15-2 Evidence of Evolution

1. 15-2 Evidence of Evolution

2. Fossil record - by examining fossils from sequential layers of rock, one could view how a species had changed and produced different species over time, as shown in the figure at right. Geographical distribution of living species Comparative Biochemistry Comparative Embryology 5. Homologous structures of living organisms structures that have different mature forms in different organisms but develop from the same embryonic tissues Not all homologous structures serve important functions. Vestigial organs (the organs of many animals are so reduced in size that they are just vestiges, or traces, of homologous organs in other species. Evidence of Evolution:

3. Evolution Chapter 15 15.2 Evidence of Evolution • The fossil record • Fossils provide a record of species that lived long ago. • Fossils show that ancient species share similarities with species that now live on Earth. Armadillo Glyptodont

4. Evolution Chapter 15 15.2 Evidence of Evolution • Derived traits are newly evolved features, such as feathers, that do not appear in the fossils of common ancestors. • Ancestral traits are more primitive features, such as teeth and tails, that do appear in ancestral forms. • Anatomically similar structures inherited from a common ancestor are called homologous structures.

5.  Homologous Body Structures Section 15-3 Turtle Alligator Mammals Bird Typical primitive fish

6. Evolution • Evolutionary theory predicts that features of ancestors that no longer have a function for that species will become smaller over time until they are lost. Chapter 15 15.2 Evidence of Evolution Vestigial Structures • Structures that are the reduced forms of functional structures in other organisms.

7. Evolution • Analogous structurescan be used for the same purpose and can be superficially similar in construction, but are not inherited from a common ancestor. Chapter 15 15.2 Evidence of Evolution • Show that functionally similar features can evolve independently in similar environments

8. Evolution Chapter 15 15.2 Evidence of Evolution Comparative Embryology • Vertebrate embryos exhibit homologous structures during certain phases of development but become totally different structures in the adult forms.

9. Changes in developmental genes are one major pattern of macroevolution. • Fossil evidence shows that some ancient insects (top left) had no wings, but others (top right) had winglike structures on many body segments. • In modern insects (bottom), genes may turn off wing development in all except one or two body segments.

10. All of these organisms probably share some of the same genes. • All of these organisms show many body changes during their development as embryos. • This diagram shows descent with modification, which indicates common ancestry.

11. Evolution Chapter 15 15.2 Evidence of Evolution Comparative Biochemistry • Common ancestry can be seen in the complex metabolic molecules that many different organisms share.

12. Evolution Chapter 15 15.2 Evidence of Evolution • Comparisons of the similarities in these molecules across species reflect evolutionary patterns seen in comparative anatomy and in the fossil record. • Organisms with closely related morphological features have more closely related molecular features.

13. Evolution Chapter 15 15.2 Evidence of Evolution Geographic Distribution • The distribution of plants and animals that Darwin saw first suggested evolution to Darwin. Rabbit Mara

14. Evolution Chapter 15 15.2 Evidence of Evolution • Patterns of migration were critical to Darwin when he was developing his theory. • Evolution is intimately linked with climate and geological forces.

15. Evolution Chapter 15 15.2 Evidence of Evolution Types of Adaptation • An adaptation is a trait shaped by natural selection that increases an organism’s reproductive success. • Fitness is a measure of the relative contribution an individual trait makes to the next generation.

16. Evolution Chapter 15 15.2 Evidence of Evolution Camouflage • Allows organisms to become almost invisible to predators Leafy sea dragon

17. Evolution Chapter 15 15.2 Evidence of Evolution Mimicry • One species evolves to resemble another species. California kingsnake Western coral snake

18. Evolution Chapter 15 15.2 Evidence of Evolution Consequences of Adaptations • Some features of an organism might be consequences of other evolved characteristics. • They do not increase reproductive success. • Features likely arose as an unavoidable consequence of prior evolutionary change.

19. Adaptation: • Organisms adapt to their environment in many different ways. • Mimicry is the process of natural selection shaping one species of organisms to look similar to another species. This increases an organisms fitness • Camouflage- morphological adaptations that allow organisms to blend into their surroundings. As a result, more of the camouflaged individuals survive and reproduce.

20. Viceroy Butterfly Monarch Butterfly

21. Conclusion Question: • Hypothesize why the viceroy and monarch butterflies have bright colors that are highly visible.