1 / 11

Biology: Evolution Unit

Biology: Evolution Unit. Mechanisms of Evolution. Lets Get Ready! Wed 11/13. What does the Hardy-Weinberg equation show you ? Tell me what these variables mean. What is Genetic Drift?. Any change in allele frequencies in a population due to chance

darius
Download Presentation

Biology: Evolution Unit

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: Evolution Unit Mechanisms of Evolution

  2. Lets Get Ready! Wed 11/13 • What does the Hardy-Weinberg equation show you? Tell me what these variables mean.

  3. What is Genetic Drift? • Any change in allele frequencies in a population due to chance • In large population, typically keeps %’s the same • In smaller populations, more pronounced & can lead to losing an allele

  4. Compare Founder and Bottleneck effects • Bottleneck Effect • When a population declines to a very low number and then rebounds • Reduced variety • Founder Effect • Small sample of population settles in location away from the rest of the population • Reduces gene pool

  5. What are the types of natural selection? • Stabilizing: most common form; eliminates extremes of a trait • Directional: increases expression of extreme versions of trait • Disruptive selection: splits a population into two groups

  6. Allopatric A physical barrier divides two populations Over enough time, the two species cannot breed with each other Sympatric Species evolve into a new species without a physical barrier Happens frequently in plants due to mutation in chromosome numbers What are the types of speciation?

  7. Which is which? Albert squirrel Kaibab squirrel Apple maggot flies

  8. Prezygotic isolation: Prevent reproduction by making fertilization unlikely (geographic, behavioral, mate at different times, etc.) Postzygotic isolation: Fertilization has occurred, but offspring cannot develop or offspring are sterile How does this speciation occur?Reproductive Isolation liger Leopard frog Wood frog

  9. Gradualism: Change proceeds in small, gradual steps over long periods of time Punctuated Equilibrium: Attempts to explain gaps in fossil record Theory states that rapid spurts of genetic change cause species to diverge quickly What are the rates of speciation?

  10. Today’s Assignments • Natural Selection Bean Lab: ALL OUTSIDE (explain) • HW: Types of Natural selection graphing on front table is to be done after you finish and turn in your lab • What STUCK with you today? Post it on front board.

  11. GROUPS FOR BEAN LAB SIDEWALK 1st GRASS 1st Naz & Jeffery Armando & Andrea Akilah & Alexis Yinka & Samantha Denisha & Amani W Maleek & Jake Adam & Josue Elijah & Jason Juwon & Daniel Ayanna & Demetric Amani C & D’Airah Justin & Tianna Shantez & Jatalya STAY TO THE LEFT OF THE BELL TOWER!!!

More Related