1. GENE STUFF
1.1. GENE POOL the total set of gene in a population of species.
1.2. GENE FLOW is the movement of alleles from one population to another
1.3. GENETIC DRIFT is the changes of allele frequencies due to chance events and not necessarily representative of the original population. Decreases genetic diversity as the population becomes smaller and is vulnerable to extinction.
1.3.1. FOUNDER EFFECT
1.3.2. BOTTLE-NECK EFFECT
1.3.3. EFFECT OF GENETIC DRIFT
2. Sources of Genetic Variation
2.1. FRAMESHIFT is a shift in the reading frame of the mRNA affecting all the codon downstream of the mutation.
3. Human Evolution
3.1. MAMMALS (class) - milk-producing mammary glands - fur and/or hair - single jaw bone
3.2. PRIMATES (order) - Binocular 3D vision (spatial awareness, colour vision, forward-facing eye) - Prehensile hands and feet with 5 digits & flat nails - Opposable Thumb - Social animals (lived in groups)
3.3. HOMINID?HOMINOIDS (genus) {the group consisting of all modern and extinct Great Apes including modern humans, gorillas, orang-utans and chimpanzees). - Lack of tail - Longer arm length to leg length - Y5 shaped molar teeth - Broad rib cage and pelvis (sit upright) - Increased cranium size (larger brains compared to primates)
3.4. HOMININS (species) {the group consisting of all modern Humans and their bipedal ancestors, including Homo genera species, Australopithecus, Ardipithecus}.
3.4.1. Bipedalism is the ability to walk upright and many structural changes as well as an increase in cognitive capabilities. Bipedalism enabled efficient locomotion (energy efficient), thermoregulation and detect any predators (as they can see above grassy planes), increasing the chance of survival. It freed their arm allowing them to carry/make tools and weapons which helped them become better hunters, cook food, making food more nutritious and helped the development of the brain, enhancing cognitive abilities.
3.4.2. AUSTRALOPITHECUS TO HOMO SAPIENS - S-shaped spine: support weight vertically and aid upright mobility - Foramen Magnum: positioned at the base of the skull allowing the head to sit forward and rest on top of the spinal column - Parabolic jaw allowed for chin - Increased cranium capacity as the brain size increased as the cognitive abilities enhanced - Decrease in brow ridge angle - More bowl-shaped pelvis: provides support for upper body when standing and walking upright - Barrel-shaped Rib Cage: maintains upright posture for longer periods of time - Increase Femur Angle: allows greater stability for bipedalism and stablisies centre of gravity.
4. Master Genes
4.1. Master regulatory genes are regulatory genes that control the timing and the intensity/amount of protein production or the expression of genes downstream in early development.
4.2. MUTATIONS IN MASTER REGULATORY GENES affect the timing or the amount/intensity of expression of downstream genes, resulting in a significant phenotypic change in organisms which is more rapid and visible compared to mutations in the structural genes.
4.3. THE ROLE OF BMP4: BMP4 is master regulatory gene that codes for BMP4 protein that controls cell differentiation and cell growth (in vertebrate embryos).
4.3.1. MUTATION IN BMP4 EXPRESSION enables adaptive radiation (rapid divergent evolution), especially after mass extinction, to occur in Finches and cichlids. BMP4 is a master gene that, when mutated, affect the timing and the amount/intensity of the expression of downstream genes, resulting in a significant phenotypic change in organism which is more rapid and visible. Thus, fewer mutation required for speciation.
4.4. BMP4 in GALAPAGOS FINCHES: the timing and amount of the expression of the BMP4 proteins in finches embryos regulate the size and shape of the beak. Increased expression of BMP4 leads to a stronger, larger, wider and deeper beak
4.5. BMP4 in AFRICAN CICHLIDS: The timing and amount of the expression of BMP4 protein in cichlid embryos regulates size and shape of jaw. Increased expression of BMP4 proteins leads to a stronger and more muscular jaw.
5. Molecular Homology
5.1. Molecularly Homology is a technique used to determine the evolutionary relationship between different species by comparing molecules such as DNA sequences, amino acid sequences and chromosome banding.
5.2. Species that have more similarities in DNA sequences and amino acid sequences (chromosome banding) are more closely related and share a more recent common ancestor.
5.3. DNA HYBRIDISATION: 1. Heat DNA from two different species to separate strand. 2. The separated strands are cooled allowing the formation of Hybrid DNA. 3. Reheat hybrid strand and records melting temperature (temp. for 50% to separate). 4. The higher the temperature, the more complementary (similarities) between the strands, indicating that they are more closely related and share a more recent common ancestor.
5.4. PHYLOGENETIC TREES display evolutionary relationships of divergent evolution using evidence from molecular homology. Nodes - represent recent common ancestor
5.5. MOLECULAR CLOCK is a technique in which predictable mutation rates of DNA (mtDNA) is used to estimate the time for 2 species to evolve and diverge
5.5.1. Mitochondrial DNA acts as molecular clock as it has predictable mutation rate which is used to estimate the time for two species to evolve and diverge.
6. Natural Selection
6.1. NATURAL SELECTION is the natural process in which organisms that are best adapted to their environment tends to survive longer, reproduce and pass their gene to their offspring.
6.2. SELECTION PRESSURE is an external agent (biotic or abiotic) that affects an organism's ability to survive
6.3. There is variation present in the _____ population with regards to ______. The selection pressure __________ confers a selective advantage on the individual with __________ phenotype. Overtime, the individual with the selective advantage survive longer and produce more offspring, shifting the allele frequencies towards the ________ allele.
7. Evolution of Life
7.1. 1. Prokaryotes emerge 2. Eukaryotic single cellular organisms (endosymbiosis theory) 3. Rise of muliticellular eukaryotic organisms (900 million ya) 4. Marine Animals 5. Animals of Land (amphibians/reptiles) (530-400) 6. Land plants 7. Mammals (250) 8. Flowering plants (140 or 160)
8. Evidence of Evolution
8.1. FOSSILS are preserved remains or traces of an organism.
8.1.1. TRANSITION FOSSILS contains characteristics of two or more groups of classifications at a particular level like class or order. e.g. Archaeopteryx is considered a transition fossil as it includes characteristics of both reptile and bird.
8.1.2. STEPS TO FOSSILISATION The dead organism with hard parts undergoes a rapid burial by sediment and in place withlow levels of oxygen prevent decaying of fossil. The remains should the undisturbed for a long time with the lack of scavengers.
8.2. DATING METHODS
8.2.1. ABSOLUTE DATING is a technique used to determine the actual age of fossil, indicated by the half lives of the radioactive isotopes such as carbon 14 (5730, useful up to 50,000) and potassium 40 (1.25 billion years)
8.2.2. RELATIVE DATING is a method to determine the relative age of a fossil based on its location in strata rock. Stratigraphy and the law of superposition state that the lower the strata layer, the older it is. Index fossils can be found in the layers.
8.2.2.1. INDEX FOSSILS The principle of correlation states that index fossils (aid in determining other fossils age in the same strata) must be abundant (geographically wide spread), distinctive and short lived species.
8.2.2.1.1. present in only one rock strata - time period
8.3. BIOGEOGRAPHY
8.3.1. PANGEA
8.4. COMPARATIVE ANATOMY or STRUCTURAL MORPHOLOGY is the comparison of the anatomy between 2 organisms to determine their evolutionary relationship.
8.4.1. HOMOLOGOUS STRUCTURES, arise from organisms sharing recent common ancestors and evolve as a result of divergent evolution, have the same basic structure but serve different functions due to different selection pressures.
8.4.2. ANALOGOUS STRUCTURES, evolve as a result of convergent evolution and does not arise from common ancestors, have different structures but serve similar functions due to similar selection pressures.
8.4.3. VESTIGIAL STRUCTURES are reduced remants of organ that once were present and functional but now have no apparent function
8.5. COMPARATIVE EMBRYOLOGY is comparing the pattern in embryonic development of different species indicated by homologous structures to suggest a recent common ancestor
8.5.1. If similar structure are found, they indicate that is it derived from a recent common ancestor.
9. Speciation
9.1. Species are individual that can produce viable and fertile offspring.
9.2. ALLOPATRIC SPECIATION is when speciation occurs due to a geographical barrier
9.2.1. There is variation present in the __________ population with regards to ________. A geographical barrier (__) separates the population into two, inhibiting gene flow. Mutations may arise, exposure to different selection pressures confer different selectively advantageous phenotypes, shifting alllele frequencies. Accumlation of differences of the separated species lead to species (new species) as they can no longer produce viable and fertile offspring.
10. Patterns of Evolution
10.1. DIVERGENT EVOLUTION is when species have originated/evolved from the same (recent) common ancestor. -> Accumulation of differences within a group of lead to speciation ->Homologous structures serve as evidence for this.
10.2. ADAPTIVE RIADATION is rapid divergent evolution, producing a wide array of new species.
10.3. COVERGENT EVOLUTION is the evolution of analogous traits due to similar selection pressures and does not arise from the same recent common ancestor.
10.4. MASS EXTINCTION is rapid extinction which eliminates many species. e.g. asteroid strikes, low genetic diversity, human predation or loss of habitat
10.4.1. Adaptive radiation occurs especially after mass extinction since there are vacant habitats/niches for the survived species to occupy. They spread, undergo diversification, adapt to new environments and are exposed to different selection pressures allowing adaptive radiation.