EK 1B2Phylogenetic trees and cladograms are graphical representations (models) of evolutionary history that can be tested.

Difference between Phylogenetic Trees and Cladistics

• http://www.youtube.com/watch?v=fQwI90bkJl4

• http://www.youtube.com/watch?v=fQwI90bkJl4

Convergent Evolution

• Describes the independent evolution of similar features in different species.• Example – wings

7 DEFINITIONS

Different means of obtaining evidence to create Phylogenetic trees and cladograms

Definitions • Homoplastic evolutionary changes: acquisition of a similar

form or structure between species of different lineages as a result of convergent evolution

• Biogeography: the study of the geographical distribution of species and their evolutionary relationships. Species appear to have colonized island habitats from mainland areas and then been modified by natural selection

• Fossil Record: the fossilized remains of organisms provide a historical record of life on earth. Reveals the vast time scale over which the process of evolution has occurred

• Homology: structures in closely-related species have been a similar underlying structure that appears to have been modified by natural selection in different environments

• Analogy: Structures in distantly-related species have no similarity in underlying structure but have a similar function. These structures appear to have evolved under natural selection in similar environments.

• Embryology: similarities and differences in embryological stages indicate evolutionary relationships among organisms.

• Molecular biology: similarities and differences in the structures of DNA and protein indicate evolutionary relationships among organisms.

Phylogenic trees and cladograms are constantly being revised• New research with biological data• New mathematical and computational

ideas• Current knowledge compared to emerging

knowledge

HARDY WEINBERG EQUILIBRIUM• Requirements for H/W equilibrium• No mutation takes place• No migration (emigration or immigration)• Random mating• Very large population• No selection occurs (leaving more offspring than

competing organisms)• If all five are met, the allele and genotypic

frequencies will remain the same from generation to generation.