Welcome Introduce Zoology Syllabus Lecture Evolution and Zoology

• • Welcome Introduce Zoology Syllabus Lecture – Evolution, and Zoology – Theory of Evolution by Natural Selection – Origin of Species – Properties of Life Origins of Life – Prokaryotic and Eukaryotic – Levels of organization – Cell division and inheritance

• Biology is the study of Life • Single cell to multicellular organisms

• Cell is the basic unit of life • Unique plant cell and animal cell

• Zoology- zoon, animal + logos, to study – is the study of Animals • Is one of the broadest fields in all of science – Variety of animals – Complexity of and the processes

Specializations in Zoology • • • Anatomy Ecology Genetics Parasitology Physiology • Entomology • Ichthyology-

Ichthyologistwork to understand structure, function, ecology and evolution of fishes Studies have uncovered an amazing diversity of fishes Cichlid (‘sick-lid’)- freshwater fishes • 1000 species in Africa • 300 in South America • 3 in India • 1 in North America

Animal classification and Evolutionary Relationship • Evolution not only explanation why animals appear and function as they do • It explains family relationships • i. e cichlid species – Groups share more of their DNA – Thus resemble each other – Genetic studies suggest • Oldest African cichlid found in Lakes Tanganyika and Kivu • These fish invades rivers, lakes Malawi, Victoria and others • Most rapid known origin of species of any animal groups

Members of this group • Variety of color patterns • Habitats • Body forms • Feeding habits

Binomial nomenclature • Karl von Linne also known as Carolus Linnaeus (1707 -1778) • Named and classified plants into hierarchy of relatedness • Binomial Nomenclature- systematic way of naming organisms– Two part name describes each kind of organism – First part- indicates the genus – Second part indicates the species to which the organism belongs. – i. e. Perissodus microlepis Field of taxonomy [Gk. taxis, arrange, put in order + nomos, law].

Figure 1. 4 Hierarchy of Relatedness

Eretmodus Nip algae with chisel-like teeth

Tanganicodus Insect pickers

Perissodus Scale eaters

• Brood their young • Dogtooth cichlid

The Fontosa Body form

An Evolutionary Perspective • Share a common evolutionary past and evolutionary forces that influence their history – Resulted in 4 to 100 million species of animals • Understand evolutionary process to understand – What it is – How it originated

• Evolutionary concepts hold the key to understanding – why animals look and act – Habitat – Characteristics

Ecological Perspective • Ecology- (Gr. okois, house + logos, to study) • Study of the relationships between organisms and their environment • Human dependence on animals (food, medicine, clothing) • Humans upset the delicate ecological balances that has evolved

In the 1950’s in an attempt to increase the lake’s fishery • Nile perch introduced into Lake Victoria • Reduced cichlid population from 99% to <1% • Most cichlid feed on algae, the algae grew • Algae died and decayed • Lake depleted of oxygen • Introduced nonnative plant (water hyacinth) • Water hyacinth has overgrown and resulted in further habitat loss • Darwins nitemare • Fishhead video Nile perch

• The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species • In order to understand why Darwin’s ideas were revolutionary – We need to examine his views in the context of other Western ideas about Earth and its life

• The historical context of Darwin’s life and ideas Linnaeus (classification) Hutton (gradual geologic change) Lamarck (species can change) Malthus (population limits) Cuvier (fossils, extinction) Lyell (modern geology) Darwin (evolution, nutural selection) Mendel (inheritance) American Revolution 1750 Wallace (evolution, natural selection) French Revolution U. S. Civil War 1800 1850 1900 1795 Hutton proposes his theory of gradualism. 1798 Malthus publishes “Essay on the Principle of Population. ” 1809 Lamarck publishes his theory of evolution. 1830 Lyell publishes Principles of Geology. 1831– 1836 Darwin travels around the world on HMS Beagle. 1837 Darwin begins his notebooks on the origin of species. 1844 Darwin writes his essay on the origin of species. 1858 Wallace sends his theory to Darwin. 1859 The Origin of Species is published. 1865 Mendel publishes inheritance papers. Figure 22. 2

Lamarck’s Theory of Evolution • Lamarck hypothesized that species evolve – Through use and disuse and the inheritance of acquired traits • Environmental changes generate new needs • These needs determine the use or disuse of some organs • Such organs develop or are diminished • The acquired characters are hereditary – But the mechanisms he proposed are unsupported by evidence functions create organs and heredity determines the change in offspring

Fossils, Cuvier, and Catastrophism • The study of fossils – Helped to lay the groundwork for Darwin’s ideas • Fossils are remains or traces of organisms from the past – Usually found in sedimentary rock, which appears in layers or strata

• Darwin’s interest in the geographic distribution of species – Was kindled by the Beagle’s stop at the Galápagos Islands near the equator west of South America England NORTH AMERICA EUROPE ATLANTIC OCEAN PACIFIC OCEAN Galápagos Islands HMS Beagle in port SOUTH AMERICA AUSTRALIA Andes Darwin in 1840, after his return AFRICA Cape of Good Hope Cape Horn Tierra del Fuego Tasmania New Zealand

Darwin’s Focus on Adaptation • As Darwin reassessed all that he had observed during the voyage of the Beagle – He began to perceive adaptation to the environment and the origin of new species as closely related processes

• From studies made years after Darwin’s voyage – Biologists have concluded that this is indeed what happened to the Galápagos finches (a) Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. Figure 22. 6 a–c (c) Seed eater. The large ground finch (Geospiza magnirostris) has a large beak adapted for cracking seeds that fall from plants to the ground. (b) Insect eater. The green warbler finch (Certhidea olivacea) uses its narrow, pointed beak to grasp insects.

• In 1844, Darwin wrote a long essay on the origin of species and natural selection – But he was reluctant to introduce his theory publicly, anticipating the uproar it would cause • In June 1858 Darwin received a manuscript from Alfred Russell Wallace – Who had developed a theory of natural selection similar to Darwin’s • Darwin quickly finished The Origin of Species – And published it the next year

Evolutionary Processes • Organic evolution- change in the genetic makeup of populations over time. – Source of animal diversity – Explains family relationships within animal groups • Charles Darwin • Published The Origin of Species- evidence of evolution in 1859 • Proposed a mechanism • Understanding diversity of animal structure and function arose is one of the many challenges • i. e cichlid scale eaters of Africa

Resistance to the Idea of Evolution • The Origin of Species – Focused biologists’ attention on the great diversity of organisms – Shook the deepest roots of Western culture – Challenged a worldview that had been prevalent for centuries

• Darwin made two major points in his book – He presented evidence that the many species of organisms presently inhabiting the Earth are descendants of ancestral species – He proposed a mechanism for the evolutionary process, natural selection

Descent with Modification • The phrase descent with modification – Summarized Darwin’s perception of the unity of life – States that all organisms are related through descent from an ancestor that lived in the remote past

Sirenia Hyracoidea (Manatees (Hyraxes)and relatives) Mammuthus Stegodon Platybelodon Mammut Deinotherium Elephas. Loxodonta maximus africana cyclotis (Asia) (Africa) Barytherium Moeritherium Millions of years ago Years ago • In the Darwinian view, the history of life is like a tree – With multiple branchings from a common trunk to the tips of the youngest twigs that represent the diversity of living organisms

phylogenetic tree (Gk. phylon, stock, tribe + genus, birth, origin):

Natural Selection and Adaptation • Evolutionary biologist Ernst Mayr – Has dissected the logic of Darwin’s theory into three inferences based on five observations

• Observation #1: For any species, population sizes would increase exponentially – If all individuals that are born reproduced successfully Figure 22. 8

• Observation #2: Nonetheless, populations tend to be stable in size – Except for seasonal fluctuations • Observation #3: Resources are limited • Inference #1: Production of more individuals than the environment can support – Leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving

• Observation #4: Members of a population vary extensively in their characteristics – No two individuals are exactly alike Figure 22. 9

• Observation #5: Much of this variation is heritable • Inference #2: Survival depends in part on inherited traits – Individuals whose inherited traits give them a high probability of surviving and reproducing are likely to leave more offspring than other individuals

• Inference #3: This unequal ability of individuals to survive and reproduce – Will lead to a gradual change in a population, with favorable characteristics accumulating over generations

Artificial Selection • In the process of artificial selection – Humans have modified other species over many generations by selecting and breeding individuals that possess desired traits Terminal bud Lateral buds Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Kale Flower and stems Broccoli Stem Wild mustard Kohlrabi

Summary of Natural Selection • Natural selection is differential success in reproduction – That results from the interaction between individuals that vary in heritable traits and their environment

• Natural selection can produce an increase over time – In the adaptation of organisms to their environment (a) A flower mantid in Malaysia (b) A stick mantid in Africa Figure 22. 11

• If an environment changes over time – Natural selection may result in adaptation to these new conditions

• Darwin’s theory explains a wide range of observations • Darwin’s theory of evolution – Continues to be tested by how effectively it can account for additional observations and experimental outcomes

Homology, Biogeography, and the Fossil Record • Evolutionary theory – Provides a cohesive explanation for many kinds of observations – – We will explore these key questions: What is homology? How do we identify anatomical homologies? What do genes do? How do genes control other genes to build complex structures like eyes? How can genes be homologous?

Anatomical Homologies • Homologous structures between organisms – Are anatomical resemblances that represent variations on a structural theme that was present in a common ancestor Homology Is similarity resulting from common ancestry Human Cat Whale Bat

• Comparative embryology – Reveals additional anatomical homologies not visible in adult organisms Pharyngeal pouches Post-anal tail Chick embryo Figure 22. 15 Human embryo

• Vestigial organs – Are some of the most intriguing homologous structures – Are remnants of structures that served important functions in the organism’s ancestors

Molecular Homologies • Biologists also observe homologies among organisms at the molecular level – Such as genes that are shared among organisms inherited from a common ancestor

Homologies and the Tree of Life • The Darwinian concept of an evolutionary tree of life – Can explain the homologies that researchers have observed

• Anatomical resemblances among species – Are generally reflected in their molecules, their genes, and their gene products Species Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide 100% Human Rhesus monkey 95% Mouse 87% Chicken 69% Frog Figure 22. 16 Lamprey 54% 14%

Biogeography • Darwin’s observations of the geographic distribution of species, biogeography – Formed an important part of his theory of evolution

• Some similar mammals that have adapted to similar environments – Have evolved independently from different ancestors Sugar glider NORTH AMERICA AUSTRALIA Flying squirrel Figure 22. 17

The Fossil Record • The succession of forms observed in the fossil record – Is consistent with other inferences about the major branches of descent in the tree of life

• The Darwinian view of life – Predicts that evolutionary transitions should leave signs in the fossil record • Paleontologists – Have discovered fossils of many such transitional forms

• What Is Theoretical about the Darwinian View of Life? • In science, a theory – Accounts for many observations and data and attempts to explain and integrate a great variety of phenomena