Biodiversity

1. Biodiversity How Diverse is Life?

2. How did Life Originate? • A small pond? • In hydrothermal vents at the bottom of the ocean? • In heat-stressed ponds near ancient volcanoes? • In clay beds in estuary or bays?

3. Early Speculation • 1920s and 1930s • A.I. Oparin and J.B.S. Haldane hypothesized about the Earth’s early atmosphere. • Little free oxygen and abundance of methane, ammonia, nitrogen, water vapor and perhaps free hydrogen. • Earthquakes and lightening very common. • Speculations not well-received due to lack of evidence.

4. Experiments Spontaneously Produced Organic Compounds • 1952: Miller and Urey built an apparatus to model Oparin’s and Haldane’s hypothesized atmosphere. • After a week, amino acids were formed.

5. Experiments Spontaneously Produced Organic Compounds • Other scientists repeated experiments and varied the gas composition and other conditions. • Carbohydrates, lipids, components of RNA and DNA and other amino acids were produced. • Astronomers commonly observed carbon-based compounds throughout the universe

6. Experiments Spontaneously Produced Organic Compounds • More recently, astronomers and geologists are convinced Earth’s atmosphere was different than Haldane and Oparin hypothesized. • Earth atmosphere was more likely composed of carbon dioxide, nitrogen and water vapor. • Speculation continues.

7. Next Step Was to Move Beyond Isolated Carbon-Based Compounds to Cells • Possible scenarios for producing proteins: • In ancient oceans, evaporation would concentrate amino acids which would make them likely to combine to form proteins. • Ocean bubbles would have powerful electrostatic forces inside that would attract amino acids, drawing them closer to interact. • Iron pyrite crystals and clay crystals could attract and concentrate amino acids.

8. Next Step Was to Move Beyond Isolated Carbon-Based Compounds to Cells • Possible scenarios for producing phospholipids: • Ancient bubbles made of phospholipids could exist. • Would pop and allow mixing of chemicals contained inside the bubble. • Ultimately result in the production of protocells.

9. Next Step Was to Move Beyond Isolated Carbon-Based Compounds to Cells • Protocells • Non-living organism • Important characteristic of life: • Ability to reproduce. • 1993, scientists found small molecule of synthetic RNA that could quickly make copies of itself. • Current investigations are trying to determine how life evolved on the Earth.

11. What Were the Major Milestones in the Earth’s Evolving Biodiversity? • Tendency to view organisms appearing later in life as superior to those appearing earlier in the history of the Earth. • Important to remember: • From a biological standpoint, complexity does not equate success . • Success involves surviving and acquiring enough energy and nutrients to reproduce and pass useful characteristics to offspring.

12. First Cells Evolved into the Different Cell Types We See Today • Earth’s first organisms • Single-celled heterotrophs (lack an ability to make food) • Consumed naturally occurring carbon-based compounds • With exhaustion of compounds, heterotrophs evolved single-celled and multicellular decomposers, scavengers and predators.

13. First Cells Evolved into the Different Cell Types We See Today • Autotrophs evolved from heterotrophs. • Autotroph: cells that produce chemicals that store energy. • Trapped light-absorbing pigments that made it possible to utilize energy from the sun. • Later these organisms evolved and were able to photosynthesize.

14. Simple Cells Evolved into More Complex Cells • Eukaryotic cells evolved from prokaryotic cells. • Two processes involved • In-pocketing of cell membranes that specialized and evolved into organelles. • Examples: nucleus, Golgi complex, endoplasmic reticulum • Endosymbiosis: • theory that mitochondria and chloroplasts were prokaryotes that developed means to efficiently obtain energy. • Mitochondria and chloroplasts intimately associate with eukaryotic cell and become an organelle in eukaryotic cells.

15. Single-Celled Organisms Evolved into Multicelled Organisms • Multicelluarity evolved whenever some colonial cells specialized. • Example: concentrating on movement, food digestion, reproduction. • As a result, other cells depend on specialized cells for those functions.

16. Milestones in Evolution of Animals • Presence or absence of tissue • The body type: • Symmetry, radial, or bilateral • The number of embryonic germ layers • Either two or three

17. Milestones in Evolution of Animals • Presence or absence of body cavities (coeloms). • Bilateral animals fall into 3 categories: • No cavities = acoelomates • Cavity between mesoderm and endoderm = psuedocoelomates • Coeloms are surrounded by mesoderm= coelomates

18. Milestones in Evolution of Animals • The embryonic timing of cell specialization among the coelomates • Primitive coelomates cells commit early cell specialization. • Advanced coelomates cells commit later in embryonic development. • Location and method tissues develop. • Primitive coelomates: blastopore becomes the mouth. • Advanced coelomates: blastopore becomes the anus.

19. Milestones in Evolution of Animals • Presence or absence of a skeleton, as well as the type of skeleton. • Segmented worms have hydrostatic skeleton • Shellfish and arthropods have exoskeleton • Spiny-skinned animals and those with backbones have endoskeleton

21. How Do Biologists Keep Track of So Many Species? • Same problem exists in the grocery store. • How to categorize different foods • Biologist need to categorize more than 1.5 million species.

22. Purposes of Biological Classification: • To assist in species identification. • To assign formal, consistent scientific names to species. • To describe ancestral relationships between species.

23. Initial Classification was Concerned With Describing “Natural Order” • Taxonomy began with Aristotle • Classified groups using “either-or” comparison • Example: animal or plant • Early days of classification, dominant philosophical view: • Species were fixed, unchanging and could be arranged in natural order. • Species description sought to list each species idealized characteristics. • Became the archetype.

24. Karl von Linne • 1707-1778 • Wrote meticulous detailed descriptions about plants and animals. • Described over 8,000 plants and animals. • Gave each two Latinized names. • Unique to each

25. Karl von Linne • First name: genus • Closely related forms could share this name and be grouped together. • Second name: species • Not shared by closely related forms. • Called binomial nomenclature.

26. Karl von Linne • Generated higher taxonomic categories • Related genera combined into Orders • Related orders combined into Classes • Highest categories were Kingdoms • Two kinds: Plant and Animal

27. Classification after Darwin and Mendel • Archetype replaced by type specimen. • First specimen collected or a representative specimen of the given species • Effect of Mendel • Taxonomists shift to emphasizing the characteristics that differentiate one distinct population of species from another.

28. Classification Today • Primary objective today: • describe the evolutionary relationships between species. • Use modern tools to describe relationships.

29. Classification Today • Molecular biochemistry allows scientists to compare proteins, DNA and RNA from different species. • More accurate for determining relationships than relying upon comparisons of structure and form.

30. How Does The System Work? • Place organisms into a series of hierarchical groups called taxa. • Broadest group contains most organisms • These are subdivided into smaller categories until level of individual species is reached. • All organism within a particular taxa share certain characteristics.

31. History of Classification

32. At First Two Kingdoms, Now at Least Five • From Aristotle to middle of 20th century: • Two kingdoms: Plant and Animal • There were exceptions such as: fungi • Sessile and had thick-walled cells like plants • But were not photosynthetic

33. Transitions • Another exception • Euglena • One-celled organism with tail and no cell wall • In the summer, had chloroplasts and would perform photosynthesis • Winter would function as a decomposer • Is it an animal or plant?

34. Transitions • Create more kingdoms to solve the problem. • Protista would include Euglena and other similar organism. • Monera would accommodate bacteria (single-celled prokaryotes). • Additional new kingdom to accommodate Fungi.

35. Transitions • Recently a need to create category larger than kingdoms, the domains. • Due to Archaea which are different than prokaryotes and eukaryotes.

36. Within Each Kingdom, There Are Additional Categories • Domain Eukarya • All members have one characteristic in common: their cells are eukaryotes. • Much diversity in the kingdom. • Requiring subdivision to classify organisms.

37. Within Each Kingdom, There Are Additional Categories • Since kingdoms contain wide variety of organisms, it becomes important to classify organisms into sub-categories. • The taxa indicate evolutionary relationships.

38. Domain Eukarya Has Four Kingdoms: • Protista • single-celled and simple multicelled eukaryotes. • Fungi • single-celled and multicelled, eukaryotic, heterotrophic organisms with thick-walled cells. • Plantae • Multicellular, eukaryotic, autotrophic organisms with thick-walled cells. • Animalia • Multicellular, eukaryotic, heterotrophic organisms with cells that have no walls.

39. What Is Happening to Earth’s Biodiversity? • Life on Earth is disappearing: • Today only a fraction of the estimated 75 million bison that greeted the first Europeans. • Songbird numbers are consistently down throughout the world.

40. Human Activities are Causing Mass Extinctions • Root of the problem is human population growth. • Resulting in competition for resources with other species and humans usually win.

41. Human Activities are Causing Mass Extinctions • Size of human population results in: • Habitat loss: • 50 years ago, cities with 1 million people were rare • Not true today. • A need for more farmland. • A need for various infrastructure such as • Roads, railways, dams.

42. Human Activities are Causing Mass Extinctions • Chemicals produced by human activities and released into the environment: • Plastics, fuels, solvents, cleaning compounds leak or are purposely put into soils, waterways, or the atmosphere. • Adversely affecting reproductive rates of animals and their populations.

43. Human Activities are Causing Mass Extinctions • Alien species • Those that flourish in regions where they are not native. • Introduced to new environments due to human activities. • Replace native species and overwhelming local resources.

44. Humans Are Dependent on Healthy Populations of Other Organisms • Plants convert the carbon dioxide we produce into oxygen we cannot live without. • Deforestation contributes to increased flooding. • As human population increases, so does our waste. • Wetlands can help with the decomposition of waste.

45. Humans Are Dependent on Healthy Populations of Other Organisms • Penicllium • a fungus that spoils fruit and bread also produces a product that kills bacteria. • Yew trees • Bark from this tree contains an extract that helps control human cancers.

46. We Can Preserve Our Biodiversity • Human activities can be directed to building up rather than tearing down our environment. • Preserve habitats by establishing parks and refugees specifically for wildlife. • Restoration ecology: goal is to transform spent mines, worn-out farmland, deforested slopes and even unprofitable shopping centers. • Most important to maintaining biodiversity is citizen involvement.