Population ecology


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Population ecology

  1. 2. <ul><li>Geographic distribution/ range </li></ul><ul><li>Population density </li></ul><ul><li>Population dispersion </li></ul><ul><li>Immigration </li></ul><ul><li>Emigration </li></ul><ul><li>Logistic growth </li></ul>
  2. 3. <ul><li>Exponential growth </li></ul><ul><li>Biotic potential </li></ul><ul><li>Environmental resistance </li></ul><ul><li>Carrying capacity </li></ul><ul><li>Density-dependent factors </li></ul><ul><li>Density independent factors </li></ul>
  3. 5. <ul><li>Geographic distribution </li></ul><ul><li>Density </li></ul><ul><li>Dispersion </li></ul><ul><li>Growth rate </li></ul><ul><li>Age structure </li></ul>What is a population? A population is a group of individuals of the same species occupying the same general area.
  4. 6. <ul><li>geographical range of a species or a group of species </li></ul><ul><li>the suitability of habitats influences the distribution of a species (each species is adapted to a rather limited range of abiotic and biotic conditions) </li></ul>Population density <ul><li>the number of individuals per unit area or volume </li></ul>
  5. 7. <ul><li>pattern of spacing among individuals in a habitat </li></ul><ul><li>Types of dispersion: </li></ul><ul><li>RANDOM </li></ul><ul><li>- habitat conditions are uniform / resource availability is steady </li></ul><ul><li>- individuals neither attract nor avoid each other </li></ul><ul><li>- rare in nature </li></ul><ul><li>UNIFORM </li></ul><ul><li>- individuals are evenly spaced in a habitat </li></ul><ul><li>- due to competition or territorial behavior </li></ul><ul><li>CLUMPED </li></ul><ul><li>- species are aggregated in patches </li></ul><ul><li>- most common in nature because: </li></ul><ul><li> cluster around patchy resources </li></ul><ul><li> live in social groups </li></ul><ul><li> species has limited dispersal powers </li></ul>
  6. 8. <ul><li>increase in the size of a population of organisms </li></ul><ul><li>population size  the number of individuals that contribute to a population’s gene pool </li></ul>
  7. 9. For mobile animals  Individuals are captured and marked in some way, then the marked animals are released.  Later, animals are captured and checked for marks.  In the later sample, the proportion of marked individuals should be representative of the proportion marked in the whole population.
  8. 10. <ul><li>increase in the size of a population of organisms </li></ul><ul><li>population size  the number of individuals that contribute to a population’s gene pool </li></ul><ul><li>Factors that affect population size: </li></ul><ul><li>1. Number of births (natality) </li></ul><ul><li>2. Number of deaths (mortality) </li></ul><ul><li>3. Immigration/Emigration </li></ul><ul><li>Immigration – the arrival of new residents from other areas </li></ul><ul><li>Emigration - individuals permanently move out of the population </li></ul>
  9. 11. <ul><li>– no overall increase or decrease during a specified interval; population size is stabilized (assuming that immigration and emigration balance each other  number of births = number of deaths) </li></ul>
  10. 12. 07/20/10 Free PowerPoint Template from www.brainybetty.com
  11. 13. <ul><li>Individuals in population have constant rate of reproduction </li></ul><ul><li>Over time, becomes infinitely large </li></ul><ul><li>Under ideal conditions with unlimited resources, population will grow exponentially </li></ul><ul><ul><li>Ideal condition- abundant space, food, protection against predator and disease </li></ul></ul>
  12. 14. <ul><li>Does not continue naturally for a long time </li></ul>
  13. 15. 07/20/10 Free PowerPoint Template from www.brainybetty.com Carrying capacity
  14. 16. <ul><li>Due to decrease in resources that lead to decrease in population growth </li></ul><ul><li>Decrease in pop growth maybe caused by decrease in death rate, increase in death rate or the occurrence of both at the same time at the same rate </li></ul><ul><ul><li>Is also true for emigration and immigration </li></ul></ul>
  15. 17. <ul><li>Recall: limiting factors determine the primary productivity of an area </li></ul><ul><li>In population, a limiting factor causes population growth to decrease </li></ul>
  16. 18. Pop size competition predation Parasitism and disease Drought and other climate extremes Human disturbances
  17. 19. <ul><li>Depends on the population size </li></ul><ul><li>Is due to population density </li></ul>
  18. 20. <ul><li>Major force of evolution </li></ul><ul><li>Competition should be decreased </li></ul><ul><li>Evolution will lead separation of niches </li></ul><ul><ul><li>No same species can occupy the same niche at any given place and time </li></ul></ul>
  19. 21. <ul><li>One of the best population control </li></ul><ul><ul><li>Characterized by fluctuations of the prey and predator populations </li></ul></ul>
  20. 22. <ul><li>Limiting factor that affects the population regardless of its size </li></ul><ul><ul><li>Characterized by a CRASH in the population size </li></ul></ul>
  21. 23. <ul><ul><li>biotic potential/reproduction potential </li></ul></ul><ul><ul><ul><ul><li>maximum rate of growth of a population </li></ul></ul></ul></ul><ul><ul><ul><ul><li>conditions are optimal / ideal </li></ul></ul></ul></ul><ul><ul><ul><ul><li>high reproduction, low mortality </li></ul></ul></ul></ul>
  22. 24. <ul><ul><li>environmental resistance </li></ul></ul><ul><ul><ul><ul><li>factors that limit population growth </li></ul></ul></ul></ul><ul><ul><ul><ul><li>limiting factors: food, space, O 2 , shelter, accumulation of wastes </li></ul></ul></ul></ul>
  23. 25. <ul><ul><li>carrying capacity </li></ul></ul><ul><ul><ul><ul><li>maximum number of individuals in a population (or species) that a given environment can support indefinitely </li></ul></ul></ul></ul><ul><ul><ul><ul><li>in the steady state (of logistic growth)  size oscillates around this number </li></ul></ul></ul></ul>
  24. 26. <ul><li>Age structure </li></ul><ul><li>the number of individuals in each of several age categories: </li></ul><ul><li>1. prereproductive age – have the potential to produce offspring when they mature </li></ul><ul><li>2. reproductive age – actual reproducing members </li></ul><ul><li>3. postreproductive age </li></ul><ul><li> 1 & 2 make up the population’s reproductive base </li></ul><ul><li>  </li></ul>
  25. 27. <ul><li>The biotic potential of an ecosystem is affected by environmental resistance, thus resulting in a maximum carrying capacity </li></ul><ul><li>Understanding patterns in human population growth is important in addressing population problems around the world. </li></ul>