Evidences and Theories of Biological Evolution — Important Questions

13-14 species of finches with different beak shapes from one ancestor

On the Galapagos Islands, Darwin observed 13-14 species of finches, each with different beak morphologies adapted to different food sources, all descended from a single South American mainland ancestor. This is the classic example of adaptive radiation and provided key evidence for natural selection.

Ontogeny recapitulates phylogeny

Ernst Haeckel's Biogenetic Law (1866) states 'Ontogeny recapitulates phylogeny' — the embryonic development (ontogeny) of an individual organism retraces the evolutionary history (phylogeny) of its species. Evidence: all vertebrate embryos show gill clefts and notochord at early stages.

True

This is the core postulate of Lamarckism — the inheritance of acquired characters. Lamarck proposed that structural or functional changes acquired due to use/disuse or environmental influence during an organism's lifetime would be passed to offspring. This was disproved by Weismann's experiment and modern molecular genetics.

Charles Darwin

Charles Darwin (1859) proposed the theory of natural selection in 'On the Origin of Species.' It was co-proposed independently by Alfred Russel Wallace. Darwin's theory had five main postulates: overproduction, variation, struggle for existence, natural selection, and inheritance.