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At least 145 records · Page 8Linked to original sources
PubMed1994

Blood meal manipulation and in vitro colony maintenance of Haematobia irritans (Diptera: Muscidae).

A series of experiments was conducted to determine survival and reproductive potential of Haematobia irritans (L.) adults that were fed sodium citrated-bovine blood diluted with deionized water, 0.5 M glucose, or 0.15 M sodium chloride (NaCl), or supplemented with adenosine triphosphate (ATP). Reproductive potential, measured by total number of larvae produced per female during 10-d experimental periods, improved when adult H. irritans were fed blood diluted by < 22% with deionized water, NaCl, or glucose, whereas female survival improved when fed blood diluted with deionized water or NaCl (by approximately 25%). Male survival declined whenever blood meals were diluted. Larval production also improved when blood previously stored at -20 degrees C was diluted by approximately 21% with deionized water. Addition of ATP to blood stored at 3 degrees C did not improve larval production or female survival; however, ATP added to blood stored at -20 degrees C increased larval production and female survival. Male survival was not improved by addition of ATP to previously refrigerated or frozen blood. Blood meals were toxic to H. irritans when > or = 5 x 10(-2) M ATP was added to previously refrigerated or frozen blood. A colony of H. irritans was maintained for five generations by feeding adult flies on citrated bovine blood that had been stored at -20 degrees C, supplemented with 5 x 10(-3) M ATP, and diluted with deionized water. Flies were fed through a nylon-reinforced silicone membrane throughout this experimental period. Female survival and larval production were unaffected by the adult fly feeding regimen. Male survival was reduced during the F1, F2, and F3 generations; however, declines did not affect colony maintenance. Percentage pupation increased during the F2 and F3 generations and adult eclosion declined in the F3 and F4 generations, changes attributed to conditions of larvae rearing. Potential for colony population growth was estimated using F4 female survival and resulting larval production, pupation, and adult eclosion. An approximate of 24-fold increase in population size per generation could be realized by collecting all eggs produced by 6-12-d-old females.

Adenosine Triphosphate↗
PubMed2001

Evaluation of the efficacy of extrapolation population modeling to predict the dynamics of Americamysis bahia populations in the laboratory.

An age-classified projection matrix model has been developed to extrapolate the chronic (28-35 d) demographic responses of Americamysis bahia (formerly Mysidopsis bahia) to population-level response. This study was conducted to evaluate the efficacy of this model for predicting the population behavior of A. bahia held (for more than three generations) under controlled laboratory exposure conditions. The research involved the performance of a standard life-cycle test and a multigenerational (greater than three mysid generations, 55 d) assay using A. bahia to experimentally evaluate model predictions regarding population-level risks of chemical exposure. The organic compound para-nonylphenol was chosen as the chemical stressor in assays. This compound is a ubiquitous contaminant and suspected endocrine disruptor. Utilizing data obtained during the standard life-cycle test, aggregate estimates of population growth rate (lambda) and measured p-nonylphenol concentration were used to develop an exposure-response model of population-level effects. These estimates provided the basis of predictions for the long-term dynamics of mysid populations exposed to p-nonylphenol. The veracity of the mysid population model was evaluated through quantitative comparisons of model predictions based on the life-cycle test with dynamics of the experimental populations (multigenerational assay results). The results indicate that the population model was able to project within a few micrograms per liter the concentration where population-level effects would begin to occur (projected 16 micrograms/L from the model vs measured 19 micrograms/L from the multigenerational assay).

Aging↗
PubMed2004

Testing nested phylogenetic and phylogeographic hypotheses in the Plethodon vandykei species group.

Mesic forests in the North American Pacific Northwest occur in two disjunct areas: along the coastal and Cascade ranges of Oregon, Washington, and British Columbia as well as the Northern Rocky Mountains of Idaho, Montana, and British Columbia. Over 150 species or species complexes have disjunct populations in each area, and a priori hypotheses based on phytogeography and geology potentially explain the disjunction via either dispersal or vicariance. Here, we test these hypotheses in the disjunct salamander complex Plethodon vandykei and P. idahoensisby collecting genetic data (669 bp of Cyt b) from 262 individuals. Maximum likelihood analysis indicated reciprocal monophyly of these species, supporting the ancient vicariance hypothesis, whereas parametric bootstrap and Bayesian hypothesis testing allow rejection of the dispersal hypothesis. The coalescent estimate of the time since population divergence (estimated using MDIV) is 3.75 x 106 years, and the 95%credibility interval of this value overlaps with the geological estimate of vicariance, but not the hypothesized dispersal. These results are congruent with the pattern seen in other mesic forest amphibian lineages and suggest disjunction in amphibians may be a concerted response to a geological/climatological event. WithinP. idahoensis, we tested the corollary hypothesis of an inland Pleistocene refugium in the Clearwater drainage with nested clade analysis and coalescent estimates of population growth rate (g). Both analyses support post-Pleistocene expansion from the Clearwater refugium. We corroborated this result by calculating Tajima's Dand mismatch distribution within each drainage, showing strong evidence for recent population expansion within most drainages. This work demonstrates the utility of statistical phylogeography and contributes two novel analytical tools: tests of stationarity with respect to topology in the Bayesian estimation, and the use of coalescent simulations to test the significance of the population growth-rate parameter.

Analysis of Variance↗
PubMed1987

[Demographic consequences of genetic load: a model of the origin of the incest taboo].

The prohibition of copulations among near relatives may raise the fitness of population. This effect being irregular and insignificant for a distinct generation, becomes apparent in evolutionary time intervals through the natural selection of populations with incest-taboo. The "characteristic selection time" theta depends on typical population size, genetic damage and the mean rate of population growth. The estimation obtained for theta permit us to assert that the model describes the phenomenon of "socio-cultural selection" in prehistory. The model shows the demographic specificity of small populations. The problem of the number of consanguineous marriages is considered in detail. New explanation for deviation of the observed frequency of consanguineous marriages from classical estimations is proposed.

Genes, Lethal↗