Chapter Four and Five

Biological Evolution
consists of genetic change in organisms across gernations. change often leads to change in the appearance
Natural Selection
the process by which traits that enhance survival and repoduction are passed or more frequently to future generations than those that do not, altering genetic makeup of a population
Charles Darwin/ Alfred Russel Wallace
They each proposed the concept of natural selection as a mechanism for evolution and as a way to explain the great variety of living things.

adaptive trait/ adaptation
species will evolve to posses characteristics that lead to better and better success in a given enviroment
accidental alterations that arise during DNA replication
artificial selection
the process of selection conducted under human direction
biological diversity/ biodiversity
refers to the sum total of all organisms in an area, taking into account the diversity of species, their genes, their populations, and their communities
group of individuals of a particular species that live in the same area.
particular type of organism/ population/ share certain characteristics and can freely breed with one another and produce fertile offspring.
new species are generated. due to physical seperation of populations over some geographic distance
phylogenetic trees
treelike diagrams that explain relationships between among species, major groups of species, populations, or genes.
fossil record
the cumulative body of fossils worldwide
the disappearance of a species from earth
mass extinction events
killed off massive numbers of species at once
cumulative total of living things on earth and the areas they inhabit
population ecology
investigates the quantitative dynamics of how individuals within a sepcies interact with one another
community ecology
interactions among species, from one to one interactions to complex interrelationships involving entire communities.

a species…reflects its use of resources and its funcitonal role in a community.
organisms vary in the breadth of their niche. species with narrow breadth and thus very specific requirements are said to be…

those with broad tolerance, able to use a wide array of habitats or resources
population size
expressed as a number of indivisuals
population density
describes the number of individuals within a population per unit area
population distribution
describes the spatial arrangement of organisms within an area, random, uniform, or clumped
limiting factors
physical, chemical, and biological characteristics of the environment that restrain population growth
logistic growth curve
rises sharply at first, then drifts as limiting factors become stronger
density independent
factors are limiting factors whose influence is not affected by population density
k- selected/ r-selected
k-stabilize near carrying capacity/ r-focus on quantity not quality
resource partionting
when species divide because they use their resources in different ways
when species benefit from each other
species in close physical contact/ mutation
assemblage of species living in the same place at the same time
the first trophic level. plants. energy
organisms that consume producers.

primary. secondary trophic level. grazing deer/ cattle

detritivores/ consume non-living things.
keystone species
animal that has a strong impact on life. holds the structure together
if a disturbance is severe enough to eliminate all or most of the species in a community, the affected site will undergo a somewhat predicatable series of changes that ecologists cal…
secondary succession
begins when a disturbance dramatically alters an existing community but does not destroy life all together
pioneer species
animals that are well adapting for colonization, they arrive first and colonate
invasive species
can alter a community substantially/ one of the central ecological forces into todays world
restore it back to its natural position
a major regional complex of similar communities/ a large ecological unit recognized primarily by its dominant plant type and vegetation structure
lose their leaves