Ap Bio Chapter 22 Outline - Evolution­ D?escent with Modification or a Change in the Genetic Composition of a Population from Generation to Generation

Chapter 22 Outline

Evolution­ d​escent with modification or a change in the genetic composition of a population

from generation to generation

I. The Darwinian revolution challenged traditional views of young Earth inhabited by

unchanging species

A. ScalaNaturaeandClassificationofSpecies

1. Before Darwin several greek philosophers had ideas of evolution

a) Aristotle recognized certain affinities among organism's

(1) said life could be arranged in a ladder or scale increasing in complexity

(a) scala naturae

b) Linnaeus developed a two part naming system

(1) still used today

(2) Nested classification system which grouped similar species

into general categories

B. IdeasAboutChangeOverTime

1. Fossils­​the remains or traces of organisms of the past

a) Darwin drew a lot of his work from these

b) many fossils are found in sedimentary rocks formed in the same

and mud that settled in the mud of various sea waters (1) new layers of land are called s​trata

(a) paleontology​is the study of fossils

(i) the older the fossil stratum the more

dissimilar its fossils were to current life

forms

c) catastrophism­t​heprinciplethateventsinthepastoccurred

suddenly and were caused by mechanisms different from those operating in the present

(1) each boundary between strata represented a catastrophe d) James Hutton proposed that change could occur gradually by

mechanisms that still occurred in the present day

(1) the ideology of u​niformitarianism​was incorporated

Hutton’s ideas.

(a) states that mechanisms of change are constant

over time C. Lamarck’sHypothesisofEvolution

1. Only a few proposed ideas on how evolutionary change occurred a) he is known for his incorrect hypothesis of how life evolved

2. Use and Disuse

a) the useful traits are passed on to future offspring meanwhile the

not useful traits are not passed on

3. Evolution occurred because organisms have an innate drive to become

more complex

II. Descent with modification by natural selection explain the adaptations of organisms and the unity and diversity of life

A. Darwin’sResearch

1. At a young age, Charles Darwin always loved nature and science.

However he did not find the world of medicine appealing so he went into

the field of clergy. B. TheVoyageoftheBeagle

1. Primary mission was the chart poorly known structures of the South American coastline

a) while out, he observed the various plants and animals were well adapted to the conditions and displayed similar characteristics as some of the other south american plants.

b) Landed in Galapagos where he observed most of his ideas

C. Darwin’sFocusonAdaptation

1. Adaptations­​inherited characteristics of organisms that enhance their survival and reproduction in specific environments

a) he saw that various finches had different types of beaks, and each beak had a specific job.

(1) from this came n​atural selection

D. OriginofSpecies

1. Descent with modification

a) Darwin scarcely used the word evolution in The Origin of Species. (1) Instead he used the phrase descent with modification.

(a) All organisms are related through descent from a common ancestor that lived in the remote past.

(b) Over evolutionary time, the descendents of that

common ancestor have accumulated diverse modifications, or adaptations, that allow them to survive and reproduce in specific habitats.

b) Viewed from the perspective of descent with modification, the history of life is like a tree with multiple branches from a common trunk.

(1) Closely related species, the twigs on a common branch of the tree, shared the same line of descent until their recent divergence from a common ancestor.

c) Linnaeus recognized that some organisms resemble each other more closely than others, but he did not explain these similarities by evolution.

(1) However, his taxonomic scheme fit well

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