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Irregular- erratic and the reasoning is typically not
undersFtoigo.d.10–6
© Brooks/Cole Publishing Company / ITP
Carrying capacity (K)
Environmental resistance
Biotic potential
Exponential growth
Time (t)
Population Dynamics
Factors that tend to increase or decrease population size:
Exponential vs. Logistic Growth
Exponential growth occurs when resources are not limiting.
Logistic growth occurs when resources become more and more limiting as population size increases.
[Population Change] = [Births + Immigration] – [Deaths + Emigration]
• If the number of individuals added are balanced by those lost then there is zero population growth (ZPG)
Fig. 10–4
© Brooks/Cole Publishing Company / ITP
Exponential Population Growth
Exponential growth occurs when resources are not limiting.
• During exponential growth population size increases faster and faster with time
Carrying Capacity
There are always limits to population growth in nature.
• Carrying capacity (K) is the number of individuals that can be sustained in a given space
Fig. 10–4a
© Brooks/Cole Publishing Company / ITP
Logistic Population Growth
Logistic population growth occurs when the population growth rate decreases as the population size increases.
• The concept of carrying capacity is of central importance in environmental science
• If the carrying capacity for an organism is exceeded, resources are depleted, environmental degradation results, and the population declines.
AP Environmental Science
Population Dynamics, Carrying Capacity and Conservation Biology
© Brooks/Cole Publishing Company / ITP
1. Characteristics of Populations
© Brooks/Cole Publishing Company / ITP
2. Population Dynamics and Carrying Capacity
Population size is governed by births, deaths, immigration, and emigration:
Biotic potential and environmental resistance determines the carrying capacity
Fig. 10–3
© Brooks/Cole Publishing Company / ITP
Population Density
• Density-dependent population controls- reliant on a dense population for effect: • Pests • Infectious diseases • Competition for resources • Predation
Fig. 10–4b
© Brooks/Cole Publishing Company / ITP
Exceeding the Carrying Capacity
During the mid–1800s sheep populations exceeded the carrying capacity of the island of Tasmania. This "overshoot" was followed by a "population crash". Numbers then stabilized, with oscillation about the carrying capacity.
• Currently the human population is undergoing exponential growth
• Exponential growth can not occur forever because eventually some factor limits population growth.
• **Carrying capacity is determined by climatic
changes, predation, resource availability and
interspecific competition.
© Brooks/Cole Publishing Company / ITP
age group (e.g., prereproductive, reproductive, and postreproductive) of a population.
© Brooks/Cole Publishing Company / ITP
Characteristics of Populations
• Population density- the number of individuals per unit area in terrestrial ecosystems or per unit volume in aquatic ecosystems
• Dispersion- the spatial patterning of individuals • Age structure- is the proportion of individuals in each
Fig. 10–5
© Brooks/Cole Publishing Company / ITP
Population Curves in Nature
Natural populations display a broad diversity of population curves.
Stable- populations are relatively constant over time, fluctuating slightly above and below carrying capacity such as those in undisturbed tropical rain forests.
In terms of dispersion, individuals of a population can be clumped, uniform, or randomly distributed.
CLUMPING MOST COMMON!!!
(a) Clumped (elephants)
(b) Uniform (creosote bush) (c) Random (dandelions)
• Populations vary in their capacity for growth, also known as biotic potential.
Fra Baidu bibliotek
• Intrinsic rate of growth (r)- is the rate at which a population will grow if it had unlimited resources.
Changes in population size, density, dispersion, and age distribution are known as population dynamics.
• Population size- the number of individuals in a population at a given time
• Carrying capacity (K)- the number of individuals in a population
that can be supported in a given area.
© Brooks/Cole Publishing Company / ITP
Population size (N)
Cyclic- population size changes over a regular time period. (e.g., seven–year cicada or lynx and snowshoe hare)
Irruptive- characteristic of species that only have high numbers for only brief periods of times and then experience crashes due to seasons or nutrient availability such as algae and many insects
• Note that when the population is small the logistic population growth curve looks like exponential growth
• Over time, the population size approaches a carrying capacity (K).
• Density-independent population controls- affect population size regardless of density: • Weather • Fire • Habitat destruction • Pesticides • Pollution
Population Crash
Fig. 10–5
© Brooks/Cole Publishing Company / ITP
Exceeding the Carrying Capacity
Reindeer introduced to a small island off of Alaska in the early 1900s exceeded the carrying capacity, with an "overshoot" followed by a "population crash" in which the population was totally decimated by the mid–1900s.
undersFtoigo.d.10–6
© Brooks/Cole Publishing Company / ITP
Carrying capacity (K)
Environmental resistance
Biotic potential
Exponential growth
Time (t)
Population Dynamics
Factors that tend to increase or decrease population size:
Exponential vs. Logistic Growth
Exponential growth occurs when resources are not limiting.
Logistic growth occurs when resources become more and more limiting as population size increases.
[Population Change] = [Births + Immigration] – [Deaths + Emigration]
• If the number of individuals added are balanced by those lost then there is zero population growth (ZPG)
Fig. 10–4
© Brooks/Cole Publishing Company / ITP
Exponential Population Growth
Exponential growth occurs when resources are not limiting.
• During exponential growth population size increases faster and faster with time
Carrying Capacity
There are always limits to population growth in nature.
• Carrying capacity (K) is the number of individuals that can be sustained in a given space
Fig. 10–4a
© Brooks/Cole Publishing Company / ITP
Logistic Population Growth
Logistic population growth occurs when the population growth rate decreases as the population size increases.
• The concept of carrying capacity is of central importance in environmental science
• If the carrying capacity for an organism is exceeded, resources are depleted, environmental degradation results, and the population declines.
AP Environmental Science
Population Dynamics, Carrying Capacity and Conservation Biology
© Brooks/Cole Publishing Company / ITP
1. Characteristics of Populations
© Brooks/Cole Publishing Company / ITP
2. Population Dynamics and Carrying Capacity
Population size is governed by births, deaths, immigration, and emigration:
Biotic potential and environmental resistance determines the carrying capacity
Fig. 10–3
© Brooks/Cole Publishing Company / ITP
Population Density
• Density-dependent population controls- reliant on a dense population for effect: • Pests • Infectious diseases • Competition for resources • Predation
Fig. 10–4b
© Brooks/Cole Publishing Company / ITP
Exceeding the Carrying Capacity
During the mid–1800s sheep populations exceeded the carrying capacity of the island of Tasmania. This "overshoot" was followed by a "population crash". Numbers then stabilized, with oscillation about the carrying capacity.
• Currently the human population is undergoing exponential growth
• Exponential growth can not occur forever because eventually some factor limits population growth.
• **Carrying capacity is determined by climatic
changes, predation, resource availability and
interspecific competition.
© Brooks/Cole Publishing Company / ITP
age group (e.g., prereproductive, reproductive, and postreproductive) of a population.
© Brooks/Cole Publishing Company / ITP
Characteristics of Populations
• Population density- the number of individuals per unit area in terrestrial ecosystems or per unit volume in aquatic ecosystems
• Dispersion- the spatial patterning of individuals • Age structure- is the proportion of individuals in each
Fig. 10–5
© Brooks/Cole Publishing Company / ITP
Population Curves in Nature
Natural populations display a broad diversity of population curves.
Stable- populations are relatively constant over time, fluctuating slightly above and below carrying capacity such as those in undisturbed tropical rain forests.
In terms of dispersion, individuals of a population can be clumped, uniform, or randomly distributed.
CLUMPING MOST COMMON!!!
(a) Clumped (elephants)
(b) Uniform (creosote bush) (c) Random (dandelions)
• Populations vary in their capacity for growth, also known as biotic potential.
Fra Baidu bibliotek
• Intrinsic rate of growth (r)- is the rate at which a population will grow if it had unlimited resources.
Changes in population size, density, dispersion, and age distribution are known as population dynamics.
• Population size- the number of individuals in a population at a given time
• Carrying capacity (K)- the number of individuals in a population
that can be supported in a given area.
© Brooks/Cole Publishing Company / ITP
Population size (N)
Cyclic- population size changes over a regular time period. (e.g., seven–year cicada or lynx and snowshoe hare)
Irruptive- characteristic of species that only have high numbers for only brief periods of times and then experience crashes due to seasons or nutrient availability such as algae and many insects
• Note that when the population is small the logistic population growth curve looks like exponential growth
• Over time, the population size approaches a carrying capacity (K).
• Density-independent population controls- affect population size regardless of density: • Weather • Fire • Habitat destruction • Pesticides • Pollution
Population Crash
Fig. 10–5
© Brooks/Cole Publishing Company / ITP
Exceeding the Carrying Capacity
Reindeer introduced to a small island off of Alaska in the early 1900s exceeded the carrying capacity, with an "overshoot" followed by a "population crash" in which the population was totally decimated by the mid–1900s.