Ecology of a PopulationBy:Tara Hill
Population DefinedA population is:A group of organisms of the same speciesoccupying a particular space at a particulartime
Population Characteristics:Distribution:where organisms are found onearth, determined by biotic/abiotic factorsDispersion:...
clumped (aggregated) dispersion -- individualsclumped together -- resources in a habitatmay be patchy in distribution whic...
Uniform-individuals are about equal distancefrom one another-caused by competition among individuals in thesame population
Random-habitat is relatively uniform soindividuals are neither repelled or attracted toone another.
Population SizeA balance between:• Natality=birth rate (b)• Mortality=death rate (d)(b)>(d)=population size increases(b)<(...
Factors affecting population size besidesnatality/mortality• Immigration rate (i) (increases pop. size)• Emigration rate (...
Population GrowthBiotic Potential=-promotes positive growth-intrinsic factors(litter size, gestation)Environmental Resista...
Patterns of growthExponential growth (J shaped curve)• biotic potential(rm)=maximum value
Logistic growth (S shaped)K=carrying capacity=population size that isbased on number of resources available
Limiting factors:Density dependent:-competition-disease-predation-foodDensity independent:-weather-catastrophes
Natural Selection:• limiting factors placestresses on a population• the best adapted organismswill survive and get torepro...
Population GrowthBiotic Potential=-promotes positive growth-intrinsic factors(litter size, gestation)Environmental Resista...
Patterns of growthExponential growth (J shaped curve)• biotic potential(rm)=maximum value
Logistic growth (S shaped)K=carrying capacity=population size that isbased on number of resources available
Limiting factors:Density dependent:-competition-disease-predation-foodDensity independent:-weather-catastrophes
Natural Selection:• limiting factors placestresses on a population• the best adapted organismswill survive and get torepro...
• proportionally massive eyesmaking vision acute for locatingprey• movable ears for better hearingmaking them good nocturn...
Survivorship curves:-based on a cohort of individuals from birth untildeath-cohort=a group of individuals of the same age-...
Type 1=good early survival, die of old age, lowbirth rates, provide lots of parental care(humans)Type 2=die at constant ra...
Life History Patterns:r selected species: species inhabiting fluctuatingor unpredictable environments-environmentskeep pop...
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Bio351 tarahillextracredit

  1. 1. Ecology of a PopulationBy:Tara Hill
  2. 2. Population DefinedA population is:A group of organisms of the same speciesoccupying a particular space at a particulartime
  3. 3. Population Characteristics:Distribution:where organisms are found onearth, determined by biotic/abiotic factorsDispersion: spatial distribution of individuals ofa population -- three general kinds ofpatterns:
  4. 4. clumped (aggregated) dispersion -- individualsclumped together -- resources in a habitatmay be patchy in distribution which causesorganisms to form "clumps"
  5. 5. Uniform-individuals are about equal distancefrom one another-caused by competition among individuals in thesame population
  6. 6. Random-habitat is relatively uniform soindividuals are neither repelled or attracted toone another.
  7. 7. Population SizeA balance between:• Natality=birth rate (b)• Mortality=death rate (d)(b)>(d)=population size increases(b)<(d)=population size decrease(b)=(d)=population size is constant
  8. 8. Factors affecting population size besidesnatality/mortality• Immigration rate (i) (increases pop. size)• Emigration rate (e) (decreases pop. size)Growth rate equation:r=(b-d) + (i-e)
  9. 9. Population GrowthBiotic Potential=-promotes positive growth-intrinsic factors(litter size, gestation)Environmental Resistance=-limits growth-extrinsic factor(weather, food supply)
  10. 10. Patterns of growthExponential growth (J shaped curve)• biotic potential(rm)=maximum value
  11. 11. Logistic growth (S shaped)K=carrying capacity=population size that isbased on number of resources available
  12. 12. Limiting factors:Density dependent:-competition-disease-predation-foodDensity independent:-weather-catastrophes
  13. 13. Natural Selection:• limiting factors placestresses on a population• the best adapted organismswill survive and get toreproduce and pass on theirgenes with the adaptationto their offspring• over long periods of timethis can lead to a change inspecies
  14. 14. Population GrowthBiotic Potential=-promotes positive growth-intrinsic factors(litter size, gestation)Environmental Resistance=-limits growth-extrinsic factor(weather, food supply)
  15. 15. Patterns of growthExponential growth (J shaped curve)• biotic potential(rm)=maximum value
  16. 16. Logistic growth (S shaped)K=carrying capacity=population size that isbased on number of resources available
  17. 17. Limiting factors:Density dependent:-competition-disease-predation-foodDensity independent:-weather-catastrophes
  18. 18. Natural Selection:• limiting factors placestresses on a population• the best adapted organismswill survive and get toreproduce and pass on theirgenes with the adaptationto their offspring• over long periods of timethis can lead to a change inspecies
  19. 19. • proportionally massive eyesmaking vision acute for locatingprey• movable ears for better hearingmaking them good nocturnalhunters• can rotate their heads a full 180degrees to help them avoidpredators such as wild cats• Long back legs to help themjump twenty feet, an importantsurvival skill in the jungle• Long tail providing power forjumping and holding onto treeEx:Phillipine Tarsier
  20. 20. Survivorship curves:-based on a cohort of individuals from birth untildeath-cohort=a group of individuals of the same age-survivorship curves are meant to show thenumber of individuals surviving at each agefor a particular species-three types of curves
  21. 21. Type 1=good early survival, die of old age, lowbirth rates, provide lots of parental care(humans)Type 2=die at constant rate regardless of age(birds, lizards)Type3 =poor early survival,survival thatimproves withage, lots of offspring, lowparental care(fish,plants)
  22. 22. Life History Patterns:r selected species: species inhabiting fluctuatingor unpredictable environments-environmentskeep populations below carrying capacity (lotsof predation, competition over resources)k selected species-species inhabiting stable,predictable environments-keep populationsize near carrying capacity and resources arescarce

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