Madar 10E Chapter 16

concepts 16 How Populations Evolve hen your grandp arnts were young, infectious diseases, such as tuberculosis, pneumonia, and syphilis, killed thousands of people both year. Then in the 1940s, penicillin and other antibiotics were developed, and state-supported health officials ideal infectious diseases were a thing of the past. Today, however, some(prenominal) infections be spur with a vengeance. Why? Because natural selection occurred. As with staph aureus, a few bacteria were skanky to penicillin. Therefore, they were selected oer and over again to reproduce, until the entire population of bacteria became resistant to penicillin. A new antibiotic called methicillin became available in 1959 to treat penicillin-resistant bacterial strains, but by 1997, 40% of hospital staph infections were caused by methicillin-resistant Staphylococcus aureus, or MRSA. Now, community-acquired MRSA (CA-MRSA) disclose spread freely through the agentral populace, particularly when pe ople are in close contact. This chapter gives the principles of evolution a genetic stand and shows how it is feasible to genetically recognize when a population has undergone evolutionary changes. evolutionary changes observed at the population level are termed microevolution. MRSA can spread between members of a human fond group. 16.

1 tribe GENETICS ? Genetic diversity is a necessity for microevolution to occur, and today investigators are interested in desoxyribonucleic acid sequence differences between individuals. It exponent be possible to confrere particular variations with illnesses. 284 The Hard y-Weinberg principle provides a way to know ! if a population has evolved. Allele absolute frequency changes in the adjacent generation signify that microevolution has occurred. 28586 Microevolution volition occur unless 5 conditions are met: no mutations, no gene flow, mating is random, no genetic drift, and no selection of a particular trait. 28688 ? ? 16.2 NATURAL SELECTION ? A change in phenotype frequencies...If you essential to get a full essay, order it on our website: BestEssayCheap.com

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