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Diversity of Life How can this diversity be explained? Charles Darwin and the Beagle -left England in 1831 -took 5 years to complete -was a volunteer naturalist position -he was 22 years old -collected plants and animals at every stop -spent much time on the Galapagos Islands making observations -noticed many variations of plants and animals from island to island HMS Beagle Natural Genetic Variation- differences among individuals of a species -found in all organisms Ex: fruit size, bacterial resistance, cows milk (volume) Genetic Variations Gene Pool-combined genetic information of all the members of a population. -typically contain 2 or more alleles for an inheritable trait EX: Blood Types, Coat color 4 Sources of Genetic Variation 1 Mutation- change in the sequence of DNA -some may effect an individuals fitness (for better or worse) 2 Gene Shuffling -23 pair of chromosomes can produce 8.4 million combinations of genes -Crossing over- produces recombinants (new combinations) with different phenotypes (Meiosis I) -Sexual Reproduction- produces many phenotypes but doesn’t change frequencies (deck of cards) 3 Single Gene Traits- a single gene with 2 alleles will give you 2 phenotypes (widow’s peak) 4 Polygenic Traits-traits controlled by 2 or more genes -may have multiple alleles (human skin color, height) -produces many genotypes ( gene combos.) and phenotypes (looks) Evolution = Descent with Modification Evolution only occurs when there is a change in gene frequency within a population over time. Evolution is a long term change. Compare these two examples of change in beetle populations. Which one is an example of evolution? 1. Beetles on a diet Imagine a year or two of drought in which there are few plants that these beetles can eat. All the beetles have the same chances of survival and reproduction, but because of food restrictions, the beetles in the population are a little smaller than the preceding generation of beetles. 2. Beetles of a different color Most of the beetles in the population (say 90%) have the genes for bright green coloration and a few of them (10%) have a gene that makes them more brown. Some number of generations later, things have changed: brown beetles are more common than they used to be and make up 70% of the population Natural Selection-is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift. Darwin's grand idea of evolution by natural selection is relatively simple but often misunderstood. To find out how it works, imagine a population of beetles: Evolution by Natural Selection -many different actions are at work in order to make natural selection concept successful including: 1 There is variation in traits. For example, some beetles are green and some are brown. OUCH! 2 There is differential reproduction- Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential. In this example, green beetles tend to get eaten by birds and survive to reproduce less often than brown beetles do. 3 There is Heredity. The surviving brown beetles have brown baby beetles because this trait has a genetic basis. 4 End result: The more advantageous trait, brown coloration, which allows the beetle to have more offspring, becomes more common in the population. If this process continues, eventually, all individuals in the population will be brown. What happened to all the green guys? Extinction: in some cases all variations may be selected against and the entire population my disappear If you have variation, differential reproduction, heredity, and extinction, you will have evolution by natural selection as an outcome. Survival of the fit enough (fittest) high fitness individuals live to reproduce, low fitness individuals perish. Artificial Selection-choosing the traits that we want to show up in the offspring -nature provided the variations, humans chose the ones that were useful -Known as Selective Breeding There can be a down side to artificial selection. Because this process essentially removes variation in a population, selectively bred organisms can be especially susceptible to diseases or changes in the environment that would not be a problem for a natural population. Inbreeding — the mating of closely related individuals — is also a problem. In dogs, this has resulted in breeds that have health issues ranging from decreased life span to hip dysplasia. Teosinte a relative of corn Struggle for existence- members of each species compete regularly for food, living space An organism competes most closely with other members of its own species, because they have the most similar ecological needs to its own; other species, in decreasing order of ecological similarity, also compete and exert a negative influence on the organism's chance of survival. Interspecific Competition-members of different species competing for limiting factors Intraspecific Competition -members of the same species competing Evidence to support Evolution More Modern Evidence Which Supports The Theory of Evolution Embryonic Development and relative ages of evolution T I M E 1 2 3 4 5 6 7 8 Match these organisms with the numbered embryo Human, fish, salamander, turtle, chicken, pig, rabbit, calf More Modern Evidence Which Supports The Theory of Evolution Embryonic Development and relative ages of evolution 1 Fish 2 3 Salamander Tortoise 4 Chick 5 Pig 6 Calf 7 Rabbit 8 Human Looking at embryonic development can give you a relative age as well as help you determine how closely related different organisms are. This is OLD School due to the advances in DNA analysis Which organism Would be our closest Ancestor ________? The Pig, the turtle, or the salamander Even more Evidence for The THEORY of EVOLUTION Homologous Structures are of the same basic structure but used differently in the adult Humorus Ulna radius wrist Phalangies The STRONGEST & MOST MODERN EVIDENCE which SUPPORTS the THEORY of EVOLUTION DNA Cytochrome C- protein in the electron transport chain of the mitochondria How do we get new species? SPECIATION What Is a Species? A species is a potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so. 1.Hybridization/Artificial Selection: When 2 different species interbreed so frequently that the resulting hybrid species will begin to intrabreed enough to sustain itself. 2.Adaptive radiation: The formation of a number of diverse species from a single ancestral one is called an adaptive radiation. Example: Darwin’s Finches. 3.Geographic Isolation: The Kaibab squirrel (Sciurus aberti kaibabensis, left) became geographically isolated from the common ancestor with its closest relative, the Abert squirrel (Sciurus aberti aberti, right) in the North Rim of the Grand Canyon about 10,000 years ago. Since then, several distinguishing features, such as the black belly and forelimbs have gradually evolved. A geographic barrier (mountain range, river, ocean, etc.) results in reproductive isolation and eventual changes occur in the newly separated species. Example: Grand Canyon Squirrels. Lonesome George the last Pinta Island Giant tortoise Can you predict the different Vegetation heights on which these tortoises fed?? What keeps Similar Species from Interbreeding to possibly result in new species? x = ? REPRODUCTIVE ISOLATION Polargrizz- New Species or Hybrid Liger “Hercules” the Liger (12 ft., 900 lbs.). Male lion & tigress Cama Due to size difference of the parents they are born through artificial insemination, and most noticeably they have no hump. Their flat backs and durability make them great pack animals. Wolphin A rare crossbreed of a bottlenose dolphin and a false killer whale this is probably the best example of an animal that is half and half. Killer whales have 88 teeth, bottlenose dolphins have 44 teeth and kekaimalu the wolphin has 66 teeth. 1. STERILIZATION: The Mule is a cross between a donkey stallion (called a jack) and a horse mare. Hinnies are just the opposite - a stallion horse crossed to a donkey jennet. For all purposes, hinnies and mules are classified and shown together under the general term Mule. A mule or hinny may be a male (horse mule or horse hinny) or a female (mare mule or mare hinny). Sometimes horse mules (the males) are called Johns, and the mares are called Mollies. Both male and female mules have all the correct "parts" but they are sterile and cannot reproduce. 2. MECHANICAL ISOLATION: Two different species may try to reproduce but are unable to do so due to physical differences. Physical differences prevent hybridization, organs are incompatible A friendly dog & man 3. Geographic Isolation- two populations are separated by geographic barriers (rivers, mountains, oceans) 4. Temporal Isolation- two or more species reproduce at different times - some rain forest orchids open release pollen on a single day different from the others 5. Behavioral Isolation- two populations can breed but have different courtship rituals or other behaviors Western Meadowlark Eastern Meadowlark Different Mating songs Patterns of Evolutions in Populations do Exist These Patterns of Natural Selection are best represented by graphs There are 3 basic patterns of population evolution: STABILIZING SELECTION: When the individuals in the center of the bellshaped curve have the selective advantage. The population is stable. DIRECTIONAL SELECTION: When individuals at one end on the bell-shaped curve have the selective advantage. Change is ocuring in the population. DISRUPTIVE SELECTION: When individuals at the upper and lower end of the bell-shaped curve have the selective advantage. What used to be an advantage is no longer the case Toxic newts video clip how does a new species form? 1 Founding of a new population 2 Geographic Isolation 3 Changes in the gene pool 4 Reproductive Isolation 5 Geographic Overlap Guppy Selection Expt http://www.pbs.org/wgbh/evolution/educators/lessons/lesson4/act2.html The moral of the story is that if you can not adapt to changes in your Environment then you will be outcompeted & die or (worse?) not reproduce. You have encountered this animal while backpacking in the Idaho wilderness. What is it? Is it the same animal as these? How do you know? What is its name? Common Names Mountain lion, Puma, Cougar, Painter, Catamount, Panther Puma concolor Taxonomy- the science of naming organisms and placing them into groups To avoid confusion scientific names are used whenever possible when describing organisms Good Try! - the first efforts of grouping organisms was a very lengthy descriptive process "Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges" Introducing: Carolus Linnaeus -Father of Taxonomy -Highly acclaimed Botanist and Ecologist - Swedish -Invented Binomial Nomenclature 1707-1778 100 Kroner (Sweden) He’s a big deal there! Carl von Linne coat of arms Binomial Nomenclature Homo sapiens Binomial Nomenclature- each species is assigned a two part name - always written in italics - first word is always CAPATILIZED (Genus) - second word is always lower case (species) Pseudotsuga menziesii Douglas Fir Artemesia tridentata (Genus) (species) Pinus ponderosa Basin Sagebrush Ponderosa Pine Linnaeus developed 7 classification levels (taxa) Each level is included in the level above it. Most General Most Specific Bear Family (Ursidae) The bear family includes eight species: the polar bear, American black bear, spectacled bear, giant panda, sloth bear, sun bear, brown bear, and Asiatic black bear. Ursus americanus Ursus arctos Ailuropoda melanoleuca *has it's own genus and species *it is highly specialized Ursus maritimus A schematic cladogram of the major evolutionary relationships of the Carnivora modified from Flynn et al. Nash W G et al. J Hered 2008;99:241-253 © The American Genetic Association. 2008. All rights reserved. For permissions, please email: [email protected]. Modern Classification Systems • Have added a new taxa called a DOMAIN • More genetically based than physical characters • Try to show common descent along with physical descriptions • Has 8 or more taxa where Linnaeus had just 7 taxa Domains of Life SIX KINGDOMS of LIFE How are you classified? How do you remember the order? Dumb King Phillip Cried Oh For Goodness Sake or Dumb Kings Play Chess On Fridays Generally Speaking Domain- Eukarya Kingdom- Animalia Phylum- Chordata- have notochords Subphylum- Vertebrata- vertebral column Superclass- Tetrapoda- terrestrial, 4limbs, bony skeletons Class- Mammalia- hair, milk glands, endothermic Subclass- Eutheria- offspring develop within mother, nourished by placenta Order- Primata- fingers, flat nails Family- Hominidae- upright posture, flat face, stereoscopic vision, large brain, hands and feet Genus- Homo- double curved spine, long life, long youth Species- sapiens -well-developed chin, high forehead, thin skull bones Which 2 species would be more closely Canis lupus Ursus arctos related? Canis domesticus SIX KINGDOMS of LIFE Kingdom When Evolved Structure Photosynthesis 1. Bacteria 3 to 4 billion years ago Unicellular Sometimes 2. Archaea 3 to 4 billion years ago Unicellular No 3. Protista 1.5 billion years ago Unicellular Sometimes 4. Fungi 1 billion years ago Unicellular or Multicellular No 5. Animalia 700 million years ago Multicellular No 6. Plantae 500 million years ago Multicellular Yes Prokaryotes:- No Nucleus Eukaryotes:- True Nucleus Plants Animals Kingdom Archeabacteria Kingdom Eubacteria Kingdom Protista Kingdom Fungi Phylogenetic Tree of Life Bacteria Archaea Eukarya Archae Eubacteria Protista Fungi bacteria Prokaryote ProEukaryote Euk- Plantae Euk- Animalia Euk- without Unicellular Uni- Autotroph Autoheterotroph Hetero- Multicell ular AutoHetero- Hetero- Auto- MultiHetero- Eukaryote vs. Prokaryote Eukaryotic organisms have a TRUE Nucleus Prokaryotic organisms have DNA or RNA But it is NOT contained in a nucleus Variations to the Classification System Botanists use a division instead of phylum The species level can be further divided: -Animals can be divided into subspecies(ssp.)- morphologically different and often geographically separated (see following slide) -Fruits (plants) are divided into different varieties(var.)morphologically different but not geographically separated, some produced by humans (see following slide) -Bacteria are divided into different strains(str.)- biochemically dissimilar group within a species Example: E coli Royal Gala Honeygold Jonagold Golden delicious Braeburn Fugi Malus domestica Pink Lady Map of Wolf subspecies of North America Canis lupus tundrarum (Tundra wolf) Canis lupus arctos (Arctic wolf) Canis lupus baileyi (Mexican wolf) Canis lupus crassodon (Vancouver Island wolf) Where do viruses fit? Are they alive? Do they meet the requirements of living organisms? These can be just As bad as the others Avoid at all costs! How does a virus attack your body?