Download Evolution Terms and Pictures

EVOLUTION TERMS & PICTURES
LAMARKISM
• If an organism
changes during life
in order to adapt to
its environment,
those changes are
passed on to its
offspring
• Lamark said that
change is made by
what the organisms
want or need
NATURAL SELECTION ON POLYGENIC TRAITS
• Stabilizing selection: phenotypes in
the middle range confer greater
survival/reproduction, while
phenotypes at both extremes lead
to decreased fitness
• Directional selection: phenotypes at
one end of the spectrum lead to
greater survival/reproduction
• Disruptive selection: phenotypes at
both ends of the spectrum lead to
greater survival/reproduction, while
phenotypes in the mid range are a
disadvantage (least common of the
three types )
GENETIC DRIFT
• In each generation, some
individuals may, just by
chance, leave behind a few
more descendants (and
genes) than other
individuals.
• The genes of the next
generation will be the
genes of the "lucky"
individuals, not necessarily
the healthier individuals
GENETIC DRIFT – BOTTLENECK EFFECT
• Occurs when there is
a disaster of some sort
that reduces a population
to a small handful, which
rarely represents the
actual genetic makeup of
the initial population
• This leaves smaller
variation among the
surviving individuals.
GENETIC DRIFT - THE FOUNDER EFFECT
ADAPTIVE RADIATION
• Process in which organisms
diversify rapidly from an
ancestral species into a
multitude of new forms
• Particularly when a
change in the environment
makes new resources
available, creates new
challenges, or opens new
environmental niches
HOMOLOGOUS STRUCTURES: PARTS OF THE BODY THAT ARE
SIMILAR IN STRUCTURE TO OTHER SPECIES' COMPARATIVE PARTS
CONVERGENT EVOLUTION
Process whereby
organisms not closely
related independently
evolve similar traits as
a result of having to
adapt to similar
environments or
ecological niches
COEVOLUTION: WHEN CHANGES IN AT LEAST TWO
SPECIES' GENETIC COMPOSITIONS RECIPROCALLY
AFFECT EACH OTHER'S EVOLUTION