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1.
Urolepis rufipes Ashmead, a recently discovered parasitoid of house flies at New York dairies, was reared at 15, 20, 25, 30 and 34°C to measure
daily fertility, fecundity and adult survivorship. Little reproduction occurred at 15°C, and only a few ♀ successfully emerged
at 34°C. The intrinsic rate of growth was fastest at 30°C (0.282 ♀/day), but fecundity was highest at 25°C (165.5 hosts attacked,
producing 124.5 progeny). Some reproductive statistics at 25°C were: net reproductive rate (R0=72.1 ♀/♀, generation time =18.7 days, intrinsic rate of increase (rm)=0.228, finite rate of increase (λ)=1.26, daily birth rate =0.302, daily death rate =0.021 and Fisher's reproductive value
=418. Sex ratio (average =75.9%) did not vary significantly with temperature (between 20–30°C) nor with mother's age.
相似文献
2.
The effects of spirotetramat on life history traits and population growth of Tetranychus urticae (Acari: Tetranychidae) 总被引:1,自引:0,他引:1
Marcic D Petronijevic S Drobnjakovic T Prijovic M Peric P Milenkovic S 《Experimental & applied acarology》2012,56(2):113-122
The effects of spirotetramat, a tetramic acid derivative, on gross fertility, net fertility, female longevity and the instantaneous
rate of increase of two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) were investigated after treatment of female teleiochrysalises (the first assay) and pre-ovipositional
females (the second assay). Spirotetramat was applied to the leaf discs by Potter spray tower and the following series of
concentrations was applied: 200, 60, 18, 5.4 and 1.62 mg/l. In both assays after 24 h of exposure, surviving females without
symptoms of poisoning were used for further procedure. In the first assay, gross fertility of treated females was reduced
by 2.4–64.7% and net fertility by 12.4–88.8%, compared to the control. Gross fertility of the females treated with 1.62 and
5.4 mg/l did not significantly differ from the control, whereas all concentrations, except the lowest, significantly reduced
net fertility and female longevity. Treatments with 200, 60, and 18 mg/l significantly reduced the instantaneous rate of increase.
In the second assay, gross fertility and net fertility were reduced by 43.7–93.3% and 73.8–98.5%, respectively. All concentrations,
except the lowest, significantly reduced gross fertility, whereas net fertility and longevity in all treated females were
significantly lower compared to the control. All concentrations, except the lowest, significantly reduced the instantaneous
rate of increase, provided that concentrations of 200, 60 and 18 mg/l caused population decline. The effects of spirotetramat
and its impact on T. urticae management are discussed. 相似文献
3.
We analysed the effects of temperature and photon fluence rate on meiospore germination, growth and fertility of gametophytes,
and growth of young sporophytes of Laminaria ochroleuca. Maximum percentages of germination (91–98%) were obtained at 15°C and 18°C, independent of photon fluence rate. Optimal
development of female gametophyte and maximum fecundity and reproductive success of gametophytes occurred at 15°C and 18°C
and at 20 and 40 μmol m–2 s–1. Maximum relative growth rate of young sporophytes after 2 weeks of culture was achieved under the same conditions. L. ochroleuca gametophytes cannot reproduce and growth of its sporophytes is not competitive at temperatures close to 10°C.
Received in revised form: 31 August 2001
Electronic Publication 相似文献
4.
Dejan Marcic Irena Ogurlic Slavka Mutavdzic Pantelija Peric 《Experimental & applied acarology》2010,50(3):255-267
Laboratory bioassays were conducted to evaluate the effects of spiromesifen on gross fecundity, gross fertility, net fertility
and population growth of two-spotted spider mite (Tetranychus urticae Koch) after treatments with four acaricide concentrations: 180 mg/l, i.e. maximum recommended concentration for use in glasshouses
against spider mites, 18, 1.8, and 0.18 mg/l, i.e. concentration discriminative for eggs and immatures in preliminary studies
which produced 100% mortality of these stages. Quiescent female deutonymphs were treated in the first assay, and young pre-ovipositing
females in the second and third, in which exposure lasted 6 h and 20 h, respectively. In the first assay, the 180, 18, and
1.8 mg/l concentrations significantly reduced gross fecundity (61–85%), gross fertility (64–87%) and net fertility (85–94%)
of the surviving females. In the second one, only the highest concentration achieved a significant statistical reduction in
gross fecundity (52%), gross fertility (67%) and net fertility (84%). In the third assay, fecundity and fertility reduction
under the two highest concentrations was 98–99% and 93–98%, whereas it was 50–74% under the 1.8 mg/l concentration, and statistically
different from control values. In all three trials, treatments with 180, 18, and 1.8 mg/l concentrations significantly reduced
the instantaneous rate of increase. In the third assay, treatments with the two highest concentrations caused population decline.
Sublethal activity of the 0.18 mg/l concentration was not found in any assay to be statistically significant. Sublethal effects
of spiromesifen and its impact on T. urticae management are discussed. 相似文献
5.
Nico Varo Andy J. Green Marta I. Sánchez Cristina Ramo Jesús Gómez Juan A. Amat 《Hydrobiologia》2011,664(1):163-171
Chemical communication may inform about the location of prey, predators, co-specifics, and mate partners in zooplankton. In
this study, we evaluated several life-history traits of the rotifer, Brachionus calyciflorus, exposed to conditioned media by a rotifer predator (Asplanchna brightwelli) and a cladocera competitor (Daphnia similis), quantifying population growth and life-table demography at two algal food levels (2.0 and 0.5 × 106 cells ml−1 of Chlorella pyrenoidosa). At both food levels, B. calyciflorus grown in predator-conditioned media had lower population abundance and slower population growth rate than controls. Conversely,
the competitor-conditioned media treatments produced both higher rotifer population abundance and faster population growth
rate than controls. Life-history parameters varied significantly depending on the presence of predator and competitor-conditioned
media. The Asplanchna-conditioned media significantly decreased gross reproductive rate (GRR): 8–9 offsprings per female; net reproductive rate
(R
0): 6–7 offsprings per female; population growth rate (r): 0.34–0.37 day−1; and increased generation time (T): 5.5–5.6 days. On the other hand, The Daphnia-conditioned media significantly increased the GRR (13–14 offsprings per female); net reproductive rate (8–9 offsprings per
female); population growth rate (0.42–0.43 day−1); and decreased generation time (4.9–5.0 days). However, the effects of food level on the life-history characteristic were
not significant in both treatments. Maximum values of the population abundance and the population growth rate are significantly
influenced by the predator densities and pre-culture time. This study suggests that rotifers use variable life-history strategies
(low reproduction and high survivorship versus high reproduction and low survivorship) based on the presence of predators
and competitors. 相似文献
6.
Carly A. Strasser Michael G. Neubert Hal Caswell Christine M. Hunter 《Theoretical Ecology》2012,5(2):167-179
Studies of time-invariant matrix metapopulation models indicate that metapopulation growth rate is usually more sensitive
to the vital rates of individuals in high-quality (i.e., good) patches than in low-quality (i.e., bad) patches. This suggests
that, given a choice, management efforts should focus on good rather than bad patches. Here, we examine the sensitivity of
metapopulation growth rate for a two-patch matrix metapopulation model with and without stochastic disturbance and found cases
where managers can more efficiently increase metapopulation growth rate by focusing efforts on the bad patch. In our model,
net reproductive rate differs between the two patches so that in the absence of dispersal, one patch is high quality and the
other low quality. Disturbance, when present, reduces net reproductive rate with equal frequency and intensity in both patches.
The stochastic disturbance model gives qualitatively similar results to the deterministic model. In most cases, metapopulation
growth rate was elastic to changes in net reproductive rate of individuals in the good patch than the bad patch. However,
when the majority of individuals are located in the bad patch, metapopulation growth rate can be most elastic to net reproductive
rate in the bad patch. We expand the model to include two stages and parameterize the patches using data for the softshell
clam, Mya arenaria. With a two-stage demographic model, the elasticities of metapopulation growth rate to parameters in the bad patch increase,
while elasticities to the same parameters in the good patch decrease. Metapopulation growth rate is most elastic to adult
survival in the population of the good patch for all scenarios we examine. If the majority of the metapopulation is located
in the bad patch, the elasticity to parameters of that population increase but do not surpass elasticity to parameters in
the good patch. This model can be expanded to include additional patches, multiple stages, stochastic dispersal, and complex
demography. 相似文献
7.
Source–sink dynamics may be ubiquitous in ecology. We developed a theory for source–sink dynamics using spatial extensions
of the net reproductive value, R
0, which has been used elsewhere to define fitness, disease eradication, population growth, and invasion risk. R
0 decomposes into biologically meaningful components—lifetime reproductive output, survival, and dispersal—that are widely
adaptable and easily interpreted. The theory provides a general quantitative means for relating fundamental niche, biotic
interactions, dispersal, and species distributions. We applied the methods to Dreissena and found a resolution to a paradox in invasion biology—competitive coexistence between quagga (Dreissena bugensis) and zebra (D. polymorpha) mussels among lakes despite extensive niche overlap within lakes. Source–sink dynamics within lakes between deepwater and
shallow habitats, which favor quagga and zebra mussels, respectively, yield a metacommunity distribution where quagga mussels
dominate large lakes and zebra mussels dominate small lakes. The source–sink framework may also be useful in spatial competition
theory, habitat conservation, marine protected areas, and ecological responses to climate change. 相似文献
8.
Bruce M. Leaman 《Environmental Biology of Fishes》1991,30(1-2):253-271
Synopsis The characteristics of lightly and heavily exploited Pacific ocean perch,Sebastes alutus, stocks are evaluated relative to the predictions of life history theory. These long-lived species (50–100 year lifespan)
show limited phenotypic plasticity and have little buffering against the effects of reduced lifespan. Reduced stock abundance
has generated some compensatory increase in growth rate. Length at first maturity varies only slightly with increased growth
rate, although age at maturity may decrease by 1–4 years. Grooth increases yield larger (15–20%) size at age and increased
reproductive effort at younger ages, but lower size-specific fecundity for these faster-growing fish. This suggests an energy
allocation protocol favouring growth over reproduction in these long-lived animals. Rockfishes have late recruitment to fisheries
(ages 10–15), and the detection time for results of management actions is equally long. Their vulnerability to overfishing
means that indices of population changes, more representative of fishing effects than the catch rate index presently used,
are required. Reproductive value indices are shown to be extremely sensitive and continuous with population abundance changes.
Their incorporation into monitoring programs would permit more timely evaluation of management actions. Management policies
developed for shorter-lived species are shown to be inappropriate for rockfishes. The need for an improved match in the time
frame of the species' life history, and that of management strategies, is stressed. 相似文献
9.
The Tongass National Forest (Tongass) is the largest national forest and largest area of old-growth forest in the United States.
Spatial geographic information system data for the Tongass were combined with forest inventory data to estimate and map total
carbon stock in the Tongass; the result was 2.8 ± 0.5 Pg C, or 8% of the total carbon in the forests of the conterminous USA
and 0.25% of the carbon in global forest vegetation and soils. Cumulative net carbon loss from the Tongass due to management
of the forest for the period 1900–95 was estimated at 6.4–17.2 Tg C. Using our spatially explicit data for carbon stock and
net flux, we modeled the potential effect of five management regimes on future net carbon flux. Estimates of net carbon flux
were sensitive to projections of the rate of carbon accumulation in second-growth forests and to the amount of carbon left
in standing biomass after harvest. Projections of net carbon flux in the Tongass range from 0.33 Tg C annual sequestration
to 2.3 Tg C annual emission for the period 1995–2095. For the period 1995–2195, net flux estimates range from 0.19 Tg C annual
sequestration to 1.6 Tg C annual emission. If all timber harvesting in the Tongass were halted from 1995 to 2095, the economic
value of the net carbon sequestered during the 100-year hiatus, assuming $20/Mg C, would be $4 to $7 million/y (1995 US dollars).
If a prohibition on logging were extended to 2195, the annual economic value of the carbon sequestered would be largely unaffected
($3 to $6 million/y). The potential annual economic value of carbon sequestration with management maximizing carbon storage
in the Tongass is comparable to revenue from annual timber sales historically authorized for the forest. 相似文献
10.
The potential speed at which the range of an introduced species expands in its optimal environment can be predicted by using
the gamma model proposed by Yamamura (Popul Ecol 46:87–101, 2004). In this paper we first clarify the difference between the
gamma model and Einstein’s Brownian motion model. We then apply the model to the ragweed beetle, Ophraella communa LeSage that rapidly expanded its distribution in Japan after it was first found in 1996. The parameters of the model are
estimated by conducting a field experiment. The species’ net reproductive rate is examined in the laboratory. By combining
these estimates, we estimate the potential speed of range expansion to be 82 km per generation and 329 km per year, while
the observed speed is estimated to be 77 km per year, the observed speed being considerably slower than the potential speed.
This discrepancy may be due to the low reproductive rate caused by mortality in the actual field. The applicability of the
gamma model to the econometric data is also briefly discussed. 相似文献
11.
应用Jackknife技术统计昆虫生命表参数变异的VFP实现 总被引:7,自引:0,他引:7
研究昆虫种群的动态,掌握种群增长的潜力是非常重要的。应用生殖力生命表可进行种群增长动态的估计,常用5个主要参数来描述净增殖率、内禀增长率、世代平均周期、种群倍增时间和周限增长率,Jackknife技术可以用来估计内禀增长率等参数的变异程度,利用VFP编程实现了生命表参数变异程度的计算。 相似文献
12.
Effects of temperature (18, 24, and 30°C), salinity (5–40 ppt, five intervals) and algal foods (Synechococcus sp., Chlorella pyrenoidosa, Isochrysis zhanjiangensis, Dunaliella salina and Tetraselmis cordiformis) on the life table demography of six geographical Brachionus plicatilis sensu stricto clones, which had been identified according to the prevalent taxonomy and biometric analysis of B. plicatilis sensu lato, were studied. The results showed that temperature, salinity and temperature × salinity significantly influenced
the life history parameters. Genotype (clone) had no effect on the population growth rate but did influence the net reproductive
rate, generation time and lifespan. All rotifer clones showed the expected increase in population growth rate with increasing
temperature. B. plicatilis s. s. attained a higher population growth rate at low–medium salinities (5–20 ppt) than at high salinities (25–40 ppt). The
equivalent spherical diameter (ESD) of food algae, salinity and ESD × salinity had significant effects on the life history
parameters. In this case, genotype had no effect on population growth rate, net reproductive rate and generation time but
did influence lifespan. The population growth rate of B. plicatilis s. s. evaluated against particle retention spectrum of algae at two salinities resulted in bell-shaped curves. Dunaliella salina with an ESD = 7.7 μm was considered to be the best food for B. plicatilis s. s. while Synechococcus appeared to be an inadequate food algae. 相似文献
13.
Life history theory aims to explain the relationship between life events, recognizing that the fertility and growth schedules
of organisms are dependent on environmental conditions and an organism’s ability to extract resources from its environment.
Using models from life history theory, we predict life expectancy to be positively correlated with educational investments
and negatively correlated with adolescent reproduction and total fertility rates. Analyses of UN data from 193 countries support
these predictions and demonstrate that, although variation is evident across world regions, strong interactions exist among
life expectancy, reproductive investments, and educational attainment, and these relationships occur independently of economic
pressures and disease burdens. The interactions are strongest, however, in countries with a life expectancy of ≥60 years as
these countries tend to have stable economies and a limited HIV/AIDS burden. These findings suggest that policies aimed at
influencing education and reproductive decisions should consider environmental characteristics that drive people’s expectations
about their longevity. 相似文献
14.
Lack of association of bovine MHC class I alleles with carcass and reproductive traits 总被引:1,自引:0,他引:1
The present study was carried out to examine whether a relationship between bovine major histocompatibility complex (BoLA) class I alleles and carcass traits or reproductive performance exists in Braunvieh and Fleckvieh A1 (artificial insemination) bulls. The influence of BoLA class I (BOLA-A) alleles on deregressed breeding values for net growth rate, carcass index and thigh volume was assessed in Braunvieh crosses and Fleckvieh bulls with a gene substitution model. The reproductive traits: non-return rate and interval between first and last insemination of daughters (female fertility), as well as non-return rate of inseminated cows (male fertility), were only investigated in Fleckvieh animals. No influence of the BOLA-A region on the traits evaluated could be demonstrated. An improper, i.e. less restrictive analysis would have led to spurious results. 相似文献
15.
The aim of this study is an analysis of the possible adaptive consequences of delivery of low birth weight infants. We attempt to reveal the cost and benefit components of bearing small children, estimate the chance of the infants’ survival, and calculate the mothers’ reproductive success. According to life-history theory, under certain circumstances mothers can enhance their lifetime fitness by lowering the rate of investment in an infant and/or enhancing the rate of subsequent births. We assume that living in a risky environment and giving birth to a small infant may involve a shift from qualitative to quantitative production of offspring. Given high infant mortality rates, parents will have a reproductive interest in producing a relatively large number of children with a smaller amount of prenatal investment. This hypothesis was tested among 650 Gypsy and 717 non-Gypsy Hungarian mothers. Our study has revealed that 23.8% of the Gypsy mothers had low birth weight (<2,500 g) children, whose mortality rate is very high. These mothers also had more spontaneous abortions and stillbirths than those with normal weight children. As a possible response to these reproductive failures, they shortened birth spacing, gaining 2–4 years across their reproductive lifespan for having additional children. Because of the relatively short interbirth intervals, by the end of their fertility period, Gypsy mothers with one or two low birth weight infants have significantly more children than their ethnic Hungarian counterparts. They appear to compensate for handicaps associated with low birth weights by having a larger number of closely spaced children following the birth of one or more infants with a reduced probability of survival. The possible alternative explanations are discussed, and the long-term reproductive benefits are estimated for both ethnic groups. 相似文献
16.
J. M. Cushing 《Journal of mathematical biology》1984,20(3):259-276
The existence of positive equilibrium solutions of the McKendrick equations for the dynamics of an age-structured population
is studied as a bifurcation phenomenon using the inherent net reproductive rate n as a bifurcation parameter. The local existence and uniqueness of a branch of positive equilibria which bifurcates from the
trivial (identically zero) solution at the critical value n=1 are proved by implicit function techniques under very mild smoothness conditions on the death and fertility rates as functional
of age and population density. This first requires the development of a suitable linear theory. The lowest order terms in
the Liapunov-Schmidt expansions are also calculated. This local analysis supplements earlier global bifurcation results of
the author.
The stability of both the trivial and the positive branch equilibria is studied by means of the principle of linearized stability.
It is shown that in general the trivial solution losses stability as n increases through one while the stability of the branch solution is stable if and only if the bifurcation is supercritical.
Thus the McKendrick equations exhibit, in the latter case, a standard exchange of stability with regard to equilibrium states
as they depend on the inherent net reproductive rate. The derived lower order terms in the Liapunov-Schmidt expansions yield
formulas which explicitly relate the direction of bifurcation to properties of the age-specific death and fertility rates
as functionals of population density.
Analytical and numerical results for some examples are given which illustrate these results. 相似文献
17.
We formulate a Dynamic Energy Budget (DEB) model for the growth and reproduction of individual organisms based on partitioning
of net production (i.e. energy acquisition rate minus maintenance rate) between growth and energy reserves. Reproduction uses
energy from reserves. The model describes both feeding and non-feeding stages, and hence is applicable to embryos (which neither
feed nor reproduce), juveniles (which feed but do not reproduce), and adults (which commonly both feed and reproduce). Embryonic
growth can have two forms depending on the assumptions for acquisition of energy from yolk. By default, when the energy acquisition
rate exceeds the maintenance rate, a fixed proportion of the resulting net production is spent on growth (increase in structural biomass), and the remaining portion is channelled to the reserves. Feeding organisms,
however, modulate their allocation of net production energy in response to their total energy content (energy in the reserves
plus energy bounded to structural biomass). In variable food environment an organism alternates between periods of growth,
no-growth, and balanced-growth. In the latter case the organism adopts an allocation strategy that keeps its total energy
constant. Under constant environmental conditions, the growth of a juvenile is always of von Bertalanffy type. Depending on
the values of model parameters there are two long-time possibilities for adults: (a) von Bertalanffy growth accompanied by
reproduction at a rate that approaches zero as the organism approaches asymptotic size, or (b) abrupt cessation of growth
at some finite time, following which, the rate of reproduction is constant. We illustrate the model's applicability in life
history theory by studying the optimum values of the energy allocation parameters for constant environment and for each of
the dynamic regimes described above.
Received: 11 May 1998 / Revised version: 18 February 2000 / Published online: 4 October 2000 相似文献
18.
Many populations live in ‘advective’ media, such as rivers, where flow is biased in one direction. In these environments,
populations face the possibility of extinction by being washed out of the system, even if the net reproductive rate (R) is greater than one. We propose a formal condition for population persistence in advective systems: a population can persist at any location in a homogeneous habitat if and only if it can invade upstream. This leads to a remarkably simple recipe for calculating the minimal value for the net reproductive rate for population
persistence. We apply this criterion to discrete-time models of a semelparous population where dispersal is characterized
by a mechanistically derived kernel. We demonstrate that persistence depends strongly on the form of the kernel’s ‘tail’,
a result consistent with previous literature on the speed of spread of invasions. We apply our theory to models of stream
invertebrates with a biphasic life cycle, and relate our results to the ‘colonization cycle’ hypothesis where bias in downstream
drift is offset by upstream bias in adult dispersal. In the absence of bias in adult dispersal, variability in the duration
of the larval stage and in oviposition sites have a large effect of the persistence condition. The minimization calculations
required in our approach are very straightforward, indicating the feasibility of future applications to life history theory. 相似文献
19.
Delay of mating was examined as a possible mechanism for population decreases associated with mating disruption for codling moth, Cydia pomonella L., and obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). We examined the effect of delaying female mating 0, 2, 4, or 6 d while holding male age constant on life table parameters of both species. We found that increasing delays in mating were accompanied by two responses: (1) an increase in the percentage of sterile pairs and (2) a reduction in net reproductive rate and population growth unrelated to sterility. On a percentage basis, obliquebanded leafroller population growth was more strongly affected than codling moth. However, the net fertility rate of obliquebanded leafroller was nearly eight-fold higher than that of codling moth, so that obliquebanded leafroller females that experienced a 4-d delay in mating had nearly the same reproductive rate as codling moth females that experienced no delay. Leslie matrix simulations using life tables with field-based adult longevity estimates showed that codling moth females experiencing >2-d delay in mating resulted in decreases in population density or extinction within two generations. In contrast, obliquebanded leafroller females delayed <6 d showed rapid population growth that decreased as female age at mating increased; only the 6-d delay treatment resulted in decreased population levels. Our results indicate that obliquebanded leafroller females must on average experience a much longer delay in mating to significantly reduce population growth compared with codling moth females, suggesting that delay of mating likely plays a greater role in codling moth mating disruption than for obliquebanded leafroller. 相似文献
20.
We developed a simple, versatile system for applying a range of biaxial loads to cell–matrix constructs for the study of
mechanobiology. The system consists of porous polyethylene bars that are polymerized into a square fibroblast-populated gel
and loaded by freely hanging weights attached to sutures routed through a custom loading rig. The cost to manufacture each
mold/loading rig pair was less than US $250 and the expected life of the components is up to 10 years. Neonatal and adult
cardiac fibroblasts contracted gels to a decreasing extent as external load was increased (P=0.003) and achieved contraction forces of up to 1.4 mN per million cells. Strain distributions were reasonably homogeneous
in the central region of the gel (25% of gel area), but clearly nonhomogeneous outside that central region. The primary advantages
of this system are simplicity, low cost, biaxial loading, and the ability to test for a dose–response effect of mechanical
load. The current disadvantages are the inability to apply cycling loading and the inhomogeneities introduced by the use of
rigid loading bars.
Received: 15 November 2001 / Accepted: 30 January 2002 相似文献