Lecture3_Population Dynamics Flashcards
What is Population Dynamics?
The study of how population size and density change over time and space, reflecting organism-environment interactions
What are the three main purposes of studying population dynamics?
Conservation strategies, management planning, and risk analysis/projections
Define a population
All organisms of a species in a specified area.
Define Metapopulation
A population consisting of subpopulations that interact through genetic mixing
What is recruitment?
refers to the process by which juvenile organisms, settle, survive, and become part of a specific population or community.
Often describes the transition from larval/juvenile stage to a breeding adult
What conditions enable exponential growth?
Exponential growth is idealized and rare in nature. It can occur temporarily under exceptional conditions, such as:
Species introduced to a new environment without predators or plankton blooms in nutrient-rich waters
when lookings at a per capita rate of population growth vs population size graph what does density independence look like?
density independence looks like a horizontal line, the rate is the same no matter what the pop. size
What characterizes exponential growth?
No individual distinctions (no age/size classes)
no density dependence
constant per capita growth rate
What is Sigmoidal Growth? (Logistic Model)?
Density dependent growth
Initially, the population grows rapidly (exponential phase).
Growth slows as resources become limited.
Population stabilizes at the carrying capacity K
What is a structured population model?
Typically visualized as population pyramids, which graphically display age and sex distributions.
age structured
sex structured
What does R₀ > 1 indicate?
Population is growing
whats a life table?
Summarize the likelihood of survival, mortality, and reproduction by age.
What do like tables show?
Age Class X
Number in each age class Nx
Proportion of surviving individuals from age 0: Ix
Average fertility of a female of x age class mx
What can you calculate from life tables?
reproductive rate: lxmx
stable age distribution: Cx
reproductive value: Vx
intrinsic growth rate: r
What is r?
Intrinsic growth rate
What information does a Leslie Matrix contain?
Fecundity on top row and survival probabilities on sub-diagonals
Why are size-structured models advantageous?
They don’t require age determination and use size compositions for flexible modelling. good for many species such as corals
What are the three types of variability in stochastic models?
Environmental, demographic, and measurement error
What is the basic population growth equation?
N(t+1) = N(t) + B - D + I - E
What parameters are included in stage-based models?
Probability of remaining in stage (Pi), probability of stage transition (Gi), and stage fecundity (Fi)
What factors influence recruitment in marine environments?
Stock size and environmental conditions
What is the purpose of sensitivity analysis?
To determine which parameters have the greatest effect on population growth
Increase one parameter (e.g., survivorship or fertility) by a set percentage (e.g., +25%).
Measure the effect on λ
Reset the parameter to its original value and repeat with other parameters
Whats a stochasticity in Models
Adds variability to model parameters (e.g., fecundity, survival) to reflect real-world uncertainty.
Produces multiple trajectories to reflect variability in outcomes
