Lectures Flashcards
(44 cards)
Whats Population?
All the individuals of a species that constitute a specific group or occur in a specific habitat.
What are species?
Related organisms capable of interbreeding.
What is Community?
Assemblage of different species that occur together in a habitat.
What is Habitat?
The place or environment where a species lives. Exhibits all the necessary requirements to fulfill its life cycle. Some species use different habitats for different parts of their life cycles.
Describe what is meant by niche?
Defined as the “specific ecological role” of a species in an ecosystem.
Fundamental vs. realized
What is meant by realized niche?
The net result of competition with other species.
explain Symbiosis.
what are the 3 possibilities of these relationships?
A close and continual interraction between two species that benefits one or both of them.
Can be one of these 3
- Commensalism: benefits one, no harm or benefit to the other
- Mutualism: both benefit
- Parasitism - one is harmed or experiences detrimental effects.
Define tolerance
The ability to withstand adverse environmental conditions.
What are some factors that influence populations?
Survivorship (demographics) Growth (exponential or logistic) Equilibrium, (carrying capacity) Reproduction (R vs K) Distribution (uniform or clumped) Density (competition, disease, predation) Cycles (species env. interactions.)
What does release refer to?
Rapid expansion of a species when conditions change favourably. (removal of competition/ opening of the canopy)
What is displacement?
Decrease of a species when an unfavourable condition is introduced. (ex. introduced predators or invasive species)
What is a keystone species?
Central to the overall function of the environment
What are the 3 types of survivorship? give examples.
Type 1 curve - high late mortality (Humans)
Type 2 curve - equal chance of mortality (mice)
Type 3 curve - high early mortality (Trees, Some animals like Sea Turtles)
What are demographics?
Age distribution
Explain r and K reproductive strategies
r refers to rate. Strategy is to create a large number of inexpensive offspring to increase the chances of survival. This happens in unstable environments where population density is not an issue because it never reaches full size. Exhibits type 3 survivorship
K refers to carrying cap. Strategy is to create Few expensive offspring and it is common in stable environments where populations reach carrying capacity. Exhibits a type 1 survivorship pattern where units have a long life expectancy and mature and die later in life.
What is Succession?
A sequence of changes in plant/animal communities that occupy an area over a period of time.
-Can also be seen as the process of change by which biotic communities replace eachother, with alterations to the physical environment.
What is primary succession?
Starting from scratch (No biotic components to start from)
Usually after a catastrophic disturbance
ex. Post glacial soils, sometimes the upper part of landslides, sand dunes.
What is secondary succession?
When there is a disturbance that does not completely wipe out the ecosystem.
ex. Logging, windthrow, fires etc
-Biotic material left behind to provide a base population for other species to establish from.
What is ecological succession?
The interaction of biotic and abiotic components of ecosystems, resulting in changes to both.
What is a SERE?
Entire sequence of biotic communities that occupy a site and replace each other over time, following disturbance of original community.
What are seral stages?
Specific stages of a sere with regards to the species present during that time.
What are autogenic and allogenic disturbances?
Autogenic - biotic
- Colonization
- Competition
Allogenic - abiotic
- fire
- flood
- landslides
- volcanic eruption
What things affect the rate of change in succession?
- The degree of environmental change that must occur before one community can replace another
- The productivity of organisms
- The longevity of organisms (Typically early lived species in earlier seral stages.)
- Resistance to invasion by other species occupying site
Briefly define a “Climax” forest
Relatively stable over time and self regenerating.
