Communtity (part 1)

What is species?

a group of individuals capable of interbreeding and producing viable, fertile offsprings

What is a population?

An interacting group of individuals of one species

What is a community?

An interacting group of organisms of multiple species

What is community ecology?

The study of how interactions between species shape community structure and function

What is disturbance in ecology?

A discrete disruptive event/force that causes a major change in an ecosystems structure, species composition, or resource availability 

What is exogenous disturbance?

A disturbance caused by external factors such as fires, storms, or floods

What is endogenous disturbance?

A disturbance caused by internal biological processes such as a disease or species interactions

What is disturbance regime?

The pattern of disturbances over time, which includes:

• Timing, magnitude, frequency, and predictability 

What is the intermediate disturbance hypothesis?

A non-equilibrium model used to describe the relationship between disturbance and species diversity

What happens when there is high disturbance in a habitat?

Species diversity is reduced as high disturbance selects disturbance tolerant species that can survive or quickly recolonize

What happens when there is low disturbance in a habitat?

Species diversity is reduced as low disturbance selects strong competitors (or late-successional species) that outcompete others

When does maximum species diversity occur?

when disturbance is neither too frequent nor too rare

Why is species diversity at its maximum at intermediate levels of disturbance?

bc both early- and late- successional species can co-exist

What is succession?

A type of disturbance where Gradual and predictable changes to an ecosystem occur over time

• Two types: primary and secondary

• There are 3 stages: Pioneer species, intermediate community, and climax community

What is primary succession?

A type of succession that follows catastrophic disturbance and begins on bare substrate with no soil

• Ex: lava or glaciers

What type of specie starts primary succession?

Pioneer species (ex: linchens or mosses) start it

What is secondary succession?

A type of succession that follows small disturbances and occurs after a disturbance when soil already exists

What is intermediate community?

A transitional stage in succession between pioneer species and the climax community, with increasing species diversity and complexity

What is climax community?

A relatively stable, mature community at the end of succession

How does disturbance play a role in succession?

It can reset succession and start the process again

What are traits that define Early successional (r-selected) species?

• Many small offspring's

• Dispersed by wind or water

• High photosynthetic rate

• Low low-light efficiency

• High growth rate

• Low root:shoot

• Small at maturity

• Short lifespan

What are traits that define late successional (k-selected) species?

• Few large offspring's

• Dispersed by animals

• Low photosynthetic rate

• High low-light efficiency

• Low growth rate

• High root:shoot

• Large at maturity

• Long lifespan

What is a low root:shoot ratio?

A ratio where a plant invests more energy into their shoots for rapid above-ground growth and capturing light

What is a high root:shoot ratio?

A ratio where a plant invests more energy into their roots to better acquire water and nutrients

What does a low low-light efficiency mean?

A plant needs strong sunlight and performs poorly in the shade

What does a high low-light efficiency mean?

A plant can survive and grow in shaded environments with limited sunlight

What are the 3 mechanism models that can drive the succession of an ecosystem?

Facilitation, inhibition, and tolerance model of succession

What is the facilitation model of succession?

• A model where early successional species enhance and make an area more suitable for later successional species to establish themselves in

  • They do so by

    • Improving soil quality

    • Fixing nitrogen

    • Increasing nutrients availability

    • Providing shade

What is the inhibition model of succession?

• A model where early successional species make an area less suitable for later successional species to establish themselves in

  • They do so by

    • Competing for resources

    • Monopolizing light, water, and nutrients, which leads to slow recovery

What is the tolerance model of succession?

A model where early successional species don’t significantly modify the environment in a way that benefits or inhibits later species, with the success of later species depending on individual fitness/ability

What determines which species succeed in the tolerance model of succession?

Life history traits