Download WHAT IS EVOLUTION? General definition: a change or modification

WHAT IS EVOLUTION?
HISTORICAL DEVELOPMENT OF EVOLUTION
General definition: a change or modification through time (e.g., galaxies
and language evolves)
I. Classical Thinking
biological or organic evolution: change in the properties of organisms
that transcend the lifetime of a single individual
Greeks thought that the world changes, but by
Plato’s time the idea of a static world came into
prominence
: in biology, more specifically,
changes that are heritable
: changes in allele frequency
A. Static World by Plato (427 to 347 BC)
-there is the “essence” or “form” that
doesn’t change, and things on earth
are a reflection of this
-so things on earth can show variation, but
the form never changes.
B. Purpose in Life: Natural Order "Will of God"
Scala Naturae or “the ladder of life”
HISTORICAL DEVELOPMENT OF EVOLUTION
II. Pre-Darwinian Thinking
A. (1500-1700) No purpose in physical world: Newton and Copernicus
B. Geologist: Earth is old!!
James Hutton (1788): uniformitarianism
Charles Lyell (1830)
Based on rocks, earth is billions of years old (about 4.6), not 5668,
according to Archbishop James Usher, who used lineages in the Old
Testament to estimate this.
C. Jean Baptiste de Lamarck (1744-1829): evolve to be better by design
of God (in his book Philosophie Zoologie, 1809); use and disuse of
traits, then passed on to the next generation
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
A. Basic types of evidence that challenged old paradigm
1. Homology: the study of likeness
a) ontogeny: development of embryo to adult
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
A. Basic types of evidence that challenged old paradigm
1. Homology
b) Structural:
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
A. Basic types of evidence that challenged old paradigm
2. Change Through Time:
a) fossil record: old things resembled new and transitional animals
so why similar? Creator or because of common descent
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
A. Basic types of evidence that challenged old paradigm
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
A. Basic types of evidence that challenged old paradigm
2. Change Through Time:
2. Change Through Time:
c) extinction in fossil records
b) vestigial parts: parts that are now useless were once useful
-creationist: extinct due to
flooding
-biologist: extinct species are
relatives of extant species
other examples: whale femur, human appendix
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
A. Basic types of evidence that challenged old paradigm
HISTORICAL DEVELOPMENT OF EVOLUTION
III. Darwin's time:
B. Darwin
2. Change Through Time:
Charles Darwin: 1809-1882
1831-1836 joined the crew of the HMS Beagle to travel around
the world as the ship's naturalist.
d) marine fossils in arid areas: earth itself is dynamic! (grand canyon,
see figure)
1844: he wrote an essay on Natural Selection
coral fossil in AnzaBorrego State Park
(desert in CA)
3. Age of the earth: Geology – earth is old (4.6 by)
1858: another biologist, Alfred Wallace (1823-1913), sent Darwin
a manuscript outlining natural selection, identical to his!
So at the urging of his colleagues, Darwin presented his work,
along with Wallace's, at a meeting of the Linean Soceity of
London in 1858. In 1858, he published his seminal “abstract”
-- On the Origin of Species.
Evolution was really accepted, but the mechanisms is what was
controversial (and the idea of no design!)
HISTORICAL DEVELOPMENT OF EVOLUTION
C. Natural Selection
a. Darwin proposed 4 steps, how Natural Selection drives evolution:
1.
2.
3.
4.
individuals need to be variable
traits that are variable are heritable -- passed on to next generation
excess offspring is produced
differential production or survival – linked to specific traits (see 2)
HISTORICAL DEVELOPMENT OF EVOLUTION
IV. Neo-Darwinian
How are traits passed on?
A.Lamarckism
B. Mendelian Genetics: Gregor Mendel, in 1854 carried out breeding
experiments in a monastery using the garden pea Pisum sativum
In 1865 he reported his results, but his results were not widely read until
the 1900's
HISTORICAL DEVELOPMENT OF
EVOLUTION
IV. Neo-Darwinian
How are traits passed on?
B. Mendelian Genetics
Experiment:
smooth x wrinkled seeds.
The f1: all smooth
The f2: 3/4 smooth and 1/4 wrinkled.
NATURAL SELECTION
V. Example of Evolution by Natural Selection
A. Observations: Galapagos Finches by
Grants and colleagues
-
Galapagos Archipelago, dramatic
differences among finch “species”’’
Is this evolution in action?
One of Mendel’s basic outcomes:
inheritance of genes is discrete, no
mixing
2. Traits that are variable are heritable
1. Individuals need to be variable
- Medium ground finch (Geospiza fortis) on Isla Daphne Major
3. Excess offspring is produced
4. Differential reproduction or survival
V. Example of Evolution by NS
A. Observations: Galapagos
Finches by Grants and
colleagues
Remember, NS works:
3. Excess offspring is produced
4. Differential reproduction or
survival
– linked to specific characters
V. Example of Evolution by NS
A. Observations: Galapagos
Finches by Grants and
colleagues
Remember, NS works:
3. Excess offspring is produced
4. Differential reproduction or
survival
– linked to specific characters
V. Example of Evolution by NS
A. Observations: Galapagos
Finches by Grants and
colleagues
Are populations evolving??
V. Example of Evolution by NS
V. Example of Evolution by NS
B. Type of Natural Selection
B. Type of Natural Selection
2. STABILIZING SELECTION
1. DIRECTIONAL SELECTION
w = fitness (how well an animal does)
w
e.g., larger trait results in higher fitness
w
trait
trait
w = frequency of
animal with specific
trait
f
f
trait
trait
V. Example of Evolution by NS
V. Example of Evolution by NS
B. Type of Natural Selection
B. Type of Natural Selection
2. STABILIZING SELECTION:
EXAMPLE
3. DISRUPTIVE SELECTION
BIRTH WEIGHT IN HUMANS
w
By Karn and Penrose
trait
•13,730 birth records at University
College Hospital between 1935-1946
•7037 males and 6693 females
•Survivorship (to 28 days), weight,
gestation time and mother
•Stabilizing Selection for birth weight
•Stabilizing Selection for gestation time and age of mother (not
shown)
MORE RECENT SURVEY IN ITALY (1954-1985) FOUND
A 4-FOLD DECREASE IN INTENSITY OF SELECTION
f
trait
V. Example of Evolution by NS
Beak Size in Seedeater Finches,
Pyerenestes ostrinus
B. Type of Natural Selection
3. DISRUPTIVE SELECTION
Two forms: large and small billed
Feed on two species of sedge: hard and soft
shelled (10 fold difference in hardness)
Consumption of seeds (handling time)
related to bill morphology
Two rainy seasons, split by dry season –
survival across dry season is low
By T. B. Smith
VI. Forces that Drive Evolution
A. Natural Selection
B. Genetic Drift: changes in gene frequencies occur because of
chance events (sampling errors) that occur when populations
are finite in size (small).
Population could be small due to founder event or bottle neck
•Banded and measured > 2500 birds
•Found (in general) 20% survival across seasons
•Bill morphology heritable – discrete and
dominant
raised in zoo
s x s = all small
l x l = 3:1 large to small
s x l = 1:1
VI. Forces that Drive Evolution
VI. Forces that Drive Evolution
A. Natural Selection
A. Natural Selection
B. Genetic Drift
B. Genetic Drift
e.g., Clegg and colleagues work
C. Mutation
on Silvereyes (Zosterops lateralis)
-populations have colonized islands off
Australia
-founder populations lose alleles
D. Gene Flow
VII. SOURCES OF GENETIC VARIATION
A. MUTATION
VII. SOURCES OF GENETIC VARIATIONa) POINT MUTATION
“TRUE” SOURCE OF VARIATION
b) DELETION: REMOVAL OF 1 OR MORE NUCLEOTIDES IN A DNA
SEQUENCE
MISTAKES DURING REPLICATION OF
DNA RESULTS IN MUTATIONS
THAT ARE HERITABLE
1.
TYPES OF MUTATIONS
a)
Point Mutation: Substitution of
single base pair
c) INSERTION: ADDITION OF ONE OR MORE NUCLEOTIDES IN A
DNA SEQUENCE
VII. SOURCES OF GENETIC VARIATION
VII. SOURCES OF GENETIC VARIATION
MECHANISMS OF DELETION AND INSERTION
1. unequal crossing over during recombination
2. transposition: jumping of genetic material from one position to
another chromosome (transposable elements)
MECHANISMS OF DELETION AND INSERTION
1) unequal crossing over during recombination
2) transposition
3) slippage
VII. SOURCES OF GENETIC VARIATION
VII. SOURCES OF GENETIC
VARIATION
d) INVERSION: 180 DEGREE ROTATION OF DNA
A. MUTATION
B. RECOMBINATION
-DURING METAPHASE,
HOMOLOGOUS
CHROMOSOMES
EXCHANGE
C. GENE FLOW
e) POLYPLOIDY: INHERITING EXTRA COPIES OF
CHROMOSOMES
-COMMON IN PLANTS
Copyright © 2002 Pearson Education, Inc.
VIII. Sexual Selection
Peahen and chick drab and cryptic
VIII. Sexual Selection
Peacock elaborate
A. Causes of Sex Differences
1. Anisogamy: DIFFERENTIAL INVESTMENT IN GAMETES
Male Birds:
Female Birds:
Fairywren: 8 billion
sperms at one time
One egg = 15-20% of
body weight
In Kiwi, it’s 25%, 1 lbs
SALMON: FEMALES LAY 3500 EGGS DURING SPAWNING,
MALES FERTLIZE THEM WITH 400,000,000,000 SPERM!
Peacocks highly conspicuous and vulnerable to predators
Why does this evolve?
Sexual Selection: Differential Reproduction Related to Elaborate Male Display
Traits
HUMANS: FEMALES PRODUCE ONE VIABLE EGG PER MONTH
MALES CAN FERTILIZE THE ENTIRE WORLD WITH 1 EJACULATION
VIII. Sexual Selection
VIII. Sexual Selection
A. Causes of Sex Differences
B. Effects of Sex Differences
1. Reproductive Potential – Bateman’s Rule
1. Anisogamy: DIFFERENTIAL INVESTMENT IN GAMETES
2. Parental Investment (post gametes)
e.g., mammals:
females nourish and carry embryo, nurse offspring
vs.
males fertilize eggs and leave
males
9
reproductive success
-females typically invest more than males
females
9
8
8
7
7
6
6
5
5
4
4
3
3
2
2
1
1
0
0
0
2
4
6
8
10
0
2
4
6
8
number of mates
-males increase their mating success with more females
-females do not necessarily increase their mating success with more
males
VIII. Sexual Selection
VIII. Sexual Selection
C. Test
Differential Parental Investment Dictates Which Sex is Choosy
B. Effects of Sex Differences
2. Operational Sex Ratio (by Emlen and Oring)
The ratio of available males to available females NOT just the
ratio of males to females
-note: if a female is mated, she is no longer available for mating
while males after being mated are still available for mating
-as season progresses, skew towards more males than
available females
FEMALES ARE CHOOSY SEX BECAUSE OF THESE TWO
FACTORS!
1. Mormon Cricket Observations
By D. Gwynne
MALES PRODUCE SPERMATOPHORES:
NUTRIENT RICH PRODUCTS
SPERMATOPHORE IS UP TO 25% OF MALES
WEIGHT!
IN AREAS WHERE FOOD IS SCARCE AND OSR
IS FEMALE BIASED, MALES ARE THE CHOOSY
SEX
10
VIII. Sexual Selection
Differential Parental Investment Dictates Which Sex is Choosy
2. Australian Katydids Lab Experiment By D. Gwynne
VIII. Sexual Selection
C. Test Differential Parental Investment Dictates Which Sex is Choosy
3. Australian Katydids Field Experiment By D. Gwynne and L. Simmons
•Different food quality:
CAGE
Shaded = high quality
•Placed 8
fiberglass cages
in the field
Unshaded = low quality
-FEMALES MATED MORE OFTEN WHEN
FOOD QUALITY IS LOW; MALES MATED
MORE OFTEN WHEN FOOD QUALITY IS
HIGH
•Four – extra
food, Four –
intact/control
•24 males, 24
females released
in each cage
-WITH HIGH QUALITY FOOD,
SPERMATOPHORE PRODUCTION IS
EASY (LOW PI FOR MALES), SO
FEMALES BECOME MORE VALUABLE
AND CHOOSY
-WITH LOW QUALITY FOOD, MALES
BECOME CHOOSY
IX. Modes of Sexual Selection
A. Intrasexual Competition
MEAN NO. OF
CALLING ♂
%
INTERACTION
S WITH ♀-♀
COMPETITION
CONTROL 1
0.4
1.4
15
CONTROL 2
0.7
1.2
22
CONTROL 3
0.1
1.4
27
CONTROL 4
0.3
1.3
30
EXTRA FOOD
1
8.1
0.6
0
EXTRA FOOD
2
4.7
0.7
0
EXTRA FOOD
3
5.7
0.8
0
EXTRA FOOD
4
7.9
0.6
0
IX. Modes of Sexual Selection
B. Intersexual Choice
MEAN NO. OF
MATINGS PER
♀
A. Intrasexual Competition:
Elephant Seal work by T. S. McCann
(also B. LeBoeuf)
- Differential Mating Success Among Individuals
•Size dimorphic: Males 3x > Females
•Females gather at beaches for 3 months – breed
•Males fight to dominate these “harems”
IX. Modes of Sexual Selection
IX. Modes of Sexual Selection
B. Intersexual Choice:
A. Intrasexual Competition:
Elephant Seal work by T. S. McCann
(also B. LeBoeuf)
1. Combat:
* Largest and oldest males win
male-male combats
*Winner of combats are the
dominant males in a harem: 8
most dominant males
inseminated 348 females
1. Premating Female Choice
e.g. widowbird work by Andersson
-dimorphic, males with long tails and red
epaulet
- males defend territories for female nesting
-alter tail length
2. Endurance Rivalry
- Males stay on the beach for 90 days without
feeding = lose over 40% of body weight by end
IX. Modes of Sexual Selection
B. Intersexual Choice:
-longer tails = more females
-shorter tails = lost females
X. MALE MATE CHOICE – SEX ROLE REVERSAL
2. Postcopulatory Female Choice
e.g., fish family Syngnathidae – seahorses and
pipefish, where male “pregnancy” occurs
e.g. jungle fowl work by
Westneat
Rosenqvist’s work on broad-nosed pipefish
-male provide all of parental care
-dimorphic
-females prefer males with
redder comb
-females prefer dominant
males
-force copulations are
common
-female preferentially eject
sperm low ranking males
-males have brood pouches where females deposit
eggs, and male provide oxygen, nutrients, protection
until they hatch
-females can produce eggs much quicker than males
rearing eggs to hatchling, so PI greater in males
X. MALE MATE CHOICE – SEX ROLE
REVERSAL
Rosenqvist’s work on broad-nosed pipefish
X. MALE MATE CHOICE – SEX ROLE REVERSAL
Drosophila
a) Bateman’s Principle
-not energetically costly, but time is the key cost
-males more valuable, so females should compete over males, and males should be
choosy
pipefish test by Jones, Rosenqvist,
Berglund and Arnold 2000
-in barrels: 4 males and 4 females or 2
male and 6 females (results same, so
pooled)
open, solid line=male
filled, dashed line=female
X. MALE MATE CHOICE – SEX ROLE REVERSAL
e.g., pipefish by Rosenqvist and colleagues
two species: Syngnathus typhle and Nerophis ophidion
in both species, males choose
in Nerophis, use female
traits
in Syngnathus, use “parasite”
infestation
two species: Syngnathus typhle and Nerophis ophidion
-In both species, male provide all of parental care
comparing Bateman’s Drosophila work in
1948 with current work on pipefish
As predicted, female reproductive success
increases more steeply with more
mates than for males
e.g., pipefish by Rosenqvist and colleagues
N. ophidion: females are larger and
have dark blue stripes and skin
folds on their bellies
Pipefish
S. typhle: same size, but females
court (zigzag)