Presentation on theme: "1 Review Why are fossils important evidence for evolution Interpret Visuals use the figure on pg 394-395 to describe how a modern mystcete whale is different."— Presentation transcript:
11 Review Why are fossils important evidence for evolution Interpret Visuals use the figure on pg to describe how a modern mystcete whale is different from Ambulocetus 2 Explain what is the relationship between Hox genes and embryological development Draw Conclusions Organisms A and B have very similar Hox genes, and their embryos, in early development, are also very similar. What do these similarities indicate about the ancestry of organisms A and B 3 Explanation In your own words, write a paragraph that explains how evidence since Darwin’s time has strengthened his theories.
2Ch 16 Darwin’s Theory of Evolution 16.4 Evidence of Evolution
3The fields of geology, physics, paleontology, chemistry, and embryology, did not have the technology or understanding to test Darwin’s assumptions during his lifetimeGenetics and molecular biology didn’t exist.
4In the 150 years since Darwin published On the Origin of Species, discoveries in all these fields have served as independent tests that have supported Darwin’s ideas about evolution.
5BiogeographyStudy of where organisms live now and where they and their ancestors lived in the past.
6Closely Related but Different Biogeography of Galapagos species suggested that populations on the island had evolved from mainland speciesNatural selection on the islands produced variations among populations that resulted in different, but closely related, island species.
7Distantly Related but Similar Rhea, Ostriches, and EmusDifferences in body structures provide evidence that they evolved from different ancestorsSimilarities provide evidence that similar selection pressures had caused distantly-related species to develop similar adaptations.
8The Age of Earth and Fossils Fossils form series that trace the evolution of modern species from extinct ancestors.
9The Age of Earth Evolution takes a long time Hutton and Lyell argued that Earth was indeed very old, but couldn’t determine just how oldGeologists use radioactivity to establish the age of certain rocks and fossils which indicates the Earth is about 4.5 billion years.
10Recent Fossil Finds Since 1859 MANY more fossils have been found Page
11Limb structure suggests that these animals could both swim in shallow water and walk on land.
12The hind limbs were short and probably not able to bear much weight Spent most of their time in water.
13Streamlined body and reduced hind limb Streamlined body and reduced hind limb. suggest it spent its entire life swimming in the ocean.
14Retain reduced pelvic bones and some even upper and lower limb bones No longer play a role in locomotion.
15Comparing Anatomy and Embryology Homologous structures adapted to different purposes as the result of descent with modification from a common ancestor.
16Homologous Structures Similar structures that may serve different functions in various organisms.
18Analogous StructuresBody parts that share a common function, but not structureWing of a bee and a wing of a bird.
19Vestigial StructuresInherited from ancestors, but have lost much or all of their original function due to different selection pressuresHipbones of bottlenose dolphinsWings of flightless cormorant .
20EmbryologyEarly developmental stages of many vertebrates look very similarSame groups of embryonic cells develop in the same order and in similar patterns to produce many homologous tissues and organs in vertebrates.
21Life’s Common Genetic Code All living cells use information coded in DNA and RNA to carry information from one generation to the next and to direct protein synthesis.
22Homologous MoleculesMany different organisms share homologous proteinsHox gene.
23Testing Natural Selection Grants tested the Galapagos finches.
24Two Testable Assumptions There must be enough heritable variation in beak size and shape to provide raw material for natural selectionDifferences in beak size and shape must produce differences in fitness.
25Used medium ground finch on the island of Daphne Major Supports good-sized finch populationsAllows them to catch, tag, and identify nearly every bird of the species.
26Periodically recapture the birds Record which individuals are alive and which have died, which have reproduced and which have notRecord anatomical characteristics like wing length, leg length, beak length, beak depth, beak color, feather color, and total mass of each bird.
27When food becomes scarce during dry periods, birds with the largest beaks are more likely to survive.
28The Grants have documented that natural selection takes place in wild finch populations frequently, and sometimes rapidlyWithout heritable variation in beak sizes, the medium ground finch would not be able to adapt to feeding on larger, tougher seeds during a drought.
29Like any scientific theory, evolutionary theory is constantly reviewed as new data are gathered There is significant uncertainty about exactly how life beganQuestions that remain are about how evolution works - not whether evolution occurs.
30Competition and environmental change drive natural selection Traits that don’t matter much under one set of environmental conditions became adaptive as the environment changes during a drought.