The treeʹs horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Letʹs say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.

According to this tree, what percent of the species seem to be extant (i.e., not extinct)?

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#Question id: 15719

#Section 2: Evolution

Carolus Linnaeus (1707–1778), who established the framework of modern taxonomy in his Systema Naturae (1735), won worldwide fame for his exhaustive classification of plants and animals, undertaken in the hope of discovering the pattern of the creation. Linnaeus classified,

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#Question id: 15720

#Section 2: Evolution

The geologists ________ expounded the principle of uniformitarianism, holding that the same processes operated in the past as in the present and that the data of geology should therefore be explained by causes that we can now observe.

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#Question id: 15721

#Section 2: Evolution

Lamarck argued that species differ from one another because they have different needs, and so use certain of their organs and appendages. This hypothesis is known as?

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#Question id: 15722

#Section 2: Evolution

The variation that arises is directed toward fixed goals, so that a species evolves in a predetermined direction by some kind of internal drive, without the aid of natural selection. This hypothesis is known as,

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#Question id: 15723

#Section 2: Evolution

Neutral theory of molecular evolution of is given by,

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#Question id: 15724

#Section 2: Evolution

Neo-Lamarckism includes several theories based on the old idea of inheritance of modifications acquired during an organism’s lifetime. In a famous experiment done by,