Enviro test 2 Flashcards
Population
Group of the same species living in an area.
Population Ecology
Study of factors causing populations to increase or decrease.
Migration
Seasonal movement affecting population size temporarily.
Population Density Formula
Population ÷ Area.
Low Density
More resources, harder to find mates.
High Density
Easier to find mates, more competition/disease.
Exponential Growth
J-curve; occurs in ideal conditions but unsustainable.
Logistic Growth
S-curve; slows due to limiting factors like food or space.
Carrying Capacity (K)
Max sustainable population for an area.
Exceeding leads to overshoot → resource depletion → population decline.
K-Strategists
Stable, long life, few offspring (e.g., humans).
r-Strategists
Unstable, short life, many offspring (e.g., mice).
Type I Survivorship curve
High survival until old age (e.g., humans).
Survivorship Curves Type II
Constant survival rate (e.g., birds).
Survivorship Curves Type III
High mortality in youth (e.g., fish).
Current global growth
Exponential (J-Curve)
Baby Boom (1946–1964)
High births post-WWII.
Baby Bust:
Declining birth rates due to birth control, delayed marriage, and career-focused women.
Global Growth Rate:
(CBR - CDR) ÷ 10.
National Growth Rate
[(CBR + Immigration) - (CDR + Emigration)] ÷ 10.
Doubling Time
Rule of 70 (70 ÷ Growth Rate).
Demographic Transition Model
Phase 1
Preindustrial - High birth & death rates, slow growth.
Demographic Transition Model
Phase 2
Transitional - Death rates drop, rapid growth.
Demographic Transition Model
Phase 3
Industrial - Birth rates decline, stabilization.
Demographic Transition Model
Phase 4
Post-industrial - Population declines (e.g., Italy).
