POPULATION SIZE AND RATE OF EVOLUTION

 

It has been supported by the evidence that very small populations can have rapid genetic changes. In fact very tiny populations that have been isolated from a parent population can change rapidly to the point that its individuals can no longer interbreed with its larger parental population. A small number of individuals that become geographically isolated is called a “founder population.” The very small population is then called a “splinter population.”

In very large populations that are well adapted to environmental conditions usually have very slow or virtually no genetic changes due to gene flow. So those populations often remain unchanged for many years, perhaps centuries or thousands of years. On the other hand, splinter populations often change rapidly due to genetic drift followed by genetic fixation. So frequently that we see large populations remain in “equilibrium” for long periods of time, but that “equilibrium” is punctuated infrequently by brief bursts of speciation due to the isolated tiny populations that have splintered off from the mainland parental population. This process is called “punctuated equilibrium” and very well may be the most common way by which new species evolve.

It appears that population size determines the rate of evolutionary change and speciation. The formation of fossils is a rare event even in very large populations. Most animals that die are torn apart by predators leaving little left to fossilize. In addition, soil erosion, flooding, volcanism, and other geological events scatter many remains so it is difficult to find whole fossil specimens in tact. Since most new species form from tiny splinter populations, the chance of finding a that rare fossil “link” is very, very small. As a result, paleontologists find many “fossil gaps.”

Unfortunately, creationists jump on this rarity of fossils as “evidence” of special creation, claiming that if gradual evolutionary change occurred then a smooth lineage of many fossils would have been found linking all groups of plants and animals. This shows the necessity of ignorance that creationists depend on to propagate their lies to gullible people.

 

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