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Population Growth
Biotic Potential=
-promotes positive growth
-intrinsic factors(litter size, gestation)
Environmental Resistance=
-limits growth
-extrinsic factor(weather, food supply)
Patterns of growthExponential growth (J shaped curve)
• biotic potential(rm)=maximum value
Logistic growth (S shaped)
K=carrying capacity=population size that is based on number of resources available
Limiting factors:
Density dependent:
-competition
-disease
-predation
-food
Density independent:
-weather
-catastrophes
-natural disasters (typhoons, volcanoes)
Natural Selection:
• limiting factors place stresses on a population
• the best adapted organisms will survive and get to reproduce and pass on their genes with the adaptation to their offspring
• over long periods of time this can lead to a change in species
Population Growth
Biotic Potential=
-promotes positive growth
-intrinsic factors(litter size, gestation)
Environmental Resistance=
-limits growth
-extrinsic factor(weather, food supply)
Patterns of growthExponential growth (J shaped curve)
• biotic potential(rm)=maximum value
Logistic growth (S shaped)
K=carrying capacity=population size that is based on number of resources available
Limiting factors:
Density dependent:
-competition
-disease
-predation
-food
Density independent:
-weather
-catastrophes
-natural disasters (typhoons, volcanoes)
Natural Selection:
• limiting factors place stresses on a population
• the best adapted organisms will survive and get to reproduce and pass on their genes with the adaptation to their offspring
• over long periods of time this can lead to a change in species
• proportionally massive eyes
making vision acute for locating
prey
• movable ears for better hearing
making them good nocturnal
hunters
• can rotate their heads a full 180
degrees to help them avoid
predators such as wild cats
• Long back legs to help them
jump twenty feet, an important
survival skill in the jungle
• Long tail providing power for
jumping and holding onto tree
branches for stability
Ex:Phillipine Tarsier
Survivorship curves:
-based on a cohort of individuals from birth until death
-cohort=a group of individuals of the same age
-survivorship curves are meant to show the number of individuals surviving at each age for a particular species
-three types of curves
Type 1=good early survival, die of old age, low birth rates, provide lots of parental care (humans)
Type 2=die at constant rate regardless of age (birds, lizards)
Type3 =poor early survival,survival thatimproves with
age, lots of offspring, low parental care(fish,plants)
Life History Patterns:
r selected species: species inhabiting fluctuating or unpredictable environments-environments keep populations below carrying capacity (lots of predation, competition over resources)
k selected species-species inhabiting stable, predictable environments-keep population size near carrying capacity and resources are scarce