Marcoevol

• Subpopulations are geographically isolated by (large water body) which acts as a physical barrier . • Different environments exert different selection pressures, • selecting for individuals with advantageous traits best adapted within a subpopulation . • Different changes in allele freq occur in each subpopulation. - Each population accumulates mutations, evolving independently via natural selection over many generations . • Upon accumulation of reproductive isolating mechanism (RIMs), the 2 sub species can no longer interbreed to produce fertile, viable offspring. - A new species produced via allopatric speciation

• organisms share a common gene pool • same species can interbreed In nature to produce fertile, viable offspring

• The strucs are similar in (the arrangement of bones) • These traits are homologous and likely originate from a common ancestor, showing “descent” . • However, there are differences in (functions of the structures eg: humans use hand/struc to grasp, whales use fin/struc to swim) • This is because the organisms adapted differently to different environments via natural selection **, showing **“descent w modification”