Allopatric Speciation Statements Isolation of a Species are Less New or Species group of populations adapted favourable generally give individuals due within which organisms fail to alleles are rise to fertile to mountain genes are free to pass on their passed onto the offspring. ranges, oceans mix by alleles to the next generation. or migration. interbreeding. next generation. Genetic Over time and Individuals Environmental differences, due many within a Best selection to mutations in generations population may survive (survival pressures are the separated different not be able to of the fittest). different for populations, characteristics compete as well each group. begin to begin to emerge. as others. accumulate. The original Starting off with Geographical Healthiest or New phenotypes environment one population, barriers prevent best individuals gradually appear may be very a common gene interbreeding of will be the most in the different from pool. populations. likely to breed. population. the isolated area. Genetic drift Individuals (random Healthiest or Different within a Mutations give mutations/ best individuals mutations arise population may rise to different differences) will be the most in different become better at phenotypes. occurs likely to breed. populations. exploiting their independently. environment. Members of the Usually a good different Evolution occurs Mutations correlation with populations may Often isolated and new occurring in the phenotype become so populations are biological each population (underlying new distinct that they very small. species are will be different. alleles) and the can no longer formed. environment. breed.
Allopatric Speciation Statements Species generally give rise to fertile offspring. Isolation of a group of individuals due to mountain ranges, oceans or migration. Species are populations within which genes are free to mix by interbreeding. New or favourable alleles are passed onto the next generation. Less organisms fail to pass on their alleles to the next generation. Best adapted survive (survival of the fittest). Over time and many generations different characteristics begin to emerge. Environmental selection pressures are different for each group. Genetic differences, due to mutations in the separated populations, begin to accumulate. Individuals within a population may not be able to compete as well as others. Starting off with one population, a common gene pool. The original environment may be very different from the isolated area. Geographical barriers prevent interbreeding of populations. Healthiest or best individuals will be the most likely to breed. New phenotypes gradually appear in the population. Genetic drift (random mutations/ differences) occurs independently. Healthiest or best individuals will be the most likely to breed. Different mutations arise in different populations. Mutations give rise to different phenotypes. Individuals within a population may become better at exploiting their environment. Mutations occurring in each population will be different. Usually a good correlation with the phenotype (underlying new alleles) and the environment. Members of the different populations may become so distinct that they can no longer breed. Often isolated populations are very small. Evolution occurs and new biological species are formed.
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