BIOLOGY 1500 OUTLINE FOR CHAPTER 4 Evolution and Biodiversity Evolution definitions to know: 1. Biological evolution 2. The theory of evolution 3. Microevolution 4. Macroevolution 5. Natural selection 6. Gene pool 7. Mutation 8. Adaptation Evidence of Evolution (there are five) 1) fossils: skeletons of organisms trapped in bedrocks and sediments and date back to as much as millions of years 2) Homologuous body structures: similar bone arrangement in the skeletons of animals is considered to be an evidence of evolution from a common ancestor. 3) Embryology: the early embryo of many animals is highly similar 4) Genetic evidence: a. Cytochrome C: a protein found in many organisms and is considered an evidence of common ancestors given its abundance in different organisms b. Human DNA: the research confirms the “Out of Africa” hypothesis that all modern humans stem from a single group of Homo sapiens who emigrated from Africa 2,000 generations ago and spread throughout Eurasia over thousands of years 5) Biogeography: it studies the distribution of plants and animals and the processes that influence their distribution including evolution and natural selection. Only geologic change and evolution can explain the distribution of many species such as the distribution of camel-like animals. Steps of the Evolution by Natural Selection Excess individuals produced Struggle for existence Mortality of excess individuals Variation that affects survival and reproduction Variation is heritable Favorable traits will be passed down and unfavorable traits will be eliminated Result, more individuals will have favorable traits over time. Ecological Niches Niche: refers to the “job” or “role” of an organism in its habitat. It includes all of the variation in environmental factors within which an organism can survive and reproduce. An example is the Placentals versus the Marsupials occupying similar niches at geographically distinct locations. Two types of Niches Fundamental niche: is the range of all possible environments in which an organism could live in absence of competition, predation, or parasitism Realized niche: consists of the environment(s) in which an organism is actually found in nature. Habitat Refers to the location and kind(s) of communities in which an organism lives; its home or address Species A species is a group of organisms that resemble each other in terms of appearance, lifestyle, behavior, chemistry, and genetics (a variation of the morphological species concept). Also: is a set of individuals that can mate and produce fertile offspring. Generalists: live in a very wide range of habitats and have very broad fundamental niches Specialists: live in a few habitats (or maybe just one) and have very narrow niches. Both (generalists and specialists) can succeed in a stable environment Generalists are more successful in an unstable or variable environment Misconceptions about Evolution: 1. If a trait is not available to counteract a threat, then organism cannot adapt, it dies 2. Fittest does not equal strongest 3. There is no plan to move to perfection; all organisms are bundles of compromises. Speciation The common mechanism of speciation involves reproductive and geographic isolation and evolution in different environments. Happens due to a barrier: first geographic (such as river, street, wind, tectonic plates, volcano…etc) then reproductive isolation. Extinction and Biodiversity Extinction - extinction is the fate of all species - there is a constant low extinction rate called the background extinction rate. Every year one in million species goes extinct. - Speciation minus extinction equals biodiversity - The largest cause of the growing rate of species extinctions and ecosystem disruptions is the loss, fragmentation, and degradation of terrestrial and aquatic habitats. - Mass extinction: o Involves episodes in which more than 25% (up to 95%) of species are wiped out. o Extinction rates greatly above background. o Is important, because it allows new groups of organisms to take over many niches in the long run. However, in the short run it greatly lowers biodiversity and results in ecosystem collapse. Biodiversity variety of different species (species diversity), genetic variability among individuals within each species (genetic diversity), variety of ecosystems (ecological diversity), and functions such as energy flow and matter cycling needed for the survival of species and biological communities (functional diversity). Artificial Selection - Process by which humans select one or more desirable genetic traits in the population of a plant or animal species then use selective breeding to produce populations containing many individuals with the desired traits. - Promotes those traits in other organisms that are beneficial to humans. - Artificial selection can increase diversity in pets and other non-food animals. - It can also increase uniformity (decrease diversity) and productivity in crops. Biotechnology (genetic engineering) - Genetic engineering transfers traits from one organism to another. - Creates pesticides resistance, such as Round-Up ready corn by Monsanto. - Uses bacteria to produce human insulin. - Creates novel combinations not found in nature. - Unintended consequences: BT corn pollen can poison more than just corn pests. Kills monarch butterfly. - Divided reaction to GM foods: Increasing adoption in some countries, banning in others Commonalities Both artificial selection and genetic engineering can decrease diversity in some organisms (such as potato) and increase it in others (such as dogs), while making novel combinations not found in nature.