Mutations:CCG ACT AAG TAC CGGCCG ACT AGG TAC CGT

Genetic Variation

The Fuel

The Raw Materials

Production Order:Organisms Adapted to Cambrian Selective Pressures: The fuel for natural

selection is genomic variation that enables evolutionary adaption to proceed. Without fuel, the machine stops, at least until replenished by the accumulation of new mutations.

Chemicals in land, sea and air

Cambrian Explosion Timeframe

Begins at base of Cambrian period of Paleozoic Era, some 540 million years ago

Fossil Record suggests:• 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

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.

Population A: blue

Population B: red

Phylum Vetulicola