Ecological Scale & The Physical Environment- Unit 3

Ecology (42)

study of how organisms interact with each other and their environment

studied at 5 main biological levels:

Organismal ecology (42)

study of how morphological, physiological, and behavioral adaptations increase fitness in a particular environment

• How do individuals interact with each other and their physical environment?

Population (42)

a group of individuals of the same species that live in the same area at the same time

Population ecology (42)

how the number and distribution of individuals in a population change over time (evolutionary change)

• How and why does population size change over time and space?

Community (42)

consists of populations of different species that interact with each other within a particular area

Community ecology (42)

ask questions about the nature and consequences of species interactions

• How do species interact and what are the consequences?

Ecosystem (42)

consists of all the organisms in a particular region along with non-living components

Ecosystem ecology (42)

study how nutrients and energy move among organisms and through the surrounding atmosphere, soil, or water

• How does energy flow and how do nutrients cycle through the local environment?

Abiotic (42)

nonliving components

Biotic (42)

living components

Biosphere (42)

a thin zone surrounding the Earth where all life exists

• 5 km below the land surface to over 10 km up into the atmosphere

Global ecology (42)

study the effects of human impacts on the biosphere

• How is the biosphere affected by global changes in nutrient cycling and climate?

Climate (43)

the prevailing, long-term weather conditions found in an area

Weather (43)

specific short-term atmospheric conditions of temperature, precipitation, sunlight, and wind

Global Climate system is powered by solar radiation (43)

1. High energy, shortwave (UV) solar radiation comes to Earth from the sun

2. 30% of the sunlight that reaches the atmosphere is reflected back into space

3. The other 70% is absorbed by the Earth’s surface and atmosphere

4. The Earth radiates that back as lower energy longwave radiation (IR)

5. Greenhouse gases trap some of outgoing longwave radiation, reflecting some back to Earth, warming the system

   • molecules with at least three atoms that can absorb and remit solar radiation

   • make up less than 1% of the atmosphere: Nitrogen (N2) 78% & Oxygen (O2) 21%

Temperature varies across the globe due to the shape of the Earth (43)

• regions near the equator receive more sunlight per unit area than regions that are close to the poles

• as latitude increases, average temperature of the region decreases

Hot air is less dense (43)

• has lower pressure

• rises

• holds more water

Cold air is more dense (43)

• has higher pressure

• falls

• holds less water

The Hadley Cells result in heavy rainfall at the equator (43)

1. Air is heated by solar radiation at the equator

   • air at the equator is the hottest

2. Heating causes the air to warm, reducing its pressure

3. Warm, moist air begins to rise

4. As it rises, it begins to cool, reducing its ability to hold water, causing rain at the equator

5. The cool air is pushed poleward, becomes denser, and begins to fall

6. Warm, dry air results in bands of deserts around 30 North and South

There are three main cells that influence global patterns of precipitation (43)

1. Hadley Cell

2. Mid-latitude (Ferrel) cell

3. Polar cell

• the direction and size of cells are determined by tradewinds

• these cells produce bands of low precipitation at 30, 60, and 90 North and South

Seasons (43)

regular, annual fluctuations in temperature, precipitation, or both

• are caused by the tilt of Earth on its axis- 23.4 d

As the Earth orbits (revolves around the sun).. (43)

• N hemisphere is titled toward the sun in June

• S hemisphere is titled toward the sun in December

• Earth’s spin (rotation) creates days (daily fluctuation in light/temperature)

• if earth were not titled on its axis, there would be no seasons

Seasonality (43)

degree of difference between summer and winter temperatures in a region (annual variation in temperature)

• seasonality is higher at the poles- the impact of Earth’s tilt is greater at higher latitudes

• the equator is hit directly by solar radiation year round (only slight variation from summer and winter)

• at higher latitudes, the distance from the sun varies by season, resulting in large changes in the degree of incoming radiation

Mountain ranges influence regional climate (43)

West

• moisture-laden air blows from ocean

Air rises over mountains and cools; rain falls

East

• dry air creates desert conditions

Creating a rain shadow

Oceans influence regional climate (43)

• oceans have a moderating influence on temperature because water has a specific heat (capacity for storing heat energy)

• islands and coastal areas have more moderate climates than do inland areas

• ocean currents influence local climate patterns

Gyres (43)

cyclical ocean currents that move warm water to more northern latitudes and colder water to more tropical latitudes

Biomes (44)

regions defined by the dominant types of vegetation (plants)

Terrestrial biomes are associated with distinctive abiotic conditions (44)

1. temperature

2. moisture

3. sunlight

4. wind

• biomes are primarily governed by the annual temperature and precipitation

• both the average and variation matter

Different biomes have different net primary productivity (NPP) (44)

Total amount of generated biomass (plant energy)

• warmer, wetter biomes have higher NPP

Arctic Tundra (44)

• found at northern latitudes

• high seasonality, low temperatures, and low precipitation

• low primary productivity

• low diversity of plants and animals

• below freezing much of the year and the soil often remains permanently frozen

Boreal forests (44)

• found at northern latitudes, below the tundra

• high seasonality, low temperatures, and low precipitation

• low diversity of plants and animals, forests dominated by evergreens

• low structural diversity in forests and low productivity

Temperate forests (44)

• found in mid-latitudes in both the southern and northern hemispheres

• moderate seasonality, temperatures, and precipitation

• forests dominated by deciduous trees that lose their leaves during winter- moderate productivity that fluctuates throughout the year

• moderate diversity of plants and animals

Temperate grasslands (44)

• found at mid-latitudes in both the southern and northern hemispheres

• moderate seasonality, temperatures, and precipitation

• highly fertile soil, dominated by fast growing grasses and shrubs; maintained by frequent disturbance

• lower diversity and productivity than temperate forests

Deserts (44)

• found around 30 N and S

• moderate seasonality and extreme temperatures

• low precipitation

• low diversity of plants and animals; plants have needles instead of leaves and all organisms have adaptations to reduce water loss

• very low productivity

Tropical grasslands/savannah (44)

• found around 14-20 N and S

• low seasonality, warm temperatures, moderate precipitation

• moderate diversity of plants and animals; dominant plants are grasses maintained by frequent disturbance and grazing by large herbivores

Tropical rainforest (44)

• found around the equator

• low seasonality, warm temperatures, high precipitation

• highest diversity of plants and animals; dominant plants have broad leaves and are evergreen

• forests have high structural diversity

• very high productivity

Aquatic biomes (44)

• 97.5% of Earth’s water is saltwater

• 2% of fresh water is locked in ice caps and glaciers

• 0.5% of fresh water is in groundwater, ponds, lakes, and rivers

Distribution (45)

How organisms are arranged over space

• a species distribution is where you can find that species geographically (also called its range)

Organisms are limited in their distribution through present abiotic conditions (45)

• no species can survive all environmental conditions present on Earth

• species are adapted to a limited set of abiotic conditions

Fitness trade-off (45)

evolutionary compromise that must be made between traits that can’t be optimized simultaneously

Temperature and Precipitation (45)

• are the primary drivers of species distribution across the globe

  • enzymes (proteins) can only function optimally in a narrow band of temperatures

Performance curve (45)

illustrates organismal tolerance for an abiotic condition (physiology of an organism)

Thermal performance curve (45)

illustrates temperature tolerance

• physiology curves are evolved traits of an organism but can also be influenced by acclimation to the environment

Organisms are limited in their distribution through present biotic factors (45)

• organisms cannot reach every environment with suitable abiotic conditions- they are limited by their dispersal ability

  • dispersal is the spread of individuals away from each other (parents or siblings), leaving some behind. This can lead to gene flow or a founder’s effect

• interactions between organisms of different species can affect their distribution

Organisms are limited in their distribution through past conditions (45)

• as the Earth has changed over time, fluctuations in climate cause changes in abiotic conditions on long time scales

• past conditions on Earth have shaped evolutionary trajectory of the species living today

Ecological niche (46)

the limits for all environmental features within which individuals of a species can survive, grow, and reproduce

• can use info about the abiotic determinants of an organism’s niche to predict the species distribution

Fundamental niche (46)

determined by abiotic conditions

• All the places the organism could live if nothing else limits their distribution

Realized niche (46)

determined by biotic conditions

• the portion of the fundamental niche actually occupied by a species

• organisms are limited in their distribution and use of the niche space by other species in their environment

All organisms realized niche can equal its fundamental niche but will not be larger than the fundamental niche

Species ranges are determined by the distribution of populations over space (47)

• if a species range is small, it may consist of a single population

• usually, species consist of independent populations connected by dispersal (geneflow)

Random (47)

the dispersal of seeds, gametes, or larvae is random due to variations in factors such as wind and currents

• the average fitness of populations increases in variable environments when dispersal distributes individuals

Clumped (47)

individuals associate in social groups for feeding, mating, and/or avoiding predators; or resources are patchy

• individuals experience higher fitness when they associate in groups; selection favors individuals that find patchy resources

Uniform (47)

individuals distance themselves from each other as they compete for nutrients, nesting space, or other resources

• competition reduces the fitness of individuals; selection favors traits that minimize competition

Demography (48)

the study of factors that determine the size and structure of populations over time

Populations gain individuals.. (48)

through births and immigration

if birth rate + immigration rate > death rate + emigration rate, the population will grow

Populations lose individuals.. (48

through deaths and emigration

if birth rate + immigration < death rate + emigration, the population will decline

Life tables (48)

use information on survivorship and reproduction to model how the structure of a population changes over time

• tracks a cohort over time: a group of individuals of the same age

• summarizes the probability that an individual will survive and reproduce at a given time interval of the course of their life

Net productive rate (48)

combines likelihood of survival and reproduction at each life stage to model how the population will change at each life stage

Type 1 (48)

survivorship throughout life is high and then drops dramatically in old age (common for humans and many mammals)

• parental care

• small number of offspring

• slow development

Type 2 (48)

individuals have about the same probability of dying in each year of life

• common in organisms with some parental care in early life but vulnerability to predation or adverse abiotic factors at any age

Type 3 (48)

extremely high death rates in early life stages, but high survival rates for individuals that make it past this stage

• common in insects and plants that produce lots of offspring and provide little to no parental care

Fecundity (48)

the number of female offspring produced by each female in the population

• changes over the lifespan of a female

• reproductive strategies are an evolved trait

Life history (48)

how an individual allocates resources to growth, reproduction, or survival

• traits that affect timing and amount of reproduction or the development of offspring are life history traits

• life history traits are the result of fitness trade-offs: every individual has a restricted amount of time and resources at its disposal

  • maximize the number of offspring, devote less time to growth and nutrition which then decreases survival

Growth curves predict how populations size changes over time (49)

• this term indicates how the number of individuals change at each step (rate of change)

• population growth curves only consider birth and deaths when estimating population size

Exponential growth (49)

• resources are not limiting (infinite)

• growth is density independent, meaning that growth rate is not constrained by the number of individuals

• birth rate - death rate= r, Per capita rate of increase

• every species has a r max where birth rates are as high as possible and death rates are as low as possible= intrinsic rate of increase

• varies among species because of differences in reproductive rates

• different r values impact the exponential curve

• r is almost always less than r max

  The population size (density) does not limit growth. Common in nature on two scenarios:

  1. colonization of a new habitat

  2. recovery after a disaster

     (ex. variation in weather or extreme events, usually abiotic)

Logistic growth (49)

• resources are limiting

• growth is density dependent: as the population grows, the growth rate decreases

• carrying capacity(k): the max number of individuals in a population that can be supported in a particular habitat over a sustained period of time

  • is not fixed- it can change over time as resources in the environment change

• occurs when resources are limiting usually due to biotic factors

Species interactions are characterized by their outcome (50)

• to determine +/0/- effect, you need to measure the impact of one species on the fitness of other species

• common fitness proxies: population size, reproductive success, organismal health, death rate, offspring survival

Mutualism (51)

interaction in which both species benefit

• individuals are not altruistic in mutualism- not “trying” or “choosing” to be nice

• evolved interactions where individuals maximize fitness- benefits of he mutualism outweigh the cost

• can lead to “cheaters” in mutualisms, depending on the environment

Commensalism (51)

one species benefits from the interaction while the other is not affected

Parasitism (51)

parasite lives in or on host and feeds off the flesh or fluid of the host

Symbiosis (51)

an interaction between two organisms living in close physical association

Predation (51)

one animal benefits by preying on another, which is negatively affected

Herbivory (51)

animal species benefits by feeding on a plant species, which is negatively affected

Competition (51)

an interaction between individuals in which each is harmed by their shared use of a limiting resource:

• food

• water

• territory

• space/light

is often unequal and one species is harmed more than the other

Intraspecific competition (51)

among individuals of the same species

Interspecific competition (51)

among individuals of different species

Competitive exclusion (52)

if two species require identical resources, they cannot coexist indefinitely

• do not see often in natural communities because individuals within competing populations adjust or evolve to allow coexistence

Niche partitioning (52)

occurs when competing species use different resources to reduce the effects if competiton

Character displacement (52)

is genetically based divergence in phenotypic traits that results in decreased competition between species

These processes often happen simultaneously (52)

• character displacement allows for niche partitioning

• nice partitioning can be the driver (selection pressure) for character displacement

Species interactions can change based on environmental conditions (53)

• coral provides the zooxanthellae with a protected environment and the inputs for photosynthesis

• algae produce oxygen, nutrients and help the coral remove waster

Coevolution (54)

is a pattern of evolution in which two interacting species reciprocally influence each other’s adaptations over time

• occurs in species that are interacting closely

• a change in the trait of one species acts as a selection pressure on the other species

  • leads to species becoming uniquely adapted to each other

Evolutionary arms race (54)

a mechanism of coevolution that occurs in ± (consumptive) species interactions

a repeating cycle of reciprocal interactions:

• traits that increase feeding efficiency evolve in predators, herbivores, and parasites

  • in response, traits evolve that make prey and hosts unpalatable or elusive

Coevolution can also occur in mutualisms (54)

• leads to adaptations in the two species that make the mutualism more effective and often more specialized

Most likely to occur in mutualisms that are:

• symbiotic

• obligate (mutualism required for survival of at least one of the species)

Dominant species (55)

most abundant species in a community

Keystone species (55)

a species with a much greater impact on the distribution and abundance of the surrounding species than predicted by the abundance

Disturbance (56)

any strong, short-lived disruption to a community that changes the distribution of biotic and abiotic resources

Impact of disturbance depends on: (56)

1. type of disturbance

2. frequency of disturbance

3. severity

Disturbance regime (56)

predictably frequency and severity of characteristics of disturbances in a community

Succession (56)

predictable pattern of community dynamics after a disturbance where a species with a certain life history pattern succeed each other

Primary succession (56)

occurs when a disturbance removes the soil

Secondary succession (56)

occurs when a disturbance removes some of the organisms from an area but leaves the soil intact, including the seeds and organisms within the soil

Pioneering species (56)

adapted for growth in disturbed soils, devote most of their energy to reproduction, not competition

• small seeds, many seeds, rapid growth, short life span, reproduce at an early age, high rmax

• as plants establish in later stages, they must out compete or coexist with earlier species

Climax species (56)

larger and less seeds, slower growth, longer life span, low r max, high competitive ability

Facilitation (56)

an earlier arriving species that makes conditions more favorable for the arrival of a later species

• provide shade, reducing soil temperatures & increase humidity

• increase in nutrients in the soil, especially in nitrogen

Inhibition (56)

Prescence of one species inhibits the establishment or regrowth of another

• as canopy establishes, less light reaches the forest floor

• chemical inhibition

  • competition

Species diversity (57)

a measure of community complexity

• # of species nicheness

• abundance of each species (species evenness)

Diversity Indices (57)

a mathematical measure of diversity that takes both species richness and evenness into account

Primary producers (58)

transform solar energy into chemical energy stored in sugars and carbohydrates

• also called autotrophs or “self-feeders”

• transform energy through photosynthesis

Gross Primary Productivity (GPP) (58)

measures the total amount of chemical energy produced in an area over a given time period

Primary producers use this to produce:

1. Cellular respiration: turns sugars into ATP (cellular energy)

2. Growth and reproduction

Net Primary Productivity (NPP0 (58)

GPP-cellular respiration heat + energy loss

• represents the total amount of chemical energy stored in organic material in an ecosystem

• is higher on land and in the wet tropics

Plant biomass of an ecosystem reflects NPP: measures the amount of energy allocated to growth and reproduction

• amount of energy available to consumers

  • only a small percentage is actually transformed up the good chain