Unity in the Diversity of Life Underlying life’s diversity is a striking unity, especially at lower levels of organization In eukaryotes, unity is evident in details of cell structure Cilia of windpipe cells Cilia of Paramecium

Cross section of cilium, as viewed with an electron microscope LE 1-16b 0.1 µm Cross section of cilium, as viewed with an electron microscope Cilia of Paramecium Cilia of windpipe cells

Concept 1.4: Evolution accounts for life’s unity and diversity The history of life is a saga of a changing Earth billions of years old

The evolutionary view of life came into sharp focus in 1859, when Charles Darwin published On the Origin of Species by Natural Selection

The Origin of Species articulated two main points: Descent with modification (the view that contemporary species arose from a succession of ancestors) Natural selection (a proposed mechanism for descent with modification)

Darwin’s Observations Population of organisms Hereditary variations Overproduction and competition Differences in reproductive success Evolution of adaptations in the population

Natural selection can “edit” a population’s heritable variations LE 1-21a Natural selection can “edit” a population’s heritable variations Population with varied inherited traits

Elimination of individuals with certain traits LE 1-21b Elimination of individuals with certain traits

Reproduction of survivors LE 1-21c Reproduction of survivors

Increasing frequency of traits that enhance LE 1-21d Increasing frequency of traits that enhance survival and reproductive success

Bat wings are an example of adaptation Video: Soaring Hawk

South American mainland The Tree of Life Large ground finch Large cactus Sharp-beaked Geospiza magnirostris conirostris Medium ground finch fuliginosa Small Woodpecker Camarhynchus psittacula tree finch Cactus difficilis Cactus flower eaters scandens Seed eater Ground finches Seed eaters Tree finches Common ancestor from South American mainland Insect eaters Bud eater Warbler finches Mangrove fortis Cactospiza pallida pauper parvulus Green warbler Gray Certhidea olivacea fusca Vegetarian Platyspiza crassirostris heliobates Biologists often show evolutionary relationships in a treelike diagram Phylogenetic Tree

Inquiry is a search for information and explanation, often focusing on specific questions Two main processes of scientific inquiry: Discovery science: describing nature Hypothesis-based science: explaining nature

Types of Data Two types of data: Quantitative data: numerical measurements Qualitative data: recorded descriptions

Hypothesis-Based Science In science, inquiry usually involves proposing and testing hypotheses Hypotheses are hypothetical explanations

The Role of Hypotheses in Inquiry In science, a hypothesis is a tentative answer to a well-framed question A hypothesis is an explanation on trial, making a prediction that can be tested

Observations Question Hypothesis #1: Dead batteries Hypothesis #2: LE 1-25a Observations Question Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb

Test falsifies hypothesis Test does not falsify hypothesis LE 1-25b Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test prediction Test falsifies hypothesis Test does not falsify hypothesis

A Closer Look at Hypotheses in Scientific Inquiry A scientific hypothesis must have two important qualities: It must be testable It must be falsifiable

The Myth of the Scientific Method The scientific method is an idealized process of inquiry Very few scientific inquiries adhere rigidly to the “textbook” scientific method

Limitations of Science The limitations of science are set by its naturalism Science seeks natural causes for natural phenomena Science cannot support or falsify supernatural explanations, which are outside the bounds of science

Theories in Science A scientific theory is much broader than a hypothesis A scientific theory is: broad in scope generally enough to generate new hypotheses supported by a large body of evidence

The Culture of Science Science is an intensely social activity Both cooperation and competition characterize scientific culture

Science, Technology, and Society The goal of science is to understand natural phenomena Technology applies scientific knowledge for some specific purpose

A set of themes connects the concepts of biology Science as a Process Evolution Energy Transfer Continuity and Change Relationship of Structure and Function Regulation Interdependence in Nature Science, Technology, and Society