1 / 30

Principles of Evolution :

Principles of Evolution :. 1. Natural Selection. Require a “struggle for existence” Occurs at individual level “nature” selects individuals to die or survive Traits better adapted for their environment become more common.

nelson
Download Presentation

Principles of Evolution :

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. Principles of Evolution:

  2. 1. Natural Selection • Require a “struggle for existence” • Occurs at individual level • “nature” selects individuals to die or survive • Traits better adapted for their environment become more common

  3. 2. Adaptation: any heritable characteristic which improves an organism’s chance of survival • Does not arise in an individual • Requires variation • Individuals selected for/against based on their adaptations

  4. 3. Fitness: the ability of an organism to survive and reproduce • Measured by relative contribution to gene pool • Survival of the Fittest: individuals best adapted to the environment survive and reproduce

  5. 1. Variation: pheno/genotypic differences between members of the same species

  6. 2. Struggle for Existence: the competition for needed resources/reproduction

  7. 3. Fitness: the ability to survive and reproduce – based on genetic contribution to gene pool

  8. 4. Adaptation: inherited characteristics that improve an organism’s chances of survival

  9. 5. Survival of the Fittest: the organisms best adapted to their environmental conditions survive and reproduce

  10. 6. Natural Selection: organisms displaying the best adaptations/traits become more common over generations

  11. Populations: units of evolution • Individuals do not evolve in a lifetime -Nature selects some for survival some for death based on traits * Rate of evolution = change in certain allele prevalence • Gene pool: collection of genes in a population at a given time

  12. Mutation: change in nucleotide sequence of DNA • Typically harmless • If it affects protein = harmful • Rarely beneficial • Leads to variations • Usually not heritable, unless it happens in gametes

  13. Evidence For Evolution:

  14. 1. Fossil Evidence -Supports the theory – especially in aquatic organisms -many holes still in the fossil record

  15. 2. Homologous Structures: similar structures with different functions/same embryological origin

  16. 3. Vestigial Organs: organs/structures which have lost function over geological time

  17. 4. Embryological Similarities: all vertebrates have similar embryological development

  18. 5. Radiometric Dating: the use of radioactive elements to calculate the age of geological substances • Half life: the length of time required for half of the radioactive atoms in a sample to decay into non-radioactive atoms • Ex: Carbon-14 decays to form carbon 12 (5730 years) – comparing the amount of C14 to C12 allows us to age samples

  19. 6. DNA similarities: genomic data indicate that all life forms are closely related to one another Ex. Humans and Bananas share 50% of the same DNA -Humans and Chimps= 98.5%

  20. Types of Evolution:

  21. Adaptive Radiation: process of a single species or small group evolving into a diverse group of organisms

  22. Convergent Evolution: unrelated organisms come to resemble one another

  23. Coevolution: process by which two species evolve in response to changes in each other

  24. Gradualism: life is in a constant, small state of flux and small changes evolve slowly into large differences

  25. Punctuated Equilibrium: life is stable, for long periods of time but is interrupted with periods of dramatic change

  26. Speciation:creation of new species Species: a group of individuals which bear similar characteristics, can breed with one another, and produce viable offspring Two Types of Speciation:

  27. 1. Allopatric Speciation: a population is separated and their genes drift apart • Only occurs if environmental differences are significant • Genetic Drift: change in allele frequency in a population

  28. 2. Sympatric Speciation: new species arise in the same area - Arises due to changes in sexual selection and habitat preference

  29. Genetic Drift: in populations, one allele becomes more common in descendents

More Related