Evollecsspr2010 - Evolution (Biol 3339/5311) - Chippindale...

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1 Evolution (Biol 3339/5311) -- Chippindale Lecture notes, Spring 2010 Intro, review syllabus, etc. Evolution: process that explains diversity of life on Earth -- all life on Earth descends from a common ancestor. Precise definition of evolution: Change in allele frequencies in a species or population over generations. -organisms continuously evolve (i.e., populations and species change from generation to generation); we can see this happening with some organisms even on a short-term basis (HIV will provide one example; think also of antibiotic resistance in bacteria) -evolution results from a combination of random events (mutations) and non-random factors (natural selection on randomly-generated variants); some evolution is due to purely random factors (genetic drift -- deal with this later; start w/ natural selection = NS) HIV and AIDS: major public health problem that requires an understanding of rapid evolution to address properly HIV: human immunodeficiency virus: retrovirus that can cause the syndrome called AIDS (acquired immune deficiency syndrome) Chapter 1 addresses the following questions: 1) Why have some treatments for HIV infections like AZT failed in long term? 2) Why are some people apparently immune to HIV, or if infected, don't progress to AIDS? 3) Why is HIV infection usually fatal? 4) Is an HIV vaccine possible? 5) Where did HIV come from? What does this have to do with evolution? Evolutionary biology addresses two main questions (as well as others): 1) How pop'ns of organisms change over time (generations), especially in response to environmental change;
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2 2) How new species and variants arise and persist. So, evol. biol. investigates adaptation and diversity, both of which are crucial to understanding HIV. HIV/AIDS: At least 40 million people on Earth infected w/ HIV; by now, probably responsible for more deaths than almost any other disease epidemic in recorded history -- or soon will be. As of 20027 over 65 million infected & most will die; about 25 million deaths so far, with about 90 million deaths predicted by 2020 (note that epidemic of Spanish flu in 1918 killed 50-100 million people worldwide, and plague in Middle Ages killed tens of millions, so other deadly diseases do appear -- but HIV is unusual, in part in how long it takes to be lethal, yet can be spread during latent period). Really, two major epidemics: 1) Heterosexual males and females in sub-Saharan Africa, S. and SE Asia; 2) Homosexual males and IV drug users in N. America and Europe. Africa: huge epidemic: as of 2000, 20+ million Africans infected (up to 39% of adults in Botswana in 2002); in some cities, more than 3/4 of adult deaths due to AIDS, and growing; most infections in Africa, China, India, SE Asia due to heterosexual intercourse. (Note: as of 2006, 58% of HIV-infected people worldwide were female) See maps of HIV prevalence worldwide. N. America, Europe: mostly due to homosexual intercourse and needle-sharing; frequency of
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This note was uploaded on 02/20/2010 for the course BIOL 3339 taught by Professor Chippindale during the Spring '10 term at UT Arlington.

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Evollecsspr2010 - Evolution (Biol 3339/5311) - Chippindale...

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