Transcript Ch. 14 Evolutionary Theory

History of ideas
Where did all the
species come from?
• Special creation of species –
each was individually created
• Transmutation of species – each
species can change over time to
produce new species
• Evolution – species can change
and give rise to new forms –
descent with modification
Biodiversity = total variety of living things
on Earth
Explaining biodiversity
• De Maillet - species could originate
instantaneously
• Erasmus Darwin – recognised that all
warm-blooded animals originated
from one living organism and had the
ability to change and improve over
time
• Jean Baptise Lamarck – individual
organisms could respond to changes
in their lifetime and pass these
adaptations on to next generation
Charles Darwin – Alfred
Russel Wallace
• Theory of evolution by natural
selection
• Presented 1858 & published 185961
• Based on observations made on
voyages to remote islands
• Noted very different species in
Southern Hemisphere compared
to Northern, even in similar
Evidence of Evolution
Fossilisation = preservation of the remains of an organism long
after death
• Fossil Record – bones, teeth, shells,
leaves, footprints, casts, pollen grains
• Transitional fossils – demonstrate the
transition from one species to another
• Comparative biochemistry – comparing
genes and proteins
• Comparative anatomy – comparing
structures, organs and embryos
• Bio-geographic distribution – examining
diversity of species in different
geographical areas
Fossil Formation
• When organisms die, their
remains may be compressed
under layers of sediment
• With pressure, this sediment
forms rock, trapping the
remains and preserving them
for long periods of time
Fossil
Record
Fossils are dated based
on the type of rock that
they are found in
A record of fossils found
is kept and aligned with
the geological timescale that related to the
age of the Earth
Geological time-scale
• Estimated age of Earth 4500
million years ago (Mya, Ma, Myr)
• Based on studies of rock of relative
ages
• Developed in 18th and 19th
centuries
• Divided into intervals of time –
eons, era, period, epoch
Ma = million
years ago
Estimating Relative
Rock Ages
• Principle of superposition –
deepest rock is oldest
• Principle of correlation – based
on identifying key fossils within
the rock type that correlate to a
particular period of time
Rock Layers
Problems with
estimating relative age
Calculating Absolute
Rock Ages
• Radiometric dating – with radioactive
isotopes
• These are able to decompose by losing
protons and neutrons to form a new
element
• They have known a half-life
• Electron Spin Resonance – measures
amount on energy in electrons of
substance
• For substances 50,000-500,000 years old
Radioactive half-life
Half life
Examples of
Radioactive isotopes
Radioactive
Parent
Isotope
Stable
Daughter
Isotope
Half-life
Useful for
Potassium
-40
Argon-40
1,300,000,000
Dating igneous rock
500,000 years or older
Rubidium87
Strontium87
47,000,000,000
The most ancient
igneous rocks
Uranium235
Lead-207
710,000,000
Dating igneous rock
1000-1,000,000,000
years old
Carbon-14
Nitrogen-14
5,730
Dating organic matter up
to 60,000 years old
Fossil
Record
This shows
evolution of horses
through natural
selection
- Hooves better
suited to grass
plains
- Teeth better suited
to eating grass
Transitional
Fossils
Land
mammal
ancestor
to modern
whale
Transitional
Modern whale
Comparative Anatomy
• Homologous features – similar
structure evolved from common
ancestor – may have different functions
(eg pentadactyl limb)
• Analogous features – structures with
similar functions but different
evolutionary origins (eg. Wings)
• Vestigial organs – structure evolved
from common ancestor but
functionless (eg. Appendix in humans)
Homologous –
pentadactyl
limb
Pentadactyl = five fingers
All have same evolutionary
origins but may have different
functions
Analogous – the wing
Moth
wing
Bird
wing
Bat wing
Comparative
Embryology
The very
beginnings of
embryology show
many similarities
The embryos
diversify over the
period of
gestation
Mammal embryos
display gill slits
during
development – due
to common
ancestor?
Comparative
biochemistry
• Proteins – amino acid sequence
• DNA hybridisation – mixing single strand
of DNA from one species with single
strand of another
• High or low complementarity determined by
melting temp of hybrids
• Estimates ‘genetic distance’
• Observe Chromosome banding patterns
and chromosome ‘paint’ using karyotype
techniques
Hybridisation
Comparing
DNA
Comparing bands in
chromosomes
Chromosome Paint