1-17-08 notes

1-17-08 notes - Biology January 17, 2008 Chapter 25:...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology January 17, 2008 CQ: Does natural selection create variation? a) YES b) NO Natural selection acts on existing variation and over time can produce new traits Inferring evolutionary history: using the data o With either molecular or morphological data, we look for homologies : shared characteristics with a shared ancestry Determining which similarities between species are relevant to grouping the species in an evolutionary tree is a challenge. o Homology : similarities that are attributable to common ancestry= homologies o Analogy: similarities that are attributable to convergence= homoplasies Homologous Structures o EX. human arm and seal flipper o Derived from a common ancestral structure Analogous Structures o Ex. Bee wing and bird wing o Derived independently, no common ancestral structure Homology: Similar in structure because of shared evolutionary origin Homoplasy: Similar in function , but not in structure or evolutionary origin
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Homology: Humans, cats, whales, and bats inherited their structure from a common ancestor Convergent Evolution creates analogous traits=homoplasies o Convergent Evolution - similar environmental pressures and natural selection produce similar (analogous) adaptations o Even though organisms are from very
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/26/2009 for the course EBIO 1220 taught by Professor Demig-addams during the Spring '07 term at Colorado.

Page1 / 5

1-17-08 notes - Biology January 17, 2008 Chapter 25:...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online