History of Evolutionary Thought

• Review of Biology, Term 3, Cycles 2, 3 and 4, Instagram: @kkcrstmo

History of Evolutionary Thought

• Aristotle believed species are unchanged.
• Hutton stated changes in nature is gradual and is considered uniformitarianism.
• Buffon stated species change as they spread from their original location.
• Lamarck believed new species come from existing species through environmental forces.
• Cuvier stated fossils represent extinctions and species reappear after catastrophes.
• Lyell stated all the changes in nature are gradual and also renewed uniformitarianism.
• Darwin & Wallace: Individuals in a population are different; species arise through natural selection.

Contributions of Past Scientists

Georges-Louis Leclerc

• French naturalist, worked on a 44-volume natural history series, describing plants and animals
• Provided evidence of evolution and proposed various causes.

Carolus Linnaeus

• Swedish botanist, developed the Binomial System of Nomenclature
• Developed a system of classification for living organisms.
• Believed in scala naturae and the fixity of species.

Erasmus Darwin

• British physician and naturalist
• Formulated one of the first formal theories on evolution in Zoonamia.
• Based conclusion on changes in animals during development, animal breeding by humans and the presence of vestigial structures.

George Cuvier

• A French zoologist who established the sciences of comparative anatomy and paleontology.
• Developed his theory of catastrophies, species are destroyed, and new species evolve after that.

James Hutton & Charles Lyell

• Developed the concept of uniformatism
• Believed Earth's landscapes formed over a long period through gradual processes.

Jean Baptiste Lamarck

• A French Biologist known for idea that acquired characteristics are inheritable.
• Proposed 2 principles, the law of use and disuse, and inheritance of acquired characteristics.

Thomas Malthus

• English economist who limited the size of human populations is limited by available resources.
• English naturalist, whose scientific theory of evolution by natural selection becoming the foundation of modern evolutionary studies.
• Charles Darwin used his principle to formulate his idea of natural selection.

Charles Darwin

• Voyage of the Beagle, Darwin observed life and geology throughout the world.
• Ideas about natural selection and evolution originated from the observations on the Galapagos Islands.
• Darwin observed massive geological changes, the Earth must be old.
• Collected fossil specimens differing from modern species (ex: Glyptodon)

Biogeographical Observations

• Animals on different continents differ, similar environments on each continent had similar-looking animals.
• Wondered whether each Galapagos Islands' type of tortoises were descended from a common ancestor.
• Darwin observed finches exhibited significant beak variation.

Publication of "On the Origin of Species"

• Darwin received a manuscript from British naturalist Alfred Russel Wallace.
• Wallace collected and identified thousands of species in the Malay Archipelago for 8 years.

Natural Selection and Adaptation

• Individuals differ, with heritable variation
• Every habitat has limited, essential resources
• Populations have overproduction, more born than can survive

The Modern Synthesis (New-Darwinian Theory)

• Modern evolutionary synthesis unifies DNA, mutations, inheritance, and natural selection
• Genes are responsible for hereditary characteristics.
• The population, not individuals, evolves due to natural selection and genetic drift.
• Speciation occurs due to small genetic changes.

Microevolution

• Evolution is change in frequency of a gene in a population.
• Microevolution is evolutionary change within a population, shifts in genes.

Causes of Microevolution

• Variation means a population differs from one another.
• Increased fitness means individuals are better adapted to their environment and are likely to reproduce.

Natural Selection

• It is the ability to adapt to the environment and the chance of survival.

Types of Selections

• Directional selection means one phenotype is favored.
• Disruptive selection means two phenotypes are favored.
• Stabilizing selection means intermediate phenotype is favored.
• Disruptive Selection involves small or large, rather than medium selection.
• Adaptive changes increases the chances of finding a mate by sexual selection

Mutation

• A random change in the genetic sequence of a living thing's DNA.
• Change on base, ends with an entirely different amino acid.

Gene Flow (Migration)

• Movement of alleles between populations (migration)
• New allele frequency in the text generation changes.

Genetic Drift (By Chance)

• Chance Effects happens in a gene pool.
• Loss of individuals and their genes

Types of Genetic Drift

• Genetic diversity loss, natural disasters, disease, or habitat loss due to bottleneck effect.
• Few individuals break away from a larger population causes founder effect.

Non Random Mating

• Preferences affect how alleles in the gene pool assort in genotypes.
• Assortative mating occurs when similar types of individuals mate more frequently
• Dissortative mating occurs when dissimilar types of individuals mate more frequently.

The Hardy-weinberg Principle

• Allele frequencies do not change overtime.
• Genetic equilibrium is stable
• No natural selection
• No mutation
• No migration
• No large population
• No random mating!

Terminologies

• Gene pool is a combination of all the genes present in an reproducing population
• Extensive genomic diversity to withstand environmental challenges.
• Relative frequency of an allele, at a particular focus is the gene.

Gene or Allele Frequency

• Allele can be found in a population. For instance, in pea plants purple (W) and white (w) alleles
• Fraction of individuals with a given genotype is Genotype frequency
• Fraction of individuals with a Phenotype. Phenotype Frequency
• Equation for alleles P + Q = 1 (must always equal to 1)
• Equation is Genotypes P=2 + 2PQ + Q=2 = 1 (must always equal to 1) Heterozygous dominant

Macroevolution

• Darwin's finches, observing finches.

Macroevolution

• Patterns and processes,evolutionary change above the species level.
• Results in speciation, formation of new species.
• Speciation, formation of new species.

Patterns of Macroevolution

• Interbreeding species diverged into two evolutionary groups means divergent evolution.
• Caused by changes in environment or migration
• Distinct different species becomes similar in structure and function is convergent Evolution
• Parallel evolution is two species that develop from a common ancestor.
• Co evolution occurs when one species changes, the other will change.
• Can continue in a relationship

Reproductive Isolating Mechanisms

• Pre zygotic Isolation means before forming a zygote
• Reproductive attempts are prevented

Pre-Zygotic isolation

• Habitat isolation involves space and no mating
• When two species occupy different habitats
• They are less likely to meet and attempt to reproduce.
• Example genus species and the genus Rhagoletis

Temporal Isolation

• No Mating and Time
• It can live in the local but if they reproduced at the different times of the year they don't attempt to mate.
• For Example skunk in the species Spilogale
• Courtship patterns attract mates and behaviours are unique and effective reproductive barriers.

Mechanical Isolation

• No mating and sperm and reproductive organs
• Animal genitalia means can’t occur reproduction
• Two species of snails in bradbaenia, spiral in different directions
• Even it there's gametes two species, they fuse to become a zygote
• Post-Zygotic isolations occurs after zygote formation,

Hyper Inviability

• May interact in ways that effective way the hybrid impact the hybrid. Ex, some Salamander's habitat.

Hybrid Fertility

• Hi Zygote may develop into a Serol adult. Differ in number to produce Gamates.

Hybrid Breakdown

• Generational hybrid Are viral fertile, but is feeble. Stringes are recessive

Modes of Speciation

• Allopatric Speciation creates physical barrier, a new species that cannot interbreed
• It occurs when two populations live in neighbouring areas, BUT SHARE A BORDEZONE
• Sympatric speciation develops reproducitely isolate

Evidence of Evolution

• Fossils are remains of traces of organism in sediment rocks

Fossil Formation

• Compression is fossils in leaves.

Petrification

• Usually fossilized of bones and teeth, and ancestors will found
• A fossi that reveals
• The horizonal is a caral, living material that dissolves
• Fossils can be prescribed

Transitional Fossils

• It bares resemblance to two group the classified. The fastille record are, because there are no plates are

Biogeographical Evidence

• Disprobrion for fossil and livings is
• Distinct pattern of animals if an imaginar

Anatomical Evidence

• Structures with same set of Bones evolved
• Performing same function development

Analogous Structures

• Vestigial structure, anatomical a group.
• Structure, tailbone, muscle, nipples appen

Molecular Biology

• Have similar from a comment

Taxonomic Levels

• Arrange to organized life
• Scheme is classified
• Linnaeus includes, Domain, kingdom, genius family
• Bacteria, Eukarya and the, and include
• Plural texa is ranked

Binomial Nomenclature

• The name scientific, institute l