biological evolution
genetic changes in the populations of living organisms
Charles Darwin
Proposed natural selection as mechanism for biological evolution
"On the Origin of Species by Means of Natural Selection" - 1859
natural selection
process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species
chemical evolution
chemical changes that occured to earth during its first billion years of existence that allowed it to become hospitable for living organisms
fossils
used to determine which organisms lived in the past; mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, seeds, etc.
ice cores
used to determine which organisms lived in the past; drilled from glacial ice to analyze chemicals found within
DNA analysis
used to determine which organisms lived in the past; genetic samples from fossilized remains are compared to genetic samples from organisms alive at the present
mutation
change or mistake in the DNA of an organism; occur naturally and sometimes caused by exposure to toxins and/or radiation; lead to genetic variability in a population; can be good, bad or neutral
differential reproduction
some organisms get to reproduce at higher rates than others; organisms with traits that help them survive and allow them to well suited for their environment will reproduce at higher rates than organisms that are ill adapted to their environment
adaptation / adaptive trait
genetic characteristic that allows an organism to survive better
coevolution
2 organisms/populations changing genetically in response to each other; ex: bats and moths
hybrid / hybridization
2 distinct species breeding and creating a new unique species; rarely occurs in nature; more common due to human research and human influences; ex: beefalo, liger, etc.
horizontal gene transfer
transfer of genes from one organism/genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms
tectonic plates
sections of the Earth's crust that move due to convection currents
ecological niche / niche
organisms way of life; what resources it uses, how and when it uses those resources, etc.
generalist species
broad habitat and niche; can live in many places and many conditions; ex: grey squirrel, white-tail deer, cockroach, raccoon, etc.
specialist species
narrow habitat and niche; can only live in very specific places and under very specific conditions; ex: giant panda, orchids, etc.
evolutionary divergence
process whereby natural selection causes populations to become more different over time
speciation
formation of new species
geographic isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water
reproductive isolation
separation of species or populations so that they cannot interbreed and produce fertile offspring
extinction
total loss of a species
endemic species
organism that is found only in one very specific location
background extinction
natural extinction rate; some species will go extinct under normal conditions as environmental conditions change; ex: one to five species for each million species on earth
mass extinction
large number of species going extinct in a very short period of time; ex: there have been 5 mass extinctions over the last 500 million years; ex: dinosaurs going extinct is an example of a mass extinction
mass depletion
widespread, often global period during which extinction rates are higher than normal but not high enough to classify as a mass extinction
artificial selection
selection by humans for breeding of useful traits from the natural variation among different organisms; ex: different breeds of dogs
genetic engineering
the transfer of a gene from the DNA of one organism into another organism, in order to produce an organism with desired traits
gene splicing
the process by which the DNA of an organism is cut and a gene from another is inserted
recombinant DNA
genetically engineered DNA made by recombining fragments of DNA from different organisms
genetically modified organisms (GMO's)
organisms whose genetic code has been altered by artificial means such as interspecies gene transfer; Currently 82% soybeans, 71% cotton and 1/4 corn grown in US are GMO's
cloning
making a genetically identical copy of DNA or of an organism