1 / 27

Mechanisms of Evolution and Genetic Variation: Insights into Diversity and Change

This section discusses the crucial role of mutations and genetic recombination in increasing genetic variation within populations. It explores how biological diversity is fueled by the emergence of new species and diminished by extinction. Additional mechanisms of evolutionary change, such as genetic drift and gene flow, are outlined to provide a broader understanding of evolution beyond natural selection. The Hardy-Weinberg principle is examined to list conditions for genetic equilibrium and its implications in nature, and it concludes with predictions on genotype frequencies from phenotypic observations.

siyavash
Télécharger la présentation

Mechanisms of Evolution and Genetic Variation: Insights into Diversity and Change

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. BIOLOGY NOTESEVOLUTION PART 2 PAGES 326-346

  2. Standards: 6.3 6.4 ____ Describe how mutation and genetic recombination increases genetic variation ____ Describe how biological diversity is increased by the origin of new species and how it is decreased by the process of extinction ____ Discuss mechanisms of evolutionary change other than natural selection such as genetic drift and gene flow ____ List the conditions for Hardy-Weinberg equilibrium in a population and why these conditions are not likely to appear in nature. Use the Hardy-Weinberg equation to predict genotypes in populations from observed phenotypes 6.5 6.6

  3. Essential Question: What mechanisms have allowed for diversity in organisms? 1.

  4. I. Evolution & Genetic Frequency Mendel inheritance The study of evolution was able to advance in the 1930’s with the work of _______ and his theories of ___________. • Scientists were able to confirm the _____ was the unit of inheritance for all organisms • With the work of genetics, scientists were able to express __________ as a force that action upon genetic _________ within a ___________ gene evolution variation population

  5. mutation • What process allows for new genes to appear within a group? _________ • What process allows the reshuffling of genes to occur in order to produce new phenotypes? __________________ MUTATIONS AND SEXUAL REPRODUCTION INCREASE GENETIC VARIATION WHICH IS WHAT EVOLUTIONS ACTS UPON!!! sexual reproduction

  6. population A. Genetic Variation and Evolution • Gene pool = all the variations of genes present within a __________ • Population = a group of individuals of the same ________ that __________ and live in the same environment. species interbreed

  7. allele • Gene Frequency = the number of times an ______ occurs within a population e.g. In a rabbit population, if B (Black) has an allele frequency of 60% and b(brown) has an allele frequency of 40%, what percentage of the population have genotypes that are: a. Homozygous Black?_____ b. Homozygous brown?_____ c. Heterozygous Black?_____ 36% BB = .60 x .60 16% bb = .40 x.40 48% Bb and bB = (.60 x .40) x 2

  8. constant genetic NO • If over time the allele frequencies are _________ then we say the population is in ________ equilibrium and ____ evolution is occurring • Hardy-Weinberg Principle = allele frequencies in a __________ will remain constant unless one or more factors cause those frequencies to _______ population change

  9. a. Conditions Necessary for Genetic Equilibrium (NO EVOLUTION): 1. Random mating • if there is preferential mate selection, certain alleles would become more __________ 2. Large population • large populations ensure there is a less noticeable effect by _______ drift 3. No mutations • mutations could introduce ____ alleles into a population prominent genetic new

  10. immigration emigration into leaving 4. No Migration (____________ or __________) • individuals coming ____ a population could introduce new alleles while individuals _______ a population may eliminate alleles 5. No Natural Selection • all __________ must have an equal chance of ________ • this implies that the environment must remain relatively _________ genotypes survival constant

  11. GENTIC EQUILIBRIUM IS HIGHLY UNLIKELY WHICH MEANS EVOLUTIONS MUST OCCUR!!!! • Using Hardy-Weinberg equations it can be proven that over time (generations), if there are changes in the frequency of alleles for a population, then we say the population is ________ or changing evolving

  12. nature adapted B. HOW Populations Evolve (Sources of Evolutionary Change): a. Natural Selection: when _______ selects the best ________ individuals to survive • If the ____________ changes, then nature will select new individuals and the ______ frequency for a given population will change e.g. environment allele dinosaurs & the meteor

  13. allele small 2. Genetic Drift = evolution that occurs because of random changes in ______ frequencies that occur in ______ populations • In small populations, individuals that carry a particular ______ may by chance have more offspring that inherit the ______ • over time, this could cause that particular ______ to be present in a population at a _______ frequency which, overall, changes the population dynamics allele allele allele higher

  14. In a ______ population this would be less noticeable larger

  15. variation identical • Genetic drift, however, decreases genetic _________ because it makes small populations genetically _________ which means these populations are less likely to experience _______ selection natural

  16. event • bottleneck effect = genetic drift that occurs because an ______ lessens the overall population • founder effect = genetic drift that occurs because a small number of __________ colonize a new area individuals

  17. migrate alleles c. Gene Flow = evolution that occurs when individuals ________ into another population and introduce new _______ into that population • This __________ the genetic _________ of a population (opposite of _______ drift in terms of genetic variation) • Neighboring populations can begin to look _______ increases variation genetic similar

  18. isolated • If there is no gene flow, and populations become ________ from one another, speciation may occur • this occurs because each population is now independently subject to _________ and genetic _____ • speciation = the rise of two or more ________ from one existing species mutations drift species

  19. Eastern vs. Western Meadowlark Populations

  20. mates preference polydactylism d. Non-random mating: choosing specific _______ due to ___________ i.e.

  21. anatomy C. Possible Outcomes of Evolution • Convergent Evolution = evolution toward similar _________ in unrelated species due to a similar environment i.e. shark vs. dolphin tails

  22. anatomy environments b. Divergent Evolution = evolution toward dissimilarity of _________ within closely related species due to varying ______________ i.e. kit fox vs. red fox

  23. response c. Co-Evolution = two or more species evolving in _________ to each other d. Extinction e. Speciation

More Related