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History Changes (history + change)

Distribution by Scientific Domains
Life Sciences66%

Kinds of History Changes

  • life history change
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    Selected Abstracts

    SYNTHESIS: Life history change in commercially exploited fish stocks: an analysis of trends across studies

    EVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 3 2009
    Diana M. T. Sharpe
    Abstract Age and size at maturation have declined dramatically in many commercial fish stocks over the past few decades , changes that have been widely attributed to fishing pressure. We performed an analysis of such trends across multiple studies, to test for the consistency of life history changes under fishing, and for their association with the intensity of exploitation (fishing mortality rate). We analyzed 143 time series from 37 commercial fish stocks, the majority of which originated from the North Atlantic. Rates of phenotypic change were calculated for two traditional maturation indices (length and age at 50% maturity), as well as for probabilistic maturation reaction norms (PMRNs). We found that all three indices declined in heavily exploited populations, and at a rate that was strongly correlated with the intensity of fishing (for length at 50% maturity and PMRNs). These results support previous assertions that fishing pressure is playing a major role in the life history changes observed in commercial fish stocks. Rates of change were as strong for PMRNs as for age and size at 50% maturity, which is consistent with the hypothesis that fishing-induced phenotypic changes can sometimes have a genetic basis. [source]

    Historical changes in the phenology of British Odonata are related to climate

    GLOBAL CHANGE BIOLOGY, Issue 5 2007
    CHRISTOPHER HASSALL
    Abstract Responses of biota to climate change take a number of forms including distributional shifts, behavioural changes and life history changes. This study examined an extensive set of biological records to investigate changes in the timing of life history transitions (specifically emergence) in British Odonata between 1960 and 2004. The results show that there has been a significant, consistent advance in phenology in the taxon as a whole over the period of warming that is mediated by life history traits. British odonates significantly advanced the leading edge (first quartile date) of the flight period by a mean of 1.51 ±0.060 (SEM, n=17) days per decade or 3.08±1.16 (SEM, n=17) days per degree rise in temperature when phylogeny is controlled for. This study represents the first review of changes in odonate phenology in relation to climate change. The results suggest that the damped temperature oscillations experienced by aquatic organisms compared with terrestrial organisms are sufficient to evoke phenological responses similar to those of purely terrestrial taxa. [source]

    Nature and the economy,

    JOURNAL OF APPLIED ECOLOGY, Issue 3 2007
    PARTHA DASGUPTA
    Summary 1In this lecture I first offer what one could call the World Bank view of the recent macroeconomic history of a number of countries in the poor and rich worlds. Secondly, I demonstrate how our view of macroeconomic history changes if Nature is included as a capital asset in production activities. 2I conclude that high population growth in the world's poorest regions (South Asia and sub-Saharan Africa) has been an obstacle to the achievement of sustainable economic development in those areas. It is believed that people in those regions are, on average, less wealthy now than they were 35 years ago. 3When population growth is taken into account, the accumulation of manufactured capital, knowledge and human capital (health and education) has not compensated for the degradation of natural capital in South Asia and sub-Saharan Africa and, in all probability, even in the United Kingdom and the United States. 4It is possible that China is an exception to the economic forces experienced in other areas of the world. 5Synthesis and applications. The conclusions drawn here are very tentative and there is much further work to be conducted in understanding how ecological concerns can be incorporated into economic theory. It is important, therefore, that growth economists, demographers, governments and international agencies take this approach. [source]

    Which traits promote persistence of feral GM crops?

    OIKOS, Issue 1 2005
    Part 1:implications of environmental stochasticity
    Transgenes in plants affect life history traits including seed survival and germination. With stochastic matrix models we predict population-level consequences of transgene induced life history changes. We assess systematically which changes in life history traits, resulting from genetic modification, may increase the risk of invasion and persistence of feral crops or increase fitness in case of introgression from arable fields into conspecific, feral populations. We apply our method to feral populations of oilseed rape. Like many annual weeds, oilseed rape depends critically on disturbance; in undisturbed habitats it is generally outcompeted by perennials. The associated inherent variability and unpredictability render deterministic models inappropriate. With a stochastic matrix model we study population growth rate, elasticities and quasi-extinction times. Our results indicate that changes in survival in the seed bank impact population growth and persistence most. Less important are dormancy, fecundity and seedling survival. The predicted distribution of extinction times is highly skewed, with some patches persisting for decades. [source]

    Which traits promote persistence of feral GM crops?

    OIKOS, Issue 1 2005
    Part 2: implications of metapopulation structure
    Transgenes may spread from crops into the environment via the establishment of feral populations, often initiated by seed spill from transport lorries or farm machinery. Locally, such populations are often subject to large environmental variability and usually do not persist longer than a few years. Because secondary feral populations may arise from seed dispersal to adjacent sites, the dynamics of such populations should be studied in a metapopulation context. We study a structured metapopulation model with local dispersal, mimicking a string of roadside subpopulations of a feral crop. Population growth is assumed to be subject to local disturbances, introducing spatially random environmental stochasticity. Our aim is to understand the role of dispersal and environmental variability in the dynamics of such ephemeral populations. We determine the effect of dispersal on the extinction boundary and on the distribution of persistence times, and investigate the influence of spatially correlated disturbances as opposed to spatially random disturbances. We find that, given spatially random disturbances, dispersal slows down the decline of the metapopulation and results in the occurrence of long-lasting local populations which remain more or less static in space. We identify which life history traits, if changed by genetic modification, have the largest impact on the population growth rate and persistence times. For oilseed rape, these are seed bank survival and dormancy. Combining our findings with literature data on transgene-induced life history changes, we predict that persistence is promoted by transgenes for oil-modifications (high stearate or high laurate) and, possibly, for insect resistence (Bt). Transgenic tolerance to glufosinate herbicide is predicted to reduce persistence. [source]