Covers the two main evolutionary processes, anagenesis and cladogenesis, then the steps of generating and sorting genetic diversity. It goes on to sources of variation such as point mutations, regulatory changes, gene and genome duplication, and how eukaryotes and prokaryotes combine beneficial mutations. Examples include lactase persistence, histone H4 and FoxP2. The note also gives four mnemonics and recap questions, and it ends with a separate section on Trypanosoma and protozoa that is unrelated to the topic.
Topic 78 of 105 in the MU Sofia syllabus for Biology (Medicine, Year 1). The free AceMed note covers it in 9 sections, about 1,561 words (11 min of reading), with 10 flashcards.
In this note
Molecular evolution.
Understanding Evolution at the Molecular Level
Core Process of Molecular Evolution
Sources of Genetic Variation
Molecular Aspects Beyond Mutation
Molecular Clues from Human Evolution
RECAP QUESTIONS
MNEMONICS
Protozoa. Phylum Sarcomastigophora. Subphylum Mastigophora (Flagellata). Genus Trypanosoma
Understanding Evolution at the Molecular Level
1. Two Key Processes of Evolution
Evolution operates through two primary mechanisms:
Phyletic evolution, also known as anagenesis, refers to the gradual transformation of a single species over time without branching. It is a linear progression. Once enough changes accumulate, the species is reclassified, and the ancestral form is considered extinct, even though it still has descendants.
Speciation, or cladogenesis, is the branching of evolutionary lineages. This occurs when a single species splits into two or more distinct species, leading to biodiversity.
Together, these mechanisms explain both the gradual transformation within a lineage and the appearance of new species.
Core Process of Molecular Evolution
2. Steps of Evolutionary Change
Generation of Diversity: This involves the random creation of new genetic material through mutations and other mechanisms that mix genes.
Sorting of Diversity: Natural selection and genetic drift then determine which variations persist in a population. Selection is non-random and depends on survival and reproduction, while drift is random.
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