Zoology • Zoon = animal • Logos = study of • Zoology = study of animals • Zoology is the study of animal diversity, the way they function, live, reproduce and interact.
History and Evolution • Animal life existed more than 600 million years ago • From earliest animals to millions of animal species present today, history demonstrates perpetual change we call evolution.
phylogeny • We depict the history of animal life as a branching geneological tree called a phylogeny. • Earliest species, ancestral to all animals are at the trunk, then all living animals species fall at the growing tips of the branches. • Each successive branching event represents formation of a new species from an ancestral one.
Two goals of scientific study of animal diversity • 1. Reconstruct a phylogeny of animal life and find where in evolutionary history we can locate the origins of features that comprise animal diversity as we know it. • 2. Understand historical processes that generate and maintain diverse species and adaptations throughout evolutionary history.
Principles of Science • Using scientific method • Characteristics of scientific hypotheses: • Testable against the empirical world • Relying on or derived from observation or experiment • Verifiable or provable by means of observation or experiment • Conclusions are tentative • It is falsifiable
Scientific Method • Generate hypothesis (based on prior observations) • State your methods. Methods are the blueprint for your experiment such as sample size, number of replications, etc. • Gather and analyze data • Draw conclusions.
Theory • If a hypothesis is very powerful in explaining a large variety of related phenomena, it may be called a theory. • This differs from the common use of the word theory which basically means speculation.
Experimental and Evolutionary Sciences • Questions about animal life can be grouped into two major categories: • 1. Questions which seek to understand proximate causes that underlie functioning of biological systems at all levels of complexity. • 2. Questions addressing ultimate causes that have generated biological systems and their properties through evolutionary time.
Questions of the first type represent experimental science. • Include problems of explaining how animals perform their metabolic, physiological and behavioral functions at molecular, cellular, organismal and population levels. These use the experimental method.
Questions of the second type are examples of evolutionary science. • Include questions such as: • What factors have caused some birds to acquire complex patterns of seasonal migration between temperate and tropical regions? • Answering these questions requires the comparative methods.
Examples of experimental sciences: • Molecular biology • Cell biology • Endocrinology • Immunology • Physiology • Developmental biology • Community ecology
Examples of evolutionary sciences • Comparative biochemistry • Molecular evolution • Comparative cell biology • Comparative anatomy • Comparative physiology • Phylogenetic systems
Early evolutionary theory • In mid-1600’s Archbishop James Ussher fixed year 4004 B.C. as time of life’s creation. • French Naturalist Georges Louis Buffon (1707-1788) stressed environmental influences on modifications of animal type. • Jean Baptiste de Lamarck • Inheritance of acquired characteristics • Transformational Evolution • Giraffe example
Charles Lyell • 1797 – 1875 • Established principles of geology – the principle of uniformitarianism • Uniformitarianism encompasses two principles: • Laws of physics and chemistry remain consistent throughout earth’s history. • Past geological events occurred by natural processes similar to those that we observe in action today. • He concluded that earth’s age must be reckoned at millions of years.
Charles Darwin • Noticed that though many islands similar in climate and topography, there were differences in flora and fauna. • Recognized that Galapagos plants and animals related to those of South America but differed in curious ways. • They had undergone modification to environment.
Darwin’s theory of evolution • Five major theories that make it up: • Perpetual change • Common descent • Multiplication of species • Gradualism • Natural selection
Perpetual Change • Living world is neither constant nor perpetually cycling but constantly changing • Characteristics of organisms undergo modification across generations throughout time
Common Descent • All forms of life descended from a common ancestor through a branching of lineages. • An opposing argument that different forms of life arose independently and descended to the present in linear unbranched geneologies has been refuted by comparative studies of organismal form, cell structure and macromolecular structures.
Multiplication of species • Evolution produces new species by splitting and transforming older ones. • Individual species do not interbreed
Gradualism • Large differences in anatomical traits that characterize different species originate by accumulation of many small incremental changes over very long periods of time.
Natural Selection • Natural selection explains why organisms are constructed to meet the demands of their environments – adaptation. • Darwin developed his theory of natural selection as a series of five observations and three inferences from them.