BIOL 101 Unit #5 Ch. 19

what is demography?

the statistical study of changes in populations over time; mathematical tools designed to describe populations and how they change

what are life tables?

table showing life expectancy of a population member basd on its age

- initially started by life insurance industry

what is population size?

number of individuals in a population

- can affect the amount of genetic variation & adaptation

what is population density?

number of population members divided by the area being measured

- effects on competition for food and ability of individuals to find a mate

what is a quadrat?

metal square randomly placed on the ground and used to count the number of individuals that lie within its boundaries; determines population size/density in slow moving or stationary organisms

what is mark and recapture?

method used to determine population size in mobile organisms

- large population = less likely of organism to be captured (vice-versa for smaller populations)

what is the species distribution pattern?

the distribution of individuals within a habitat at a given point in time

what is mortality rate?

the proportion of a population that survives to the beginning of an age interval but dies during that age interval

what is the survivorship curve?

a graph of the number of surviving population members (individuals) versus the relative age of the member

what are the types of survivorship curves?

Type I

Type II

Type III

what is a type I curve?

mortality is low in early and middle years of year interval (older individuals prob higher); organisms that exhibit type I provide good vare to the offspring, increasing chances of survival

- human population exhibits this survivorship curve

what is the type II curve?

mortality is relatively constant throughout the entire lifespan, mortality equally likely to occur at any point in the lifespan

- common in bird populations

what is the type III curve?

early ages experience the highest mortality rate than if they were to advance later in years with a lower mortality rate; produces large # of offspring with little to no care

- seen in tree and marine life

- (ex.) the sea-turtle population

what are the distribution PATTERNS?

random (dandelions), clumped (Oak trees drop seeds directly below/herding animals), and uniform (territorial; toxic root system that prevents other plants from growing next to it

what is population growth?

based on birth & death rate

- birth rate greater than death rate (population is growing)

- birth rate less than death rate (population is shrinking)

what is exponential growth (J-shaped curve growth)?

describes the theoretical populations that increase in numbers without any limits to their growth

- can be seen with bacteria prokaryotes with binary fission

what is logistic growth (S-shaped curve growth)?

limits the reproductive growth that become more intense as the population size increases

what is death rate (D)?

number of deaths within a population at a specific point in time

what is birth rate (B)?

number of births within a population at a specific point in time

what is zero population growth?

steady population size where birth rates and death rates are equal

what is the carrying capacity?

maximum number of individuals of a population that can be supported by the limited resources of a habitat

- population overshoots capacity = death rate increasing beyond the birth rate (population declines back to capacity)

what is intraspecific competition?

competition among population members of the same species

what is density-dependent?

regulation of a population in which birth and death rates are dependent (rely) on a population size

- factors include predation, inter/intraspecific competition

what is density-independent?

regulation of a population in which the death rate is independent of the population size

- factors: natural disasters, changes in population regardless of density

what are K-selected species?

a species suited to stable environments that produce a few, relatively large offspring and provide parent care

- (ex.) elephants, humans

what are r-selected species?

species suited to changing environments that produce many offspring and provide little to no parental care

- (ex.) dandelion plant, cockroaches

- unstable environment

what are some carrying capacity changes?

annual change, winter/summer, natural events, interspecific competition

- always fluctuates (goes over, goes down, remains constant, REPEAT)

what are some long-term exponential growth risks?

disease, death, crime, hunger crisis (famine), alteration of ecosystem to the point of collapse

- global climate change caused by humans (fossil fuels)

what is age structure?

the proportion of a population in different age classes

what are the age structure stages?

1) rapid growth

2) slow growth

3) stable

4) decline

what is rapid growth?

common in underveloped countries

- not as many individuals reach old age; lots of reproduction though

- (ex.) Africa

what is slow growth?

common in developed countries (USA, Canada)

- more older, fewer younger individuals

what is mimicry?

adaptation in which an organism looks like another organism that is dangerous, toxic, or distasteful to its predators

- harmless species imitates the warning coloration of a harmful species

what is the competitive exclusion principle?

no two species within a habitat can co-exist indefinitely when they compete for the same resources at the same time and place

what are the symbiotic relationships?

mutualism, commensalism, parasitism

- close long-term interactions between individuals of different species

what is symbioses?

Any relationship in which two species live closely together

what is commensalism?

one organism benefits and the other is unaffected

what is mutualism?

symbiotic relation where both organisms benefit

what is species richness?

the number of different species in a community

- greater at equator, lower at poles

what is island biogeography?

influences species richnes; study of life on island chains and how their geography interacts with the diversity of species found there

what is relative species abundance?

number of individuals in a species relative to the population size of other species within the community

- foundation species have the highest relative abundance of species

what are foundation species?

species that are considered the "base" of a community, forming the major structural portion of the habitat

- coral in coral reefs

what are keystone species?

species whose presence is key to maintaining biodiversity in an ecosystem, upholding an ecological community's structure

what is environmental disturbances?

change in the environment caused by natural disasters or human activities

- volcanoes, climate change, storms, earthquakes

what is succession?

appearance and disappearance of species in a community over time after a severe disturbance

what is primary succession?

the succession on land that previously has had no life

- occurs when new land forms following an eruption of a volcanoe

what is secondary succession?

succession in response to environmental disturbances that move a community away from its identity/relationships

what are pioneer species?

first species to appear in primary and secondary succession

- (lava new island ex.) species breaks down mineral-rich lava into soil, where other species such as grass, shrubs, and trees (intermediate species) will grow and eventually replace the pioneer species

what is the climax community?

the final stage of succession, where a stable community is formed by a characteristic assortment of plant and animal species

- forests reaches its equilibrium point and resembles the forest community before the fire (remains until next disturbance)

what is biodiversity?

number of different species and their abundance

what is community dynamics?

changes in a community's structure and composition over time

what is the equlibrium (biology)?

constant number of species