Exam 4 Guide - Evolution PDF

Chapter 19 : \*Artificial Selection is the process by which humans select who lives and reproduces based on traits of animal or plant - Artificial selection can result in great changes in phenotype - Fossil record as evidence of evolution When an animal or plant converges on the same morphol...

Chapter 19 : \*Artificial Selection is the process by which humans select who lives and reproduces based on traits of animal or plant - Artificial selection can result in great changes in phenotype - Fossil record as evidence of evolution When an animal or plant converges on the same morphological trait it is known as an analogous trait. For ex. A cat's leg and a ant's leg - Analogous traits arise from animals surviving in the same ecological niches who do not have close relation. - A penguin's fin is analogous to a dolphin's fin because they both live in aquatic environment - Differing structure, similar function - Not from a common ancestor - Ex: wing of a bird vs wing of wing of a bee. Different structure but same function Homologous traits are made from anatomy. For ex a human arm with a whale's fin - Homologous is when the animal is close enough that their anatomy is similar but evolve in different environments - A penguin's fin and a eagle's wing are homologous because they are both birds and a common ancestors has wings - Have similar structure, differing function (arm vs wing) - Form from a common ancestor - Ex: Arm of a monkey vs the fin of a narwhal they have a similar structure but different functions \*The evolution of similar forms in different lineages when exposed to the same selective pressures is called convergent evolution \*The wings of birds and butterflies are examples of structures that resemble each other and have similar function but are the result of parallel evolution in separate lineages. These structures are called analogous structures \*The observation that different geographical areas sometimes exhibit plant and animal communities of similar appearance, even though the individual plants and animals are not closely related, is called convergent evolution Divergent evolution - Two or more diverge from a common ancestor - Example: the modern elephant and the mammoth \> share common ancestor yet evolved indepently. They all diverge from a common ancestor Convergent Evolution - Two or more distinct species share traits not due to a common ancestor - Example: birds, butterflies, and bats all have wings that allow to fly but they don't share a common ancestor. Each evolved to have wings independently. evolution converged in different species; their wings aren't due to a common ancestor. \*A friend is trying to understand the concept of convergent evolution. Which one of the following statements best describes this concept? \- Convergent evolution occurs when two unrelated species living in different habitats evolve similarities through natural selection acting on those characteristics. \*What observations lead Charles Darwin and Alfred Wallace to figure out the mechanism by which species originate? \- Species in nearby islands tend to look similar but not identical \- Some species have structures that resemble those found in other species but have no current function (vestigial structure) \- species that are more closely related look more alike \- each species has variations that make it better suited to its environment \*Charles Darwin and Alfred Wallace argued that evolution is accomplished by the process of natural selection. Which of the following are important to the concept of natural selection? \- Phenotypic variation can influence reproductive success \- Phenotypic variation within a species is due in part to inherited characteristics \- Phenotypic variation exists within populations \- Most organisms can produce more offspring than typically survive \*What is true about evolution? \- Natural Selection varies depending on the environment \- Natural Selection favors those who have more offspring so that their genes are passed onto the next generation \- Mutations are random but which mutations are kept in the population depends on the advantage they provide Lamarks Theory: acquitted variation is passed on descants (not possible) - If a father starts going to the gym and has a baby, the baby is going to have big muscles? no wrong Darwin's theory: natural selection or genetically based variation leads to evolutionary change Every population will have genetic variation Evolution is when a change has happened A population that is in Hardy Weinberg equilibrium means no evolution. Population that is stable and the same alleles are present generation after generation. For alleles to stay in equilibrium: - No mutation - No migration - Random mating - Large population size - No selection 5 requirements for a population to be in genetic equilibrium: - Mutation - A change in the DNA causing a change in the protein coded by that gene - Gene flow - Individuals from one population moving into another - Nonrandom mating - Females preferring mates with a. particular phenotype - Genetic drift -- change in allele due to random events - Random events that change the frequency of the alleles independently of the advantage or disadvantage of those alleles - Selection -- one allele makes it more likely to be passed on - A predator predominantly hunting prey with a particular allele over another Hardy Weinberg Equilibrium? 1. Frequency of Alleles in a population ? a. 60% alleles are B b. 40% of allels are b 2. Does that frequency change over time ? c. Is B still 60% 3. Notice : 0.6 (B) + 0.4 (b) = 1 If the allele frequencies do not change over time than the population is in the equation P= dominant allle Q= recessive From allele frequency to genotype frequency - Probability of BB (homozygous dominant) = p x p + p\^2 - Probability of Bb (heterozygous) = 2 x p xq - Probability of bb q x q = q\^2 (homozygous recessive) Types of Selection Stabilizing: removes the extreme ends of the trait variation favoring individual with the intermediate trait. Mice of medium size are more likely to survive and reproduce than larger or smaller mice Disruptive: Favors both extremes of the trait. In a environment with patches of dark rocks and sand, dark mice survive by mimicking the rocks and light color mice survive by mimicking the sand, but intermediate color mice are easily spotted by predators. Directional: Favors either extreme of the variation in the trait. If the environment only hsa dark rocks, darker color mice will be favored as they will be less likely to be seen by predators. Generation after the generation the population will be darker. Selection may increase genetic variation \*Why hasn't natural selection gotten rid of huntingotons disease? \- Because the effect of Huntingtons gene appears later in life, after the indidivduals reproduce Prezygotic : before the cycle forms 1. Geographical isolation: live in different areas wont be able to reproduce 2. Ecological isolation: live in same area and might not find each other bc they might have different habitats ( particular spaces). Geographical doesn't mean habitiat 3. Temporal isolation: breed in different points in time 4. Behavioral isolation: behavior is different in each animals 5. Mechiancal isolation: the organs of the species cannot match each other 6. No gamete fusion: sperm is not able to fertilize the egg Postzygotic 1. Hybrid in viability : cycle doesn't develop into a baby 2. Hybrid infertility Where does speciation happen? - Allopatric: different location - Sympatric: in the same location