* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 10. Darwin and more
Survey
Document related concepts
Objections to evolution wikipedia , lookup
Sociocultural evolution wikipedia , lookup
Sexual selection wikipedia , lookup
Unilineal evolution wikipedia , lookup
On the Origin of Species wikipedia , lookup
Hindu views on evolution wikipedia , lookup
The Expression of the Emotions in Man and Animals wikipedia , lookup
Natural selection wikipedia , lookup
Hologenome theory of evolution wikipedia , lookup
Creation and evolution in public education wikipedia , lookup
Acceptance of evolution by religious groups wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
Catholic Church and evolution wikipedia , lookup
Transcript
_____. Darwin “Nothing in biology makes sense except in the light of evolution.” Biologist (1900 – 1975) Charles Darwin at age 31 Charles Darwin in later years What is Evolution? Evolution - the gradual change in a species over time. Darwin at age 31 in 1840 (4 years AFTER his voyage) Darwin’s Voyage of Discovery A reconstruction of the HMS Beagle sailing off Patagonia (South America). The Voyage of the Beagle The Galapagos Islands Darwin’s Finches Observe the different feather colors, and different size and shape of the beaks. AdaptationA trait that helps an organism survive and reproduce. Ex. The Finch’s Beak helps it to obtain food. Draw this table with only the column headings. Make this table VERY LARGE! Darwin’s Observations 1 2 3 4 Darwin’s Conclusions In your own words! Darwin’s Observations and Conclusions Observation 1: Species over-produce (reproduce in excess). Many more are produced than can ever survive to adulthood. Observation 2: Environmental resources (food, water, habitat) are limited. Conclusion #1: When the environment cannot support the number of individuals, it leads to a struggle for existence (competition) among individuals, with only some of offspring surviving in each generation. Over-production + limited resources competition In other words…. When there are too many organisms in one place, they have to compete for: – Food – Living Space – Water »They do not all survive. Darwin’s Observations and Conclusions Observation 3: There is variation in characteristics of individuals in a population - no two individuals are exactly alike. Observation 4: Much of this variation between individuals is inheritable (passed from parents to offspring). Variation in Birds Variation in Dogs Variation in Humans Darwin’s Observations and Conclusions Conclusion 2: Survival in the struggle for existence depends partly on the inherited characteristics of individuals. Individuals who inherit characteristics best fitted to their environment are more likely to survive and reproduce than less fit individuals. Inherited Variations + Competition Natural Selection In other words…. Survival of the Fittest! Organisms that are best suited (adapted) to their environment will survive and reproduce! Their offspring will inherit this helpful adaptation and will survive and reproduce. Their offspring will inherit this helpful adaptation and will survive and reproduce. And so on….. Example Page 143 Example Page 144 Darwin’s Observations and Conclusions Conclusion 3: The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations. Natural Selection + Time Evolution Taken together, these three conclusions are a statement of Darwin’s Theory of Evolution. Darwin’s Points • Species over-produce (reproduce in excess). Many more offspring are produced than can ever survive to adulthood. • Limited resources (food, water, shelter) lead to competition for these resources. • There is variation within the population. Some of these variations have an advantage over others. • Those species members with an advantage will be selected to survive and reproduce, and their offspring will inherit this advantageous trait. • As a consequence the species will change over time. V*I*S*T V V = Variation: All life forms have variations (differences in I I = Inheritance: Genetic traits are inherited from parents S T traits between members of a species). Some examples in humans: height, skin color, eye color and are passed on to offspring. S = Selection: Organisms with traits that are favorable to their survival get to live and pass on their genes to the next generation. T = Time: Evolution takes time; usually, millions of years. Evolution can happen in a few generations (for example, in bacteria and viruses), but major changes take long periods of time. Evolution “Equations” O Overproduction + LR C Limited Resources Competition Evolution “Equations” IV Inherited Variations C + Competition NS Natural Selection Evolution “Equations” NS Natural Selection + T E Time Evolution How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant mutation! How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant Generation 3: 0.76 not resistant 0.24 resistant How natural selection works Resistance to antibacterial soap Generation 1: 1.00 not resistant 0.00 resistant Generation 2: 0.96 not resistant 0.04 resistant Generation 3: 0.76 not resistant 0.24 resistant Generation 4: 0.12 not resistant 0.88 resistant Evolution’s Core Principle Natural Selection “I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection.” —Charles Darwin from "The Origin of Species" Mutation = random, inheritable changes in DNA sequences that introduce new alleles into a species’ gene pool. •members.tripod.com/~Alphacentaur/ X-men.JPG The Missing Link: HOW does Evolution occur? A major problem in Darwin’s theory was the lack of a mechanism to explain natural selection. How were favorable variations (adaptations) passed on to later generations? With the rediscovery of Mendel’s work in the first half of the 20th century, the missing link in evolutionary theory was forged. Darwin’s theory supported by genetics is known as the modern synthesis. Darwin Is evolution progressive? This is not an easy question to answer. From a plant's perspective, the best measure of progress might be photosynthetic ability; from a spider's it might be the efficiency of its web in catching insects. The problem is that we humans think it’s “all about us”! We often define progress by how it affects our species. But that definition is anthropocentric. It is tempting to see evolution as a grand progressive ladder with Homo sapiens emerging at the top. But evolution produces a tree, not a ladder — and we are just one of many leaves on the tree. The “Tree of Life” •Animals are the newcomers in the evolution of life on Earth. •All living things are “cousins”; some more distant than others. Plant Evolution Cone-bearing plants Ferns and their relatives Flowers; Seeds Enclosed in Fruit Mosses and their relatives Seeds Water-Conducting (Vascular) Tissue Green algae ancestor Flowering plants Evolution links Evolution Exploratour Understanding Evolution Univ. Calif. Museum of Paleontology Evolution: PBS