Gene flow is genes moving between two populations.
the transfer of genes from one gene pool to another
two populations transferring genes
There are two forms of "theory." Colloquial usage associates the word with a "guess." However, the scientific usage of the word calls upon a body of evidence to explain scientific phenomenon. For instance, we know the universe is comprised of Atoms; Atomic theory explains the makeup through physics equations. Likewise, Evolution theory explains the mechanism that powers speciation, namely natural selection. Both Atomic and Evolutionary theory are supported by a large body of evidence.
Second answer
Evolution, the change in allele frequency over time in a population of organisms, is fact.
The theory of evolution by natural selection explains much about the fact of evolution.
That is what theories in science do. They explain phenomenon by being the result of many tested hypothesis, supported by myriad lines of converging evidence, be internally consistent and be able to generate prediction for further testing.
Speciation Adaptive radiation refers to changes in a species in response to varying environmental conditions.
many new species form
The distribution of alleles changes due to random chance.
or
The allele frequency of a population changes due to a bottleneck effect. <apex>
Tissue development
Development of a coelom
Population bottlenecks
Reproductive isolation
Niche availability
Which of these organisms is considered the most complex?
by assembling large amounts of information in a single location
The island finches have more gene flow
Panel discussion
Lizards evolved after earthworms.
Apex is Mergus serrator and Mergus merganser.