Understanding Change: The Principles of Biological Evolution

The Theory of Evolution

Charles Darwin’s theory of evolution by natural selection is the cornerstone of modern biology. It posits that species are not fixed but change over time, adapting to their environments. This adaptation relies on inherited variations within populations.

Darwin initially proposed that individuals with advantageous traits were more likely to survive and reproduce – a process he termed ‘natural selection’. This leads to an increase in the frequency of those beneficial alleles within a population.

Natural Selection

Natural selection is the driving force behind adaptive evolution. Organisms with traits better suited to their environment are more likely to survive and pass on those traits.

This isn't about ‘survival of the fittest’ in a simplistic sense; it’s about reproductive success. Individuals best adapted to *reproduce* will contribute more genes to the next generation.

Fitness = Reproductive Success

Mechanisms of Evolution

Beyond natural selection, other mechanisms contribute to evolutionary change. Genetic drift refers to random fluctuations in allele frequencies, particularly significant in small populations.

Gene flow, the movement of alleles between populations, can also introduce new variation and alter existing allele frequencies.

Evidence for Evolution

The evidence supporting evolution is overwhelming. It’s based on fossil records, comparative anatomy, embryology, biogeography, and molecular biology.

Fossils demonstrate transitional forms – organisms with characteristics intermediate between ancestral and descendant groups. Similarities in DNA sequences across diverse species provide strong genetic evidence.

Frequently asked questions

Try it live

Everything above runs in your browser — open Biological Evolution Simulator: Natural Selection in 3D and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.