Evolution Central theme of Biology Look at any organism Differences from other other organisms Organism features show some relationship to where organism lives and what it does in its environment

Clown, Fool, or Simply Well Adapted? All organisms have evolutionary adaptations Inherited characteristics that enhance their ability to survive and reproduce Universal characteristic of living things. The blue-footed booby of the Galápagos Islands has features that help it succeed in its environment Large, webbed feet help propel the bird through water at high speeds

Specialized salt-secreting glands manage salt intake while at sea A streamlined shape, large tail, and nostrils that close are useful for diving Specialized salt-secreting glands manage salt intake while at sea

13.1 A sea voyage helped Darwin frame his theory of evolution EVIDENCE OF EVOLUTION 13.1 A sea voyage helped Darwin frame his theory of evolution Anaximander suggested all life from water, and simpler forms came before more complex. Aristotle, and tater advanced by the Judeo-Christian culture, believed that species are fixed or were created about 6000 years ago, and did not evolve Buffon thought the earth was older, and thought different species from common ancestors (later changed mind) Fossils suggested that life forms change This idea was embraced by Lamarck in the early 1800s Mechanism for change was inheritance of acquired characteristics. ???, You need something you get it

similarities between living and fossil organisms While on the voyage of the HMS Beagle in the 1830s, Charles Darwin observed similarities between living and fossil organisms the diversity of life on the Galápagos Islands, such as blue-footed boobies and giant tortoises Figure 13.1A

The voyage of the Beagle Great Britain Europe North America Pacific Ocean Atlantic Ocean Africa Galápagos Islands Equator South America Australia Andes Cape of Good Hope Tasmania Cape Horn New Zealand Tierra del Fuego Figure 13.1B

Darwin became convinced that the Earth was old and continually changing (He was influenced by Lyell). Compared fossils on the different Galapagos Islands to each each. Compared fossils on the Galapagos to fossils in S. America. He concluded that living things also change, or evolve over generations Wallace conceived same theory based on observations in Indonesia. Both presented work to scientific community Darwin also stated that living species descended from earlier life-forms: descent with modification, encapsulates idea of evolution

The history of life is like a tree You have a base that grows and eventually branches out. Species on one branch are closer related than species on another branch

13.2 The study of fossils provides strong evidence for evolution Fossils and the fossil record strongly support the theory of evolution Hominid skull Petrified trees Figure 13.2A, B

Fossilized organic matter in a leaf Ammonite casts Fossilized organic matter in a leaf Figure 13.2C, D

Scorpion in amber “Ice Man” Preserved for 5000 yrs Figure 13.2E, F

The fossil record shows that organisms have appeared in a historical sequence. These are layers of sedimentary rock, formed from accumulation of waterborne sediments Younger strata on surface with more recent organisms Oldest fossils, prokaryotes, date back to 3.5 billion years ago in bottom layers of strata. Ongoing sequence of intermediate steps going from simple to more complex Figure 13.2G, H

Many fossils link early extinct species with species living today These fossilized hind leg bones link living whales with their land- dwelling ancestors

13.3 A mass of evidence validates the evolutionary view of life Other evidence for evolution comes from Biogeography Related life forms around world Island species look like closest mainlaind, not always closest island Comparative anatomy (all basic limb structure) Comparative embryology (all vertebrates and chordates had gill pouches in throat region Human Cat Whale Bat Figure 13.3A

Molecular biology Universality of genetic code Similar homeotic genes in different species Human Rhesus monkey Mouse Chicken Frog Lamprey Last common ancestor lived 26 million years ago (MYA), based on fossil evidence 80 MYA 275 MYA 330 MYA 450 MYA Figure 13.3B

13.4 Darwin proposed natural selection as the mechanism of evolution DARWIN’S THEORY AND THE MODERN SYNTHESIS 13.4 Darwin proposed natural selection as the mechanism of evolution Darwin observed that organisms produce more offspring than the environment can support organisms vary in many characteristics, expression of traits these variations can be inherited, genetic

Darwin saw natural selection as the basic mechanism of evolution Darwin concluded that individuals best suited for a particular environment are more likely to survive and reproduce than those less well adapted Darwin saw natural selection as the basic mechanism of evolution As a result, the proportion of individuals with favorable characteristics increases Populations gradually change in response to the environment

This is called artificial selection Darwin also saw that when humans choose organisms with specific characteristics as breeding stock, they are performing the role of the environment This is called artificial selection Example of artificial selection in plants: five vegetables derived from wild mustard Figure 13.4A

Example of artificial selection in animals: dog breeding English springer spaniel German shepherd Yorkshire terrier Mini-dachshund Golden retriever Hundreds to thousands of years of breeding (artificial selection) Ancestral dog Figure 13.4B

Thousands to millions of years of natural selection These five canine species evolved from a common ancestor through natural selection African wild dog Coyote Fox Wolf Jackal Thousands to millions of years of natural selection Ancestral canine Figure 13.4C

Two important point’s from Darwin’s theory of Natural Selection Ancestral species gave rise to diverse life forms by transfer of heritable traits to offspring that best promote reproduction = “descent with modification Over vast amounts of time, gradual accumulation of changes in the characteristics among the individuals in a population changes

13.5 Connection: Scientists can observe natural selection in action Evolutionary adaptations have been observed in populations of birds, insects, and many other organisms Example: camouflage adaptations of mantids that live in different environments Figure 13.5A

Insecticide application The evolution of insecticide resistance is an example of natural selection in action Apply same theory to antibiotics – don’t finish, build up of bacterial resistance Insecticide application Chromosome with gene conferring resistance to insecticide Additional applications of the same insecticide will be less effective, and the frequency of resistant insects in the population will grow Survivor Figure 13.5B

Natural selection is regional and timely Natural selection is regional and timely. Populations tend to evolve in response to environmental conditions during one time period Change can occur in very short periods of time, think of life span or life cycle of organism Or over long periods of time

13.6 Populations are the units of evolution A species is a group of populations whose individuals can interbreed and produce fertile offspring Human populations tend to concentrate locally, as this satellite photograph of North America shows The modern synthesis connects Darwin’s theory of natural selection with population genetics Figure 13.6

Evolution is measured as a change in frequency of a given characteristic within a population over succession of generations. i.e. Height, average goes up, humans are evolving to be taller as a species Opportunities for breeding among a population varies depending on species and isolation of certain populations. City vs. Forest

13.7 Microevolution is change in a population’s gene pool over time A gene pool is the total collection of genes in a population at any one time Microevolution is a change in the relative frequencies of alleles in a gene pool Frequencies of alleles governing characteristics change Insect resistance. Insects with resistance alleles w/ higher frequency then insects with minimal resistance alleles depending on if a field sprayed with pesticide or not