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Diversity of life and prokaryotes (Lecture 3)

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McGill University
Biology (Sci)
BIOL 111
Irene Gregory- Eaves

Biology Lecture 3 Diversity of life and prokaryotes 9/8/2011 6:25:00 AM Diversity of life/biodiversity:  Degree of differences in: 1. genetic variation 2. species composition 3. interactions within and between ecosystems All among and within species Species diversity: this is commonly reserved for indices that measure both the number of species in a habitat as well as their relative abundances in a defined area More diverse environments are even healthier, which provides certain services for humans i.e. they purify water make toxic not toxic Life Species:  about 1.5 million species are already named  about 13,000 new species named each year  but 3000 of those are synonyms—they’ve already been described in literature but there’s so much that it’s difficult to keep track of them all (duplicated species)  Terry Erwin 1983: tree fogging (SUPLIMENTAL READING IN MY COURSES) - In one species of tropical tree found 160 beetle species unique to that tree species, about 50000 tropical tree species, beetles are about 2/5 of insects which are about ½ all species According to May 2002 taxonomists estimate:  3-100 million extant “living today” eukaryotic species (may’s guess: 7 million)  very large margin of error  bacteria and Archaea numbers are completely unknown (e.g. ~10,000 bacteria species are identified but could easily be millions or 100s of millions bacteria live in very diverse and strange environments that we haven’t seen yet)  ~99% of species are already extinct through all those big mass extinctions A lot more diversity in all of the tropical climates: warmer, wetter habitats are better than cooler, drier habitats Animal Diversity:  Amphibians in North America: in southern latitudes—warmer, wetter climates  Mammals in North America: spread out a bit more in the southern latitudes because they can handle the drier climates that you’d see in areas such as Nevada Which group has the greatest diversity? 1. Fungi 2. P Pllantss 3. Worms Fact4. Arthropodsrol biodiversity:  5. Vertebratesal doubling area increases number of species by 10-25%. A general rule in ecology. (Bigger land mass, more species)  climate: warm and wet areas have more species but we don't know why The most diverse groups on earth:  Arthropods are the most diverse eukaryotic group on earth 15 - Beetles make up greater percentage of the species of arthropods (35%) - 62% of all species on earth, plants come after with 17%  Fish are the most diverse (49%) of the vertebrates  Mammals represent <1% of the diversity of eukaryotic organisms  Beetles represent ~22% of the diversity of eukaryotic organism Which groups are most diverse? Crustacea Algae, ns, Spiders, 40,000 , 40,000 , 75,000 , Protozoa, 3% Fungi, 4% 8% 40,000 , 70,000 , Other Beetles, 3% 4% Insects, 340,000 , 510,000 , 35% Plants, 53% 270,000 , 17% Worms, 25,000 , Mammals, 5,4Bids,9% Arrhopodss, 2% 10,000 , Fish, 965,000 , 17% 28,000 , 62% Molluscs, 49% 70,000 , Reptiles + Vertebrates 5% Amphibian , 57,600 , s, 14,200 , 4% 25% Taxonomists: they are the scientists who study organisms and place them in the proper genus and species names Other measures of diversity: 8  So far we have focused on number of species (=numeric diversity)  There are other measures: - Genetic diversity: measure of genetic distance (=evolutionary separation) - Functional diversity: differences in shape, size, and generally ways of making a living (types of food, places lived, etc) Prokaryote Outline • prokaryotes vs eukaryotes Group with the greatest genetic diversity: • cell structure & diversity  Prokaryotes are the oldest species • They show the greatest genetic diversity – reproduction  They also show the greatest functional diversity – maintain homeostasis Summary on diversity of life: – enerrgy transforma atonn  There are likely ~7-10 million extant species  ~99% of Earth’s species are extinct  DiversityOldest extant organismequat3.5 billion year old fossil good climates  Taxonomists have quantified animals/insects/beetles as most divers  Other measures of diversity - Functional: bacteria most diverse - Genetic/evolutionary: bacteria  Humans are biased to vertebrates and plants Prokaryotes: Prokaryotes are the  They are the Earth’s oldest extant organisms Earth’s oldest organisms.  Two major groups: - Bacteria Two major groups of prokaryotes: - Archaea Bacteria Archaea Domains of Life = eukaryotes  How they address the 3 challenges of life: - Make nearly faithful copies of themselves (reproduce) - Respond to the outside environment by resisting internal changes in physical and chemical characteristics (maintain homeostasis) 12 - Transform energy to synthesize new molecules (energy transformation) 25  Their cell structure and diversity: - The first species that existed were a single cell (unicellular) organism Differences between prokaryotes & eukaryotes: Key differences kary = kernel Pro- = beforeEu- = true karyote karyote Nucleus Noo Yes DNA 1 chromosome Linear (circular) + plasmidschromosomes Organelles None with Yes membranes Ribosomes Smaller Larger Cytoskeleton No Yes Cell wall Yes – peptidoglycan Yes (in some) in bacteria only Photosynthesis Yes (in some) Yes (in some) There are some major differences among the prokaryotic domains: Bacteria & Archaea  Plasmids: extra DNA DefinigProkaryotes don’t have membrane-bound organelles  Ribosomes: where protein synthesis takes place • Absence of peptidoglycan in cell wallthe cell wall Many differences in between the prokaryotic domains themselves: the bacteria and the Archaea • DDiistinctive lipids present tin the
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