications. The highest median age of death in the island is
found in Manchester, the parish with the highest average Cd concentration. While we have identified a possible Cd linked renal
dysfunction, significant indications of morbidity are not present in the general population. 相似文献
5.
Parental care may be costly to parents because it decreases resources allocated to self-maintenance and may thus reduce survival
and future reproductive success. An inter-sexual conflict may exist in animals with obligatory bi-parental care, such as birds
of prey, in which females incubate and brood, whereas males provision food for their families. We analysed 29 years of data
(1981–2009) from a study population of Tengmalm’s owls Aegolius funereus in western Finland to examine the occurrence and timing of brood desertion and sequential polyandry, and recorded a total
of 1,123 monogamous and 12 polyandrous females. These data were supplemented with the 29-year nationwide Finnish ringing data,
which included 11,590 monogamous and 20 polyandrous females. The 12 polyandrous females started egg-laying in their two nests
at intervals of 54–68 days (mean 60 days), thus deserting their first broods when the age of oldest young averaged 21 days.
Thirty-two polyandrous females re-mated and raised a second brood at a median distance of 4.5 km (range 1–196 km). These females
produced 79% more eggs, 93% more hatchlings and 73% more fledglings than did females that laid simultaneously but remained
monogamous. Our results show that not only males, but also females of altricial species with bi-parental care can increase
their fitness by deserting their first brood when it will be cared for by the males. Earlier studies have shown that male
owls can increase their lifetime reproductive success by simultaneous polygyny, and we suggest that an inter-sexual “tug-of-war”
over bi-parental care exists in Tengmalm’s owls. 相似文献
6.
A. H. M. Selim Reza Jiin-Shuh Jean Huai-Jen Yang Ming-Kuo Lee Hua-Fen Hsu Chia-Chuan Liu Yao-Chang Lee Jochen Bundschuh Kao-Hong Lin Chi-Yu Lee 《Environmental geochemistry and health》2011,33(3):235-258
Humic substances in groundwater and aquifer sediments from the arsenicosis and Blackfoot disease (BFD) affected areas in Bangladesh
(Bengal delta plain) and Taiwan (Lanyang plain and Chianan plain) were characterized using fluorescence spectrophotometry
and Fourier transform infrared (FT-IR) spectroscopy. The results demonstrate that the mean concentration of As and relative
intensity of fluorescent humic substances are higher in the Chianan plain groundwater than those in the Lanyang plain and
Bengal delta plain groundwater. The mean As concentrations in Bengal delta plain, Chianan plain, and Lanyang plain are 50.65 μg/l
(2.8–170.8 μg/l, n = 20), 393 μg/l (9–704 μg/l, n = 5), and 104.5 μg/l (2.51–543 μg/l, n = 6), respectively. Average concentrations and relative fluorescent intensity of humic substances in groundwater are 25.381 QSU
(quinine standard unit) and 17.78 in the Bengal delta plain, 184.032 QSU and 128.41 in the Chianan plain, and 77.56 QSU and
53.43 in the Lanyang plain. Moreover, FT-IR analysis shows that the humic substances extracted from the Chianan plain groundwater
contain phenolic, alkanes, aromatic ring and amine groups, which tend to form metal carbon bonds with As and other trace elements.
By contrast, the spectra show that humic substances are largely absent from sediments and groundwater in the Bengal delta
plain and Lanyang plain. The data suggest that the reductive dissolution of As-adsorbed Mn oxyhydroxides is the most probable
mechanism for mobilization of As in the Bengal delta plain. However, in the Chianan plain and Lanyang plain, microbially mediated
reductive dissolution of As-adsorbed amorphous/crystalline Fe oxyhydroxides in organic-rich sediments is the primary mechanism
for releasing As to groundwater. High levels of As and humic substances possibly play a critical role in causing the unique
BFD in the Chianan plain of SW Taiwan. 相似文献
7.
A suite of characteristics is often used to assess egg quality as these properties potentially play important roles in progeny survival and growth. Our objective was to assess egg characteristics including lipid biocomposition of an iteroparous, batch-spawning teleost of wild origin. Maternal allocation to egg number was generally dome-shaped (5 of 8 females) and egg size declined over the breeding season for eight breeding pairs of wild Atlantic cod (Gadus morhua) (n = 43 batches). Egg lipid composition ranged considerably among females and between egg batches within females (e.g., phospholipids 40–86 %; polar 47–87 % and neutral lipids 15–52 % of total lipids; polyunsaturated fatty acids 16–50 % of total fatty acids). Principal component analyses revealed significant inter-relationships among maternal traits, batch sequence and fecundity, and egg size and composition. Seasonal trends with regard to lipid deposition were variable; three females showed consistent declines in lipid parameters (μg egg−1) with both batch number and egg diameter, one female showed consistent increase and the four remaining females showed no trend. The three females that exhibited seasonal declines in egg lipid content were characterized as having high fertilization success (>75 %). Our findings highlight the variability in lipid allocation to eggs of batch spawners of wild origin and characterize the composition of endogenous reserves available during embryogenesis and yolk sac larval stages. 相似文献
8.
The Salí River Basin in north-west Argentina (7,000 km2) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by fluvial and
aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality
problems, including arsenic (concentrations in the range of 12.2–1,660 μg L−1), fluoride (50–8,740 μg L−1), boron (34.0–9,550 μg L−1), vanadium (30.7–300 μg L−1) and uranium (0.03–125 μg L−1). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep (>200 m) and artesian groundwater
in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate
concentrations (50.0–1,260 mg L−1) and pH (6.28–9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although
sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the
aquifers. In addition, concentrations of chromium lie in range of 79.4–232 μg L−1 in shallow groundwater, 129–250 μg L−1 in deep groundwater and 110–218 μg L−1 in artesian groundwater. All exceed the WHO guideline value of 50 μg L−1. Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions. 相似文献
9.
Ping Li Xinbin Feng Guangle Qiu Lihai Shang Guanghui Li 《Environmental geochemistry and health》2009,31(6):683-691
The total mercury (T-Hg) and methyl mercury (Me-Hg) concentrations in the hair were measured to evaluate mercury (Hg) exposure
for the residents in Da-shui-xi Village (DSX) and Xia-chang-xi Village (XCX) in the Wanshan Hg mining area, Guizhou Province,
Southwestern China. The mean concentrations in the hair of DSX residents were 5.5 ± 2.7 μg/g and 1.9 ± 0.9 μg/g for T-Hg and
Me-Hg, respectively. The concentrations in the hair of XCX residents were 3.3 ± 1.4 μg/g and 1.2 ± 0.5 μg/g for T-Hg and Me-Hg,
respectively. Hair Me-Hg concentrations were significantly correlated to T-Hg (r = 0.42, P < 0.01) in the two sites; on average, hair Me-Hg concentration accounted for 40 and 44% of T-Hg for DSX and XCX residents,
respectively. Age has no obvious correlation with hair Hg and the hair Hg levels showed a significant gender difference, with
higher T-Hg and Me-Hg concentrations in the hair from males than females. The rice collected from the two sites showed high
levels of T-Hg and Me-Hg concentration. The results indicated a certain Hg exposure for the residents in DSX and XCX in the
Wanshan Hg mining area. 相似文献
10.
Cecily M. Costello Scott R. Creel Steven T. Kalinowski Ninh V. Vu Howard B. Quigley 《Behavioral ecology and sociobiology》2009,64(1):125-134
We determined annual male reproductive success in black bears (Ursus americanus) using DNA and field data from two populations in New Mexico. We identified the likely father for 78 of 120 genotyped cubs
born during 1994–2000 and calculated reproductive success for 102 males known or presumed present within designated mating
regions. Age was a strong determinant of reproductive success. The observed peak in reproductive success occurred at roughly
the same intermediate age (10 years) as milder peaks in body size characteristics (11–12 years) and frequency of bear-inflicted
wounds (13 years), suggesting body size and fighting might be important for mating. Success was negatively associated with
the distance between home range centers of males and mothers. Success of young males (<7 years old) was also negatively associated
with mature male (≥7 years old) density, and increasing density shifted the peak age of reproduction higher. The dispersed
distribution of females likely limited the capacity of large mature males to dominate reproduction; therefore, success was
determined by a complex set of variables. 相似文献
11.
For the first time, gender-related differences in some important functional parameters of haemocytes from the clam Ruditapes philippinarum have been studied. Clams were collected during the pre-spawning phase, when sex can be distinguished by microscopic observation
of gonadal smears, in order to ascertain whether the two sexes reach the stressful spawning period with different degrees
of immunosurveillance. Total haemocyte count (THC), haemocyte size frequency distribution, capability of haemocytes to assume
the vital dye neutral red (NR, indicative of endocytotic activity), lysozyme-like and acid phosphatase activities in both
haemocyte lysate (HL) and cell-free haemolymph (CFH), and superoxide dismutase (SOD) and catalase (CAT) activities in HL were
all evaluated. No differences in THC values were found between the two sexes, but differing haemocyte size frequency distributions
were observed: the fraction of larger haemocytes (7–9 μm diameter, 200 fl volume) was markedly increased in females and that
of smaller haemocytes (<5 μm diameter, <200 fl volume) markedly increased in males. Interestingly, when haemocytes were observed
under the light microscope, a significantly higher percentage of granulocytes was found in haemolymph from females, compared
with that of males. Significantly increased NR uptake was recorded in female haemocytes. No significant variation in lysozyme-like
activity was observed in HL, whereas in CFH, enzyme activity was significantly higher in females. HL acid phosphatase activity
was significantly higher in males with respect to females; no significant variations in enzyme activity were observed in CFH.
HL SOD and CAT activities were significantly higher in females than in males. Overall, on the basis of the cell parameters
studied here, gender-related differences in immune parameters were found in R. philippinarum, indicating that females have more active haemocytes than males during the pre-spawning period. 相似文献
12.
Increasing threats to deep-sea corals highlight the need to expand knowledge of these taxa so that conservation measures can
be developed. The present study focused on the reproductive patterns of the deep-sea solitary coral Flabellum angulare. A series of samples (n = 398) collected in 2006–2008 in the northwest Atlantic at depths of 925–1,430 m revealed that gametogenesis was synchronous
among males and females and fluctuated seasonally. Initiation of gamete synthesis was estimated to be in August–September
and spawning in June. Further analysis and daily monitoring of 30–60 individuals maintained in a flow-through mesocosm showed
that gamete release occurred in March–June with a peak in May. Release of oocytes coincided with rising seawater temperatures
and high deposition rates indicative of elevated water column productivity. Oocytes (900–1,200 μm diameter) were released
through the oral cavity, generally in bundles of 3–5 surrounded by mesenterial filaments and attached to a thread (30–50 mm
long). As oocytes became free in the water column, ovulation occurred followed by fertilization. Eggs/embryos initially remained
on the tentacles of the spawner before either falling onto the substratum or floating to the surface. The embryos developed
into planula larvae measuring 2–3 mm in length within about 24 h. Together, these findings shed new light on the strategies
used by deep-sea corals to maximize their reproductive success. 相似文献
13.
Most social primates live in cohesive groups, so travel paths inevitably reflect compromise: decision processes of individuals
are obscured. The fission–fusion social organisation of the chimpanzee, however, allows an individual's movements to be investigated
independently. We followed 15 chimpanzees (eight male and seven female) through the relatively flat forest of Budongo, Uganda,
plotting the path of each individual over periods of 1–3 days. Chimpanzee movement was parsed into phases ending with halts
of more than 20 min, during which individuals fed, rested or engaged in social activities. Males, lactating or pregnant females
and sexually receptive females all travelled similar average distances between halts, at similar speeds and along similarly
direct beeline paths. Compared to lactating or pregnant females, males did travel for a significantly longer time each day
and halted more often, but the most striking sex differences appeared in the organisation of movement phases into a day's
path. After a halt, males tended to continue in the same direction as before. Lactating or pregnant females showed no such
strategy and often retraced the preceding phase, returning to previously visited food patches. We suggest that female chimpanzee
movements approximate an optimal solution to feeding requirements, whereas the paths of males allow integration of foraging
with territorial defence. The ‘continually moving forwards’ strategy of males enables them to monitor their territory boundaries—border
checking—whilst foraging, generally avoiding the explicit boundary patrols observed at other chimpanzee study sites. 相似文献
14.
Female distribution affects mate searching and sexual selection in male northern water snakes (Nerodia sipedon) 总被引:2,自引:0,他引:2
Mating systems and sexual selection are assumed to be affected by the distribution of critical resources. We use observations
of 312 mating aggregations to compare mate-searching success of male northern water snakes (Nerodia sipedon) in two marshes in which differences in mating substrate availability resulted in more than fourfold differences in female
dispersion. Reproductive males had significantly larger home ranges where females were dispersed than where females were clumped.
The number of females encountered by males increased significantly with male home range size where females were dispersed,
and decreased significantly where females were clumped. Where females were clumped, males were more likely to encounter other
males when they located females. We found no evidence in either population that mate searching was energetically expensive
or that males with relatively more energy had larger home ranges. However, males with greater fat reserves at the start of
the season participated in more mating aggregations when females were dispersed, suggesting that fat reserves could affect
a male’s willingness to attempt mating or to persist in aggregations. When females were dispersed there was weak stabilizing
selection acting to maintain male body size (β=–0.14), but strong directional selection favoring larger (β=0.50) and fatter
(β=0.37) males. Over 7 years, the intensity of selection favoring larger males varied substantially (β=0.14–1.15), but that
variation was not related to variation in the operational sex ratio. We found no evidence of directional selection on either
body size (β=0.05) or fat reserves (β=0.10) of males when females were spatially clumped. Overall, the distribution of females
had a pronounced effect on male behavior, on the factors that affected male success in locating females, and probably on the
extent of sperm competition once females had been located.
Received: 23 November 1998 / Received in revised form: 9 August 1999 / Accepted: 18 August 1999 相似文献
15.
Smyth PP Burns R Huang RJ Hoffman T Mullan K Graham U Seitz K Platt U O'Dowd C 《Environmental geochemistry and health》2011,33(4):389-397
Thyroid hormone levels sufficient for brain development and normal metabolism require a minimal supply of iodine, mainly dietary.
Living near the sea may confer advantages for iodine intake. Iodine (I2) gas released from seaweeds may, through respiration, supply a significant fraction of daily iodine requirements. Gaseous
iodine released over seaweed beds was measured by a new gas chromatography–mass spectrometry (GC–MS)-based method and iodine
intake assessed by measuring urinary iodine (UI) excretion. Urine samples were obtained from female schoolchildren living
in coastal seaweed rich and low seaweed abundance and inland areas of Ireland. Median I2 ranged 154–905 pg/L (daytime downwind), with higher values (~1,287 pg/L) on still nights, 1,145–3,132 pg/L (over seaweed).
A rough estimate of daily gaseous iodine intake in coastal areas, based upon an arbitrary respiration of 10,000L, ranged from
1 to 20 μg/day. Despite this relatively low potential I2 intake, UI in populations living near a seaweed hotspot were much higher than in lower abundance seaweed coastal or inland
areas (158, 71 and 58 μg/L, respectively). Higher values >150 μg/L were observed in 45.6% of (seaweed rich), 3.6% (lower seaweed),
2.3% (inland)) supporting the hypothesis that iodine intake in coastal regions may be dependent on seaweed abundance rather
than proximity to the sea. The findings do not exclude the possibility of a significant role for iodine inhalation in influencing
iodine status. Despite lacking iodized salt, coastal communities in seaweed-rich areas can maintain an adequate iodine supply.
This observation brings new meaning to the expression “Sea air is good for you!” 相似文献
16.
Alecos Demetriades Xiangdong Li Michael H. Ramsey Iain Thornton 《Environmental geochemistry and health》2010,32(6):529-552
In the Lavrion urban area study, Hellas, a five-step sequential extraction method was applied on samples of ‘soil’ (n = 224), affected by long-term mining and metallurgical activities, and house dust (n = 127), for the purpose of studying the potential bioaccessibility of lead and other metals to humans. In this paper, the
Pb concentrations in soil and house dust samples are discussed, together with those in rocks and children’s blood. Lead is
mainly associated with the carbonate, Fe–Mn oxides and residual fractions in soil and house dust. Considering the very low
pH of gastric fluids (1–3), a high amount of metals, present in soil (810–152,000 mg/kg Pb) and house dust (418–18,600 mg/kg Pb),
could be potentially bioaccessible. Consequently, children in the neighbourhoods with a large amount of metallurgical processing
wastes have high blood-Pb concentrations (5.98–60.49 μg/100 ml; median 17.83 μg/100 ml; n = 235). It is concluded that the Lavrion urban and sub-urban environment is extremely hazardous to human health, and the
Hellenic State authorities should urgently tackle this health-related hazard in order to improve the living conditions of
local residents. 相似文献
17.
A robust and rapid methodology for the determination of iodine by inductively coupled plasma mass spectrometry in environmental
samples is presented. Data were initially obtained for the validation of the analytical measurements, using 17 commercially
available soil reference materials. The methodology was then tested on soil and water samples collected in Afghanistan where
iodine deficiency and its effects are reportedly prevalent. Sample collections were conducted in Greater Kabul; the iodine
in agricultural soils was determined to be in the range of 1.6–4.2 mg/kg and that in water drawn for drinking and irrigation
was found to range from 9.9 to 22.7 μg/L. Samples were also collected in a second region, Nangarhar province, which is located
to the east of Kabul, where goitres in the local population had been reported. The iodine content in soils and water at this
location was 0.5–1.9 mg/kg and 5.4–9.4 μg/L, respectively. The organic content of soils in Kabul was found to be in the range
of 1.9–4.2%; in Nangarhar, organic content ranged from 1.7 to 4.5%. All of the Afghan soils were slightly alkaline at pH 7.6–8.2. 相似文献
18.
An evaluation of ~250 samples of groundwater in the Amman Zarqa Basin for selenium along with other major and trace elements
showed that concentrations of Se ranged between 0.09 and 742 μg/L, with an average value of about 24 μg/L. Selenium concentrations
exceeded the recommended threshold for drinking water of the World Health Organization (WHO; 10 μ/L of Se) in 114 samples,
with greater than 50 μg/L (quantity equivalent to the Jordanian standard of the allowed concentration of the element in water)
of Se in nine cases. The average concentrations of Se in the lower, middle, and upper aquifers of the basin were 3.41, 32.99,
and 9.19 μg/L, respectively. Based on the correlation with geologic formations and the statistical analysis of major/minor
constituents and Piper tri-linear diagrams, we suggest that carbonate/phosphate dissolution, oxidation–reduction processes,
and fertilizers/irrigation return flow are, together, the primary factors affecting the chemistry of the groundwater. Factor
analysis helped to define the relative role of limestone-dolomitic dissolution in the aquifers (calcium, magnesium, and bicarbonate),
agricultural activities (sulfate, nitrates, phosphorus, and potassium), oxidation–reduction factor (Eh, Fe, Mn, Cu, Zn, and
Se), and anthropogenic (industrial) factor (EC, Fe, Cr, Co, Zn, and As). The high variability in Se concentrations might be
related to the possibility of a multi-source origin of Se in the area. 相似文献
19.
Eugene S. Morton Bridget J. M. Stutchbury Ioana Chiver 《Behavioral ecology and sociobiology》2010,64(6):947-954
We investigated sexual conflict over parental care in blue-headed vireos (Vireo solitarius) and documented the first example of unvarying unisexual brood desertion in passerines. Females at all nests (N = 24) that were monitored closely near fledgling, deserted their broods on or near the day of fledging leaving males alone
to complete parental care of young. No males deserted. This observational evidence was confirmed with radiotracking of females
(2004, 2007) and both pair members (2008). Radiotracked females began visiting distant males 1–4 days before young left the
nest, subsequently paired with males 355–802 m away, and laid first eggs in new nests less than 5 days after deserting. In
contrast, females suffering nest predation did not desert and renested with the same male. We suggest equal parental care
(nest building, incubation, feeding) in the sexes, genetic monogamy, and an adult sex ratio biased towards males has led to
female control of brood desertion in this species. Unisexual desertion may be more important in altricial birds than generally
realized and we discuss prerequisites to predict its occurrence. One is genetic monogamy, which may be a female tactic that
reduces the likelihood of males evolving counter-adaptations to female desertion. 相似文献
20.
Jonathan N. Pruitt Susan E. Riechert David J. Harris 《Behavioral ecology and sociobiology》2011,65(10):1957-1966
Relatively few investigations explicitly test for concordant versus conflicting selection pressures from intrasexual versus
intersexual selection. Here, we examine the effects of male body mass and behavioral type (BT) on reproductive success in
the spider Anelosimus studiosus, with emphasis placed on the potential interaction between intrasexual and intersexual selection influences. Female A. studiosus exhibit either an aggressive-active or docile-passive BT, both of which co-occur in multifemale colonies. Males, in contrast, exhibit a more continuous distribution of
behavioral tendencies. We investigated the male traits favored by females in five trial types: one docile female, one aggressive
female, four docile females, four aggressive females, and two docile and two aggressive females. Male reproductive success
was estimated by the number eggs produced by females following staged mating trials. In previous work, it was established
that large aggressive males are favored in male–male contests, an intrasexual effect. However, large aggressive males were
not universally favored here. We failed to detect an effect of male body mass or aggressiveness on reproductive success in
trials with all docile females; however, in situations involving aggressive females, large aggressive males experienced diminished
reproductive success relative to small docile males. Large, aggressive males were also more likely to be attacked and killed
by aggressive females in the first 20 min of staged encounters and were more likely to be found dead after 72 h of unobserved
interactions. Taken together, our data suggest that the reproductive consequences of male traits differ based on (1) the aspect
of sexual selection being considered (intrasexual versus intersexual) and (2) the BT of their prospective mates: large aggressive
males enjoy advantages in intrasexual selection and when courting docile females and small docile males experience reduced
risk of cannibalism and increased reproductive success with aggressive females. 相似文献