Bio 40s evolution
-
Upload
george-pearce -
Category
Technology
-
view
724 -
download
1
Transcript of Bio 40s evolution
The Origin of Life
Stage 1: Abiotic Synthesis of Organic Monomers Amino Acids
Chains of nucleotides Chains of DNA bases Chains of RNA bases
Building blocks of protein Sugars Lipids ATP
The Origin of Life
Stage 2: Abiotic Synthesis of Polymers Monomers, such as amino acids,
spontaneously fused together to form proteins.
The Origin of Life
Stage 3: Origin of Self-Replicating Molecules
inheritance
Ribozyme: catalytic RNA used to fuel RNA replication
The Origin of Life
Stage 4: Formation of Pre-cells Molecular packages
with some properties of life.
The gap between pre-cells and true cells is enormous! Natural Selection
The origin of eukaryotic cells
Endosymbiotic Theory
Membrane bound nuclear material
Organelles More complex than
prokaryotic cells Ancestors to fungi, plants
and animals
Concept Map
Evolution of LifeSection 17-2
Early Earth was hot; atmosphere contained poisonous gases.
Earth cooled and oceans condensed.
Simple organic molecules may have formed in the oceans..
Small sequences of RNA may have formed and replicated.
First prokaryotes may have formed when RNA or DNA was enclosed in microspheres.
Later prokaryotes were photosynthetic and produced oxygen.
An oxygenated atmosphere capped by the ozone layer protected Earth.
First eukaryotes may have been communities of prokaryotes.
Multicellular eukaryotes evolved.
Sexual reproduction increased genetic variability, hastening evolution.
HISTORY OF EVOLUTIONARY
THEORY
Evolution = “Descent with Modification”
1. ------------due to being spread over different habitats and therefore adapting and modifying themselves to fit the habitat.
2. Natural Selection
• A population of organisms can change over generations if certain inheritable traits leave more offspring than others and those others get the chance to reproduce and continue the lineage.
• Evolutionary Adaptation
THE ROAD TO EVOLUTIONARY THEORYEvolution Before Darwin
Greek Philosophers
• Plato’s Idealism
• Aristotle’s scala naturae (scale of nature)
special creation of each species organisms were created in their
current form the earth was only a few thousand
years old
THE ROAD TO EVOLUTIONARY THEORY
Evolution Before DarwinTHOMAS MALTHUS
economist & clergyman
published An Essay on the
Principle of Population
Populations had an inherent tendency to increase geometrically, while the resources needed to support this growth increase slowly or not at all.
Because of the continued growth of a species would outstrip needed resources, growth would be limited.
THE ROAD TO EVOLUTIONARY THEORY
Evolution Before DarwinJEAN-BAPTISTE de LAMARCK
French biologist
proposed that modern species descended from other species
Lamarckism based on two theories:
1. Inheritance of Acquired Characteristics- traits acquired by an individual during its life are passed to its offspring
2. Use and Disuse- organs of the body that were used extensively to cope with the environment became larger and stronger, while organs that were not used deteriorated
Example:
The Evolution of the Giraffe
Giraffes obtained their long necks from previous giraffes who stretched to eat the leaves of high tree branches.
Stretching increased the length of their necks, and this acquired characteristic was passed to the next generation.
THE ROAD TO EVOLUTIONARY THEORYEvolution Before Darwin
THE ROAD TO EVOLUTIONARY THEORYEvolution Before Darwin
Lamarckism
first to present a unified theory that attempted to explain the changes in organisms from one generation to the next
Although, mechanisms proposed for change was wrong, since acquired characteristics are not heritable!!!
origin of species from preexisting species ability of organisms to adapt
THE ROAD TO EVOLUTIONARY THEORY
Darwin’s Time (1800s)GEORGES CUVIER
French anatomist and naturalist and writer
palaeontologist
strongly opposed the concept of evolution
history of living organisms recorded in layers of rock containing a succession of fossil species in chronological order
fossils were organisms that had died in a series of catastrophes, after which extinct plants and animals were replaced by the immigration of distant species to the devastated region Catastrophism
THE ROAD TO EVOLUTIONARY THEORY
Darwin’s Time (1800s)
CHARLES DARWIN
voyage on the H.M.S. Beagle (1836)
published (1859)The Origin of Species
first person who proposed a mechanistic approach to evolutionary thought
the father of synthetic evolution
The Voyage of the Beagle
On the Galapagos Islands...
Galapagos tortoise
Darwin’s finches
Most organisms on the islands were endemic.
His Conclusions:
The birds were very similar (common ancestry).
They all adapted to different Niches. Niche = Your job in nature.
What you eat Where you live (on ground, in a tree)
Reproductive Isolation resulted in speciation.
Evolutionary Adaptation
Evidence of Evolution:Fossil Record
Fossils chronologically ordered in rock layers
Evidence of Evolution:Biogeography
Geographic distribution of species: Australian marsupials
Evidence of Evolution:Comparative Anatomy and Embryology
HOMOLOGY
Evidence of Evolution:Molecular Biology
Notice that a Chimp is more genetically related to a human than to an Old World Monkey!
species not specially created in their present forms, but had evolved from ancestral species
proposed a mechanism for evolution:
Natural Selection
A population of organisms can change over time as a result of individuals with certain heritable characteristics leaving more offspring than other individuals.
Radioactive Dating
Darwinism in Historical Context
THE ROAD TO EVOLUTIONARY THEORY
Darwin’s Time (1800s)GREGOR MENDEL
Austrian biologist
discovered the basic principles of heredity
father of Classical Genetics
Individual characteristics determined by inherited factors transmitted from parent to offspring.
THE ROAD TO EVOLUTIONARY THEORY Neo-Darwinian/Contemporary Times
rediscovered Mendel’s laws of heredity
the start of rediscovering evolution in terms of Mendel’s ideas
HUGO DE VRIES
CARL CORRENS
ERICH VON TSCHERMAK
THE ROAD TO EVOLUTIONARY THEORY
Neo-Darwinian/Contemporary Times
JAMES WATSONFRANCIS CRICK
elucidated the structure of DNA (genetic material)
DNA contains coded information which acts as a blueprint for the transfer of hereditary information from generation to generation
mutation as the raw material for evolution
Darwinism Meets Genetics A population is the smallest unit of evolution.
Natural selection acts on individuals. However the evolutionary impact of natural selection is
only apparent in tracking how a population changes over time.
Population Genetics emphasizes the extensive genetic variation within populations and tracks the genetic make-up of populations over time. Not all variation in a population is inheritable. Only the genetic component of variation is relevant to natural
selection. Many variable traits in a population result from the combined
effect of several genes.
Hardy-Weinberg Principle
Genetic equilibrium- allele frequenciesremain constant. Populations should be in a state of
equilibrium assuming: 1. Large Population 2. Random Mating 3. No Migration 4. No Mutation 5. No natural selection occurs.
Variables Needed to maintain Equilibrium:
Perfectly adapted organsim. Sharks Alligator Horseshoe Crab
Stable envrionment. Water (Oceans)
Punctuated Equilibrium
Speciation occurs relatively quickly with long periods of equilibrium in between. Speciation = The formation of a new species
due to evolution.
Genetic Drift
Evolution can occur without natural selection.
Genetic Drift is a change in the gene pool due to a random event. Example- Mount Saint Helens Eruption.
If the event is catastrophic and all the organisms are killed off = Mass extinction.
Speciation
= The formation of a new species due to evolution.
Reproductive Isolation- Can result in speciation. It is the separation of members of a species due to some barrier. Islands Mountains Roads Oil Pipes
• Speciation occurs only with the evolution of reproductive barriers between the isolated population and its parent population.
• If speciation occurs during geographic separation, the new species will not breed with its ancestral population, even if the two populations should come back into contact.
Mechanisms of Speciation
Allopatric Speciation A population forms a
new species while geographically isolated from its parent population.
Sympatric Speciation A small population
becomes a new species in the midst of a parent population
Sympatric Speciation
Does not widely occur among animals but may account for over 25% of all plant species.
Notice how the hybrid bread wheat has a set of chromosomes from each of its ancestors: T. monococcum (AA), Triticum (BB), T. turgidum (AA BB), T. tauschii (DD)
What can you notice about T. aestivum that might make it a good hybrid and the most important wheat species today?
Evolutionary Patterns
Convergent Evolution- Organisms of different ancestry adapting to a similar environment. Produces homologous Structures. Example: bats and Butterflies wings.
Dolphin Penguin Shark
Divergent Evolution- Organisms of common ancestry adapting to diverse environments. Produces analogous Structures. Example: Human Arm and Bird wing.
Microevolution1. Genetic Drift Def: A change in the gene pool of a small population due
to chance.
The best measure of Darwinian fitness is the number of fertile
offspring an individual leaves.
Microevolution Cont.2. Gene Flow
Def: The genetic exchange with another population.
3. Mutations A change in an organism’s DNA sequence. Ultimate source of genetic variability.
4. Natural Selection Directional Selection (selecting in favor of an extreme
phenotype) Disruptive (Diversifying) Selection (leads to a balance between
two or more contrasting phenotypic forms) Stabilizing Selection (maintains variation in a narrow range)
• Resistant Genes
• Immediate Benefits
• Long term Disaster
• Evolution direct connection to daily lives
Macroevolution
Def: Major biological changes evident in fossil record.
CONTRAST: MICROEVOLUTION
Speciation Nonbranching evolution
(transform a population enough for it to be designated a new species.)
Branching evolution (splits a lineage into two or more species)
The Origins of Species Ernst Mayr
Studied the diversity of birds in New Guinea (1927) Biological species concept
Species = “groups of interbreeding natural populations that are reproductively isolated from other such groups.”
Reproductive isolation blocks exchange of genes between species and keeps their gene pools separate.
• Reproductive barriers between species• Zygote: fertilized egg• Pre-zygotic (factors that impede
mating between species or hinder fertilization of eggs if mating is attempted)
• Post-zygotic (mechanisms that operate should interspecies mating actually occur and form hybrid zygotes)
Courtship
Sterile
Isolating Mechanisms
Tempo of Evolution
Slow adaptations
Spurts of relatively rapid change
Section 17-4
Flowchart
that are
can undergo can undergo can undergo can undergo can undergo
in underunderform inin
Species
Unrelated Related
Inter-relationshiops Similar environments
Intense environmental
pressure
Small populations
Different environments
Coevolution Convergent evolution
ExtinctionPunctuated equilibrium
Adaptive radiation
Classifying the Diversity of Life
Systematics Reconstructing evolutionary history Radioactive dating = tool The study of biological diversity: past and
present Taxonomy
Identification, naming and classification of species
Pioneer: Carolus Linnaeus (1707-1778) Binomial Nomenclature Homo sapien
Hierarchical Classification
Which step is more specific?
Class or Genus?
How is Domain Eukarya different from Bacteria and Archaea?
Phylogeny• Evolutionary
history of a species.
• Tree is based on homologous structures, NOT analogous.
• Two species will have more common nucleotide sequences based on how recently they branched from their common ancestor.
The Cladistic Revolution
The Computer Age
6 Kingdoms vs. 3 Domains
?Eubacteria
Archaea-bacteria