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ENVI 5 population FINAL

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ENVI 5 population FINAL

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ENVI 5 population FINAL

  1. 1. POPULATION ECOLOGY Chapter 5
  2. 2. • Focuses on the factors that influences population’s: Size (number of individuals) Growth rate (rate of change of population size) Density (number of individuals per unit area and volume) Population structure (relative number of individuals different ages) POPULATION ECOLOGY
  3. 3. • Is a group of individuals of same species in same area at same time • refers to the group in general and also to the size of the population—the number of individuals it contains. • a reproductive group because organisms usually breed with members of their own population POPULATION
  4. 4. Population of zebras Population of trees
  5. 5. Demography is the study of populations, but most often refers to the study of human populations Demographics  vital statistics of the populations, which include population size, density, distribution and age structure. CHARACTERISTICS OF POPULATION
  6. 6. 1. Population Density is the number of individuals of a per unit area or volume. CHARACTERISTICS OF POPULATION
  7. 7. 2. Population Distribution Is the dispersal of individuals across an area of interest The availability of resources can affect where of a species are found. CHARACTERISTICS OF POPULATION
  8. 8. Abiotic factors sunlight & temperature precipitation / water soil / nutrients Biotic factors other living organisms prey (food) competitors predators, parasites, disease Resources are non-living and living components of an environment that support living organism
  9. 9. Dispersion Pattern • is the relative distribution or arrangement of its individuals • within a given amount of space.
  10. 10. Why clumped? Results from unequal distribution of resources Why uniform? Results from interactions among individuals of population Why random? Only occurs in the absence of strong attractions or repulsions among individuals in a population.
  11. 11. 3. Growth Rate Results in population sizes A change in the size of a population over a given of time Dependent upon: natality (number of individuals born each year) and mortality (the number of individuals that die each year is the birth rate minus the death rate CHARACTERISTICS OF POPULATION
  12. 12. MIGRATION Another reason the population continued to grow was that immigration increased. The movement of individuals between areas is called migration. Movement into an area is immigration and movement out of an area is emigration. Migration between and within countries is a significant part of population change. The populations of many developed countries might be decreasing if not for immigration.
  13. 13. These graphs have a typical shape for populations with different rates of growth. The number of males and females in each age group are shown as opposite-facing bars. People between 15 and 44 years of age are likely to produce children.
  14. 14. BIOTIC POTENTIAL Is the fastest rate at which populations can grow and is achieved when resources are unlimited Depends on following factors: 1. Usual number of offspring per reproduction or (reproductive potential) 2. Chances of survival age of reproduction 3. How often each individual reproduces 4. Age at which reproduction begins
  15. 15. FORECASTING POPULATION SIZE Survivorship is the percentage of members of a group that are likely to survive to any given age. Cohort is a term used to describe population members that are the same age and have the same chances of surviving. To predict survivorship, a demographer studies a group of people born at the same time and notes when each member of the group dies. The results plotted on a graph might look like one of the types of survivorship curves.
  16. 16. Survivorship curves show how much of the population survives to a given age. A Type I curve is seen in populations where most members survive to be very old. A Type III curve is seen in populations where many children die.
  17. 17. Wealthy developed countries such as Japan and Germany currently have a Type I survivorship curve because most people live to be very old. Type II populations have a similar death rate at all ages. Type III survivorship is the pattern in very poor human populations in which many children die. Both Type I and Type III survivorship may result in populations that remain the same size or grow slowly.
  18. 18. FORECASTING POPULATION SIZE Age Structure Diagrams divide a population into age groupings Three major age groups: • Pre-productive • Reproductive • Post-productive
  19. 19. Why pyramid shaped? Results when pre- reproductive group is largest of the three groups Birth rate is higher than death rate Why bell shaped? Results when reproductive group equals the size of pre- reproductive group Why urn shaped? Results when the post- reproductive group is the largest
  20. 20. PATTERNS OF POPULATION GROWTH The number of babies born each year per 1,000 women in a population is called fertility rate Demographers also calculate the total fertility rate, or the average number of children a woman gives birth to in her lifetime. Replacement level is the average number of children each parent must have in order to “replace” themselves in the population. This number is about 2.1, or slightly more than 2, because not all children born will survive and reproduce.
  21. 21. Birth rate means the number of new individuals that are produced by a population in a period. Death rate means the number of individuals that die in a given period.  A population shrinks when birth rate is less than the death rate.  When the birth rate is greater than the death rate, a population grows.
  22. 22. The baby boom was a period of high fertility rates, and the baby bust was a period of decreasing fertility.
  23. 23. TWO TYPES OF POPULATION GROWTH 1. Logistic Growth Occurs in population that produce a single batch of offspring in a year Population increases by a constant ratio from one generation to the next 2. Exponential Growth Occurs in nature only when populations have plenty of food and space, and have no competition or predators. Populations produce offspring throughout the year
  24. 24. Population growth is graphed by plotting population size over a period of time. Exponential population growth will look like the J-curve shown here.
  25. 25. Logistic population will look like the S-curve shown here.
  26. 26. In an ideal environment (one that has no limiting factors) populations grow at an exponential rate (left). However, for all populations, exponential growth is curtailed by factors such as limitations in food, competition for other resources, or disease. As competition increases and resources become increasingly scarce, populations reach the carrying capacity (K) of their environment, causing their growth rate to slow nearly to zero (right).
  27. 27. CARRYING CAPACITY The maximum number of individuals of a population that can be maintained indefinitely by the environment.  Maintained indefinitely refers to the ability of an ecosystem to provide the same quantity and quality of environmental goods and services over time. When a population overshoots, it means the population surpasses the carrying capacity of its environment. The death rates will begin to surpass birth rate.
  28. 28. An example of carrying capacity is shown by the dashed yellow line in the graph. This line seems to be a limit on the size of the example population (blue line).
  29. 29. LIMITING FACTORS OF POPULATION 1. Density-dependent Factors Includes factors that are related to population size Operate only when the population density reaches a certain level (exponential growth) Operate most strongly when a population is large and dense They do not affect small, scattered populations as greatly  Include: competition, predation, parasitism, disease
  30. 30. LIMITING FACTORS OF POPULATION 2. Density-independent Factors Affect all populations in similar ways, regardless of the population size. Examples of density-independent limiting factors include: unusual weather natural disasters seasonal cycles certain human activities—such as damming rivers and clear- cutting forests
  31. 31. REPRODUCTIVE STRATEGIES R – ADAPTED SPECIES  Short life  Rapid growth  Early maturity  Many, small offspring  Little parental care and protection  Little investment in individual offspring  Adapted to unstable environment  Pioneers, colonizers  Niche generalist  Prey  Regulated by intrinsic factors  Low trophic level K – ADAPTED SPECIES  Long life  Slower growth  Late maturity  Few, large offspring  High parental care or protection  High investment in individual offspring  Adapted to stable environment  Late stages of succession  Niche specialist  Predators  Regulated mainly by extrinsic factors  High trophic level
  32. 32. r – strategist produces a J-curve while k – strategist produces S-curve
  33. 33. HIGHLIGHTS OF THE PHILIPPINE POPULATION 2015 CENSUS OF POPULATION Release Date: Thursday, May 19, 2016 The population of the Philippines as of August 1, 2015 was 100,981,437, based on the 2015 Census of Population (POPCEN 2015). The 2015 population is higher by 8.64 million compared with the population of 92.34 million in 2010, and by 24.47 million compared with the population of 76.51 million in 2000.
  34. 34. HIGHLIGHTS OF THE PHILIPPINE POPULATION 2015 CENSUS OF POPULATION
  35. 35. HIGHLIGHTS OF THE PHILIPPINE POPULATION 2015 CENSUS OF POPULATION The Philippine population increased by 1.72 percent annually, on average, during the period 2010 to 2015. By comparison, the rate at which the country’s population grew during the period 2000 to 2010 was higher at 1.90 percent.
  36. 36. HIGHLIGHTS OF THE PHILIPPINE POPULATION 2015 CENSUS OF POPULATION Of the country’s 18 administrative regions, Region IV-A (CALABARZON) had the biggest population in 2015 with 14.41 million, followed by the National Capital Region (NCR) with 12.88 million, and Region III (Central Luzon) with 11.22 million. The combined population of these three regions accounted for about 38.1 percent of the Philippine population in 2015. The Autonomous Region in Muslim Mindanao (ARMM) was the fastest growing region with an average annual population growth rate (PGR) of 2.89 percent.
  37. 37. HIGHLIGHTS OF THE PHILIPPINE POPULATION 2015 CENSUS OF POPULATION The country has 81 provinces. Of these provinces, Cavite was the most crowded in 2015 with 3.68 million persons, followed by Bulacan (3.29 million), and Laguna (3.04 million). Batanes was the smallest province in terms of population size with 17,246 persons. Two other provinces posted a population size of less than 100,000. These are Siquijor (95,984) and Camiguin (88,478).
  38. 38. HIGHLIGHTS OF THE PHILIPPINE POPULATION 2015 CENSUS OF POPULATION The Philippines has 33 highly urbanized cities (HUCs). Four of these HUCS had surpassed the one million population mark, namely: Quezon City (2.94 million), City of Manila (1.78 million), Davao City (1.63 million), and Caloocan City (1.58 million).
  39. 39. CURRENT PHILIPPINE POPULATION 102 617 303 Current population 51 460 843 Current male population (50.1%) 51 156 462 Current female population (49.9%) 1 694 438 Births this year 473 311 Deaths this year -102 587 Net migration this year -177 Net migration today 1 118 552 Population growth this year 1 928 Population growth today Source : United Nations Department of Economic and Social Affairs: Population Division
  40. 40. PROBLEMS OF RAPID GROWTH Rapidly growing population can use resources faster than the environment can renew them Standards of living decline when wood is removed from local forests faster than it can grow back, or when wastes overwhelm local water sources. Vegetation, water, and land are the resources most critically affected by rapid growth.
  41. 41. PROBLEMS OF RAPID GROWTH The makeshift housing shown here is one consequence of unmanaged growth.
  42. 42. PROBLEMS OF RAPID GROWTH Unsafe Water In places that lack infrastructure, the local water supply may be used not only for drinking and washing but also for sewage disposal. As a result, the water supply becomes a breeding ground for organisms that cause diseases such as dysentery, typhoid, and cholera.
  43. 43. PROBLEMS OF RAPID GROWTH The Rio Grande, shown in this figure is one example of an unsafe water source used by many people.
  44. 44. PROBLEMS OF RAPID GROWTH Impacts on Land Growing populations may have a shortage of arable lands, which is land that can be used to grow crops. Growing populations also make trade-offs between competing uses for land such as agriculture, housing, or natural habitats. Much of the world’s population is undergoing urbanization, which means that more people are living in cities than in rural areas.
  45. 45. PROBLEMS OF RAPID GROWTH Impacts on Land People often find work in the cities but move into suburban areas around the cities. This suburban sprawl leads to traffic jams, inadequate infrastructure, and the reduction of land for farms, ranches, and wildlife habitat. Meanwhile, housing within cities becomes more costly, more dense, and in shorter supply.
  46. 46. PROBLEMS OF RAPID GROWTH

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