Introduction into evolution (click Picture). Evolution Notes. What accounts for the diversity of life?. 1. Evolution — change over time ; process by which modern organisms have descended from ancient organisms. 2. Components of genetic code common to all organisms
a. DNA bases (ATGC)
b. Converting glucose to ATP for energy.
EX. Gravity, plate tectonics
a. By selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime; these traits could then be passed on to their offspring.
Example: Giraffe could not reach the leaves so it stretched it’s so that all of its offspring had long necks.
b. Problem: Did not know how traits were
Over timenatural selection results in changes in the inherited traits of a population
3. Darwin—Evolution by Natural Selection
You acquire athletic skills or the ability to play a musical instrument
1. Made observations in Galapagos Island as a naturalist-(travelled on a boat called HMS Beagle)
a. Observations made:
ii. Traits of similar species varied noticeably among different islands of the Galapagos
b. Example: Noted similarities and differences in tortoises and finches on Galapagos Islands in South America.
c. Hypothesized that animals adapted to local conditions on islands after their arrival.
a. Helped scientists recognize that Earth is many millions of years old; older than anyone believed
3. Malthus (studied human populations)
a.If the human population continued to grow unchecked, sooner or later there would be insufficient living space and food for everyone creating a struggle to survive
4. Farmers and Artificial Selection—Nature provided the variation among organisms and humans selected for the variations they found useful
1. Struggle for existence—more offspring are produced than can survive; therefore, members of each species compete regularly to obtain food, living space, and other necessitiesof life
2. Survival of the Fittest (also called Natural Selection)—individuals with an adaptation (genetic difference) that makes them more “fit” for a certain environment will survive and reproduce; those not suited will die or produce few offspring
3. Descent with modification- each living species has descended, with changes, from a common ancestor. (Phylogeny)
1. Fossil record- examples of many species that have lived for a time and then became extinct
2. Geographical Distribution of living species— when looking at similar environments on different continents, different animals had similar anatomies and behavior because of adaptation
3. Homologous body structures—structures that have different mature forms but develop from the same embryonic tissues; provide strong evidence that all four-limbed vertebrates have descended, with modifications, from common ancestors
Comparative anatomies realized that although these vertebrates evolved in different directions, with changes in size, shape, and function, they all used common bone elements, as well as homologous nerve systems, blood circulatory systems, and other organ systems, thus indicating a common vertebrate ancestor. In contrast to teleological explanation that emphasize design for particular function, the vertebrate forelimb uses a common underlying ancestral structure for different functions.
Ancient lobe-finned fish
4. Vestigial organs – organs with functions that are useless in current organisms, but functional in distant ancestors.
5. Similarities in embryology—early stages, or embryos, of many animals with backbones are very similar
1. Populations—all individuals of a species that live together in one area
2. Gene pool—consists of all genes, including all the different alleles that are present in a population
Genetic drift – a random chance in allele frequency. Certain individuals may leave more descendants than others, and over time this can cause an allele to become common in the population.
Not caused by natural selection, but by chance.
a. Behavioral Isolation—two populations are capable of interbreeding but have differences in courtship rituals or other reproductive strategies that involve behavior.
Eastern meadowlarks will not respond to western meadowlark mating songs.
b. Geographic Isolation—two populations are separated by geographic barriers such as rivers,mountains, or bodies of water
c. Temporal Isolation—two or more species reproduce at different times
3 similar species of orchid live in the same rain forest. Each species releases pollen only on a single day. Because the 3 species release pollen on different days, they cannot pollinate (reproduce with) one another.
Evolution quiz on Thursday January 13th!