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Unformatted text preview: 1/22/2009 1 Population biology of microparasites III: impacts and transmission The plague (Black Death: 1347 The plague (Black Death: 1347 ‐ 1351) 1351) • Yersinia pestis • Causes bubonic and pneumonic plague • Infects wild rodents, transmitted by fleas transmitted by fleas • Spread to Italy and from SE Asia by merchant ships • Over next five years, killed about 3 out of every 10 Europeans 1918 Influenza Pandemic 1918 Influenza Pandemic 25 ‐ 40 million people died Took 7 days to sweep across NA Emergency hospital in KS. US Time course of spread in US Human Population Human Population • From 1850 ‐ 1940: • r = 0.13 (per (per decade decade) • From From 1940 1940 ‐ 2000 2000: • r = 0.19 (per (per decade decade) • In 2000 = 6.2 billion In 2000 = 6.2 billion Effect of pathogens on human population growth • Population explosion • Partly result of decrease in (mostly juvenile) death rates due to control of infectious disease Pathogen impacts on host populations • Reduce population growth rate • Regulate population ‐ i.e. Allow increase when population is small, but 6 prevent increase when population is large • Ecological controversy – What regulates populations? Top down (predators/pathogens) or bottom up (resources) 1/22/2009 2 House finch House finch Carpodacus mexicanus Native to southwestern North America North America 1940: handful of birds released in NYC Rapid geographic range expansion: Rapid geographic range expansion: North American Christmas Bird Count data 1960 ‐ 61 1997 ‐ 98 Mycoplasmal Mycoplasmal conjunctivitis conjunctivitis Caused by the bacterium Mycoplasma gallisepticum Found in domestic poultry Found in domestic poultry First sighted in winter of 1993 ‐ 94 Novel strain infects House Finches Easily recognizable symptoms Course of infection in individual birds: Course of infection in individual birds: • 2 ‐...
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This note was uploaded on 09/22/2009 for the course ECOL 4150 taught by Professor Prin during the Spring '08 term at UGA.
- Spring '08