bio - Chapter 23: Evolution by Natural Selection...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 23: Evolution by Natural Selection --scientific theories usually have 2 parts: a pattern and a process. (ex: special creation pattern = species seemed to stay the same through time and created independently of each other; process = instantaneous and independent creation of organisms by God. --“descent with modification” from a common ancestor (Darwin) I. The PATTERN of Evolution: have species changed through time? (homology—similarities that exist because of common descent analogous/convergent traits—similar traits that did not exist in a common ancestor convergent evolution—when natural selection favors similar solutions to the problems posed by a similar way of making a living. Convergent evolution leads to analogous trits. They are shared by species even though they were not present in their common ancestor) A. Evidence that species changed through time: i. Extinction—if species went extinct then they have changed through time ii. Transitional forms—a fossil species with traits that are intermediate between those of older and younger species 1. ex) fossil records show that whales evolved from land mammals to aquatic ones. iii. Environmental change—theory of plate tectonics, seashells found in mountains. If the earth changed, animals must have iv. Vestigial traits—reduced or incompletely developed structures that have no function or reduced function, but are clearly similar to functioning organs/structures in other species. (ex: human coccyx is useless but similar to monkey tail) v. Populations changed in response to change in environment (ex: bacterial resistance to drugs) B. Evidence that species are related (and have a common ancestor): i. Phylogeny based on traits (phylogeny—family tree of populations or species)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 4

bio - Chapter 23: Evolution by Natural Selection...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online