Unit 2 - Evolution and Speciation Notes PDF

Evolution and Speciation Evolution - Evolution is the change in the heritable characteristics of a population over generations. Evidence for Evolution: DNA/RNA and Proteins: Comparison of base sequences in DNA or RNA and amino acid sequences in proteins across diffe...

Evolution and Speciation Evolution - Evolution is the change in the heritable characteristics of a population over generations. Evidence for Evolution: DNA/RNA and Proteins: Comparison of base sequences in DNA or RNA and amino acid sequences in proteins across different species. Similarities in these sequences suggest a shared evolutionary history. Selective Breeding as Evidence natural selection an evolutionary process in which humans select for or against particular features in organisms for example, by choosing which individuals to save seeds from or breed from one generation to the next. Differences between domesticated varieties and their wild ancestors show how quickly evolutionary changes can occur under artificial selection. Humans select the changes. In a sense, humans are the “environment” in this situation. so C a o hetero II  Homologous Structures Structures in different species that are similar due to common ancestry. Pentadactyl Limbs Shared structure among vertebrates (e.g., humans, whales, bats). Variation in Function: Despite similar bone structure, these limbs perform different functions in different species, indicating a divergent evolutionary path from a common ancestor. Divergent Evolution a s s same Convergent Evolution and Analogous Structures Structures in different species that have similar functions but evolved independently indicating different evolutionary origins. Similar environmental pressures can lead to the evolution of similar adaptations in unrelated species.  Unlike homologous structures, analogous structures do not imply a common ancestor. 0 00 wings Flipper 0  Natural selection Mediumbeakfinicks Mechanism driving evolutionary change I trait beakdepth trait anothe Natural selection operates continuously over billions of years: ○ Natural selection is a fundamental process in evolution that operates constantly, generation after generation, for an extremely long time. ○ It doesn't stop, and its effects accumulate over massive time scales. It results in the biodiversity of life on Earth new species It shapes the traits and characteristics of organisms, leading to the adaptation of species to their specific environments. This process, when repeated over countless generations, leads to the variety of species we see today. newallele different alleles Changesin DNA differentstrai overproductionoffspring competition allelese sets he fed Favorite.ie EeYon filature trait becomes the more common in population increased frequency allele forcertianalleles Mutation and Sexual Reproduction Mutation generates new alleles by introducing changes in DNA sequences. Mutations are the ultimate source of genetic diversity in populations. Sexual reproduction generates new combinations of alleles through the shuffling of genetic material during meiosis and fertilization. The different combinations results in massive genetic diversity within a population. goodfor species population Overproduction of offspring and competition for resources survival Overproduction of offspring - Many species produce more offspring than can survive and reproduce successfully. This overproduction leads to competition among the offspring for limited resources and not all individuals will survive to reproduce, and this competition is a driving force behind natural selection, favoring individuals with advantageous traits. Competition for resource - within a population, individuals must compete for essential resources like food, shelter, mates, and territory. Those individuals with traits that provide them with a competitive advantage in acquiring these resources are more likely to survive and reproduce, passing on their advantageous traits to the next generation. Examples of limiting resources: ○ food sources can be limited during periods of scarcity, É ○ nesting sites may be in high demand, ○ access to water can be crucial for survival, ○ sunlight is essential for photosynthesis in plants, and territory can provide safety and access to resources.  ogsel.fieerironment nonlinis Abiotic factors as selection pressures Abiotic factors include non-living environmental factors that can affect survival and reproduction. These factors can have direct or indirect effects on an organism's ability to survive and reproduce. Examples of density-independent factors High or low Can stress organisms, affecting their temperatures metabolism, behavior, and ability to find food or water. Stress can lead to natural selection because individuals with traits that better enable them to tolerate or adapt to temperature extremes are more likely to survive and reproduce. Natural disasters Natural selection comes into play as individuals with traits that increase their chances of surviving or escaping these disasters, such as better mobility or fire-resistant features, are more likely to pass on their genes to the next generation. Density Dependent and Independent Factors both abiotic biotic Density-independent factors are factors that affect populations regardless of their size or density. Density-dependent factors are factors that also affect populations, and the severity can be affected by size or density. population density Imoreorganisms lessfoodoverall Inheritable Traits This is through alleles in genes. Most traits have multiple genes and, therefor, multiple alleles that can be affected by natural selection Characteristics acquired during an individual's lifetime due to environmental factors are not heritable because they are not encoded in the base sequence of genes.  Hardy–Weinberg Equations and Types of Selection (HL Only) oo A gene pool consists of all the genes and their different alleles present in a population. a groupoforganisms that o Represents genetic diversity within a population. caninterbreed and produce Includes every allele at every gene locus in all individuals of the population. offspring c AlleleD 11 6 0466 21 Allelefrequency howcommon allele is in apopulation AH A dominantgene asressivegene Allele Frequencies of Geographically Isolated Populations Explanation: Allele frequencies can vary in populations that are geographically isolated. Isolation can lead to genetic differences due to limited gene flow. Limited gene flow can lead to speciation and the formation of a new species. Changes in Allele Frequency and Natural Selection Natural Selection: can changetheallelefrequency Better-suited traits for the environment are passed on. theallelefrequency Neo-Darwinism integrates genetics with natural selection. willchangeincrease Impact on Gene Pool: NL Datwinism Allele frequencies change in response to natural selection. Some alleles become more common in certain populations. allelefrequency Heritable traits that aid survival and reproduction become more common. Types of Selection Directional Selection: Favors one extreme of a trait. Disruptive Selection: Favors both extremes of a trait. Stabilizing Selection: Favors the average form of a trait. Weightsof babies lightdarkmoths sandyand dark darkharebetter rocks area inabirds pgf.gg canoflage whitemice better in Mediumground thesand finch largerbeak darkmice rocks are better size lightbrownmice fitanywhere don't  Hardy–Weinberg Equation Equation: p² + 2pq + q² = 1 gene presentineach individual Concepts: zwaltees p and q represent the frequency of two alleles. ADo.Aao.ua p + q = 1 (sum of allele frequencies is always 1) of one allele A. frequency P Eforot oc.eu 7 Used to calculate allele or phenotypic frequencies. q anotherallele a thesame AAhomozygousdominant phenotype Aaheterozygous I Ga homozygous recessive Tifferent phenotpe P 9 1 F t9 p 0.35 P homozygous 1 f 0.35 recessive 9 1 0.35 194 1 aa 9 1 0.35 AA heterozygous 9 0.65 Isn't Ageneities 1 p o.IS 9 0.65 individuals Population of 1000 00.1225 12.25 p 0.35 122wouldbe AA 2pq 2 0.35 0 65 0.455 45.52 455 Aa 92 0.65 0.4225 42.253 aa 422 0.1225 0 455 0.4225 Hardy–Weinberg Equilibrium Conditions Equilibrium Conditions: Large population size. Random mating. No mutation. No migration. No natural selection Significance: Deviation from the Hardy-Weinberg equation indicates a violation of these conditions. That suggests that evolution is occurring.  1 0.36 0.36 92 13 00 0.36 9 heh Yous recessive V0.56 9 homozygousdominant p 0.6 9 0.4 0.16 0.16 1000 160individuals heterozygous 2pq p 1 0.6 p 9 1 898 8 a heterozygous pt0.6 1 P 0.4 500 0.25 125individual as recessie frequency ofthehomozygous recessive 1 0.25 homozygous dominant p 0.25 92 p9 1 0.5 9 p 0.5 1 0.5 0.25 p 0.5 Heterygous 209 12.5 p widowspeak A F widowspeak Aa orAD 490 no widowspeak aa p Dominant Homozygous 0.09 9 nowidow'speat a 89 1 35 recessive 0.09 1000 90peopleAA 190g 0.49 92 a Homozygous 0.42 1000 420people Aa 0.49 1000 80719 gg of ÉÉj 0  1 I ple c 168 0.16 r 0.16 016.2000 320studentsare Rh rr 1h p 0.84 92 0.16 9p 1 12 0.71 RR 1420 9 50.16 1 9 P 2pq 2 0.84 0 4 9 0.4 1 0.16 0.84 2ps 0.24 Rr 478 p 0.84 i sicklecell 0.04 92 ii 8ft 698 Inosidelecell 0.2 9 0.32 320 2pq 2 0.2 0.8 1 0.2 P 0.8 P 91 is TorTT 09 is tt 92 0.09 9 0.3 1 0.3 P 0.7 p Species a group of organisms that can interbreed and produce fertile offspring Speciation the formation of a new species species famaestor event HQspeciation Species Spefies of the same species population a group oforganisms area livinginthe same population Population EE ID  Speciation by Splitting of Pre-existing Species Occurs when a species diverges into two or more distinct species. Microevolution vs. Macroevolution: Microevolutionary changes (like small genetic mutations) over long periods lead to macroevolutionary outcomes, such as speciation.. flower early Temporal tier floorabit Isolation later 9 in qq.iq time  different no attraction soups example to songs find Roles of Reproductive Isolation and Differential Selection in Speciation Isolation Reproductive Isolation: Populatiathatcan'tinterbreed Geographic, behavioral, temporal, mechanical, and gamete isolation. calchargcte.pt environments Species I qdiuforeg am Prevents gene flow between populations, leading to speciation. Differential Selection: tia Different environmental pressures result in different adaptations. Populations evolve to suit their specific environments, eventually becoming distinct species. Sympatric and Allopatric Speciation Allopatric Speciation: Geographic barriers like mountains, rivers, or human activities. Geographic isolation leads to independent evolution. ital Sympatric Speciation: Genetic mutations, changes in habitat preference, or behavioral changes. Species evolve from a common ancestor without physical barriers. Physical Same area Geographic Gysical behaviour isolation  Adaptive Radiation Detailed Explanation: Trigger: Often follows mass extinctions or colonization of new environments. Process: A single species evolves into multiple species, each adapted to a specific ecological niche. roles low competitions Examples: Darwin's finches, cichlid fish in African lakes. largerseeds I I I s I I I I leads nihlights reaation represent environments Finches changing different selectmsures 0 i III falatin O dita.fi fhI'habits or niches  Postzygotic Barriers to Hybridization Expanded Explanation: Prezygotic Zygote Prezygotic Barriers: Prevent mating or fertilization (e.g., different mating rituals, incompatible reproductive organs). Postzygotic Barriers: After fertilization, hybrids may be inviable or sterile. Hybrid Sterility: Hybrids like mules can't reproduce, preventing gene flow between parent species. Eatric Ees f a weaker Prezygotic ill equiped tosurvive Abrupt Speciation in Plants Polyploidy: Later don't S it farthy Definition: The possession of more than two complete sets of chromosomes. Significance in Plants: A common mechanism for rapid speciation, especially in plants. Hybridization in Plants: Process: Cross-breeding of closely related species. Result: Can lead to new species that are reproductively isolated from the parent species. Biological Species Concept In-depth Understanding: Limitations: Does not apply well to asexual organisms, fossils, or species that can hybridize. Alternative Definitions: Morphological, ecological, and phylogenetic species concepts offer different perspectives. Difficulties in Distinguishing Species enstatiaslanders Speciation as a Continuum: Evolutionary changes accumulate gradually, making it challenging to pinpoint when exactly a new species forms. Interbreeding Populations: During the speciation process, there might still be gene flow between diverging populations, complicating the distinction. Arbitrary Decisions: Scientists often make subjective decisions based on 0 genetic, morphological, or ecological differences to classify distinct species. Leethen hate are found or whatthey eatleck