BIOL 2061 1st Edition Lecture 8Outline of Last Lecture I. Sexual selectionII. MutationIII. Random mating/ non- randomIV. Migration/gene flowV. Large population sizeOutline of Current Lecture I. BottleneckII. Founder EffectIII. Neutral Theory of EvolutionIV. Chapter 20- origin of SpeciesV. Various species conceptVI. Mechanisms of keeping species distinctCurrent LectureI. Bottleneck-a. A population decreases very quickly and then rebuilds.b. Surviving species has different allele frequencies of original population.c. The new population more than likely has very little genetic diversity.d. Allele frequencies can drift substantially in small populationsII. Founder Effect-These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Small group of individuals separates from a larger population, and makes new colony.b. The new small population have less genetic diversity c. Allele frequency may be very different from original population.III. Neutral Theory of Evolution-a. Non- Darwinian evolution (not through natural selection)b. Neutral variation-i. Much of the variation seen in natural populations is caused by genetic driftii. Does not preferentially select a specific allelec. Most genetic variation is due to the accumulation of neutral mutationsd. Neutral mutations do not affect phenotypese. Modern gene variation’s is explained by neutral variation rather than adaptive variation.f. Evolution can occur without natural selectionIV. Chapter 20- Origin of Speciesa. Species- a group of organisms that maintains a distinctive set of attributes in naturei. No one know exactly how many species there areb. Macroevolution- evolutionary changes that create new species or groups of speciesi. Occurs by the change of one geneV. Various Species Concepts-a. Biological Species Concept- Members have the opportunity to interbreed with one another in nature to produce viable, fertile offspring but can not interbreed with other species.i. Reproductive isolation- prevent breeding with other speciesb. Evolutionary species- A species is derived from a single lineage that is distinct from other lineages.c. Ecological Species Concept- Each species occupies an ecological nichei. Similar niches produce competition.d. General Lineage- Combines all of the concepts together.VI. Mechanisms that keep species distinct-a. Prezygotic Mechanisms-i. No mating attempt-1. Habitat isolation- species occupy different habitats, so they never come in contact2. Temporal isolation- species have different mating and flowering seasons, times, day or sexually mature at different times.3. Behavioral Isolation- sexual attraction of different species is limited to differences in behavior of psychology.ii. Attempted mating-1. Mechanical Isolation- genitalia features do not fit together correctly. Can prevent 2 species from interbreeding.2. Gametic Isolation- Gametic transfer occurs but the gametes fail to unite. The egg rejects the sperm.b. Postzygotic Mechanisms- Fertilization happensi. Hybrid Inviability- The egg is fertilized by the sperm, but the fertilized egg fails to develop past the embryonic stage.ii. Hybrid Sterility- the interspecies hybrid survives but it is sterile.1. Expample=Muleiii. Hybrid Breakdown- The interspecies is viable and fertile but the succeeding generation is increasingly inviable and