Unit 2 Ecology Flashcards
What is age structure?
The distribution of the proportion of population members in each age class
What is birth rate?
The number of births within a population at a specific point in time
What is carrying capacity?
The maximum number of individuals of a population that can be supported by the limited resources of a habitat
What is climax community?
The final stage of succession, where a stable community is formed by a characteristic assortment of plant and animal species
What is the competitive exclusion principle?
No two species within a habitat can coexist indefinitely when they compete for the same resources at the same time and place
What is death rate?
The number of deaths within a population at a specific point in time
What is demography?
The statistical study of changes in populations over time
What is density-dependent regulation?
The regulation of population in which birth and death rates are dependent on population size
What is density-independent regulation?
The regulation of population in which death rates are independent of the population size
What are environmental disturbances?
Changes in the environment caused by natural disasters or human activities
What is exponential growth?
An accelerating growth pattern seen in populations where resources are not limiting
What are foundation species?
A species which often forms the major structural portion of the habitat
What is a host?
An organism a parasite lives on
What is intraspecific competition?
The competition among members of the same species
What is interspecific competition?
The competition among different species at the same time and place
What is island biogeography?
The study of life on island chains and how their geography interacts with the diversity of species found there
What does the J-shaped growth curve describe?
The shape of an exponential growth curve
What are K-selected species?
A species suited to stable environments that produce a few, relatively large offspring and provide parental care
What are keystone species?
A species whose presence is key to maintaining biodiversity in an ecosystem and to upholding an ecological community’s structure
What is a life table?
A table showing the life expectancy of a population member based on its age
What is logistic growth?
The levelling off of exponential growth due to limiting resources
What is the method of ‘mark and recapture’?
A method used to determine population size in mobile organisms
What is mimicry?
An adaptation in which an organism looks like another organism that is dangerous, toxic, or distasteful to its predators
What is mortality rate?
The proportion of population surviving to the beginning of an age interval that dies during that age interval
What is mutualism?
A symbolic relationship between two species where both species benefit
What is a parasite?
An organism that uses resources from another species: the host
What are pioneer species?
The first species to appear in primary and secondary succession
What is population density?
The number of population members divided by the area being measured
What is population size?
The number of individuals in a population
What is primary succession?
The succession on land that previously has had no life
What is a quadrat?
A square within which a count of individuals is made that is combined with other such counts to determine population size and density in slow moving or stationary organisms
What are r-selected species?
A species suited to changing environments that produce many offspring and provide little or no parental care
What is relative species abundance?
The absolute population size of a particular species relative to the population size of other species within the community
What does the S-shaped growth curve describe?
The shape of a logistic growth curve
What is secondary succession?
The succession in response to environmental disturbances that move a community away from its equilibrium
What is the species distribution pattern?
The distribution of individuals within a habitat at a given point in time
What is species richness?
The number of different species in a community
What is the survivorship curve?
A graph of the number of surviving population members versus the relative age of the member
What is zero population growth?
The steady population size where birth rates and death rates are equal
What is the predator-prey relationship?
Predator-prey interaction describes individuals of one population that kill and then consume the individuals of another population
How do species use defence mechanisms against predation and herbivory?
- Defences may be mechanical, chemical, physical or behavioural
- Produce or obtain chemical defences from plants and store them to prevent predation
- Use physical appearance, such as body shape and colouration, to avoid being detected by predators
- Use colouration as a way of warning predators that they are distasteful or poisonous
- They have evolved mechanisms to mimic this colouration to avoid being eaten, even though they themselves may not be unpleasant to eat or contain toxic chemicals
What is symbiosis?
- Close, long-term interactions between individuals of different species
- Symbiosis may be commensal, mutualistic or parasitic
What is a commensal relationship?
Commensal relationship occurs when one species benefits from a close prolonged interaction, while the other neither benefits nor is harmed
What is mutualism?
Mutualism occurs when two species benefit from their interaction
What are community dynamics?
Changes in community structure and composition over time, often following environmental disturbances (volcanoes, earthquakes, storms, fires and climate change)
What do population growth equations describe?
Use deterministic equations (equations that do not account for random events) to describe the rate of change in the size of a population over time
How is population growth expressed (equation)?
- The growth rate can be expressed in a simple equation that combines the birth and death rates into a single factor: r
- Population growth = rN
- r can be positive (population is increasing in size where the rate in change is positive), or negative (population is decreasing in size), or zero (population size is unchanging, also known as zero population growth)
What does the equation K-N express?
K−N = the number of individuals that may be added to a population at a given time
What does the equation [K−N]/K express?
[K−N]/K is the fraction of the carrying capacity available for further growth
What is the logistic growth equation?
Logistic growth equation: Population growth = rN [K−N]/K
What is the logistic model?
The logistic model assumes that every individual within a population will have equal access to resources and will have an equal chance for survival
What is phenotypic variation?
Phenotypic variation among individuals within a population means that some individuals will be better adapted to their environment than others
What is an ecosystem?
An ecosystem is a community of living organisms and their abiotic (non-living) environment
What do freshwater ecosystems have?
Freshwater ecosystems comprise lakes, rivers, streams and springs; and support a variety of animals, plants, fungi, protists and prokaryotes
What do marine ecosystems have?
Marine ecosystems comprise of shallow ocean, deep ocean water and deep ocean bottom
What is a biome?
A biome is a large-scale community of organisms, primarily defined on land by the dominant plant types that exist in geographical regions of the planet with similar climatic conditions
What are some examples of biomes?
- tropical rainforests
- savannas
- deserts
- grasslands
- temperate forests
- tundras
What is a disturbance?
Changes in the environment that affect their compositions, such as yearly variations in rainfall and temperature
What is the state of equilibrium?
Equilibrium is a dynamic state of an ecosystem in which, despite changes in species numbers and occurrences, biodiversity remains somewhat constant
How are changes in ecosystems measured?
Resistance and Resilience
What is resistance?
Resistance refers to the ability of an ecosystem to remain at equilibrium in spite of disturbances
What is resilience?
Resilience refers to the speed at which an ecosystem recovers equilibrium after being disturbed
What is the food chain?
A linear sequence of organisms through with nutrients and energy pass as one organism eats another
What are the levels in the food chain?
- producers
- primary consumers
- higher-level consumers
- decomposers
