Transcript Power Point Slides - Cambrian Explosion

Production Order:
Organisms Adapted to Cambrian Selective Pressures: The fuel for natural
selection is genomic
variation that enables
The Raw Materials
evolutionary adaption to
proceed.
Without fuel, the machine
Chemicals in land, sea
stops, at least until
and air
replenished by the
accumulation of new
The Fuel
mutations.
Mutations:
CCG ACT AAG TAC CGG
CCG ACT AGG TAC CGT
Genetic Variation
Cambrian Explosion Timeframe
Fossil Record suggests:
Begins at base of
Cambrian period of
Paleozoic Era, some
540 million years
ago
• Evolutionary adaptation increases ~
10 fold
• All but one of the extant animal phyla
appeared over ~ 20 million years, less
than .5% of Earth’s geologic time
• Other phyla appeared but did not
survive (e.g., Vetulicolia)
• The so called explosion abruptly
terminated at about 515 million years
ago, after which a biodiversity decline
ensued
Gene Flow
Population
B: red
Population
A: blue
Offspring of immigrated
has genotype Hh
Offspring of immigrated
has genotype Hh
Gene flow is the transfer of alleles from one population to another population through immigration of individuals. In this example, one of the
birds from population A (blue) immigrates to population B (red), which has less of the dominant alleles, and through mating incorporates its
alleles into the other population.
Phylum Vetulicola