Population Dynamics Flashcards
What is population density and how is it calculated?
Population density is the number of individuals in a given area. It’s calculated as: Dp = N/A
Where N = population size, A = area.
What does “growth rate” measure and what’s the formula?
It measures the change in population size over time.
gr=ΔN/Δt
What is cgr and how do you calculate it?
It measures the rate of change per individual. cgr=ΔN/N or (N final-N original)/N
What is biotic potential?
The highest possible per capita growth rate under ideal conditions.
What is carrying capacity?
The maximum number of individuals an environment can support over time.
What causes random distribution?
Occurs when resources are evenly spread and individuals don’t strongly interact.
What causes clumped distribution?
Common in nature—caused by patchy resources, social behavior, or protection.
What causes uniform distribution?
Usually due to territorial behavior or competition for space.
What is exponential growth?
A J-shaped curve where the population grows rapidly under ideal conditions.
What is logistic growth?
An S-shaped curve where growth slows as the population reaches carrying capacity.
What is environmental resistance?
Factors that limit population growth, like food shortages, disease, or predation.
What are r-selected species?
Species that reproduce quickly, have short lifespans, and produce many offspring.
What are K-selected species?
Species that reproduce slowly, have long lifespans, and care for few offspring.
What is intraspecific competition?
Competition between members of the same species.
What is interspecific competition?
Competition between different species for the same resources.
What is Gause’s Competitive Exclusion Principle and what does it mean?
Two species competing for the same niche can’t coexist. One will outcompete the other.
What’s a predator-prey cycle?
A repeating cycle where prey increase → predator increase → prey drop → predator drop.
How do producers and consumers affect each other?
Consumers limit producer populations; producers provide food for consumers.
What is protective coloration?
Color patterns that help organisms blend in and avoid predators.
What is Batesian mimicry?
Harmless species mimics a harmful one.
What is Müllerian mimicry?
Two harmful species evolve similar warning signals.
What is mutualism?
Both species benefit (e.g., bees & flowers).
What is commensalism?
One species benefits, the other is unaffected (e.g., remora & shark).
What is parasitism?
One species benefits, the other is harmed (e.g., tapeworm & human).
What is primary succession?
Succession that starts where no life previously existed (e.g., lava flow).
What is secondary succession?
Succession after disturbance where soil still exists (e.g., fire).
What is a pioneer community?
The first species to colonize a disturbed area.
What is a climax community?
A stable, mature ecosystem at the end of succession.
What is sustainability?
Using resources in a way that meets current and future needs without harm.
What is an age pyramid?
A graph showing the age and gender structure of a population.
What do the different shapes of an age pyramid indicate?
Triangle = rapid growth
Rectangle = stable
Inverted triangle = decline
What affects Earth’s carrying capacity for humans?
Resource use, pollution, food production, and technology.
How has human population grown?
Exponentially, especially after the Industrial Revolution.
What is biological control?
Using one species to control another (e.g., wasps for weevils).
What are the three ways bacteria can gain resistance genes?
Through plasmid transfer, viral transfer, or uptake of free DNA from the environment.
What is the role of plasmids in antibiotic resistance?
Plasmids carry resistance genes that can be shared between bacteria, allowing resistance to spread rapidly.
How can a bacterium develop antibiotic resistance without gene transfer?
Through a mutation that alters its DNA, giving it resistance.
What is genetic drift?
A random change in allele frequencies, especially significant in small populations.
What is the bottleneck effect?
When a population shrinks suddenly, reducing genetic diversity due to a limited number of survivors.
Which Hardy-Weinberg condition is violated when only alpha wolves mate?
Random mating — which reduces gene pool diversity.
What kind of relationship exists between wolves and elk?
Predator-prey relationship.
What is the relationship between wolves and coyotes?
Interspecific competition — they compete for prey and territory.
What reproductive strategy do wolves follow?
K-selected — few offspring, high parental care, affected by density-dependent factors.
What are density dependent factors?
A biotic factor that intensifies as population size increases — like disease or predation.
What are density independent factors?
An abiotic factor that affects populations regardless of their size — like temperature or natural disasters
What are the three phases in a population growth curve?
Lag phase, exponential (growth) phase, and stationary phase.
Why are invasive species like leafy spurge harmful?
They outcompete native species and often have no natural predators in the new environment.
What type of interaction is shown when invasive species displace native plants?
Interspecific competition.
