What is Evolution?
Imagine a big family tree for all life. Evolution means living things change slowly over millions of years. NOT stable world—always changing! Mutations (DNA typos) start it, but only heritable ones count.
Proof It Happens (Evidence)
Fossils: Found in sedimentary rock (layers like pages). Older = simpler, NOT like modern species. Show life's history!
Body Parts (Homologous): Same origin/structure, different use (your arm = whale flipper). Strongest evidence: DNA similarities.
NOT Homoplasy: Similar look but NO shared ancestor (bat wing vs. insect wing).
Watch Intro To Evolution:
How It Happens - Natural Selection
Organisms with good traits survive AND reproduce more. NOT acquired traits or use/disuse. Adaptation = better chance to live + make babies.
Systematics: Groups & Trees
Organize life like library. Clade: Full family with ancestor + ALL kids, defined by shared derived character (synapomorphies—like new fur).
Paraphyletic: Some but not all kids (reptiles without birds). Trees: Branch length = evolutionary change amount.
Species Concepts: Biological = can't breed (gene flow stops). Traits for ID: Consistent in populations.
Watch: Systematics And Trees
Test Flashcards⚡
Practice Quiz
DepEd MELC Biology 2 - Ace Your Pre/Post Test! (Final Version)
support@cellsatwork.com