Collection of abiotic and biotic factors together in an environment A-Ecosystem
B-organism
C-Ecology
D-species
E-abiotic
F-Biotic
G-community
H-population

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.