There have been five mass extinctions in Earth’s history, including the end-Cretaceous event that felled the dinosaurs 66 million years ago, and many believe we are in the midst of a sixth, with species disappearing at a rate that’s 100 to 1,000 times faster than normal. Don Melnick, the Thomas Hunt Morgan Professor of Conservation Biology, in the Department of Ecology, Evolution, and Environmental Biology, tackled this topic, including its causes and consequences, this fall in his three-part Mini-Core Course “The Biodiversity Crisis.” Herewith, the takeaways from his classes.
Global Trends: Humanity, through our many activities, has drastically altered the environment. This has led to mass-scale degradation of land ecosystems; destruction of aquatic ecosystems; accumulation of greenhouse gases; decline of populations and species; and increases in emerging infectious diseases.
Local Effects: Plant and animal populations are declining in size and becoming more isolated as environments are degraded and fragmented, and therefore are losing genetic diversity more quickly, which means they run a much higher risk of disappearing altogether.
Global Trends: The negative effects of environmental degradation abound: climate change; decline of fresh water; collapse of fisheries; loss of pollination, pest control and disease-buffering services; mortality, morbidity and declining economic security; and social displacement, civil disorder and eroding national security.
Local Effects: The decline of fragmented populations and species disrupts or diminishes ecological processes and the invaluable services these processes — pollination, insect control, water purification and so on — provide the human population.
Global Trends: Develop policies that incorporate the undeniable reality that nature is the infrastructure upon which our security in water, food, health, weather, money and personal safety depends and degrading that infrastructure makes us not only less secure, but takes tens of thousands of lives every day in places all over the world.
Local Effects: Stem rate of transformation of habitats, reclaim hundreds of millions of acres that have been transformed and reconnect the now-isolated habitat patches and populations of species they host — all to restore gene flow and slow erosion of genetic diversity.
EXTRA CREDIT: Read The Monk in the Garden: The Lost and Found Genius of Gregor Mendel, the Father of Genetics, by Robin Marantz Henig. Says Melnick: “His experiments were elegant in their simplicity, ahead of their time in their mathematical sophistication and led to discoveries that have stood the test of time. He laid the groundwork for everything we know about genetics today.”
Mini-Core Courses are class series that offer College alumni the opportunity to revisit the Core in a lecture/seminar-like setting with a distinguished faculty member and other alumni. Topics relate to the Core Curriculum but explore new texts or ideas. For offerings and other information, go to college.columbia.edu/alumni/career/minicore.
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