Chapter 5 - Biodiversity, Species Interactions, and Population Control

Physical Appearance (ecosystem structure)

size and stratification of species

Niche Structure

Number of diversity of ecological niches

Species diversity (richness)

number of species

Species evenness (abundance)

number of individuals of each species

Niche

a species functional role in an ecosystem

Fundamental Niche

full range of conditions and resources a species could use with no direct competition

Realized Niche

part of the fundamental niche actually used by a species

Convergence

species’ w/ similar niches tend to evolve a similar set of traits

Coevolution

the change in the gene pool of one species leading to the change in the gene pool of another species

Resource partitioning

diving up resources so they are used at different times, in different ways or places to reduce or avoid competition with other species

Predation

predators feed directly on prey

Parasitism

one species feeds on another species by living on or on the host

mutualism

relationship where both species benefit

Commensalism

a relationship where one species benefits while the other is unaffected

Population size

number of individuals in a population at a given time

population density

number of individuals of a population in a certain space at a given time

Population dispersion

spatial pattern in which the members of a population are found in their habitat

clumping pattern

appears when small groups of individuals are distributed throughout the habitat

uniform pattern

appears when individuals are distributed evenly throughout the habitat

random pattern

appears when individuals are distributed throughout the habitat without an identifiable order

age structure

the proportion of individuals in each age group (prereproductive, reproductive, postreproductive) in a population

biotic potential

a populations capacity for growth

intrinsic rate of increase (r)

rate at which a population could grow if it had unlimited resources

species with high intrinsic rate of increase

typically reproduce early in life, have short generation times, can reproduce many times, and produce many offspring when they reproduce

Environmental resistance

all the factors acting jointly to limit the growth of a population are collectively called this

Carrying Capacity (K)

Biotic potential and environmental resistance determine this, the number of individuals of a given species that can be sustained indefinitely in a given space

Exponential Growth

A population that does not have resource limitations. Starts out slowly and then proceeds faster and faster as the population increases. J-shaped curve

Logistic Growth

exponential population growth when the population is small and a steady decrease in population growth with time as the population approaches the carrying capacity. S-shaped curve

growth past K

due to reproductive lag

reproductive lag

period required for the birth rate to fall and the death rate to rise in response to resource overconsumption

J-shaped exponential curves

tend to overshoot K and suffer a population crash

S-shaped curve

tend to overshoot K only to drop and hover around K

Stable cycles

occur in a species whos population size fluctuates slightly above and below K

irruptive cycles

occurs in a species whose population is normally stable and occasionally explodes to a high peak and then crashes

cyclic

occur in a species whose population undergoes a patter of sharp increases followed by crashes

r-strategists

species with a high intrinsic rate of increase; J-shaped exponential curve

K-strategists

low intrinsic rate of increase; S-shaped logistic curve

survivorship curve

shows the number of survivors in each age group for a species

Late loss curves

K-strategists (type 1)

Early loss curves

r-strategists (type 3)

Constant loss curves

typical in species with intermediate reproductive strategies with a fairly constant rate of mortality in all age classes (type 2)

Primary succession

gradual establishment of biotic communities in an area that has not been occupied by life before

Secondary succession

re-establishment of a biotic community in an area where a biotic community was previously present

Pioneer species

first species to colonize a site as the first stage of primary succession

midsuccesional plant species

less hardy and more specialized

late successional plant species

represent an established stable community sometimes called a climax

Facilitation

occurs when one species creates a more suitable area for other species that occur later in succession (affects succession)

Inhibition

occurs when a species hinders the establishment of another that occurs later in succession (affects succession)

Tolerance

range of conditions that an organism can endure before injury or death

Natural disturbances

fires, hurricanes floods; necessary for maintaining the health of an ecosystem

human-distrubances

desforestacion and overgrazing

Inertia

ability of a living system to resist being disturbed or altered (aspect of stability)

Constancy

the ability of a living system (population) to maintain a size within the limits imposed by available resources (aspect of stability)

Resilience

ability of a living system to recuperate after an external disturbance