Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Catholic Church and evolution wikipedia , lookup
Organisms at high altitude wikipedia , lookup
Evolution of sexual reproduction wikipedia , lookup
Natural selection wikipedia , lookup
Evidence of common descent wikipedia , lookup
Punctuated equilibrium wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Theistic evolution wikipedia , lookup
Inclusive fitness wikipedia , lookup
The eclipse of Darwinism wikipedia , lookup
Bio 7: General Biology II Evolutionary, Organismal, & Ecological Biology Dr. Diane Livio [email protected] myetudes.org/portal MW 2:30-4:30 (CMS 229) TTh 3:30-4:30 (CMS 106) About this course • Majors course – rigorous and challenging, designed to be rewarding • Student responsibilities • Review the syllabus • Check Etudes regularly Expectations & Goals • What is expected of you? • What do you expect of me? Or your class mates? Of the course? • First module on Etudes has help! “Learn How You Learn” www.vark-learn.com Evolutionary Processes "Nothing in biology makes sense except in the light of evolution" - Theodosius Dobzhansky Scientific Theory • Def: a proposed explanation for a very general class of phenomena, supported by a large body of evidence • Possesses both pattern and process components Theory of Evolution • On the Origin of Species (1859) • All life evolved gradually from one primitive species [lived 3.5 bya] – Split off into many diverse species over time – Mainly by natural selection Pattern of Evolution • Descent with modification – Inherited characteristics in a population of a species change over time – Sometimes population changes over time to form a new species – Newer species descend from older species Macroevolution • Pattern of evolution over large scales – Larger than the species level – Over geologic time scale How old is the Earth? How old is life? Earth’s Early History • Estimates of Age of Earth/Solar System -- Current estimate: 4.54 by • Oceans formed by 3.8 bya • No O2, much solar radiation • Life – 3.6 to 3.8 bya Oldest fossils: 3.5 by Most history of “higher” organisms in most recent 500 million years… Macro- vs Micro- Process of Evolution Microevolution: the change in allele frequencies in a population over time Population: a group of individuals of one species living in a particular place DNA • Genetic info – heritable • Genes: code for proteins to make and maintain organisms • Allele: form of a gene GENOME CHROMOSOMES NUCLEOTIDES GENOTYPE vs PHENOTYPE Process of Evolution Microevolution: the change in allele frequencies in a population over time Mechanisms of Evolution: 1. Mutation 2. Genetic Drift 3. Gene Flow 4. Natural Selection Mutation in DNA • Def: change to the nucleotide bases (adds variation to the population) Mutation = Source of DNA Variation DNA Replication = Potential MISTAKES Genetic Drift • Def: any change in allele frequencies in a population that is due to chance – Random with respect to fitness • More pronounced in small populations • Drifting allele frequency could lead to loss of allele or fixation (100% frequency) Fig. 23.4 Genetic Drift - how it occurs: • Genetic bottleneck – sudden reduction in # of alleles in a population Conservation biologists manage “gene pool” of species with small population sizes to prevent loss of alleles through drift. Genetic Drift - how it occurs: • Founder’s effect – change occurs when a new population is established – Small subset does not represent allele frequencies of source population Gene Flow • Def: change in allele frequency due to migration between populations • Gene Flow: movement of alleles from one population to another – Tends to make one or both populations look more like the other Charles Darwin: The Origin of Species (1859) • Identified natural selection as the major mechanism of adaptive evolution • Much focus on survival aspect of reproduction “survival of the fittest” Adaptive Evolution Adaptation = a heritable trait that increases an individual’s ability to produce offspring (its fitness) in a particular environment relative to individuals lacking the trait Natural Selection • Process by which heritable variation leads to differential success in survival and reproduction • Differential reproductive success can result from differences in survival, fecundity, and mating success. • Artificial selection – deliberate manipulation by humans Summary • Natural selection adapts a population to its environment. • Selection operates on individuals. Evolution occurs in populations and species. • Other mechanisms of evolution: mutation, drift, gene flow. Speciation • Species: “an evolutionarily independent population or group of populations” – Reproductive compatibility – Similar physical appearance – Shared, unique genetic history • Allopatric vs sympatric speciation – Physically separated populations vs “living together”