Darwin & Natural Selection Chapter 22

YOU MUST KNOW How Lamarck’s view of the mechanism of evolution differed from Darwin’s. Several examples of evidence for evolution and how they support how organisms have changed over time. The difference between structures that are homologous and those that are analogous, and how this relates to evolution. The role of adaptations, variation, time, reproductive success, and heritability in evolution.

I. History of Science Carolus Linnaeus (1707 – 1778) Developed taxonomy – naming and classifying of organisms Developed binomial nomenclature – two part naming system consisting of genus and species

Georges Cuvier (1769-1832) French geologist, “father of paleontology” Opposed ideas of evolution – argued that fossils did not change gradually

Charles Lyell (1797 – 1875) 1. Geologist, friend of Darwin’s 2. Geologic processes are slow are have occurred over long expanses of time (***Earth is a lot older than was thought***)

Jean-Baptiste de Lamarck (1744 – 1829) 1. Developed a theory of evolution based on 2 principles a. Use and disuse – parts of the body used more become larger and stronger and vice-versa b. Acquired characteristics can be inherited * His idea that organisms evolve was correct, but his explanation of how was not!

Charles Darwin (1809- 1882) 1. Traveled on the HMS Beagle from 1831 – 1836, observing and collecting species 2. Developed the theory of evolution by natural selection

II. Natural Selection Individuals in a population vary in their traits, many of which are heritable a. Adaptations – heritable characteristics that enhance an organism’s ability to survive and reproduce in specific environments

2. More offspring are produced than can survive 2. More offspring are produced than can survive. There are more individuals than the environment can support  COMPETITION!!!

3. Individuals with adaptations that are better suited to the environment in which they live are more likely to survive and reproduce than those that do not have those traits.

***POPULATIONS EVOLVE, INDIVIDUALS DO NOT!!! Evolution occurs as the unequal reproductive success in a population causes an increase in numbers of individuals possessing the desirable traits and a decrease in numbers of those not possessing desirable traits ***POPULATIONS EVOLVE, INDIVIDUALS DO NOT!!!

Tip: When explaining evolution, avoid any language that makes it sound like a species/organism “needs” or “wants” a feature so it evolves. Don’t write “survival of the fittest.” Discuss how selection favors a feature that results in leaving more offspring. Evolution is not goal oriented.

III. Artificial selection – process by which species are modified by humans selecting for traits A. Darwin bred pigeons to help him further test/develop the ideas he started to formulate on the Beagle

IV. Evidence for Evolution Direct Observations 1. Insect populations rapidly become resistant to DDT and other pesticides 2. Drug-resistant bacteria and viruses 3. Guppies moved to low- predation environments produce fewer and larger offspring in less than 30 generations 4. Beak changes in Galapagos finches

Homology 1. Similarity resulting from common ancestry 2. Homologous structures – anatomical structures that have been adapted to different environments/functions, but have the same underlying structure

Embryonic homologies – early development shows similarities that are not necessarily seen in adult forms a. Ex. All vertebrate embryos have a post- anal tail and pharyngeal pouches

Vestigial Structures – remnants of structures that served a purpose in an ancestor, but have limited/no function now a. Hip bones in pythons and whales

a. Similarities in DNA, RNA, or protein sequences Molecular Homologies a. Similarities in DNA, RNA, or protein sequences *BLAST website

Convergent Evolution 1. 2 species that are not very closely related resemble each other because they have adapted to similar environments

2. Analogous structures – structures that have the same function/address the same environmental challenge but do not indicate close relatedness

The Fossil Record 1. Any remains or traces of organisms from the past (bones, footprints, etc.) a. Found in sedimentary rock 2. Show change in organisms over time 3. Transitional fossils have been found that link ancient organisms to modern species

1. Geographic distribution of species Biogeography 1. Geographic distribution of species 2. Species that live nearer each other tend to be more closely related. 3. Continental drift – break-up of Pangaea 4. Endemic species – species found only in a certain geographic location Marine iguanas are endemic to the Galapagos islands

V. Inclusive fitness A. Altruism – behavior that reduces an individual’s fitness but increases the fitness of others in the population Warning calls

B. Kin selection – natural selection that favors altruistic behavior by increasing the reproductive success of relatives

C. Inclusive fitness – the total effect an individual has on proliferating its genes by both producing its own offspring and helping close relative produce offspring