Cal Poly Bio 263 Final 2018- Lema

Niche

ecological "role" a species (or population) plays in its broader ecosystem (includes range of resources that can be used, and environmental conditions tolerated)

Biological community

complex assemblage of interacting species within defined area

Community Structure

How combinations of many species interact

What are the 4 two-species interactions, and what are the interspecific effects on fitness of each?

- Commensalism: +/0

- Mutualism: +/+

- Competition: -/-

- Consumption: +/-

Intraspecific competition

competition between members of the same species

Interspecific competition

competition between members of different species

What are the 3 classifications of consumption?

- Herbivory: plant tissues eaten

- Parasitism: host tissues eaten

- Predation: most/all of another individual eaten

Coevolutionary arms race

a repeating cycle of reciprocal adaptation

Joseph Grinnell

- coined the term 'niche' in 1917

-considered the niche to be the sum of the habitat requirements needed for a species to live and reproduce (emphasize abiotic, physical factors)

Charles Elton

- Defined niche as an "organism's place in the biotic environment, its relation to food and enemies" (1927)

- Emphasized biotic interactions and a species' role in an ecological community

Niche construction

The process whereby an organism alters its own (or another species') environment, often in a way that increases its chances of survival

e.g. Beaver building a dam

What happens when the niches of 2 different species overlap?

interspecific competition

What are the possible outcomes of competition?

1) competition exclusion principle: impossible for species within same niche to coexist

2) Coexistence of species: fitness tradeoffs; niche differentiation

niche differentiation/resource partitioning

an evolutionary change in resource use, caused by competition over generations

competition exclusion principle

impossible for species within same niche to coexist

What happens when one species is a better competitor?

- Asymmetric competition: 1 species suffers greater fitness decline

- Symmetric competition: equal decrease in fitness

What happens when niches are completely overlapping, and asymmetric competition occurs?

weaker competitor becomes extinct

Fundamental niche

resources/conditions used WITHOUT competitors

Realized niche

resources/conditions used WITH competitors

What happens when you have asymmetric competition and incompletely overlapping niches?

The weaker competitor shifts from fundamental to realized niche; cedes resources

character displacement

Species evolve non-overlapping traits to avoid competition

Competition and conservation

-diverse communities more resistant to invasion

-competition can help communities resist invasion

How predictable are communities?

-Frederic Clements: stable, predictable, extensive species interactions, predictable climax community

-Henry Gleason: not stable, not predictable, chance whether similar community develops after disturbance

Keystone species

species that have disproportionately large effects on the structure of an ecological community relative to their abundance

e.g. sea otter

How do keystone species structure communities?

The reduction or loss of a keystone species triggers an ecological chain of reactions resulting in declines in species diversity and community complexity

Foundational Species

Species that have strong interactive effects on their ecological communities, but are too numerous to be keystone species

Disturbance in Ecological communities

Disturbance: removes biomass, alters resource availability

Examples of Natural Disturbances

Fire, wind, blizzard, drought

Disturbance regime

type, frequency, and severity of disturbance

Ecological Succession

response to a disturbance

Successional pathway

specific sequence of species that appears after a disturbance:

1) Pioneering species- small, low to ground, good dispersal, high physiological tolerances, not good competitors

2) Early successional community- weedy species are pushed out

3) Mid successional community- shrubs and short lived trees

4) Climax Community- long-lived tree species mature

Ecosystem

a community plus its abiotic environment

-includes biogeochemical cycling from abiotic to biotic and back

-ecosystem function relates to flow of nutrients through system

-disruptions to this flow can cause a chain-reaction of effects

What are the six major biomes?

1. tropics

2. grasslands/savannah

3. temperate forests

4. coniferous forests or taiga

5. tundra

6. deserts

What influences the locations of all major biomes on earth?

Solar insolation and Hadley cells

Circulation cells

large-scale cells in a planet's atmosphere that transport heat between the equator and the poles:

-Warm air rises and cools at the equator, dropping rain

-Cooled air is pushed poleward

-Dense, dry air descends, warms, and absorbs moisture

What are the three types of circulation cells called?

-Polar call (above 60 degrees in latitude)

-Ferrel cell (between 60 degrees and 30 degrees in latitude)

-Hadley cell (between 30 degrees and 0 degrees in latitude)

--> there is one of each type of cell on each hemisphere

Whittaker Classification of Biomes

Rainshadow Effect

3 Important points about ecosystems

1) ecosystem boundaries are difficult to define, and change through time

2) organisms within ecosystems are dependent on ecosystem-level biological and physical processes

3) adjacent ecosystems closely interact; interdependent processes maintain the community organization of each ecosystem

Ecosystem ecology

The study of...

-communities of organisms

-trophic dynamics

-nutrient cycling

-biogeochemistry

-energy flow

-hydrology

Net primary productivity

the rate at which photosynthetic organisms produce new 'useful' energy (energy invested in new tissues or offspring)

Where does most of the Earth's net primary productivity come from?

1) open ocean

2) tropical wet forests

Four components of an ecosystem interaction

Pyramid of Productivity

Productivity

Biomass produced per unit of area each year

Efficiency

Fraction of biomass transferred from one level to another

Food webs/ food chains

the connections between trophic levels

Trophic cascade

when predators in a food web suppress the abundance of their prey, thereby releasing the next trophic level down from predation

What is a result of 'top down control'?

trophic cascades (altering top predators affects everything below)

Ecosystem Function affected by:

-resource dynamics (e.g., introduced species disrupt nutrient flow)

-trophic structure (e.g., removal of keystone species, trophic cascades)

-disturbances (e.g., change in frequency of disturbances such as by overgrazing, loss of ESS plants, and topsoil)

Terrestrial Nutrient Cycle

Three examples of biogeochemical cycles

-water cycle

-nitrogen cycle

-carbon cycle

Evidence that the Global Climate is changing

1) increasing global temperatures

2) arctic sea ice declines

--> over 40% decline in 30 years

3) Land ice declines

--> adds water to ocean; raises sea level

4) Sea level rise

Greenhouse effect

Warming resulting from the atmosphere trapping outgoing heat radiating from the Earth toward space

Keeling Curve

Graph measuring carbon dioxide concentration in atmosphere

Human Effects on Global Carbon Cycle

-Fossil Fuels: moves CO2 locked up for hundreds of millions years (petroleum, coal) to atmosphere

-Agriculture, deforestation also add CO2

What is a result of warmer surface waters?

Increased stratification in ocean (surface water is warmer and less dense= currents are less likely to bring nutrient-rich water to surface against the steeper density gradient)

climate change leads to...

-increased intensity and frequency of droughts, flooding, etc

Ice core records

-can tell us when ice formed and what the atmospheric CO2 concentrations were at the time the ice froze

-allows us to make CO2 concentration predictions

photoperiod

the period of time each day during which an organism receives illumination; day length.

What affects photoperiod?

Orbit, tilt, and curvature of earth result in increasing variation in photoperiod throughout the year at higher latitudes.

Biomagnification

accumulation of pollutants at successive levels of the food chain