Population Ecology and the Distribution of Organisms

Ecology

Objective: Understand Ecological Interactions

Ecology is the scientific study of the interactions between organisms and the environment.
Interactions studied by ecologists can be organized into a hierarchy that scales from single organisms to the globe.

Levels of Ecological Study:

Organismal Ecology: Considers how organism structure, physiology, and behavior meet environmental challenges. Includes physiological, evolutionary, and behavioral ecology.
Population Ecology: Considers factors affecting population size and change over time. A population is a group of individuals of the same species living in an area.
Community Ecology: Examines how interactions between species affect community structure and organization. A community is a group of populations of different species in an area.
Ecosystem Ecology: Emphasizes energy flow and chemical cycling between organisms and the environment. An ecosystem is the community of organisms in an area and the physical factors with which they interact.
Landscape Ecology: Focuses on factors controlling exchanges of energy, materials, and organisms across multiple ecosystems. A landscape (or seascape) is a mosaic of connected ecosystems.
Global Ecology: Examines how exchange of energy and materials at the regional scale influences the function and distribution of organisms across the biosphere. The biosphere is the global ecosystem— the sum of all ecosystems and landscapes on the planet.

Earth’s Climate

Objective: Analyze Climate's Influence on Biomes

The long-term prevailing weather conditions in an area constitute its climate.
Four important physical components of climate include temperature, precipitation, sunlight, and wind.
Abiotic factors are the nonliving chemical and physical attributes of the environment.
Biotic factors are the other organisms that make up the living component of the environment.

Global Climate Patterns:

Determined largely by solar energy and the planet’s movement in space.
Surface warming by solar radiation causes air and water circulation and latitudinal variation in temperature.

Latitudinal Variation in Sunlight Intensity:

The curved shape of Earth affects the intensity of sunlight.
Sunlight is most intense in the tropics ( $23.5º$ N latitude to $23.5º$ S latitude) where it strikes the surface most directly.
Intensity decreases with increase latitude because sunlight strikes the surface at more oblique angles.
Temperature is highest near the equator and decreases with increasing latitude.

Global Air Circulation and Precipitation Patterns:

High temperatures in the tropics evaporate water from the surface and cause warm, wet air to rise.
As rising air expands and cools, it releases water as heavy precipitation over the tropics.
High altitude air masses, now dry, flow toward the poles.
Dry air descends near the $30º$ N and S latitudes, absorbing moisture from the land and creating arid conditions.
Low altitude air flows toward the equator and the poles.
Air masses rise again at the $60º$ N and S latitudes, repeating the pattern of precipitation and drying near the poles.
Latitudinal variation in the speed of Earth’s rotation deflects the path of air flow creating global wind patterns.
- Trade winds are deflected from east to west as they flow toward the equator.
- Westerlies are deflected from west to east as they flow toward the poles.

Regional and Local Effects on Climate:

Climate varies seasonally and is affected by factors, such as large bodies of water and mountain ranges.

Seasonality:

Earth’s tilted axis of rotation and its annual passage around the sun cause seasonality in middle to high latitudes.
Seasonal variation is smallest in the tropics and increases with latitude.
Day length, solar radiation, and temperature all cycle strongly with season.
The changing angle of the sun affects local environments.
The most direct and intense sunlight hitting Earth shifts slightly north and south of the equator annually.
The belts of wet and dry air straddling the equator also shift, causing wet and dry seasons near the $20º$ N and S.
Tropical deciduous forests grow in these regions.
Seasonal changes in wind patterns can alter ocean currents.
Movement of cold, nutrient-rich water from the ocean floor to the surface (upwelling) results in some areas.
Upwelling stimulates phytoplankton growth supporting productive aquatic food webs.

Bodies of Water:

Ocean currents influence coastal climates by heating or cooling overlying air masses that pass across the land.
The northeast coast of North America is cooled by the Labrador Current carrying cold water southward.
The northwest coast of Europe is warmed by the Gulf Stream carrying warm water northward from the equator.
Large bodies of water are resistant to temperature fluctuation and can moderate the climate of nearby land.
Land heats up during the day causing overlying air to rise and pull cooler air from the water across the land.
At night, air rises over the now warmer water, and pulls cool air away from the land.

Mountains:

Air that encounters mountains flows up to higher altitudes.
Warm, moist air expands and cools as it rises, releasing moisture on the windward side of the peak.
On the leeward side, cooler, dry air descends, absorbing moisture from the land, creating a “rain shadow”.
Many deserts are found in leeward rain shadows.
Mountains affect the amount of sunlight reaching an area.
South-facing slopes receive more sunlight than north-facing slopes in the Northern Hemisphere.
Conifers grow on the cooler north-facing slopes; shrubby, drought-resistant plants inhabit south-facing slopes.
Every 1,000-m ( $3,280$ ft) increase in elevation produces an average temperature drop of $6ºC$ ( $\~11ºF$ ).
$1000'$ increase, ~ $3ºF$

Effects of Vegetation on Climate:

Forests absorb more (and reflect less) solar radiation than grasslands or deserts.
This increases rates of photosynthesis and transpiration in forests relative to other types of vegetation.
Evaporative water loss cools surface temperature and increases precipitation rate in forested regions.

Objective: Describe Terrestrial Biomes

Biomes are major life zones characterized by vegetation type (terrestrial biomes) or physical environment (aquatic biomes).
Latitudinal variation in climate influences the distribution of plants and the location of terrestrial biomes.
A climograph plots the annual average temperature and precipitation in a region.
Biomes are also affected by the pattern of temperature and precipitation through the year.
- For example, some areas receive regular precipitation throughout the year, whereas others have distinct wet and dry seasons.
Natural and human-caused disturbances alter the distribution of biomes.
A disturbance is an event that changes a community by removing organisms and altering resource availability.
- For example, frequent fires kill woody plants and can prevent savanna from transitioning into woodland.

General Features of Terrestrial Biomes:

Terrestrial biomes are often named for major physical or climatic features and for their predominant vegetation.
Biomes are also characterized by microorganisms, fungi, and animals adapted to that environment.
Terrestrial biomes usually grade into each other, without sharp boundaries.
The area of intergradation, called an ecotone, may be wide or narrow.

Species Distribution

Objective: Explain Limits on Species Distribution

Species distributions are a consequence of both ecological factors and evolutionary history.
Geographic isolation can result in the evolution of unique lineages restricted to specific areas.
- For example, the kangaroo lineage occurs only on the isolated continent of Australia.
- Ecological factors have prevented kangaroos from dispersing to other continents.
Ecologists ask questions about where species occur and why they occur where they do.
Distribution can be limited by dispersal ability, biotic interactions, or abiotic factors of the environment.

Dispersal and Distribution:

Dispersal is the movement of individuals or gametes away from their area of origin or centers of high population density.
Dispersal contributes greatly to the global distribution of organisms.

Biotic Factors:

Interactions with other species can limit species distributions.
Such biotic factors can include:
- Predation
- Herbivory
- Mutualism
- Parasitism
- Competition
The presence or absence of certain interacting species can act as a biotic limitation on a species’ distribution.
- For example, the activity of the long-spined sea urchin, an herbivore, affects the distribution of a seaweed species that it feeds upon.

Abiotic Factors:

Species are not found in areas where physical conditions prevent their survival or reproduction.
Abiotic factors limiting species distributions include
- Temperature
- Water
- Oxygen
- Salinity
- Sunlight
- Rocks and soil
Temperature limits the distribution of organisms because of its effect on biological processes.
Cells may freeze and rupture below while most proteins denature above.
Most organisms function best within a specific temperature range.
Many species have altered their geographic ranges in response to climate change.
When a species moves into a new area, it can affect other species that were already established in the area.
- For example, the sea urchin C. rodgersii expanded its distribution in response to rising water temperatures.
- Algal communities in the expanded range were destroyed by this voracious consumer.
Availability of water and oxygen are also important factors influencing species distribution.
The distribution of terrestrial organisms reflects their ability to obtain and store water to avoid desiccation.
Oxygen concentration can be limiting in some aquatic systems and soils because it diffuses slowly in water.
Salinity, salt concentration, affects the water balance of organisms through osmosis.
Most aquatic organisms are restricted to either freshwater or saltwater habitats by their limited ability to osmoregulate.
Few terrestrial plants and animals are adapted to survive extreme high-salinity habitats.
Sunlight is the energy source for photosynthetic organisms and, as such, can limit their distribution.
In aquatic environments, most photosynthesis occurs near the surface where sunlight is available.
Shading by the canopy drives intense competition for light in forests.
Rocks and soil can limit the distribution of organisms through effects on pH, mineral composition, and physical structure of the substrate.
Species distributions can be limited by pH directly or by its indirect effect on nutrient and toxin solubility.
The substrate can affect water chemistry and the types of benthic organisms found in aquatic ecosystems.

Population Ecology

Objective: Analyze Population Characteristics and Dynamics

A population is a group of individuals of a single species living in the same general area.
Populations are described by their boundaries and size.
Population ecology explores how biotic and abiotic factors influence density, distribution, and population size.

Density and Dispersion:

Density is the number of individuals per unit area or volume.
Dispersion is the pattern of spacing among individuals within the boundaries of the population.

Density: A Dynamic Perspective:

In most cases, it is impractical or impossible to count all individuals in a population.
Sampling techniques can be used to estimate densities and total population sizes.
Estimates can be extrapolated from direct samples of the population or indicators, such as the number of nests.
Density is a dynamic property resulting from processes that add and remove individuals from the population.
Additions occur through births and immigration, the influx of new individuals from other areas.
Removal of individuals occurs through death and emigration, the movement of individuals out of a population.

Patterns of Dispersion:

Environmental and social factors influence the spacing of individuals in a population.
The most common pattern of dispersion is clumped, in which individuals aggregate in patches.
Clumped dispersion can be influenced by resource availability, mating behavior, and group predation or defense strategies.
A uniform, or evenly spaced, pattern of dispersion may result from direct interactions between individuals.
Some plants secrete chemicals that inhibit growth or germination to limit the proximity of competitors.
Antagonistic social interactions, such as territoriality—the defense of a bounded space against other individuals—can cause uniform dispersion in animals.
In a random dispersion, the position of each individual is independent of other individuals.
The absence of strong attractions or repulsions among individuals can cause random dispersion.
It can also occur where key physical or chemical factors are relatively constant across the study area.

Demographics:

Demography is the study of the births, deaths, and migration rates of a population over time.
This demographic information can be summarized in a life table.

Life Tables:

A life table is an age-specific summary of survival and reproductive rates within a population.
Life tables are made by following the fate of a cohort, a group of individuals of the same age, from birth to death.
For sexually reproducing species, demographers often ignore males because only females produce offspring.

Survivorship Curves:

A survivorship curve is a graphic way of representing the survival data in a life table.
Survivorship curves plot the proportion or numbers of a cohort still alive at each age.
There are three general types of survivorship curves:
- Type I: high survivorship in early and middle life, with a steep decline as death rates increase in old age
- Type II: survivorship declines linearly due to a constant death rate over the organism’s life span
- Type III: a steep initial drop in survivorship due to high death rates for juveniles that stabilizes for survivors

Reproductive Rates:

The reproductive pattern of a population is described by the variation in reproductive output with female age.
For sexual organisms, reproductive output is measured as the average number of female offspring for each female in a given age-group.
Age-specific reproductive rates vary considerably by species.

Population Growth Models

Objective: Contrast Exponential and Logistic Growth Models

Unlimited growth occurs under ideal conditions; in nature, growth is limited by various factors.
Population ecologists study growth in both idealized and realistic conditions.

Changes in Population Size:

Change in population size can be defined by the equation:
If immigration and emigration are ignored, the change in population size equals births minus deaths:
- $Change \ in \ population \ size = Births + Immigrants — Deaths — Emigrants$
- $Change \ in \ population \ size = Births — Deaths$
The population growth rate can be expressed mathematically as
- $\frac{\Delta N}{\Delta t} = B - D$
  where $\Delta N$ is the change in population size, $\Delta t$ is the time interval, B is the number of births, and D is the number of deaths in the population during the interval
The population growth equation can be revised:
- $\frac{\Delta N}{\Delta t} = R$
  where R represents the difference between the number of births (B) and the number of deaths (D)
The per capita change in population size ( $r_{\Delta t}$ ) represents the contribution of the average individual to the population size during the time interval, $\Delta t$
- For example, for a population of 1,000 individuals that increases by 16 individuals per year: $r_{\Delta t} = \frac{16}{1,000} = 0.016$
The formula $R = r_{\Delta t}N$ is used to calculate how many individuals will be added to a population each year
- For example, if $r{\Delta t} = 0.016$ and the population size is 500: $R = r{\Delta t}N = 0.016 \times 500 = 8$ per year
Change in population size can now be written as:
- $\frac{\Delta N}{\Delta t} = r_{\Delta t}N$
Population growth can also be expressed as a rate of change at each instant in time:
- $\frac{dN}{dt} = rN$
  where $\frac{dN}{dt}$ represents very small changes in population size over short (instantaneous) time intervals
The per capita population growth rate (r) can vary depending on circumstances
The population growth equation can be changed to reflect this reality:
- $\frac{dN}{dt} = r{realized}N$ where $r{realized}$ represents the per capita growth rate that the population is actually experiencing at a given time

The Exponential Growth Model:

Exponential population growth occurs under idealized conditions where food is abundant and all individuals reproduce at maximum of their physiological capacity
Under such conditions, the population increases in size by a constant proportion at each instant in time
In exponential growth, $r*{realized}$ is always the maximum it can be for that particular species
- $\frac{dN}{dt} = r_{realized}N$
- $\frac{dN}{dt} = r_{max}N$
The equation of exponential population growth is:
- $\frac{dN}{dt} = r{max}N$ where $r{max}$ is the intrinsic rate of increase, the per capita rate at which an exponentially growing population increases in size at each instant in time
A population growing exponentially increases at a constant rate forming a J-shaped growth curve when population size is plotted over time
A population with a higher intrinsic rate of increase will have a steeper growth curve
Exponential growth can occur in populations introduced to new environments or rebounding from catastrophic events
- For example, the elephant population in Kruger National Park, South Africa, grew exponentially for 60 years after they were protected from hunting

The Logistic Growth Model:

The exponential growth model assumes unlimited resources; in nature, resources are usually limited
The maximum population size a particular environment can sustain is the carrying capacity (K)
Carrying capacity varies over space and time with the abundance of limiting resources such as energy, shelter, refuge, nutrients, water, and nesting sites
As a population approaches carrying capacity, the per capita birth rate may decrease or the per capita death rate may increase
Such changes in either (or both) of these rates cause the realized per capita growth rate to drop
In the logistic population growth model, the per capita rate of increase approaches zero as population size nears carrying capacity
This model starts with the exponential model and adds an expression that reduces per capita rate of increase as N approaches K
- $\frac{dN}{dt} = r*{max} \frac{(K - N)}{K} N$
When N is small compared to K, the term $\frac{(K - N)}{K}$ is close to 1 and $r{realized}$ will be close to $r{max}$
When N is large and resources limiting, $\frac{(K - N)}{K}$ is close to 0 and $r_{realized}$ is small
When N = K, the population stops growing
Population growth is highest when the population size is at half the carrying capacity
At half carrying capacity the realized per capita rate of increase remains relatively high and there are more reproducing individuals than at low population size
Population growth slows when the population size is greater than half the carrying capacity
The number of individuals added to the population decreases dramatically as N approaches K
The logistic model of population growth produces a sigmoid (S-shaped) curve

The Logistic Model and Real Populations:

The growth of many laboratory populations fits an S-shaped curve when resources are limited
These populations are grown in a constant environment lacking predators and competitors
Assumptions built into the logistic model do not apply to all populations
Populations often experience a delay before negative effects of increasing population are realized
- In such cases, populations overshoot K before settling down to a relatively stable density
Some populations fluctuate greatly and make it difficult to define K

Ecology

Objective: Understand Ecological Interactions

Ecology studies interactions between organisms and their environment, organized from individual organisms to the global scale.

Levels of Ecological Study:

Organismal Ecology: Studies individual organism adaptations.
Population Ecology: Studies population size and changes.
Community Ecology: Studies interactions between species.
Ecosystem Ecology: Studies energy flow and chemical cycling.
Landscape Ecology: Studies exchanges across ecosystems.
Global Ecology: Studies regional energy and material exchanges.

Earth’s Climate

Objective: Analyze Climate's Influence on Biomes

Climate is long-term weather conditions, influenced by temperature, precipitation, sunlight, and wind.
Abiotic factors: Nonliving components.
Biotic factors: Living components.

Global Climate Patterns:

Determined by solar energy and Earth’s movement.
Solar radiation warms the surface, causing air and water circulation.

Latitudinal Variation in Sunlight Intensity:

Sunlight is most intense at the tropics, decreasing with latitude.

Global Air Circulation and Precipitation Patterns:

High tropical temperatures lead to evaporation and precipitation.
Dry air descends near $30º$ N/S, creating arid conditions.
Air rises at $60º$ N/S, causing precipitation.
Latitudinal variation and Earth’s rotation create global wind patterns like trade winds and westerlies.

Regional and Local Effects on Climate:

Climate varies seasonally and is affected by water bodies and mountains.

Seasonality:

Earth's tilt causes seasonal changes, especially in middle to high latitudes.
Wet/dry belts shift near $20º$ N/S.
Upwelling stimulates aquatic food webs.

Bodies of Water:

Ocean currents influence coastal climates.
Water moderates land temperatures.

Mountains:

Mountains create rain shadows, affecting sunlight and temperature.

Effects of Vegetation on Climate:

Forests absorb more solar radiation and increase precipitation.

Objective: Describe Terrestrial Biomes

Biomes are major life zones defined by vegetation (terrestrial) or physical environment (aquatic).
Climate influences biome distribution.
Climographs plot temperature and precipitation.
Disturbances can alter biome distribution.

General Features of Terrestrial Biomes:

Biomes are named for physical, climatic features, and vegetation. Ecotones are areas of intergradation between biomes.

Species Distribution

Objective: Explain Limits on Species Distribution

Species distributions result from ecological factors and evolutionary history.
Geographic isolation leads to unique species.
Distribution limited by dispersal, biotic interactions, and abiotic factors.

Dispersal and Distribution:

Dispersal is movement from the origin.

Biotic Factors:

Biotic factors include predation, herbivory, mutualism, parasitism, and competition.

Abiotic Factors:

Abiotic factors include temperature, water, oxygen, salinity, sunlight, rocks, and soil.
Temperature affects biological processes.
Water and oxygen availability influences species distribution.
Salinity affects water balance.
Sunlight is crucial for photosynthesis.
Rocks and soil affect pH and nutrient availability.

Population Ecology

Objective: Analyze Population Characteristics and Dynamics

A population is a group of individuals of a single species in the same area.
Population ecology studies factors influencing population density, distribution, and size.

Density and Dispersion:

Density: Individuals per unit area.
Dispersion: Spacing patterns.

Density: A Dynamic Perspective:

Density changes through births, deaths, immigration, and emigration.

Patterns of Dispersion:

Clumped: Individuals in patches.
Uniform: Evenly spaced.
Random: Independent spacing.

Demographics:

Demography studies vital rates.

Life Tables:

Life tables summarize survival and reproduction.

Survivorship Curves:

Survivorship curves represent survival data.
Types: I, II, and III.

Reproductive Rates:

Reproductive output varies with age.

Population Growth Models

Objective: Contrast Exponential and Logistic Growth Models

Growth is limited by environmental factors.

Changes in Population Size:

Change in population size equals births minus deaths: $\frac{\Delta N}{\Delta t} = B - D$
Population growth rate: $\frac{\Delta N}{\Delta t} = R$
Per capita change in population size (r[Delta t}): Contribution of an individual to population size.
$\frac{dN}{dt} = rN$

The Exponential Growth Model:

Exponential growth occurs with unlimited resources (\frac{dN}{dt} = r[max}N).

The Logistic Growth Model:

Carrying capacity (K) is the maximum population size an environment can sustain.
Logistic growth model: \frac{dN}{dt} = r[max} \frac{(K - N)}{K} N

The Logistic Model and Real Populations:

Real

Ecology

Objective: Understand Ecological Interactions

Ecology studies interactions between organisms and their environment, organized from individual organisms to the global scale.

Levels of Ecological Study:

Organismal Ecology: Studies individual organism adaptations.
Population Ecology: Studies population size and changes.
Community Ecology: Studies interactions between species.
Ecosystem Ecology: Studies energy flow and chemical cycling.
Landscape Ecology: Studies exchanges across ecosystems.
Global Ecology: Studies regional energy and material exchanges.

Earth’s Climate

Objective: Analyze Climate's Influence on Biomes

Climate is long-term weather conditions, influenced by temperature, precipitation, sunlight, and wind.
Abiotic factors: Nonliving components.
Biotic factors: Living components.

Global Climate Patterns:

Determined by solar energy and Earth’s movement.
Solar radiation warms the surface, causing air and water circulation.

Latitudinal Variation in Sunlight Intensity:

Sunlight is most intense at the tropics, decreasing with latitude.

Global Air Circulation and Precipitation Patterns:

High tropical temperatures lead to evaporation and precipitation.
Dry air descends near $30º$ N/S, creating arid conditions.
Air rises at $60º$ N/S, causing precipitation.
Latitudinal variation and Earth’s rotation create global wind patterns like trade winds and westerlies.

Regional and Local Effects on Climate:

Climate varies seasonally and is affected by water bodies and mountains.

Seasonality:

Earth's tilt causes seasonal changes, especially in middle to high latitudes.
Wet/dry belts shift near $20º$ N/S.
Upwelling stimulates aquatic food webs.

Bodies of Water:

Ocean currents influence coastal climates.
Water moderates land temperatures.

Mountains:

Mountains create rain shadows, affecting sunlight and temperature.

Effects of Vegetation on Climate:

Forests absorb more solar radiation and increase precipitation.

Objective: Describe Terrestrial Biomes

Biomes are major life zones defined by vegetation (terrestrial) or physical environment (aquatic).
Climate influences biome distribution.
Climographs plot temperature and precipitation.
Disturbances can alter biome distribution.

General Features of Terrestrial Biomes:

Biomes are named for physical, climatic features, and vegetation. Ecotones are areas of intergradation between biomes.

Species Distribution

Objective: Explain Limits on Species Distribution

Species distributions result from ecological factors and evolutionary history.
Geographic isolation leads to unique species.
Distribution limited by dispersal, biotic interactions, and abiotic factors.

Dispersal and Distribution:

Dispersal is movement from the origin.

Biotic Factors:

Biotic factors include predation, herbivory, mutualism, parasitism, and competition.

Abiotic Factors:

Abiotic factors include temperature, water, oxygen, salinity, sunlight, rocks, and soil.
Temperature affects biological processes.
Water and oxygen availability influences species distribution.
Salinity affects water balance.
Sunlight is crucial for photosynthesis.
Rocks and soil affect pH and nutrient availability.

Population Ecology

Objective: Analyze Population Characteristics and Dynamics

A population is a group of individuals of a single species in the same area.
Population ecology studies factors influencing population density, distribution, and size.

Density and Dispersion:

Density: Individuals per unit area.
Dispersion: Spacing patterns.

Density: A Dynamic Perspective:

Density changes through births, deaths, immigration, and emigration.

Patterns of Dispersion:

Clumped: Individuals in patches.
Uniform: Evenly spaced.
Random: Independent spacing.

Demographics:

Demography studies vital rates.

Life Tables:

Life tables summarize survival and reproduction.

Survivorship Curves:

Survivorship curves represent survival data.
Types: I, II, and III.

Reproductive Rates:

Reproductive output varies with age.

Population Growth Models

Objective: Contrast Exponential and Logistic Growth Models

Growth is limited by environmental factors.

Changes in Population Size:

Change in population size equals births minus deaths: $\frac{\Delta N}{\Delta t} = B - D$
Population growth rate: $\frac{\Delta N}{\Delta t} = R$
Per capita change in population size (r[Delta t}): Contribution of an individual to population size.
$\frac{dN}{dt} = rN$

The Exponential Growth Model:

Exponential growth occurs with unlimited resources (\frac{dN}{dt} = r[max}N).

The Logistic Growth Model:

Carrying capacity (K) is the maximum population size an environment can sustain.
Logistic growth model: \frac{dN}{dt} = r[max} \frac{(K - N)}{K} N

The Logistic Model and Real Populations:

Real

Ecology

Objective: Understand Ecological Interactions

Ecology studies interactions between organisms and their environment, organized from individual organisms to the global scale.

Levels of Ecological Study:

Organismal Ecology: Studies individual organism adaptations.
Population Ecology: Studies population size and changes.
Community Ecology: Studies interactions between species.
Ecosystem Ecology: Studies energy flow and chemical cycling.
Landscape Ecology: Studies exchanges across ecosystems.
Global Ecology: Studies regional energy and material exchanges.

Earth’s Climate

Objective: Analyze Climate's Influence on Biomes

Climate is long-term weather conditions, influenced by temperature, precipitation, sunlight, and wind.
Abiotic factors: Nonliving components.
Biotic factors: Living components.

Global Climate Patterns:

Determined by solar energy and Earth’s movement.
Solar radiation warms the surface, causing air and water circulation.

Latitudinal Variation in Sunlight Intensity:

Sunlight is most intense at the tropics, decreasing with latitude.

Global Air Circulation and Precipitation Patterns:

High tropical temperatures lead to evaporation and precipitation.
Dry air descends near $30º$ N/S, creating arid conditions.
Air rises at $60º$ N/S, causing precipitation.
Latitudinal variation and Earth’s rotation create global wind patterns like trade winds and westerlies.

Regional and Local Effects on Climate:

Climate varies seasonally and is affected by water bodies and mountains.

Seasonality:

Earth's tilt causes seasonal changes, especially in middle to high latitudes.
Wet/dry belts shift near $20º$ N/S.
Upwelling stimulates aquatic food webs.

Bodies of Water:

Ocean currents influence coastal climates.
Water moderates land temperatures.

Mountains:

Mountains create rain shadows, affecting sunlight and temperature.

Effects of Vegetation on Climate:

Forests absorb more solar radiation and increase precipitation.

Objective: Describe Terrestrial Biomes

Biomes are major life zones defined by vegetation (terrestrial) or physical environment (aquatic).
Climate influences biome distribution.
Climographs plot temperature and precipitation.
Disturbances can alter biome distribution.

General Features of Terrestrial Biomes:

Biomes are named for physical, climatic features, and vegetation. Ecotones are areas of intergradation between biomes.

Species Distribution

Objective: Explain Limits on Species Distribution

Species distributions result from ecological factors and evolutionary history.
Geographic isolation leads to unique species.
Distribution limited by dispersal, biotic interactions, and abiotic factors.

Dispersal and Distribution:

Dispersal is movement from the origin.

Biotic Factors:

Biotic factors include predation, herbivory, mutualism, parasitism, and competition.

Abiotic Factors:

Abiotic factors include temperature, water, oxygen, salinity, sunlight, rocks, and soil.
Temperature affects biological processes.
Water and oxygen availability influences species distribution.
Salinity affects water balance.
Sunlight is crucial for photosynthesis.
Rocks and soil affect pH and nutrient availability.

Population Ecology

Objective: Analyze Population Characteristics and Dynamics

A population is a group of individuals of a single species in the same area.
Population ecology studies factors influencing population density, distribution, and size.

Density and Dispersion:

Density: Individuals per unit area.
Dispersion: Spacing patterns.

Density: A Dynamic Perspective:

Density changes through births, deaths, immigration, and emigration.

Patterns of Dispersion:

Clumped: Individuals in patches.
Uniform: Evenly spaced.
Random: Independent spacing.

Demographics:

Demography studies vital rates.

Life Tables:

Life tables summarize survival and reproduction.

Survivorship Curves:

Survivorship curves represent survival data.
Types: I, II, and III.

Reproductive Rates:

Reproductive output varies with age.

Population Growth Models

Objective: Contrast Exponential and Logistic Growth Models

Growth is limited by environmental factors.

Changes in Population Size:

Change in population size equals births minus deaths: $\frac{\Delta N}{\Delta t} = B - D$
Population growth rate: $\frac{\Delta N}{\Delta t} = R$
Per capita change in population size (r[Delta t}): Contribution of an individual to population size.
$\frac{dN}{dt} = rN$

The Exponential Growth Model:

Exponential growth occurs with unlimited resources (\frac{dN}{dt} = r[max}N).

The Logistic Growth Model:

Carrying capacity (K) is the maximum population size an environment can sustain.
Logistic growth model: \frac{dN}{dt} = r[max} \frac{(K - N)}{K} N

The Logistic Model and Real Populations:

Real

Ecology

Objective: Understand Ecological Interactions

Ecology studies interactions between organisms and their environment, organized from individual organisms to the global scale.

Levels of Ecological Study:

Organismal Ecology: Studies individual organism adaptations.
Population Ecology: Studies population size and changes.
Community Ecology: Studies interactions between species.
Ecosystem Ecology: Studies energy flow and chemical cycling.
Landscape Ecology: Studies exchanges across ecosystems.
Global Ecology: Studies regional energy and material exchanges.

Earth’s Climate

Objective: Analyze Climate's Influence on Biomes

Climate is long-term weather conditions, influenced by temperature, precipitation, sunlight, and wind.
Abiotic factors: Nonliving components.
Biotic factors: Living components.

Global Climate Patterns:

Determined by solar energy and Earth’s movement.
Solar radiation warms the surface, causing air and water circulation.

Latitudinal Variation in Sunlight Intensity:

Sunlight is most intense at the tropics, decreasing with latitude.

Global Air Circulation and Precipitation Patterns:

High tropical temperatures lead to evaporation and precipitation.
Dry air descends near $30º$ N/S, creating arid conditions.
Air rises at $60º$ N/S, causing precipitation.
Latitudinal variation and Earth’s rotation create global wind patterns like trade winds and westerlies.

Regional and Local Effects on Climate:

Climate varies seasonally and is affected by water bodies and mountains.

Seasonality:

Earth's tilt causes seasonal changes, especially in middle to high latitudes.
Wet/dry belts shift near $20º$ N/S.
Upwelling stimulates aquatic food webs.

Bodies of Water:

Ocean currents influence coastal climates.
Water moderates land temperatures.

Mountains:

Mountains create rain shadows, affecting sunlight and temperature.

Effects of Vegetation on Climate:

Forests absorb more solar radiation and increase precipitation.

Objective: Describe Terrestrial Biomes

Biomes are major life zones defined by vegetation (terrestrial) or physical environment (aquatic).
Climate influences biome distribution.
Climographs plot temperature and precipitation.
Disturbances can alter biome distribution.

General Features of Terrestrial Biomes:

Biomes are named for physical, climatic features, and vegetation. Ecotones are areas of intergradation between biomes.

Species Distribution

Objective: Explain Limits on Species Distribution

Species distributions result from ecological factors and evolutionary history.
Geographic isolation leads to unique species.
Distribution limited by dispersal, biotic interactions, and abiotic factors.

Dispersal and Distribution:

Dispersal is movement from the origin.

Biotic Factors:

Biotic factors include predation, herbivory, mutualism, parasitism, and competition.

Abiotic Factors:

Abiotic factors include temperature, water, oxygen, salinity, sunlight, rocks, and soil.
Temperature affects biological processes.
Water and oxygen availability influences species distribution.
Salinity affects water balance.
Sunlight is crucial for photosynthesis.
Rocks and soil affect pH and nutrient availability.

Population Ecology

Objective: Analyze Population Characteristics and Dynamics

A population is a group of individuals of a single species in the same area.
Population ecology studies factors influencing population density, distribution, and size.

Density and Dispersion:

Density: Individuals per unit area.
Dispersion: Spacing patterns.

Density: A Dynamic Perspective:

Density changes through births, deaths, immigration, and emigration.

Patterns of Dispersion:

Clumped: Individuals in patches.
Uniform: Evenly spaced.
Random: Independent spacing.

Demographics:

Demography studies vital rates.

Life Tables:

Life tables summarize survival and reproduction.

Survivorship Curves:

Survivorship curves represent survival data.
Types: I, II, and III.

Reproductive Rates:

Reproductive output varies with age.

Population Growth Models

Objective: Contrast Exponential and Logistic Growth Models

Growth is limited by environmental factors.

Changes in Population Size:

Change in population size equals births minus deaths: $\frac{\Delta N}{\Delta t} = B - D$
Population growth rate: $\frac{\Delta N}{\Delta t} = R$
Per capita change in population size (r[Delta t}): Contribution of an individual to population size.
$\frac{dN}{dt} = rN$

The Exponential Growth Model:

Exponential growth occurs with unlimited resources (\frac{dN}{dt} = r[max}N).

The Logistic Growth Model:

Carrying capacity (K) is the maximum population size an environment can sustain.
Logistic growth model: \frac{dN}{dt} = r[max} \frac{(K - N)}{K} N

The Logistic Model and Real Populations:

Real

Ecology

Objective: Understand Ecological Interactions

Ecology studies interactions between organisms and their environment, organized from individual organisms to the global scale.

Levels of Ecological Study:

Organismal Ecology: Studies individual organism adaptations.
Population Ecology: Studies population size and changes.
Community Ecology: Studies interactions between species.
Ecosystem Ecology: Studies energy flow and chemical cycling.
Landscape Ecology: Studies exchanges across ecosystems.
Global Ecology: Studies regional energy and material exchanges.

Earth’s Climate

Objective: Analyze Climate's Influence on Biomes

Climate is long-term weather conditions, influenced by temperature, precipitation, sunlight, and wind.
Abiotic factors: Nonliving components.
Biotic factors: Living components.

Global Climate Patterns:

Determined by solar energy and Earth’s movement.
Solar radiation warms the surface, causing air and water circulation.

Latitudinal Variation in Sunlight Intensity:

Sunlight is most intense at the tropics, decreasing with latitude.

Global Air Circulation and Precipitation Patterns:

High tropical temperatures lead to evaporation and precipitation.
Dry air descends near $30º$ N/S, creating arid conditions.
Air rises at $60º$ N/S, causing precipitation.
Latitudinal variation and Earth’s rotation create global wind patterns like trade winds and westerlies.

Regional and Local Effects on Climate:

Climate varies seasonally and is affected by water bodies and mountains.

Seasonality:

Earth's tilt causes seasonal changes, especially in middle to high latitudes.
Wet/dry belts shift near $20º$ N/S.
Upwelling stimulates aquatic food webs.

Bodies of Water:

Ocean currents influence coastal climates.
Water moderates land temperatures.

Mountains:

Mountains create rain shadows, affecting sunlight and temperature.

Effects of Vegetation on Climate:

Forests absorb more solar radiation and increase precipitation.

Objective: Describe Terrestrial Biomes

Biomes are major life zones defined by vegetation (terrestrial) or physical environment (aquatic).
Climate influences biome distribution.
Climographs plot temperature and precipitation.
Disturbances can alter biome distribution.

General Features of Terrestrial Biomes:

Biomes are named for physical, climatic features, and vegetation. Ecotones are areas of intergradation between biomes.

Species Distribution

Objective: Explain Limits on Species Distribution

Species distributions result from ecological factors and evolutionary history.
Geographic isolation leads to unique species.
Distribution limited by dispersal, biotic interactions, and abiotic factors.

Dispersal and Distribution:

Dispersal is movement from the origin.

Biotic Factors:

Biotic factors include predation, herbivory, mutualism, parasitism, and competition.

Abiotic Factors:

Abiotic factors include temperature, water, oxygen, salinity, sunlight, rocks, and soil.
Temperature affects biological processes.
Water and oxygen availability influences species distribution.
Salinity affects water balance.
Sunlight is crucial for photosynthesis.
Rocks and soil affect pH and nutrient availability.

Population Ecology

Objective: Analyze Population Characteristics and Dynamics

A population is a group of individuals of a single species in the same area.
Population ecology studies factors influencing population density, distribution, and size.

Density and Dispersion:

Density: Individuals per unit area.
Dispersion: Spacing patterns.

Density: A Dynamic Perspective:

Density changes through births, deaths, immigration, and emigration.

Patterns of Dispersion:

Clumped: Individuals in patches.
Uniform: Evenly spaced.
Random: Independent spacing.

Demographics:

Demography studies vital rates.

Life Tables:

Life tables summarize survival and reproduction.

Survivorship Curves:

Survivorship curves represent survival data.
Types: I, II, and III.

Reproductive Rates:

Reproductive output varies with age.

Population Growth Models

Objective: Contrast Exponential and Logistic Growth Models

Growth is limited by environmental factors.

Changes in Population Size:

Change in population size equals births minus deaths: $\frac{\Delta N}{\Delta t} = B - D$
Population growth rate: $\frac{\Delta N}{\Delta t} = R$
Per capita change in population size (r[Delta t}): Contribution of an individual to population size.
$\frac{dN}{dt} = rN$

The Exponential Growth Model:

Exponential growth occurs with unlimited resources (\frac{dN}{dt} = r[max}N).

The Logistic Growth Model:

Carrying capacity (K) is the maximum population size an environment can sustain.
Logistic growth model: \frac{dN}{dt} = r[max} \frac{(K - N)}{K} N

The Logistic Model and Real Populations:

Real