Our best estimate is that Earth has about how many species? Earthʼs Tree of Life 1. 1,000 2. 10,000 3. 100,000 4. 1,000,000 5. 10,000,000 Biologists have named about what percentage of the species on Earth? 1. 2% 2. 20% 3. 50% 4. 75% 5. ~ 99% Common Misconceptions about Biodiversity E.O. Wilson - Emeritus Biology Professor (Harvard); Pulitzer Prize winning author SRN Sign Up At the end of class today for those NOT in Bio 110 and who wish to participate If youʼre in Bio 110, youʼll be signing up (if you wish) in Bio 110 this week Short Story Assignment Go to the Unit 1 Learning Module on WebCT Open and read the Age of the Earth Story 2 Type and print out your answers to the four questions associated with short story #2 Bring these to class on Tuesday 9 September (5 points)
WebCT Question In the lecture today one of the slides said that the oldest animal fossils are 600 MYO and the oldest plant fossils are 500 MYO. To me this doesn't make sense because animals need oxygen to survive and oxygen is created from plants, so how would the animals to survive? Plus what would of the first animals ate if there were no plants? WebCT Question In class you said that about 2,700 MYA the oxygen level on earth begins to increase. What would have caused this to start at that peticular time? The BIG Concepts Thereʼs a WHOLE LOT of creatures out there (and, as youʼll see, in/on there...) AND - thereʼs an awful lot of work left to do to have a complete list of the species we share this planet with! Extant Biological Diversity ~ 52,000 vertebrate species ~ 290,000 plant species ~ 1,00,000 insect species (~ 350,000 of which are beetles!) Total number? Estimates range from 10-100 million species Our best estimate is that Earth has about how many species? 1. 1,000 2. 10,000 3. 100,000 4. 1,000,000 5. 10,000,000 Ancient Chinese Proverb: The beginning of wisdom is calling things by their right names
Taxonomy Goal: Classify ALL the species on Planet Earth Requires identifying diagnostic features that distinguish between closely related species Providing names for each species Approximately 1.8 million species have been named thus far (~1.8% to 18% of the estimated total) Biologists have named about what percentage of the species on Earth? 1. 2% 2. 20% 3. 50% 4. 75% 5. ~ 99% A taxonomist s eye view of the world: How many species in this picture? Thereʼs more to beeology than meets the eye Bee mites Mite Name the bee and the plant Are there associated, symbiotic, or pathogenic bacteria, protists, or fungi? What about smaller insects or arthropods? Donʼt think itʼs just bees Human eyelash mites (about 98% of humans have these) Mites Thereʼs a LOT more biological diversity than is immediately obvious How do we name all this diversity? Human Eyelash
Binomial Nomenclature First instituted in the 1700ʼs by Carolus Linnaeus Each distinct species is assigned: a Genus name (may include one, a few, or many species) a specific epithet (one particular species) Together called the scientific name or binomial Some Scientific Names Humans - Homo sapiens Corn - Zea mays Human Gut Bacterium - Escherichia coli Fruit fly - Drosophila melanogaster Morel - Morchella esculentum Protistan Parasite - Giardia intestinalis Filtering out the Giardia Once a specific epithet has been used for one species can it ever be used again? Yes - Only the combination needs to be unique within a group of organisms Laportea canadensis Sanguinaria canadensis Common Names Can be quite handy Can also be quite confusing Suppose I have a maple in my yard: sugar maple? (Acer saccharum) silver maple? (Acer saccharinum) red maple? (Acer rubrum) Some species have NO common name Some species have more than one common name
Common Names Broad-leaf Plantain Scientific name: Plantago major Common names! At least 27 common names - just in English Other common names in other languages Broad-leaf plantain Hierarchical Classification in Biology species Genus Family Order Class Phylum Kingdom Domain EACH category fits inside successively larger (more inclusive) categories JUST like Matrioshka Dolls (Russian nesting dolls) Classification (Fig 26.3) Leopard (Panthera pardus) Systematics and Phylogeny An example of a phylogenetic tree (Fig. 26.4) Grouping species so that their classification reflects their history and relationships Results in the production of phylogenetic trees Not easy to do - requires as much data as possible, including DNA sequence data Phylogeny is what the hierarchical classification of biology attempts to reflect
Classification and Phylogeny A native Iowa species that is also a member of Family Felidae is the bobcat (Lynx rufus) Bobcats belong to a different Genus than the leopard, but the same Genus as the lynx (Lynx canadensis) So, the hierarchical classification system indicates that: Lynx and bobcats are more closely related to each other than either are to leopards But, they are more closely related to leopards than they are to wolves (or other non-cat-like carnivores) The Two-Kingdom System The Big Picture So - How many major groups (Kingdoms) of organisms are there? (On Earth at least...) Mobile/no cell walls - Animals (including protozoa ) Non-mobile/with cell walls - Plants (including bacteria, fungi, photosynthetic protists) What about mobile AND photosynthetic protists? (e.g., Euglena) The Five-Kingdom System The Five-Kingdom System Proposed by Robert Whittaker in 1969 Recognizes the important distinction between prokaryotic and eukaryotic cells - not fully appreciated until the development of the electron microscope in the 1950s (see pages 95-96) Separates plants from fungi Establishes Kingdom Protista
Difficulties with the Five-Kingdom System Newer evidence indicates two quite distinct types of prokaryotic cells: Bacteria and Archaea Kingdom Protista is a grab-bag of organisms that are not closely related So - How many Kingdoms are there? Not known - weʼre still gathering data In this class we will use the 3-Domain system Fig. 26.21 As I recall, in my High School biology class we used the: 1. 2-Kingdom system 2. 5-Kingdom system 3. 3-Domain system The number of Kingdoms is still being determined The most important thing to realize is: Taxonomy and Systematics, even at the highest levels (e.g., Kingdom), is a work in progress - weʼre still learning about the diversity of life on Earth As we get more data (evidence), we have a more accurate understanding of life on Earth - and modify our classification scheme accordingly