better notes

better notes - Lecture 1 1 Chapter 22 Descent with...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 1 1. Chapter 22: Descent with modification: A Darwinian view of life a. Evolution – Two main ideas i. Change over time w/ genetic composition of a population ii. Descent of modern organisms with modification from pre-existing organisms 1. Fits what we observe in nature: common ancestor changes through time, give rises to groups of new living things 2. Explains great diversity of life on earth 3. Explains common traits we see in all living things b. Evolutionary adaptation: accumulation of inherited characteristics that enhance an organisms' ability to survive in specific environments (ADAPTING to new environments) i. Traits that help organisms survive are passed on ii. Those that are less favorable become less and less common c. Pre-Darwinian theories of evolutionary i. Jean Baptiste Lamarck : inheritance of acquired characteristics 1. Bodies of living organisms are modified through use or disuse of parts 2. Modifications are inherited through offspring 3. Idea turns out to be incorrect 4. Does not translate into traits being passed down to offspring ii. Darwin and Wallace develop theory independently 1. Darwin – voyage of the beagle 2. Wallace – naturalist in Indonesia d. Natural selection – the unequal survival and reproduction of organisms due to environmental forces, resulting in preservation of favorable traits and adaptations i. Process selects from what is available in gene pool ii. New characteristics are not created in demand Lecture 2 1. Mechanism behind natural selection (pg. 458) 2. Competition for survival and reproduction a. Potential for rapid reproduction i. Have ability to reproduce quickly in any given generation ii. Not all offspring survive/reproduce iii. If they reached potential, all populations would increase exponentially iv. Entire surface of earth would be covered by organisms v. Resources available are limited
Background image of page 1

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

View Full DocumentRight Arrow Icon
vi. Food, water, space, access to mates vii. Limit reproductive potential b. Relatively constant resources and population size over time i. Population levels remain relatively constant ii. Potential for increase, but finite resources limit ability to reproduce 3. Natural Selection – On average, the fittest organisms leave the most offspring a. Competition between organisms for resources (food, primarily) i. Affect survival and reproduction ii. Must compete for resources b. Variability in structures and behaviors (different traits) i. By observing population, no two people look alike ii. Reflection of variability we see in nature iii. Behaviors, effectiveness of enzymes, biochemical reactions, etc iv. Variability means that out of organisms competing, some have traits that help them survive and reproduce v. MAINLY DEALS WITH GENETIC MAKEUP 4. Evolution – Genetic makeup of the population changes over time, driven by natural selection a. On average, fittest organisms leave most offspring b. Some variability is inherited by offspring 5. Artificial selection a. Selective breeding of organisms to encourage occurrence of desirable traits
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/14/2011 for the course BIOL 1201 taught by Professor Wishtichusen during the Spring '07 term at LSU.

Page1 / 12

better notes - Lecture 1 1 Chapter 22 Descent with...

This preview shows document pages 1 - 3. Sign up to view the full document.

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