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-

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

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

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

Lamarck’s Theory of Evolution Lamarck hypothesized that species evolve –Through use and disuse and the inheritance of acquired traits –But the mechanisms he proposed are unsupported by evidence Figure 22.4

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 Figure 22.3

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 Figure 22.5 England EUROPE NORTH AMERICA Galápagos Islands Darwin in 1840, after his return SOUTH AMERICA Cape of Good Hope Cape Horn Tierra del Fuego AFRICA HMS Beagle in port AUSTRALIA Tasmania New Zealand PACIFIC OCEAN Andes ATLANTIC OCEAN

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 Figure 22.6a–c (a) Cactus eater. The long, sharp beak of the cactus ground finch (Geospiza scandens) helps it tear and eat cactus flowers and pulp. (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

Resistance to the Idea of Evolution The Origin of Species –Shook the deepest roots of Western culture –Challenged a worldview that had been prevalent for centuries

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

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 Figure 22.7 Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Years ago Millions of years ago Deinotherium Mammut Stegodon Mammuthus Platybelodon Barytherium Moeritherium Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa)

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 Figure Terminal bud Lateral buds Brussels sprouts Cabbage Flower cluster Leaves Cauliflower Flower and stems Broccoli Wild mustard Kohlrabi Stem Kale

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 Figure (a)A flower mantid in Malaysia (b)A stick mantid in Africa

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

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 evidence of evolution 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

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

Figure 1.3

The Origin of Species –Focused biologists’ attention on the great diversity of organisms Figure 22.1

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

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 Figure 22.2 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) Wallace (evolution, natural selection) 1750 American RevolutionFrench Revolution U.S. Civil War Hutton proposes his theory of gradualism Malthus publishes “Essay on the Principle of Population.” 1809 Lamarck publishes his theory of evolution Lyell publishes Principles of Geology. 1831–1836 Darwin travels around the world on HMS Beagle. Darwin begins his notebooks on the origin of species Darwin writes his essay on the origin of species Wallace sends his theory to Darwin The Origin of Species is published Mendel publishes inheritance papers. 1865

Homology, Biogeography, and the Fossil Record Evolutionary theory –Provides a cohesive explanation for many kinds of observations

Homology –Is similarity resulting from common ancestry

Anatomical Homologies Homologous structures between organisms –Are anatomical resemblances that represent variations on a structural theme that was present in a common ancestor Figure HumanCat Whale Bat

Comparative embryology –Reveals additional anatomical homologies not visible in adult organisms Figure Pharyngeal pouches Post-anal tail Chick embryo 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 Figure Species Human Rhesus monkey Mouse Chicken Frog Lamprey 14% 54% 69% 87% 95% 100% Percent of Amino Acids That Are Identical to the Amino Acids in a Human Hemoglobin Polypeptide

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

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

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

Binomial nomenclature Karl von Linne ( ) 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

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 Figure 22.18

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

Figure 1.4 Hierarchy of Relatedness

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

Figure 1.6 (a)

Figure 1.6 (b)

EC Figure Chapter 1 Evolution, Ecology and Zoology Chapter 4 Theory of Evolution by Natural Selection Microevolution and Macroevolution Chapter 2 Properties of Life Origins of Life Prokaryotic and Eukaryotic Levels of organization Cell division and inheritance Chapter 3 Mitotic Meiosis