Evidence and Theories of Evolution PDF

Evidence and Theories of Evolution 8/27/24, 2:14 PM Platform | Study Fetch (00:00:46 - 00:00:59)The evidence for evolution includes: Fossil record Biogeography Embryology Comparative Anatomy Biochemical methods...

Evidence and Theories of Evolution 8/27/24, 2:14 PM Platform | Study Fetch (00:00:46 - 00:00:59)The evidence for evolution includes: Fossil record Biogeography Embryology Comparative Anatomy Biochemical methods Fossil Record (00:01:10 - 00:01:28) Fossils can be actual remains or impressions/traces (e.g., footprints, scat) Petrification is the process where organic matter becomes stone over time Biogeography (00:01:28 - 00:01:57) The geographical distribution of plants and animals Pangaea was a large supercontinent that broke apart over time, allowing organisms to evolve in isolation on the new landmasses Embryology (00:02:08 - 00:02:19) The study of embryos and their development Similarities in embryological development across related organisms support common ancestry Comparative Anatomy (00:02:32 - 00:03:13) Anatomical similarities between organisms indicate a shared common ancestor Homologous structures are similar in structure but may have different functions Analogous structures have similar functions but did not evolve from a common ancestor Vestigial structures are remnants of structures that no longer serve a purpose Biochemical Evidence (00:03:59 - 00:04:21) Similarities in biochemical pathways and genome structure between organisms support evolutionary relationships Chimpanzees and humans share a high degree of genetic similarity, indicating a close evolutionary relationship https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 1/8  Mnemonic for Evidence of Evolution:Emily Compares Biochemistry, Grades, Biography Reports, 8/27/24, 2:14 PM Platform | Study Fetch and Fossils Important Figures and Theories (00:04:57 - 00:05:26)Baron George Cuvier Founder of paleontology Proposed the theory of catastrophes, where sudden environmental changes led to mass extinctions Jean Baptiste Lamarck Proposed the theory of use and disuse, where increased use of a body part leads to its growth and development, while unused parts atrophy (00:05:26 - 00:05:44) Lamarck's theory of use and disuse suggested that changes acquired during an organism's lifetime could be passed on to offspring, which is now known to be incorrect. (00:05:44 - 00:05:56) Lamarck's theory was an early attempt to explain evolution, but it was later superseded by Charles Darwin's theory of natural selection. Lamarck's Theory of Acquired Traits (00:05:56 - 00:06:10) Lamarck proposed the theory of acquired traits This theory states that if an organism acquires a trait during its lifetime, that trait can be passed on to its offspring This idea was disproven by Charles Darwin Epigenetics and Heritable Traits (00:06:10 - 00:06:29) There is some evidence that certain epigenetic factors can allow for adaptation and changes during an organism's lifetime These changes could potentially be heritable However, this is not the main mechanism by which evolution takes place Charles Darwin and Natural Selection (00:06:40 - 00:06:53) Charles Darwin proposed the theory of natural selection This theory states that organisms better adapted to their environment will survive and produce more offspring These offspring will then inherit the same beneficial traits as their parents https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 2/8  Terminology of Natural Selection 8/27/24, 2:14 PM Platform | Study Fetch (00:07:04 - 00:07:28) Natural selection is a gradual, non-random process where alleles become more or less common due to an organism's interactions with the environment Survival of the fittest refers to reproductive success, not just longevity Requirements for natural selection: Competition for scarce resources Variation in fitness among organisms Heritability of traits Organisms produce more offspring than can normally survive Types of Natural Selection (00:08:34 - 00:10:37) Stabilizing Selection Maintains a non-extreme, mainstream trait Example: Robins typically laying 4 eggs Extreme traits are selected against Directional Selection Shifts the population towards one extreme trait Example: Light-colored moths being selected for on a light background Disruptive Selection Selects for extreme traits, diversifying the population Example: Gray and Himalayan rabbits being selected for in different environments Table: Comparison of Natural Selection Types Type Description Example Stabilizing Maintains non-extreme, Robins laying 4 eggs mainstream traits Directional Shifts population towards one Light-colored moths on light extreme trait background Disruptive Selects for extreme traits, Gray and Himalayan rabbits diversifying population https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 3/8  Types of Natural Selection 8/27/24, 2:14 PM Platform | Study Fetch (00:10:52 - 00:11:06) Stabilizing Selection: A bell curve where the mainstream is favored, forcing everything to the mean. This gives a stable life. (00:11:06 - 00:11:17) Directional Selection: One extreme is favored, going in one direction. Disruptive Selection: The graph looks like a mountain, with two peaks split by disruption. Microevolution vs. Macroevolution (00:11:17 - 00:11:37)Microevolution: Changes in a gene pool, the allele frequency of a single population Genes will increase in frequency as they suit the environment Macroevolution: Sources of genetic variation Speciation (00:11:37 - 00:11:54) Example of microevolution: In a population of multicolored beetles, green beetles may have an advantage if there is a lot of plant life, so the population will shift towards being more green. Then, if the environment changes (e.g., a fire, land becomes dry), the beetles may shift towards being more brown to better suit the new environment. (00:12:04 - 00:12:18) The Hardy-Weinberg formula can be used to determine allele frequencies within a population, assuming no changes in gene frequency. P + Q = 1, where P is the frequency of the dominant allele and Q is the frequency of the recessive allele. (00:12:18 - 00:12:30) The Hardy-Weinberg formula also states that P^2 + 2PQ + Q^2 = 1, where P^2 is the frequency of homozygous dominant individuals, Q^2 is the frequency of homozygous recessive individuals, and 2PQ is the frequency of heterozygous individuals. (00:12:30 - 00:12:54) Example: If the frequency of the dominant allele (P) is 0.5, then the frequency of the recessive allele (Q) is also 0.5. The formula can be used to calculate the frequencies of different genotypes within a population. (00:12:54 - 00:13:24) The Hardy-Weinberg equilibrium requires certain assumptions to hold true: No selection No mutation No migration Large population Random mating https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 4/8 8/27/24, 2:14 PM Platform | Study Fetch (00:13:24 - 00:13:56) Example: In a garden of 100 pea plants, 86 have yellow peas and 16 have green peas (homozygous recessive). Using the Hardy-Weinberg formula, we can calculate: Q^2 = 0.16, so Q = 0.4 P = 1 - Q = 0.6 Frequency of homozygous dominant plants = P^2 = 0.36 (36 plants) Frequency of heterozygous plants = 2PQ = 0.48 (48 plants) (00:13:56 - 00:15:19) The Hardy-Weinberg equilibrium assumptions must be met for the formula to be applicable: No selection No mutation No migration Large population Random mating (00:15:19 - 00:15:46) Mnemonic for the Hardy-Weinberg equilibrium requirements: Large population Random mating Minimizing the effects of genetic drift No mutations Minimizing the effects of natural selection Allele Frequencies and Genetic Drift (00:15:57 - 00:16:07) Allele frequencies are stable and not impacted when a population is isolated with no migration Genetic drift is a factor that can cause evolution in an isolated population Mechanisms of Evolution (00:16:07 - 00:16:20) Evolution can occur through: Mutations Bottleneck effect Founder effect Non-random mating Natural selection Gene flow Bottleneck Effect vs. Founder Effect https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 5/8 8/27/24, 2:14 PM Platform | Study Fetch (00:16:20 - 00:16:49) Bottleneck Effect: A population is drastically reduced, and only a few alleles can survive Analogous to a forest fire where most of the population dies off Founder Effect: A segment of a population breaks off and forms a new population The new population may lack the same genetic diversity as the original Non-Random Mating (00:16:49 - 00:17:16) Outbreeding: Breeding with non-familiar members Inbreeding: Breeding with relatives There can be selection for non-random mating based on accessibility and desirable characteristics Natural Selection and Gene Flow (00:17:34 - 00:17:58) Natural selection favors traits based on fitness Gene flow is the movement of alleles between populations Gene flow can introduce new changes and alter the dynamics within a population Macroevolution (00:18:14 - 00:18:25) Macroevolution is major evolutionary change over long periods of time Examples include dinosaurs evolving into birds or fish evolving into mammals Pre-Zygotic Isolation Mechanisms (00:18:25 - 00:19:06) Gametic Isolation: Eggs and sperm cannot fuse Mechanical Isolation: Physical barriers prevent mating Habitat Isolation: Populations live in different habitats Temporal Isolation: Populations breed at different times Behavioral Isolation: Populations have different mating behaviors Post-Zygotic Isolation Mechanisms (00:19:21 - 00:19:43) Hybrid Mortality: Hybrid zygote is not viable Hybrid Sterility: Hybrid cannot reproduce Hybrid F2 Breakdown: Hybrid offspring have decreased fitness https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 6/8  Sources of Genetic Variation 8/27/24, 2:14 PM Platform | Study Fetch (00:20:06 - 00:21:17) Mutation: Random changes in the genetic code Sexual Reproduction: Crossing over and independent assortment during meiosis Balanced Polymorphism: Heterozygote advantage, such as sickle-cell trait providing resistance to malaria Genetic Variation and Speciation Minority Advantage and Hybrid Advantage (00:21:36 - 00:21:54) Minority Advantage: A rare phenotype is favored over a common phenotype Hybrid Advantage: Breeding two different strains of organisms produces an organism that is better adapted to its environment Neutral Variations (00:21:54 - 00:22:07) Variations that neither benefit nor harm an organism Many different polymorphisms present in a cross human species that have no discernible, positive or negative effect Polymorphisms and Polyploid (00:22:07 - 00:22:32) Some polymorphisms can be loosely associated with different disease states Polyploid: Another source of genetic variation, typically very deleterious but can occur Diploid: The dominant allele can mask the effect of recessive alleles, allowing them to drift through a population Sources of Genetic Variation (00:22:32 - 00:23:09) Mutation: A source of genetic variation Balanced Polymorphisms: Maintain genetic variation in a population Polyploid: Increased number of chromosome pairs Sexual Reproduction: Mixes genetic material, creating new combinations Speciation https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 7/8  (00:23:09 - 00:23:38) 8/27/24, 2:14 PM Platform | Study Fetch Speciation: Species formation from a single ancestral species Allopatric Speciation: Occurs due to geographical barriers, leading to adaptive radiation Patterns of Evolution (00:23:38 - 00:24:25) Divergent Evolution: Initial species branches and splits off Convergent Evolution: Two separate species become more similar over time Parallel Evolution: Two separate species change individually on their own Co-evolution: Two species impart selective pressures on each other Mimicry (00:24:25 - 00:25:36) Batesian Mimicry: Harmless animals mimic the coloring of a harmful animal Müllerian Mimicry: Different poisonous species resemble each other Phylogenetic Trees (00:25:52 - 00:26:19) Clade: A cluster of species in a phylogenetic tree Homoplasy: Convergent evolution, where two clades develop similar characteristics Parsimony: Choosing the simplest scientific explanation that fits the evidence https://www.studyfetch.com/platform/studyset/66cd116dd279f5220d947c66/material/66ce1750d56e584fb7692bcb/document?go=note 8/8