unit 4 exam Flashcards
What is a population?
group of individuals within the same species living in a particular space (have potential to interbreed)
what is population ecology?
study of populations in relation to the environment and influences on population
what are the 3 environmental influences population ecology can study
- population size
- age structure of individuals(different ages in environment)
- density and distribution of individuals
General Model of Populaion Growth
Nt+1 = Nt+ inflow - outflow
what is the intrinsic rate of population growth?
Birth rate minus the death rate
In a population of 1000 if there are 60 births what would be the birth rate?
A. 60
B. 0.06
0.06
What is formula for exponential population growth?
dN/dt = r N
what 4 factors contribute to density dependent birth and death rates?
-competition
-predation
-disease
-intrinsic social factors
what is carrying capacity
maximum number of individuals that a specific area can support
What is logistic population growth? what shape is the curve for logistic population growth?
occurs when a species is resource limited, as the population grows the birth rate slows. S shaped curve
in the logistic population growth model the population declines as what is approached?
carrying capacity
identify each of the following-
Bt
Nt
Et
It
Dt
-birth
-population
-emigration
-immigration
-death
when thinking population growth when is population growth positive?
when the number of the population is lower than the carrying capacity
what is an ecological community
a set of co-occurring species in a given time and place
what are trophic levels?
The number of hiearchal levels in a community that share the same function within a food chain
community interaction- predation (what is it?)
-asymmetrical interaction only the predator has direct benefit
-predators become more abundant as prey grows
community interaction- competition (what is it?)
-resources become limited
what is a keystone species?
species that has a disproportionately large effect on the community relative to biomass. They help maintain the ecosystem.
organisms that only feed on photosynthetic forms of life are generally referred to as?
primary consumers
what is a trophic cascade?
predators choices effect the prey population whether they are added or removed.
what is primary productivity?
the rate of organic matter production
what is an ecosystem?
organisms and biotic and abiotic factos interact to form a living environment
what controls growth of a closed population
birth rate and death rate
What does a negative intrinsic growth rate tell us about per capita
birth and death rates?
This means there are more deaths/emigrations and the population lowers. vice versa for positive
What is the difference between density-dependent versus density-independent birth and death rates?
Density-dependent birth and death rates are affected by environmental factors that change in relation to population size. independent are not
What is the role of carry capacity (K) in the logistic growth equation
number of individuals a population can hold
What happens
to population growth rate (dN/dt) when the population size (N) is greater than or less
than the carrying capacity (K)?
when greater than carrying the population decreases, when the number is less there is quicker growth
What forms of competition does the Lotka-Voltera population growth model include?
intraspective- within the same species
interspective- different species competing for same resources
What is a Central Aim of Community Ecology?
to understand how species diversity and the ecosystem changes over time.
What is the difference between species richness, evenness, and diversity?
species richness is the amount of species in a community, species evenness is the spread of the species, and species diversity is the combination
What is the ultimate source of energy used to sustain growth of an ecological
community?
the sun
What are trophic levels? Why is there more total biomass in lower trophic levels than
higher trophic levels?
different levels in the food chain, there is less energy and biomass towards the top
What is the difference between bottom-up and top-down controls on community
structure?
bottom up limits resources and top down uses predation as a control
Can the behavior of predators influence the diversity of primary producers within a
community? Is this a direct or indirect interaction?
they can do it directly by eating them or indirectly by suppressing primary consumers
What is meant by the phrase Trophic Cascade?
trophic cascade is when a organism is removed or added and it affects the other organisms.
What is a keystone species?
organism that maintains a ecosystems structure and balance
What are some of the major materials (i.e. essential elements) of life?
Carbon,Calcium, Hydrogen,oxygen,sulfur,
Nitrogen, Phosphorus
Which of the
following major elements Ca, N, P, S are derived from weathered rock? what comes from atmosphere
calcium, phosphorus come from weathered rock.
Nitrogen and sulfur come from atmosphere
What are two major ways in which predators can influence Plant Community
Composition and overall Ecosystem Function?
regulating prey population
dispersing nutrients and seeds
What was the major conclusions of the research by Oswald Schmitz entitled “Effects
of Predator Hunting Mode on Grassland Ecosystem Function”?
predators using different hunting strategies, like stalking or ambushing, have distinct effects on herbivore populations and vegetation, ultimately shaping the health and stability of grassland ecosystems.
in general, what is the observed relationship between biodiversity and annual net
primary productivity?
when there are different plants and animals, plant growth rises due to competition lowering due to a resource not being crowded
what are Quaternary consumers?
top of food chain usually carnivores
what are tertiary consumers?
second level and eat secondary consumers
What are secondary consumers?
eat primary consumers, 3rd level
what are primary consumers?
on the second level and eat plants or algae to survive
what are primary producers?
plants and algae on the first floor that are autotrophs an
What 3 broad processes / mechanisms that influence the observed assemblage of species at any given location relative to the ~2 million possible named species on Earth?
Historical filter: evolved in a different region, never dispersed to the site
Physiological filter: can it grow and reproduce
Biotic filter: does it successfully compete or avoid competition, can it defend itself, is it resistant to disease, etc.
