Transcript Analogous structures

Tuesday 2/16/2016
Agenda: Evolution Part II
 Notes: Anatomical Records
 Activity: Notes Foldable
Homework/Class Work:
No Homework Today!
**EVOLUTION EXAM FRIDAY 2/19/2016
**GRADEBOOK CLOSES TUESDAY 3/1/2016
Anatomical Record

Similar structural forms can be seen in
different living organisms
3.
Homologous structures
Analogous structures
Vestigial structures
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All vertebrates share a basic set of developmental instructions
1.
2.
Relict
developmental
forms

Analogous structures: resemble each other as a
result of needed adaptations to similar
environments (Different animals adapt in similar
fashion when challenged by similar opportunities)
 The feature has the same function but looks
different.

Homologous structures: have same structure,
DIFFERENT function. However, the structures
are derived from the same part of a common
ancestor
The same basic bones
are present in each
forelimb
Fig. 13.8
Homology among
vertebrate limbs

Vestigial structures:
 Although the structure(s) had a purpose &
function in the past but they are largely or
entirely functionless now.
 a vestigial structure may retain lesser
functions or develop new ones.
The blue whale has tiny hind leg bones under its tail.
The blind mole rat has tiny eyes completely
covered by a layer of skin.
Wednesday/Thursday 2/17-2/18/2016
Agenda: Evolution Part II
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Notes: Anatomical Records Review
Notes: Patterns and Forces of Evolution
Practice: Evolution Part II Worksheet
Review: Evolution Station Rotation
Homework/Class Work:
No Homework Today!
**EVOLUTION EXAM FRIDAY 2/19/2016
**GRADEBOOK CLOSES TUESDAY 3/1/2016
Q3 WK7 D1
PATTERNS OF EVOLUTION
Coevolution: Change of two or more
species in close association with each
other. Dependency develops
EXAMPLE:
Bumblebees and the
flowers they pollinate
have co-evolved so that
both have become
dependent on each other
for survival.
Convergent Evolution: A kind of evolution where
an organism develops structures that have similar
(analogous) structures or functions regardless of their
evolutionary ancestors being very dissimilar or
unrelated.
Analogous structures are the result of convergent evolution.
DIVERGENT EVOLUTION: 2 or
more related species that become
more dissimilar due to different
environments.
•This usually produces another species
EXAMPLE:
GALAPAGOS
FINCHES
EVOLUTIONARY FORCES

5 evolutionary forces can significantly
alter the allele(s) frequencies of a
population

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1.
2.
3.
4.
5.
Mutation
Migration
Genetic drift
Nonrandom mating
Selection
Mutation

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The MAIN source
of new variation
Errors in DNA
replication and
change in DNA due
to extraneous
factors
Mutation rates are
too low to
significantly alter
allele frequencies on
their own
Migration

Movement of individuals from one population to
another

Immigration: movement INTO a population

Emigration: movement OUT of a population
A very
potent
agent of
change
Genetic Drift
A. Random loss of alleles

More likely to occur in
smaller population
B. Founder effect

Small group of
individuals establishes
a population in a new
location
C. Bottleneck effect

A sudden decrease in
population size to
natural forces
Mating that occurs
more or less frequently
than expected by
chance
 Inbreeding
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Mating with relatives or self
Increases homozygosity
Outbreeding

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Mating with nonrelatives
Increases
heterozygosity
Nonrandom Mating
Selection
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Some individuals leave
behind more offspring
than others
Artificial selection

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Creating unnatural
characteristics by
breeding species to
promote a certain type
of offspring.
Natural selection

Environment selects for
adapted characteristics
Jack Russell + Mini Italian
Greyhound = Guapo 