Theory of Evolution Chapter 16

Idea of Evolution Charles Darwin (1809-1882) English naturalist Took a trip around the world on a ship called H.M.S. Beagle Mostly fascinated with the Galapagos Islands Best known for his theory of evolution by natural selection

Darwin’s Journey Began in 1831 Sailed on a ship called the H.M.S. Beagle Five year voyage sailing around the coast of South America and Australia

Observations Aboard the Beagle Darwin collected 68 species of beetles Wrote about the different characteristics of habitats and species that live there Species vary globally There are similar organisms around that world with similar ecological habitats Ex: Rhea birds in S. America and ostriches in Africa

Observation Aboard the Beagle Species vary locally Related animals species often occupy different habitats within a local area Ex: Tortoise shell shape among Galapagos Islands

Observation Aboard the Beagle Species vary over time Some fossils of extinct animals were similar to living species Ex: Armadillo fossils compared to modern day armadillos

Darwin’s Findings Galapagos Islands Groups of animals vary from island to island Ex: tortoises and finches on each island resemble each other but differ in the shape and function of their shells and beaks Darwin believed these unique animals all came from a common ancestor and they changed/adapted to their environment

Idea of Evolution Evolution Development of new types of organisms over time Heritable change in the characteristics within a population from one generation to the next http://ed.ted.com/lessons/myths-and-misconceptions-about-evolution-alex-gendler

Ideas of Darwin’s Time Scientists thought all species were permanent and unchanging The Earth was believed to only be a few thousand (not billions) of years old During Darwin’s time, new research was being done to figure out the geology of the Earth

Ideas that Influenced Darwin James Hutton was a geologist in 1700’s Made connections between mountains, valleys, and layers of rock Believed the Earth was older than thousands of years -- a time so old for the human mind to image The Earth changes very slowly and some layers can accumulate as the environment is changing

Ideas that Influenced Darwin Charles Lyell was a English geologist that believed the Earth’s surface continues to change He explained that past processes that occurred are still occurring now Ex: Volcanoes erupted in the past and still today Published a great work called Principles of Geology in 1830 that built on the work of Hutton Darwin read this book while on his journey around the world

Ideas that Influenced Darwin Jean-Baptiste Lamarck French naturalist that supported the idea that populations of organisms change over time

Ideas that Influenced Darwin Proposed two hypotheses: Called Theory of Acquired Traits Organisms could change during their lifetime by using or not using selected parts of the body Individuals could pass these acquired traits on to their offspring Ex: Giraffes could lengthen their neck by stretching over a period of time to get the height they needed to eat and survive and then pass the longer neck trait to their offspring

Ideas that Influenced Darwin Thomas Malthus was an English economist in the 1790s Reasoned that if the human population grew continuously, there would not be enough resources for everyone His reasoning explained why plants and animals produced more a high amount of offspring since a portion will not survive due to environmental factors Ex: Maple tree produces thousands of seeds each summer Ex: Oysters produce millions of eggs each year with the understanding that only a fraction will survive

Darwin’s Ideas Around the same time Darwin and Wallace formed theory to explain evolution Darwin was able to publish his book first called On the Origin of Species in 1858 Book explained how evolution occurs by means of natural selection Free in iBooks!

Artificial Selection Darwin studied animal breeders Farmers would select to breed only trees with the largest fruit, or the cows that produce the most milk Darwin called this process artificial selection Nature provides the variations, and humans select hose they find to be useful and allow them to breed and pass on traits to offspring http://www.youtube.com/watch?v=AJNK3FwtZFg

Evolution by Natural Selection Mechanism from descent with modification 1. Struggle for Existence Organisms produce more offspring than can survive Ex: dogs give birth to a litter of puppies, while only a majority survive 2. Variation and Adaptation Traits vary within a species and their environment called adaptations These adaptations help increase ability to survive Ex: Mimicry with coral snake and scarlet snake

Natural Selection (cont’d) 3. Survival of the Fittest Organisms best adapted for an environment will survive best and reproduce The ability for an organism to reproduce and pass on adaptations Ex: camouflage to help hide from predators 4. Natural Selection Process by which organisms with variations most suited to their local environment survive and leave more offspring Organisms choose their mate based on desired traits Ex: beetles that are not eaten because of their color, will reproduce http://www.youtube.com/watch?v=t-LTWFnGmeg

Common Descent Idea that every species must have descended by reproduction from pre-existing species that arrange over time Ex: finch beaks at Galapagos All species – living and extinct – are descended from ancient common ancestors

Transitional Species Organisms with features that are between hypothesized ancestors http://ed.ted.com/lessons/myths-and-misconceptions-about-evolution-alex-gendler

Age of the Earth & Fossils Noted that fossils of extinct animals resembled living species Relative Age Age compared to other fossils in order of old to young Absolute Age Using radioactive dating to get actual number age

Age of the Earth and Fossils Geologists are certain based on evidence via radioactive dating to indicate the Earth is about 4.5 billion years old Fossils Remains of an organism that died long ago Many fossils form a series that can trace back to an ancient extinct ancestor Superposition Idea that strata form in layers where the layers closest to the top are the younger than below

Anatomy and Embryology Anatomy: study of the body Embryology: study of development Homologous structures Anatomical structures that originated from the same common ancestor Ex: bones in arms of humans, penguins, alligator and bat Related structure but function may differ

Anatomy and Embryology Analogous Structures When structures have similar function, but did not develop the same way Ex: wings of bat vs. bird Vestigial Structures Organs that no longer serve a function in an organism Ex: human tail bone, appendix

Anatomy and Embryology Similar patterns of embryological development provide further evidence that organisms have descended from a common ancestor Many animals look similar during development and produce homologous tissue

Genetics and Molecular Biology At the molecular level, the genetic code and homologous molecules provide evidence of common descent

Phylogeny Relationships among groups of organisms Can make a “tree” of animals evolved Trunk of the tree would represent species that are closely related Branches represent a separate population or lineage

Evolution in Action Biologists tested the hypothesis by comparing DNA from the various species DNA evidence supported hypothesis 2 that each lizard evolved independently on each island Convergent Evolution Process by which different species evolve similar traits Ex: twig-dwelling species came from different ancestors but evolved similar adaptations to their environment

Divergence & Radiation Divergence evolution Process by which the descendants of a single ancestor diversify into species that each fit different parts of the environment Ex: All breeds of dog share a common ancestor with wolves

Divergence & Radiation Adaptive Radiation Pattern of diversity when a new population in a new environment undergoes divergent evolution

Coevolution Evolution is on-going and many species may evolve together When two or more species have evolved adaptations to each other’s influence Ex: Predator/Prey Interactions Introduction of new species Creating antibiotics