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Immagini e concetti della biologia Sylvia S. Mader Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

A8 - Principles of evolution Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Darwin’s journey In 1831 Charles Darwin made a journey around the world. He observed that species change from place to place and through time. Charles Darwin (1809-1882) Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Darwin’s journey Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Darwin’s observations Rheas living in South America had the same adaptations to desert as african ostriches. Darwin's Rhea Marine fossils in the rocks of the mountains. Earth’s strata contain fossils Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Darwin’s observations Similar organisms living in the Patagonia desert and in tropical forests showed different characteristics. Patagonia desert Tropical rain forest Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Darwin’s observations Galapagos iguanas had claws and muzzle adapted to the environment. Marine Iguana New species of finches on the Galàpagos had different beaks in relation to their feeding habits. Woodpecker finch Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Darwin’s knowledges supporting evolution Charles Lyell (geologist) Earth is old enough for evolution to have resulted in the species seen today. Georges Cuvier (paleontologist) Catastrophes caused evolution to occur. Jean-Baptiste de Lamarck (zoologist) Inheritance of acquired traits is a mechanism of evolution. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Artificial selection mimics natural selection wild mustard Kohlrabi Brussels sprout Chinese cabbage In agriculture humans select and maintain specific traits in certain populations. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

The natural selection Members of a population have inheritable variations Stronger individuals are more likely to reproduce A population is able to produce more offsprings than the environment can support There is always a struggle for survival Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

The natural selection Darwin observed natural selection in Galàpagos finches. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Studying the natural selection today Scientist are observing variations in the beak of Medium Ground Finch (Geospiza fortis) in relation with climate changes at Galàpagos islands. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evolution “A series of changes in a population over time, due to an accumulation of inherited differences”. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Fossils provide records for the past. Evidences for evolution Fossils provide records for the past. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evidences for evolution The fossil records indicate that life has progressed from the simplest organisms to more complex ones. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evidences for evolution Some fossils (as Archaeopteryx lithographica) have intermediate characteristics between two different groups (i.e. birds and reptiles). Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evidences for evolution COMPARATIVE ANATOMY Homologous structures are anatomically similar among certain organisms and suggest that organisms have a common descendent. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evidences for evolution COMPARATIVE ANATOMY Some organisms have vestigial structures, memories of functional structures in ancestors. Vestigial structure Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evidences for evolution BIOGEOGRAPHY Some plants and animals evolved in particular locations. Therefore similar environments, widely separated, contain different organisms with similar adaptations. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

Evidences for evolution Molecular evidences The degree of similarity of DNA (or amino acid) base sequences shows a pattern of relations between organisms. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012