Lecture 18 Flashcards
(24 cards)
artificial selection
Selective breeding of plants and animals to achieve desired traits.
biogeography
e scientific study of the
past and present geographic distributions of
species.
bottleneck effect
Genetic drift that occurs
when the size of a population is reduced, as
by a natural disaster or human actions. Typically,
the surviving population is no longer
genetically representative of the original
population.
cline
””
comparative anatomy
comparing the same structure in different organisms
descent with modification
the
idea that living species are descendants of
ancestral species that were different from
the present-day ones; also defined more
narrowly as the change in the genetic composition
of a population from generation to
generation.
evolution
the
idea that living species are descendants of
ancestral species that were different from
the present-day ones; also defined more
narrowly as the change in the genetic composition
of a population from generation to
generation.
evolutionary adaptation
Genetic changes that occur to adapt to environment.
fossil
A preserved remnant or impression of
an organism that lived in the past.
fossil record
he fossil record shows that organisms have appeared in a historical sequenceFormation of sedimentary rock and deposition of fossils from different time periodsStrata of sedimentary rock at the Grand Canyon
founder effect
Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.
gene flow
The transfer of alleles from one
population to another, resulting from the
movement of fertile individuals or their
gametes.
gene pool
The aggregate of all copies of every
type of allele at all loci in every individual in
a population. The term is also used in a more
restricted sense as the aggregate of alleles for
just one or a few loci in a population.
genetic drift
A process in which chance
events cause unpredictable fluctuations in
allele frequencies from one generation to the
next. Effects of genetic drift are most pronounced
in small populations.
microevolution
Evolutionary change below
the species level; change in the allele
frequencies in a population over
generations.
mutation
A change in the
nucleotide sequence of an organism?s DNA
or in the DNA or RNA of a virus.
natural selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
neutral variation
Genetic variation that
does not provide a selective advantage or
disadvantage.
outcomes of natural selection
Directional Selection, Diversifying Selection Stabilizing Selection
polymorphism
different forms
population
total group of organism
sexual dimorphism
Differences
between the secondary sex characteristics
of males and females of the same
species.
species
A population or group of
populations whose members have the potential
to interbreed in nature and produce
viable, fertile offspring, but do not produce
viable, fertile offspring with members of
other such groups.
transitional fossil
Many fossils link early extinct species with species living today
? These are called transitional fossils linking past and present These fossilized hind leg bones link living whales with their land-dwelling ancestors
