Title: Biological Evolution
1Biological Evolution
2Evolutionary Bush -- thousands of earlier and
later branches.
3At any given moment (e.g. the present), all we
see is current diversityall extinct forms are
gone (99.9)
Time ?
4Four Causes of Evolution
- Mutation fundamental origin of all genetic (DNA)
change.
5Four Causes of Evolution
- Mutation fundamental origin of all genetic (DNA)
change.
Point mutation
some at base-pair level
6Four Causes of Evolution
- Mutation fundamental origin of all genetic (DNA)
change.
Crossing-over
others at grosser chromosome level
7Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolated populations accumulate
different mutations over time.
In a continuous population, genetic novelty can
spread locally.
8Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolated populations accumulate
different mutations over time.
Local spreading of alleles
9Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolated populations accumulate
different mutations over time.
Local spreading of alleles
10Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolated populations accumulate
different mutations over time.
Spreading process known as gene flow.
11Four Causes of Evolution
But in discontinuous populations, gene flow is
blocked.
12Four Causes of Evolution
Variations accumulate without inter-demic exchange
13Four Causes of Evolution
Of course, this works at many loci
simultaneously
14Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolation ? accumulate mutations
- Founder Effect sampling bias during
immigration. When a new population is formed,
its genetic composition depends largely on the
gene frequencies within the group of first
settlers.
15Founder Effect.--
Human example your tribe had to live near the
Bering land bridge
16Founder Effect.--
to invade settle the New World!
17Galapagos Finches
Audeskirk Audeskirk, 1993
18Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolation ? accumulation of
mutations - Founder Effect immigrant sampling bias.
- Natural Selection differential reproduction of
individuals in the same population based on
genetic differences among them.
19Four Causes of Evolution
- Mutation fundamental genetic shifts.
- Genetic Drift isolation ? accumulation of
mutations - Founder Effect immigrant sampling bias.
- Natural Selection reproductive race
- These 4 interact synergistically
20Evidence of Evolution
21Evidence of Evolution
- Biogeography
- Geographical distribution of species
22Evidence of Evolution
- 2. Fossil Record
- Fossils and the order in which they appear in
layers of sedimentary rock (strongest evidence)
23Fossils
- Oldest fossils are the approximately 3.465
billion-year-old microfossils from the Apex
Chert, Australia - colonies of cyanobacteria (formerly called
blue-green algae) which - built real reefs
24Fossils
- 1600's - Danish scientist Nicholas Steno studied
the relative positions of sedimentary rocks - Layering is the most obvious feature of
sedimentary rocks - formed particle by particle and bed by bed, and
the layers are piled one on top of the other - any sequence of layered rocks, a given bed must
be older than any bed on top of it - Law of Superposition is fundamental to the
interpretation of Earth history, because at any
one location it indicates the relative ages of
rock layers and the fossils in them.
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26Relative and Absolute Dating
- Relative Dating
- Can determine the age of fossil with respect to
another rock or fossil. - You compare the depth of a fossils position,
layers. - Some drawbacks include limitations on accuracy.
- Absolute Dating
- Can determine the age of a fossil IN YEARS.
- You determine the age by finding the amount of
radioactive and nonradioactive isoptope in a
specimen. - Some drawbacks are that it is difficult to
perform in a lab.
27Types of Radioactive Isotopes
- Carbon 14
- Use for more recent fossils (60,000 yrs old)
- Can be used with high accuracy
- Half life of 5,730 years
- Decays into Nitrogen
- Potassium 40
- Used for older fossils
- Half life of 1.3 billion years
- Decays into Calcium
- Less common element
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29Half-life for a given radioisotope is the time
for half the radioactive nuclei in any sample to
undergo radioactive decay
30Half-life for a given radioisotope is the time
for half the radioactive nuclei in any sample to
undergo radioactive decay
31Evidence of Evolution
3. Taxonomy Classification of life forms.
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33Evidence of Evolution
- Homologous
- structures
- Structures that are similar because of common
ancestry (comparative anatomy)
Turtle
Alligator
Bird
Mammals
Typical primitive fish
34Evidence of Evolution
- Comparative
- Embryology
- Study of structures that appear during embryonic
development
35Evidence of Evolution
- 6. Molecular biology
- DNA and proteins (amino acids)
36History of Theories of Evolution
37Old Theories of Evolution
- Jean Baptiste Lamarck (early 1800s) proposed
- The inheritance of acquired characteristics
- He proposed that by using or not using its
body parts, an individual tends to develop
certain characteristics, which it passes on to
its offspring.
38The Inheritance of Acquired Characteristics
- Example
- A giraffe acquired its long neck because its
ancestor stretched higher and higher into the
trees to reach leaves, and that the animals
increasingly lengthened neck was passed on to its
offspring.
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40Charles Darwin
- Darwin set sail on the H.M.S. Beagle (1831-1836)
to survey the south seas (mainly South America
and the Galapagos Islands) to collect plants and
animals. - On the Galapagos Islands, Darwin observed species
that lived no where else in the world. - These observations led Darwin to write a book
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42Giant Tortoises of the Galápagos Islands
Pinta
Tower
Marchena
Pinta IslandIntermediate shell
James
Fernandina
Santa Cruz
Isabela
Santa Fe
Hood Island Saddle-backed shell
Hood
Floreana
Isabela Island Dome-shaped shell
43http//www.galapagosislands.com
44Charles Darwin
- Wrote in 1859
- On the Origin of Species by Means of Natural
Selection - Two main conclusions
- Species were not created in their present form,
but evolved from ancestral species. - Proposed a mechanism for evolution NATURAL
SELECTION
45Darwins Observations
- Most species produce more offspring than can be
supported by the environment - Environmental resources are limited
- Most populations are stable in size
- Individuals vary greatly in their
characteristics (phenotypes) - Variations that survive are inherited. (genotypes)
46Natural Selection
- Individuals with favorable traits are more likely
to leave more offspring better suited for their
environment - Also known as Differential Reproduction
- Example
- English peppered
- moth (Biston betularia)
47Modes of Action
- Natural selection has three modes of action
- 1. Stabilizing selection
- 2. Directional selection
- 3. Diversifying selection
481. Stabilizing Selection
- Acts upon extremes and favors the intermediate.
492. Directional Selection
- Favors variants of one extreme.
503. Disruptive Selection
- Favors variants of opposite extremes.
51Evidence for Natural Selection
52Artificial Selection
- The selective breeding of domesticated plants and
animals by man. - Question Whats the ancestor of the domesticated
dog?
53Biodiversity
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55Biodiversity
- Biodiversity
- increases with speciation
- decreases with extinction
- Give-and-take between speciation and extinction ?
changes in biodiversity - Extinction creates evolutionary opportunities for
adaptive radiation of surviving species
56Interpretations of Speciation
- Two theories
- 1. Gradualist Model (Neo-Darwinian)
- Slow changes in species overtime
- 2. Punctuated Equilibrium
- Evolution occurs in spurts of relatively rapid
change
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58Adaptive Radiation
- Emergence of numerous species from a common
ancestor introduced to new and diverse
environments. - Example
- Hawaiian Honeycreepers
59Convergent Evolution
- Species from different evolutionary branches may
come to resemble one another if they live in very
similar environments. - Example
- 1. Ostrich (Africa) and Emu (Australia).
- 2. Sidewinder (Mojave Desert) and
- Horned Viper (Middle East Desert)
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61Coevolution
- Evolutionary change, in which one species act as
a selective force on a second species, inducing
adaptations that in turn act as selective force
on the first species. - Example
- 1. Acacia ants and Acacia trees
- Yucca Plants and Yucca moths
- Lichen
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63Extinction
- Extinction of a species occurs when it ceases to
exist may follow environmental change - if the
species does not evolve - Evolution and extinction are affected by
- large scale movements of continents
- gradual climate changes due to continental drift
or orbit changes - rapid climate changes due to catastrophic events
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65Extinction
- Background extinction - species disappear at a
low rate as local conditions change - Mass extinction - catastrophic, wide-spread
events --gt abrupt increase in extinction rate - Five mass extinctions in past 500 million years
- Adaptive radiation - new species evolve during
recovery period following mass extinction
66Mass Extinctions
http//www.geog.ouc.bc.ca/physgeog/contents/9h.htm
l
Date of the Extinction Event Percent Species Lost Species Affected
65 mya (million years ago) 85 Dinosaurs, plants (except ferns and seed bearing plants), marine vertebrates and invertebrates. Most mammals, birds, turtles, crocodiles, lizards, snakes, and amphibians were unaffected.
213 mya 44 Marine vertebrates and invertebrates
248 mya 75-95 Marine vertebrates and invertebrates
380 mya 70 Marine invertebrates
450 mya 50 Marine invertebrates
67Community Relationships
68Niche
- a species functional role in its ecosystem
includes anything affecting species survival and
reproduction - Range of tolerance for various physical and
chemical conditions - Types of resources used
- Interactions with living and nonliving components
of ecosystems - Role played in flow of energy and matter cycling
69- Niche is
- the species occupation and its
- Habitat
- location of species
- (its address)
70Niche
- Fundamental niche set of conditions under which
a species might exist in the absence of
interactions with other species
Realized niche more restricted set of conditions
under which the species actually exists due to
interactions with other species
71Species Interaction
72Competition
- any interaction between two or more species for a
resource that causes a decrease in the population
growth or distribution of one of the species - Resource competition
- Preemptive competition
- Exploitation competition
- Interference competition
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74Competition
75Competition
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88Predation prey adaptations
- Avoid detection
- camouflage, mimics,
- diurnal/nocturnal
- Avoid capture
- flee
- resist
- escape
- Disrupt handling (prevent being eaten)
- struggle?
- protection, toxins
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100Rewards of Mutualism
- Food energy and nutrients
- Protection
- from other species (competition, predation)
- from the physical environment (shelter)
- Gamete or zygote dispersal (the most common of
all) - Pollination and fruit dispersal (between plants
and animals).
101Pollination (hummingbird/bee and flowering plants)
- animals visit flowers to collect nectar and
incidentally carry pollen from one flower to
another - animals get food and the plant get a pollination
service
102Yucca moth and yucca
- Yuccas only pollinator is the yucca moth. Hence
entirely dependent on it for dispersal. - Yucca moth caterpillars only food is yucca
seeds. - Yucca moth lives in yucca and receives shelter
from plant.
103Lichen (Fungi-algae)
- Symbiotic relationship of algae and
fungaeresults in very different growth formas
with and without symbiont. - What are the benefits to the fungus?
104Seed Disperser
- Many birds and mammals consume fruits and
incidentally disperse the seeds contained in
those fruits - Animals get food and the plant gets seed
dispersal (often with fertilizer)
105Ant-tended plants
- Ants live inside swollen Acacia thorns or hollow
stems, e.g. Cecropia trees. - Patrol for caterpillars or leaf predators and
storm out to repel intrudersincluding you!
106Commensalists
- Benefit from the host at almost no cost to the
host - Eyelash mite and humans
- Us and starlings or house sparrows
- Sharks and remora
107Parasites
- Parasites draw resources from host without
killing the host (at least in the short term).
108Bibliography
- Miller 11th Edition
- http//abandoncorporel.ca/medias/evolution.jpg
- http//www.ne.jp/asahi/clinic/yfc/fetus.html
- rob.ossifrage.net/images/
- http//www.mun.ca/biology/scarr/Five_Kingdoms_Thre
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llerlec5.PPT - http//www.dnr.state.md.us/education/horseshoecrab
/lifecycle.html - http//www.falcons.co.uk/mefrg/Falco/13/Species.ht
m - http//www.sms.si.edu/irlspec/NamSpecies.htm
- http//www.falcons.co.uk/mefrg/Falco/13/Species.ht
m - http//www.globalchange.umich.edu/globalchange1/cu
rrent/lectures/complex_life/complex_life.html - http//nsm1.nsm.iup.edu/rwinstea/oparin.shtm
- http//www.angelfire.com/on2/daviddarling/MillerUr
eyexp.htm - http//exobiology.nasa.gov/ssx/biomod/origin_of_li
fe_slideshow/origin_of_life_slideshow.html - http//www.geo.cornell.edu/geology/classes/Geo104/
HistoryofEarth.html - http//astrobiology.arc.nasa.gov/roadmap/objective
s/o2_cellular_components.html - http//pubs.usgs.gov/gip/fossils/
- http//hyperphysics.phy-astr.gsu.edu/hbase/nuclear
/halfli.html - http//www.accessexcellence.org/AE/AEPC/WWC/1995/t
each_rad.html