10thweekbild

10thweekbild - -the largest increase in life expectancy in...

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-the largest increase in life expectancy in the last thirty years was in Asia -the majority of population growth in the future will take place in south Asia, the Middle East, and sub-Saharan Africa -age pyramid for Cambodia= bulge in number of young children -not a lot of 20-25 year olds due to Khmer Rouge massacres -stable age pyramid=no big base Components of an Ecological niche -abiotic factors: principal determiners of what type of life can exist (i.e. intertidal region: alternating periods of exposure to water and air result in a distinction between the types of organisms that live in different parts of the intertidal zone) -life on desert rocks: Magnesium dioxide deposits on surface done by bacteria (magnesium protects them from the sun) -acidic conditions: archaeon can grow at pH 0 -stability of ecological niches over time may have a profound effect on the evolution of the way in which a species reproduces itself -organisms adapted for life in forests in which new clearings appear/disappear rapidly will be selected for short lifespans, high rates of reproduction, and an ability to disperse over long distances in order to occupy new clearings when they disappear: r selection= selects for a high intrinsic rate of increase -if the niche is long-lived, like the forest itself, the inhabitiants may be selected for longer lifespans, lower rates of reproduction, and smaller dispersal distances: K selection=selection for ability to reach a carrying capacity utilizing the resources of their niches thoroughly Selection for r and K reproduction -dandelions= asexual and are identical to parental plant, a population contains a group of clones -dandelions found in lawns frequently mowed and a less cultivated area that wasn’t mowed as often -frequently mowed lawn: produced large numbers or small rapidly developing flowers and have small number of small seeds -occasionally mowed areas: smaller number of larger flowers, with large number of big seeds -seedlings from small seeds are less likely to survive that seedlings from larger seeds, compensate by yielding large numbers of small sees (increasing chance that at least some will germinate) number of seeds per flower were small, but
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10thweekbild - -the largest increase in life expectancy in...

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