Variation among organisms, this variation is inherited

Overproduction of offspring that leads to a struggle for survival - competition

Some organisms are better equipped than others - to survive a particular environment

Traits that allow them to fit into that environment

Earth is relatively young (thousands of years)

Each species is created in a seperate act of creation, they don't change, numbers remains the same

Adaptation to environment (if exists) is the work of a creator

The Creator decided structure and function of each separately

Observations are used to substantiate the prevailing worldviews (what you already think)

Earth is old (billions of years)

For variation to occur, long amounts of time is needed

Related to Lyell and Hutton: geologists that suggested gradualism: process in earth occur gradually and are taking place over many generations

Species are related by descent (they arise from other species and science can piece together a history of life from these relationships)

Adaptation to the environment is the interplay of random variation and environmental conditions

Observations and experimentation are used to test hypotheses

Observations of living organisms

Extensive taxonomic studies of more than 500 animal species, dissection many of them

Great variation

Differences in complexity of life forms

Fixity of species

Agreed with Old Testament that everything was created perfectly

Arranged all life form into Scala Naturae (increasing complexity)

Taxonomist that developed a system of binomial nomenclature

Fixity of species (each organism has an ideal structure and function and are created that way and do not change)

Believed in fixity of species

Paleontology

Observed different fossils in various layers of sediment

Writings suggested common descent, based on artificial selection, vestigial organs, etc.

Developed theory of catastrophism - global catastrophies

Found differences in fossil layers

All caused by God

No new species

Noticed correlation between organism and environment

Theory of use and disuse: structures that organisms use will become more prominent

Simple to complex

Accepted principle of evolution

Inheritance of acquired traits

Driving force for change: perfection

Sociologist

Life is a struggle

Only the fittest survive

Competition to survive

Biogeography

Fossil record

Comparitive anatomy (comparative embryology)

Comparitive molecular biology

Study of geographic distribution of species

Assumption: that related forms initially evolved in one location and then diversified as they spread out into other areas

Darwin studied species on Africa that came from mainland and evoleved when on islands to adapt to the environment

Today the majority of animals found in Australia are endemic to Austrailia

Over 80% of the Australian mammals and reptiles, and over 90% of amphibians and fish - cannot be found elsewhere

Discovered by Donald Johanson and Tom Gray in 1974 at Hadaar in Thiopia

3.2 million years old

Was an adult female of about 25 years

About 40% of her skeleton was found, and her pelvis, femus and tibia show her to have been bipedal

Radioactive atoms break down (decay) into other material at a steady rate (isotopes - different forms of the same atom)

Carbon dating: half of an amount of carbon-14 decays into nitrogen 14 every 5600 years: this is the half - life

You compare the relative proportions of the materials (isotopes) of 14C and 14N to estimate the age of the rock

Similar structures in two or more species; inherited from common ancestor

May perform same or different functions

The limbs or humans, bats, and horses

Unrelated structures that serve same purpose

Do not share common ancestry

Wings of birds and insects evolve from unrelated structures, but have same function

Part of an organism that is fully developed in one group but has no apparent function in a similar group or an ancestral species

Python has leg bone and blue whale has pelvic bones, ostrich has feathers but does not fly

Developing organism frequently pass through stages (structures) that resemble the organism from which they evolved

Ex: tails develop into swimming structure in fish and is vestigial in humans

Compare organisms' genes and the products of those genes

Universal morphologic and biochemical features: cells, DNA, RNA, ribosomes, same process of protein synthesis, and same 20 amino acids, ATP

In general, the more closely related a species, the more similar the amino acids that make up their proteins

Populations maintain genetic equilibrium in the absence of outside influences

Both allele and genotype frequencies remain unchanged

Applies to population genetics of diploid species

p2 + 2pq + q2 = 1

p = dominant allele

q = recessive allele

p2 = homozygous dominant

q2 = homozygous recessive

pq = heterozygous

Mutations

Natural Selection

Migration

Genetic Drift

Non Random Mating

Variation among organisms (due to mutations)

Overproduction of offspring that leads to a struggle for survival (competition)

Some organisms are better equipped to survive than others (the environment)

Population: a selected group

Sample: group selected from a population for an experiment that adequately represents the sample from which it is drawn

Random sample: ignore any differences among members of a population when choosing, should represent the population

mean: average, median - range/2, mode

Standard deviation: estimate of the variation of data

Occurs when environment is changing

Extreme phenotypes are selected that can adapt to new environment

68% of population fall within +/- 1SD of the mean (5 - 9)

95% within +/-2 SD of the mean (3 - 11)

99.7% within +/- 3SD (2 -12)

Eliminates atypical phenotypes

Enhanced adaptation to current environment

Intermediate phenotypes are eliminated

Results is that same species may look dramatically different in different regions

Balancing Selection: process whereby rare recessive traits are maintained within a population

Diploidy recessive alleles are not selected against unless they are expressed in the homozygous state and are, therefore, maintained within the population

Advantage over homozygous and therefore greater success in reproduction

Sickle cell anemia

Advantage is that Ss has some resistance to malaria, SS, Ss, and ss are all maintained in the population

Recessive allele found in higher frequency in areas with malaria

Reproductive succes depends on the frequency of occurrence within the population (the fitness of a genotype varies with its frequency relative to that of other genotypes)

Right-mouthed and left-mouthed, scale eating Perissodus (small fish that lives in Lake Tanganyika -balanced polymorphism)

Random changes in genetic material

Only source of new genes in a population

Only those mutations in gametes are passed on to next generation - not those in somatic cells

May be letal, advantageous or neutral (many do not change the phenotype)

Water flea

Normally lives in water temperatures around 20 degrees

Mutation requires some to live at temperatures between 25 degrees and 30 degrees

The mutant could thrive better than the non-mutant

Typically there is one new mutation per 100.000 gene loci

Around 80, 000 genes per human zygote

Therefore, almost everyone is carrying at least one mutation

Estimated that 1/3 to 1/2 of all human zygotes spontaneously abort due to lethal mutations

Movement of individuals (alleles) from one population to another by the migration of breeding individuals

This contributes new genetic information to a population

May increase variation in a population due to new alleles

If continued, may decrease genetic diversity among population and the population become more similar

Change in gene pool (frequency of alleles) in a population that occurs by chance

Founder Effect

Bottleneck Effect

Few individuals establish a new, isolated population

Even rare alleles become significant

Amish in Pennsylvania

Rare allele for dwarfism linked with extra fingers, malformed wrists and arms

Allele frequency is much higher than normal population

Majority of phenotypes not involved in production of next generation

May be due to natural disaster or near extinction by some other factor (man)

Cheetahs suffer from infertility due to inbreeding that occurred after a bottleneck

Type of self-selection

Sexual selection (peacocks)

Females choose their mates by the size and shape of, and the number of eyespots on their tails

Assortative mating: when individuals tend to mate with those that have the same phenotype

Plant and animal breeders usually employ controlled positive assortative mating to increase the frequency of desirable traits and to reduce genetic variation in a population

This method has been used to develop purebred varieties of laboratory mice, dogs, horses, and farm animals

The amount of time it takes for this process can be much shorter than one might imagine

 If siblings mate every generation, it will only take 20 generations for all individuals in a family line to share 98%+ of the same alleles at the same loci

They will, essentially, be clones and breeding results will be close to those resulting from self-fertilization

The downside is an increase in homozygosity of harmful alleles if they are present in the gene pool

The high frequency of hip problems, epilepsy, and immune system malfunctions in some dog varieties are primarily a result of inbreeding

Group of interbreeding (actual or potentially) natural populations which are reproductively isolated from other groups

Major limitation: does not address asexually reproducing organisms

Two populations are geographically isolated

Genectic drift and adaptation to local conditions cause populations to evolve differently

Islands

Mountains

Variety (patchy) vegetation

Scattered lakes and ponds

The appearance of many new species with a wide variety of adaptations

Often occurs when a new habitat becomes available

classic example is Darwin's finches on the Galapagos Islands or the honeycreepers in Hawaii

Two populations share the same geographic area

Many varieties

Adapt to different factors found in the same area

Ecological isolation seen currently with fruit fly

Lay eggs in either hawthorne or apple trees; gene flow is diminished in nature, chromosomal aberrations include polyploidy: the instant acquistion, but a species, of multiple copies of each chromosome

Common in plants (can self fertilize)

Geographic Isolation (physical barriers)

Ecological Isolation (habitat barriers)

Temporal Isolation (different breeding seasons)

Behavioral Isolation (different courtship and mating habits)

Mechanical Isolation (reproductive structure incompatible)

5 species of the genus Rana, all found in the same geographic region

The mating periods are different and when there is an overlap they use different breeding sites

Gametic incompatibility (sperm cannot penetrate the egg: prezygotic)

Hybrid inviability (postzygotic)

Hybrid infertility (potzygotic)

Reproductive Isolation (no gene flow)

and/or

Distinct selective pressures

Small population size so that genetic drift can take place

Fish to Amphibians to Reptiles to Birds to Mammals

Feathers (bird) and wing claws

Clawed feet and teeth

Feather-covered bony tail

Darwin collected and studied numerous amounts of specimens

Read Lyell's Principles of Geology