TOPIC 7- EVIDENCE FOR THE THEORY OF EVOLUTION DAY 1

WHAT ARE WE LEARNING TODAY? SC.912.L.15.1 Explain the scientific theory of evolution is supported by the fossil record, comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary change. AA (Also addresses: SC.912.N.1.3, SC.912.N.1.6, SC.912.N.3.1, SC.912.N.3.4) Explain how evidences such as fossils, biochemical similarities, embryonic development, homologous and vestigial structures, and similarities and differences between organisms in different parts of the world are used to substantiate biological changes through time. Benchmark:LEARNING Objective:

WHAT IS THE ESSENTIAL QUESTION? What are some evidences that support the theory of evolution?

B ACKGROUND : Evolution is not just a historical process ; it is occurring at this moment. Populations constantly adapt in response to changes in their environment and thereby accumulate changes in the genes that are available to the species through its gene pool. In today's lab you will explore some of the evidence for evolution and will examine a few of the mechanisms through which evolution acts. In this laboratory you will review some of the classical examples used as evidence for evolution.

F OSSILS Evolution is "descent with modification." This basically means that evolutionary forces can act on an organisms such that it's descendants will be slightly different from the original species, and their descendants will be slightly different from them, and so on. These are called transition species because they show the transition from one species to another. Fossils can show us these relationships. Notice the slow changes in the location of the nostrils

P UNCTUATED E QUILIBRIUM IN THE F OSSIL R ECORD Punctuated equilibrium is a theory in evolutionary biology which proposes that most species will exhibit little net evolutionary change for most of their geological history, remaining in an extended state called stasis. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and rapid (on a geologic time scale) events. Compare this to gradualism which states that evolution generally occurs uniformly and by the steady and gradual transformation of whole lineage.

C OMPARATIVE E MBRYOLOGY It looks at the embryos of several species and looks at similarities and differences.

Comparative Anatomy refers to comparison of similar features and different characteristics of organism Homologous structures are structures in different species that come from a common ancestry, but may look different in the present form. Ex: human arms and whale flippers. Analogous structures do not have common ancestry, but they look similar because they serve the same purpose or evolved in the same environment (convergent evolution gives rise to analogous structures). Ex: bat wings and butterfly wings or torpedo body shape of sharks and porpoises. Both shark and porpoises population evolved in a water environment. However, they both have a different ancestry, shark is a fish and porpoise is a mammal. Convergent evolution Vestigial structures have a common ancestry, but they are no longer in use by that species. Ex: tail bones in monkeys vs human tail bones. C OMPARATIVE A NATOMY

Molecular evolution is a change in the sequence composition of cellular molecules such as DNA, RNA, and proteins over long periods of time. The fewer the differences in the sequence of the molecules the more related the species are. Forces that cause changes Mutation Genetic drift Natural selection Recombination M OLECULAR EVOLUTION DNA sequence

B IOGEOGRAPHY Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area. Biogeographers depend heavily on evidence from other disciplines. Fossil records provide a large part of the information needed to determine distributions and past interactions. Molecular biology furnished biogeographers with molecular clocks, metabolic molecules whose change over time help track the relatedness of species.

EOC Q UESTION : The scientific theory of evolution is supported by different types of evidence. The diagrams below show the skeletons of two different animal species. How does comparing the skeletons of these animals provide support for the scientific theory of evolution? A. It provides information about the organisms' habitats. B. It shows possible common ancestry between organisms. C. It provides information to determine the organisms' ages. D. It shows possible chromosomal similarities between organisms. Answer : B. It shows possible common ancestry between organisms. Animals that evolved from a common ancestor will often have similar structures and organs.

Vocabulary: 1. evolution- change over time; the process by which modern organisms have descended from ancient organisms. 2. fossil- preserved remains or traces of ancient organisms. 3. homologous structures- structures that are similar in different species of common ancestry. 4. molecular biology- A branch of biology that studies the structure and function of the macromolecules essential to life. 5. Comparative biology- A branch of biology that studies comparisons between ancestral organisms. 6. Vestigial structure- structure that is inherited from ancestors but has lost much or all of its original function