Islands epitomize allopatric speciation, where geographic isolation causes individuals of an original species to accumulate sufficient genetic differences to prevent them breeding with each other when they are reunited.

Speciation involves reproductive isolation of groups within the original population and accumulation of genetic differences between the two groups. In allopatric speciation, groups become reproductively isolated and diverge due to a geographical barrier.

when two or more species reproduce at different times. Flowers may bloom on different days and they cannot pollinate each other. Speciation in Galapagos finches occurred by founding of a new population, geographic isolation, changes in the new population’s gene pool, behavioral isolation and ecological competition.

Geographic isolation of a group of organisms eventually stops gene flow from other groups of same species. Thus isolated group evolves by accumulating new mutations not to be found in members of related groups.

What is another word for geographic isolation?

It was found that geographic isolation plays a key role in the evolution of reproductive isolation and divergent morphology and that divergence cannot be explained by molecular genetic variation.

• 3 Types of Reproductive Isolation. These are “_________________________ mechanisms” that could lead to speciation.
• Geographic Isolation. _______________________________________ occurs when two populations are separated _____________________________ by geographic barrier.
• Temporal Isolation.
• Behavioral Isolation.

The geographical isolation is the physical separation of two populations by the geographical barriers. This occurs through adaptive radiation and allopatric speciation. The reproductive isolation is the separation of two populations of the same species, preventing interbreeding and production of a fertile offspring.

The separation of two populations of the same species or breeding group by a physical barrier, such as a mountain or body of water. Geographical isolation may ultimately lead to the populations becoming separate species by adaptive radiation.

Postzygotic mechanisms include hybrid inviability, hybrid sterility and hybrid “breakdown.”

A controversial alternative to allopatric speciation is sympatric speciation, in which reproductive isolation occurs within a single population without geographic isolation. In general, when populations are physically separated, some reproductive isolation arises.

Speciation without geographic isolation is called: sympatric speciation.

One species does not “turn into” another or several other species — not in an instant, anyway. The evolutionary process of speciation is how one population of a species changes over time to the point where that population is distinct and can no longer interbreed with the “parent” population.

Speciation is an evolutionary process by which a new species comes into being. Speciation can be driven by evolution, which is a process that results in the accumulation of many small genetic changes called mutations in a population over a long period of time. …

Allopatric speciation, the most common form of speciation, occurs when populations of a species become geographically isolated. When populations become separated, gene flow between them ceases.

Gradual speciation is most likely to occur in species that live in a stable climate. Gradual speciation and punctuated equilibrium both result in the evolution of new species.

Prezygotic barriers include habitat isolation, behavioral isolation, temporal isolation, mechanical isolation, and gametic isolation.

The consequences of genetic drift are numerous. It leads to random changes in allele frequencies. Drift increases the amount of genetic differentiation among populations if no gene flow occurs among them. Genetic drift also has two significant longer-term evolutionary consequences.

Genetic drift describes random fluctuations in the numbers of gene variants in a population. Genetic drift takes place when the occurrence of variant forms of a gene, called alleles, increases and decreases by chance over time. These variations in the presence of alleles are measured as changes in allele frequencies.

GENETIC DRIFT AS A CAUSE OF INBREEDING As we have seen, inbreeding results from drift because alleles become identical by descent (IBD).

“Genetic drift is the gradual change in the frequency of specific alleles in a population to be more or less common [and]… occurs when there is a change in the environment that makes specific traits more or less favorable for fitness.”

There are two major types of genetic drift: population bottlenecks and the founder effect. A population bottleneck is when a population’s size becomes very small very quickly.