Chapter 53 Biology Population

Front 1

Population/Population Ecoloy

Back 1

A group of individuals of a single species living in the same general area

the study of populations in relation to the environment

Front 2

Density

Back 2

The number of individuals per unit area or volume.

Determined by 4 factors:
Birth rate, death rate, emigration, immigration.

Front 3

Dispersion

Back 3

The Pattern or spacing among individuals or subgroups within a population.

Influenced by scale, as well as environmental and social factors.

Front 4

Types of Dispersion

Back 4

Clumped: individuals aggregate in patches. Influenced by resource availability and behavior.

Uniform: Individuals are evenly spaced. Influenced by social interaction, such as territoriality.

Random: each individual is independent of others.

Front 5

Demography

Back 5

Study of vital statistics of a population and how they change over time.

Focus on death/birth rates.

Front 6

Life table

Back 6

Age-specific summary of survival pattern of a population.

Best constructed by following cohort.

Front 7

Survivorship curves

Back 7

Type 1: Humans. High life expectancy with a gradual taper off in later years.
Type 2: Squirels. Linear decline from birth to death.
Type 3: Clams. Poor life expectancy for young, slowly levels out for older individuals.

Front 8

Semelparity

Back 8

"Big-Bang" reproduction. Species that focus all energy into a single reproduction period before death. Annual plants. Salmon (digest internal organs to focus more energy to repro).

Front 9

Iteroparity

Back 9

Species that reproduce offspring repeatedly over time. Perrenial plants. Humans, most mammals.

Must balance reproduction and survival

Front 10

Population growth terms

Back 10

r: growth rate. If r=0, no growth. if r > 0, population growing.

K: carrying capacity of an ecosystem.

Exponential growth: uninhibited growth up to K.

Logistic growth model: per-capita rate declines as carrying capacity is reached.

dN/dT = rMAX * N * (K-N)/K

Front 11

k-selection/r-selection

Back 11

K-selection: Selects for life history traits that are sensitive to population density. Slow growth rate. Stays close to capacity.

r-selection: Selects for life history traits that maximize reproduction. (Semeparous)

Front 12

Population Change/Classes of Mortality

Back 12

Density-independent: Birth rate and death rate do not change with population density. ie: weather

Density-dependent: birth rates fall and death rates rise with population density. Negative feedback.

Negative feedback stabilizies population change. Positive feedback is rare, and typically destabilizes a population.

Front 13

Territoriality

Back 13

Territoriality can limit population growth. When the population density becomes high, all the good territories are occupied.

Front 14

Health/Predation

Back 14

Higher density population leads to more rapid spread of pathogens.

As prey population increases, acute predation may be present.

Rates of predation and predator population are higher as density increases.

Front 15

Intrinsic factors of population size

Back 15

Intrinsic (physiological) factors can regulate some population sizes.

A rise in the stress hormone Cortisol has been detected in some populations with increased population interactivity. Cortisol can reduce reproductive output.

Front 16

Population stability/fluctuation

Back 16

Extreme fluctuations in population size are typically more common in invertebrates than in large mammals.

Front 17

Metapopulations

Back 17

Groups of populations linked by IMMIGRATION and EMIGRATION.

Large populations distinct from each other, but linked. ie: groups of islands.

Front 18

Ecological footprint concept

Back 18

Summarizes the aggregate land and water area needed to sustain the people of a nation.

One measure of how close we are to the carrying capacity of earth.