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BIO 105
Mar 9, 2023
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Identifying Mendelian Genetics and its Patterns Describing Natural Selection and its Evidence THE EVIDENCE OF EVOLUTION PALEONTOLOGY SUPPORTS EVOLUTION Fossils Much of initial evidence came from fossils Incomplete but provide a concrete evidence of what extinct organisms looked like Remains of dead plants and and animals Through time, new layers of rocks press down on older layers through geological process Paleontologist revealed important lessons on evolutionary process Animals lived in different time periods Fossil that were excavated demonstrated transitional forms compared to fossils found in the previous and succeeding rock layers Fossil evidence hdd supported Darwin's findings: Different organisms thrived and lived at different periods Organisms of the past were different from the living ones today Fossils embedded in adjacent rock layers are more similar in appearance to each other than fossils from distant layers Intermediate forms of organisms are found in between rocks, which revealed transitional species Older rocks = embedded with simple organisms Rocks near the surface = contain more complex ones that are very similar to the present organisms BIOGEOGRAPHY AND CONTINENTAL DRIFT THEORY SUPPORTS EVOLUTION The geographical distribution of organisms also revealed something about how organisms evolved in their natural environments Powerful influence of the environment Continental drift theory As bigger solid rocks (plates) moved, continents move with them too COMPARATIVE ANATOMY SUPPORTS EVOLUTION Inheritance of changes Mammals evolved over time to occupy new environments and that these structures helped them survive the environment
Similar structures but found in different organisms: Bat wings Whale flippers Cat front legs DEVELOPMENT OF EMBRYOLOGY SUPPORTS EVOLUTION Humans have structures similar to present-day organisms that most probably came from same ancestor Supplies us with evidence that over time, these structures have been modified to fit our survival tasks MOLECULAR BIOLOGY With advances in molecular genetics, scientists have supported the idea that if we all share certain characteristics, evolve from a common ancestors, and gradually develop genetic changes over time, then our similar features can be tested even up to the molecular level. Biologist use proteins present in their bodies to reveal their evolutionary relationships Can witness how the changing environmental conditions, such as introducing an antibacterial agent in a population Humans and chimps have 95/98.5 percent DNA similarities No doubt on how close our evolutionary relationship to chimp is Explaining Microevolution Scientists discovered 2 kinds of patterns of evolution This patterns tells the way how organisms evolve and survive 2 major evolutionary patterns Microevolution & macroevolution MICROEVOLUTION Pertains to the minor differences in the genetic level between populations of the same species providing evidence for diversity within individuals SYNTHETIC THEORY OF EVOLUTION - biologist combine their knowledge of evolutionary theory with genetics AGENTS OF MICROEVOLUTION DNA MUTATION AS AN AGENT OF GENETIC VARIATION Cells have the complex ability to safeguard the DNA's integrity - its information is copied accurately every time the cells divide However, random mistakes could happen 1. DNA is damaged 2. When enzymes that copy a DNA insert a wrong nitrogenous base, or deletes or skips a base MUTATIONS = genetic variation Essential to natural selection Occur randomly in nature, it can be either harmful or beneficial infants produce the enzyme LACTASE = able to digest lactose milk Adults decline in lactose digestion = LACTOSE INTOLERANCE SEXUAL REPRODUCTION, SEXUAL SELECTION, AND NONRANDOM MATING GENE POOL AND FREQUENCY
Evolution is observed by examining the gene pool of a population The allele frequencies for each gene later on will determine the characteristics inherited in a population GENETIC DRIFT Gene distribution in small population evolve randomly by chance FOUNDER EFFECT observed when few individuals become separated from the rest of the population As organisms reproduce, they became the founders in the new territory BOTTLENECK EFFECT Size of population is severely reduced, leaving a few individual to reproduce and reestablish in the new environment Extinction
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