Chapter 15. Darwin’s Theory of Evolution. “…the single most important scientific idea that anyone has ever had…”. 15-1 The Puzzle of Life’s Diversity. Evolution : change over time p rocess by which modern organisms descended from ancient organisms Do you remember what a theory is?.
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Darwin’s Theory of Evolution
“…the single most important scientific idea that anyone has ever had…”
Proposed evolutionary theory about how life changes over time
If you use it, it will stay (get passed on)
If you don’t, it will go away
Tendency toward perfection
Inheritance of acquired traits*
Thomas Malthus- economist
More people are born than are dying
Uncontrolled population growth = high competition for resources
What makes some survive and others die?
Darwin questioned: How does “selection” happen in nature?
Struggle for existence: competition among members of a species for food, living space, reproduction, etc.
Process by which individuals better suited to their environment survive and reproduce most successfully
Fitness: ability of an organism to survive and reproduce
Adaptation: inherited characteristic that increases an organisms chance of survival (structural, physiological, behavioral, etc.)
Successful adaptations will increase fitness
If you survive/reproduce, you pass on genes = more of those genes in nature
Each living species has descended- with changes- from other species over time
Common descent: all living things come from a common ancestor
fossil record- organisms have come and gone but can be related/connected to current organisms
Structures that serve no useful function
Homologous structures that the organisms no longer needs
Ex: whale “legs”
similarities in embryology- many embryos look the same
common cells growing in similar ways