Chapter 4
Biological diversity/biodiversity
the variety of the earth’s species, the genes they contain, the ecosystems in which they live, and the ecosystem processes (such as energ flow and nutrient cycling) that sustain all life
What are the four components of biodiversity?
Functional, species, genetic, and ecosystem diversity
How many species have scientists identified so far?
4.8 million
270,000 –> plant species
45,00 –> vertebrate animal species
Biological evolution
The process whereby earth’s life changes over time through changes in the genes of populations
What did Darwin and Wallace discover/observe?
The two scientists observed that organisms must constantly struggle to obtain enough food and other resources to survive and reproduce. Individuals in a population (with a specific advantage over other individuals are more likely to survie, reproduce, and have offsprin with similar survival skills. The advantage was due to a trait possessed by the individuals but not by others.
Natural selection
Happens when some individuals of a population have genetically based traits that enhance their ability to survive and produce offspring with the same traits
Evolution
Change in the genetic characteristics of a population from one generation to another
Fossils
Mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, and seeds impressed of such items found in rocks
Cumulative body: (blank) record
KEY CONCEPT OF BIOLOGICAL EVOLUTION
POPULATIONS EVOLVE NOT INDIVIDUALS!
(Only thing I remember from AP Bio :D)
Mutations
Random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring
Adaptation
Any heritable trait that enables an organism to survive through natural selection and to reproduce more than other individuals under prevailing environmental conditions
Genetic resistance
The ability of one or more organisms in a population to tolerate a chemical designed to kill it
Process of biological evolution by natural selection
1. Genes mutate
2. Individuals are selected
3. Populations evolve that are better adapted to survive and reproduce under existing environmental conditions
When environmental conditions change, a population of a species face three possible futures:
1. adapt to new conditions
2. migrate to a new area
3. become extinct
Tectonic plates
Huge flows of molten rock within the earth’s interior break its surface into a series of gigantic solid plates
Speciation
Two species arise from one. A new species is formed when some members of a population have evolved to the point when they can no longer breed with other members to produce fertile offspring.
Geographic isolation
Occurs when different groups of the same population of a species become physically isolated from one another for long periods
Reproductive isolation
Long-term geographic separation of members of a particular sexually reproducing species
Extinction
A situation in which a species ceases to exist
Endemic species
Species that are only found in one area, especially vulnerable to extinction. They exist on islands and in other unique small areas, especially in tropical rain forests where most species are highly specialized.
Background extinction
Normal extinction of various species as a result of changes in local environmental conditions
Average annual background extinction rate
One to five species for each million species on the earth
Mass extinction
A significant rise in extinction rates above the background level
Species diversity
The number of different species contained combined with the relative abundance of individuals within each of those species in a given area
Species richness
Number of different species contained in a community
Species evenness
Relative abundance of individuals within each of the species in a community
Species richness seems to increase the
productivity and stability or sustainibility of an ecosystem.
Ecological niche
A species’ way of living in a community and includes everything that affects its way of survival and reproduction, such as how much water and sunlight it needs, how much space it requires, and the temperatures it can tolerate
Native species
Those species that normally live and thrive in a particular ecosystem
Nonnative species
Other species that migrate into or are deliberately or accidentally introduced into an ecosystem
(wild African bees)
Indicator species
Species that provide early warnings of damage to a community or an ecosystem
(presence/absence of trout, butterflies, birds, canaries)
Keystone species
Have a large effect on the types and abundances of other species in an ecosystem
(alligators, wolves, lions, sharks, leopards)
Foundation species
Play a major role in shaping communities by creating and enhancing their habitats in ways that benefit other species
(beavers, elephants)
For every shark that injures a person, we kill at least
1 million sharks.
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