Endosymbiotic Theory

Evolution & Adaptation 1967

Discoverers: Lynn Margulis

Overview

The proposal that mitochondria and chloroplasts originated as free-living prokaryotes engulfed by ancestral eukaryotic cells, forming a symbiotic relationship.

Significance

Explained the origin of complex eukaryotic cells and demonstrated that cooperation, not just competition, drives major evolutionary transitions.

Methodology

Comparative analysis of organelle DNA, double membranes, and ribosome structures showing bacterial ancestry of mitochondria and chloroplasts.

Impact