chapter 44 Flashcards
What is a population?
A population consists of all the individuals of a given species that live and reproduce in a particular place.
Ecology
Is the study of the relationships of organisms to one another ( the biotic components and the environment (the abiotic components)
What is closely intertwined?
Ecology and Evolution
What is a collection o individuals of the same species is called ?
A population
A collection of populations makes a ?
community
A community with the habitat makes an
ecosystem.
What are the key characteristics of populations ?
Size = headcount, Range = space occupied
Density = size/range
Distribution
of indivduals within polations Sessile, or sedentary, organisms can be counted within a defined area, and total populatiom can be extrapolated from that count, Mark and recapture is useful for counting mobile organisms.
What is mark and Recapture?
an extrapolation method
Population size (N)
Butterflies caught on the first day ( M = 100)
Marked and unmarked on the second day (C = 120)
Recaptures (R = 30)
N= C/R X M
N= 120/30 x 100 =400
what does population size do over time?
Increase or decrease
What affects population size?
Immigration, Emigration, death and birth
Morality and Emigration decreases population.
Population Growth equation
N= N2-N1=(B-D) +( I-E)
Logistic Growth
Limiting factors keep growth in check - hence a “carrying capacity” for each species in each space in each time - the K
Density - Independent Factors ( pop does not matter)
- limit population regardless of population density
- Droughts or other severe events
- Environmental conditions (temperature, light availability)
Density- Dependent factors (pop’n size does not matter)
- competition for limited resources
- Predation, parasitism
- Diseases
Density-dependent Effects
Carrying Capacity (k)
K is always what specific?
species-specific, time- specific and location-specific
What helps ecologists understand past changes and predict future changes in population size?
The age structure of a population
Population Demography
Population ecologists use demography- the study of statistics such as birth rates ,age or size structure and distribution over time and environments
The pattern of investment in growth vs. reproduction vs. survival over an organism’s lifetime is called?
Life history
Why care about the age structure?
Survival and mortality vary across age classes.
Survivorship curves show?
How survival or morality rate change with age.
Type I Survivorship
mortality rate increases later in life ( large animal (bears , humans and dogs)
- annual plants ( most seedlings survive to reproduce)
Type II survivorship
Mortality rate is constant over life Plants competing for limited space which (self- thin) , birds, reptiles
Type III Survivorship
Mortality rate is highest in the young, insects and marine organisms with tiny dispersing larvae and most tree.
Reproduction is
distributed over a schedule
- Repeated reproduction over lifetime is iteroparity
-Semelparity is single reproductive event then death
TRADE OFF
what patterns reflect predictability of environment?
REproductive patterns
what are the two models of reproductive mode?
r-strategy and K strategy
