Speciation: How New Species Arise

Short: Speciation describes the process by which two or more distinct species emerge from a single population over time. The decisive step is usually the isolation of populations, which then develop separately.

In more detail: Two populations are considered separate species when they can no longer, or no longer want to, successfully reproduce with each other.

In detail

• Allopatric speciation: Geographic barriers like mountains, rivers, or oceans spatially separate populations, which then develop independently.
• Sympatric speciation: New species arise despite shared habitat, for example through different food preferences or reproductive timing.
• Genetic drift: Random changes in allele frequency in small, isolated populations can lead to significant differences over generations.
• Reproductive isolation: Behavioral differences, different reproductive timing, or physical barriers prevent successful crossbreeding between separated populations.
• Darwin’s finches as an example: On the Galápagos Islands, several finch species with different beak shapes evolved from an original species through isolation.
• Hybrid zones: At the boundaries between two closely related species, individuals sometimes still mate, which can lead to mixed forms.
• Timeframe: Speciation can take just a few generations in rapidly reproducing organisms or millennia for long-lived species (mitose-und-meiose, dna-und-gene).