Phylogenetics and Family Trees

Short: Phylogenetics studies the evolutionary relationships between species and usually represents them as family trees. Modern methods mainly use DNA sequence comparisons to determine these relationships.

In more detail: The more similar the DNA sequences of two species, the more closely related they usually are, and the more recent their common ancestor.

In detail

• Cladograms: Branching diagrams show which species share a common ancestor and when their lineages split.
• Molecular clock: The number of mutation differences between DNA sequences can help estimate the approximate time when two species diverged.
• Morphological traits: Before genetic technology, family trees were based mainly on external and anatomical similarities, which sometimes led to misjudgments.
• Convergence as a source of error: Similar external traits can arise from convergent evolution rather than close kinship, which can distort family trees.
• Horizontal gene transfer: Especially in bacteria, the exchange of genes between unrelated species complicates the classic tree representation.
• Fossil evidence: Fossils provide important additional clues for dating and verifying molecular family trees.
• Application in medicine: Phylogenetic methods help, for example, track how viruses such as flu strains change over time (dna-und-gene, konvergente-evolution).