Download eoc review packet evolution

Unit 10: Evolution
Vocabulary to Define:
evolution
macroevolution
microevolution
fitness
species
gene pool
genetic equilibrium
speciation
gradual extinction
mass extinction
homologous structures
vestigial organs
What you should know…
 Natural selection occurs because the individual members of a population have different traits which allow
them to interact with the environment either more or less effectively than the other members of the
population. There are four main principles to natural selection. Sometimes called survival of the fittest.
o Overproduction of offspring: increases chances of survival, also increases competition
o Variation: differences in physical traits among organisms within a population
o Adaptation: leads to the increase in a particular trait, process, behavior that makes organisms better
able to survive and reproduce.
o Descent with modifications: all came from one common ancestor with changes over time

Asexual reproduction involves one parent that produces offspring that are genetically identical to parent.
o Rate is much higher than sexual and produces many offspring that are suited to survive
o May have a disadvantage in changing conditions because genetically identical offspring respond to the
environment in the same way. The entire population could die off with one big change.

Genetic variability leads to biological evolution; influenced by several factors:
o Genetic drift: random change in allele frequencies over time; due to chance
o Gene flow: movement of genes into or out of a population (example: migration)
o Non-random mating: carefully choosing mating partner
o Mutations
and
Natural Selection

Five conditions that are required to maintain genetic equilibrium are:
○ (1) Population must be large, no genetic drift occurs
(2) no gene flow
(3) no mutations
○ (4) only random mating
(5) no natural selection

There are 3 ways that organisms can be reproductively isolated from one another (speciation):
○ Timing (aka temporal), behavioral, or physical (geographic barriers)

There are 6 patterns of evolution:
○ Gradualism: gradual changes of a species in a particular way over long periods of time
○ Punctuated equilibrium: periods of abrupt changes in a species after long periods of little change
○ Divergent evolution: a number of different species diverge (split-off) from a common ancestor.
○ Convergent evolution: groups of organisms living in similar environments produces species that are
similar in appearance and behavior.
○ Coevolution: when two or more species living in close proximity change in response to each other
○ Extinction: elimination of a species; can be gradual or mass
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Unit 10: Evolution

Areas of study that are used as evidence for evolution:
○ Anatomy: study of the structures of an organism to determine the possible relationship between the
evolutionary paths of two species
○ Embryology: study of embryonic development of organisms; similar structures of embryos may suggest
that these species evolved from common ancestors.
○ Biochemistry: the study of the chemical processes in organisms; more similar the DNA and amino acid
sequences in proteins of two species, the more likely they are to have diverged from a common ancestor
○ Paleontology: the study of prehistoric life (fossils); provides evidence of life forms and environments
along a timeline and supports evolution by showing the similarities between current and ancient species

Phylogenetic tree: a scientific diagram that biologists use to represent the phylogeny (evolutionary history
of a species) of organisms
○ classifies organisms into major taxa (groups) based on evolutionary relationships
○ used to classify species in the order in which they descended from a common ancestor
Some phylogenetic trees only express the order of divergence of a species. They do not attempt to show
relative or absolute time frames.


Some phylogenetic trees indicate an estimated time of divergence. The tree below shows the relative time
that species diverged.
The most recent classification scheme includes
 three domains (Bacteria, Archaea, and Eukarya)
 six kingdoms (Eubacteria, Archaebacteria, Protista, Fungi, Plantae, and Animalia).
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