HOW GEOGRAPHY AND GEOLOGY AFFECT BIOLOGICAL DIVERSITY

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1 HOW GEOGRAPHY AND GEOLOGY AFFECT BIOLOGICAL DIVERSITY Factors Affecting Extinction Rates Natural Factors Climate change Cataclysmic event (volcano, earthquake) Human Activities Habitat Loss/Fragmentation Introduction of exotic/invasive species Pollution Commercial harvesting Accidental killing (tuna nets) Harassing Pet Trade Urbanization Damming/Flooding Agricultural conversion 1

2 Natural Extinction Density-Independent Factors A density-independent factor is a population-limiting factor whose intensity is unrelated to population density. Examples include abiotic factors like unfavorable changes in the weather (i.e., freeze in the fall) and/or abrupt environmental trauma such as fire, floods, storms, and habitat disruption by human activity. In many natural populations, density-independent factors limit population size before density-dependent factors become important. E.g.: Weather change as a density-independent factor limiting growth of an aphid population Climate Change 2

3 Climate Change and Natural Selection Changes in climate throughout the earth s history have shifted where plants and animals can live. 18,000 years before present Northern Hemisphere Ice coverage Modern day (August) Legend Continental ice Sea ice Land above sea level Note: Modern sea ice coverage represents summer months Major Causes of Climate Change Natural Causes the arctic tundra and wetlands release methane, a greenhouse gas Earth naturally has a cycle of climate change that occurs every 40,000 years the sun s solar energy output is changing and naturally increases Earth s average temperature by about 1ºC every century Earth s orbit and tilt alter in relation to the sun, which changes solar energy output Human Causes Increasing green house gas emissions from burning fossil fuels-oil, coal, gas Pollution, smog from factories Large forests have been cut down (trees absorb CO2 and pollution, deforestation creates about 6 billion tons of CO2 per year) Increasing world population-more people requires more food, energy, transportation, etc. Farms animals release methane from their wastes. More people also means more CO2 production from respiration and less trees to make room for human population 3

4 Some Effects of Climate Change An average increase in Earth s temperature during the last century Melting of polar ice polar bears and other animals are drowning Migrating birds are forced to change their time and place of migration Melting of glaciers will lead to higher sea level, which will cause floods and put many low-elevation regions at risk of disappearing under water Longer summers can disrupt animal habitation New and widespread diseases because of warm climate Damaged crops due to sudden climate change and floods Average precipitation increase around the world Droughts, heat waves, extreme winters and storms, hurricanes, typhoons More wildfires Temperature Change Data

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6 What s the difference between global warming and climate change? GLOBAL WARMING It is the increase of the Earth s average surface temperature due to a build-up of greenhouse gases in the atmosphere. CLIMATE CHANGE It is a broader term that refers to long-term changes in climate, including average temperature and precipitation 6

7 GEOLOGIC PROCESSES Cataclysmic event (volcano, earthquake) The movement of solid (tectonic) plates making up the earth s surface, volcanic eruptions, and earthquakes can wipe out existing species and help form new ones. The locations of continents and oceanic basins influence climate. The movement of continents have allowed species to move. Geological processes and biological evolution 225 million years ago 135 million years ago 65 million years ago Present 7

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9 Tectonic Cycles Plate interactions are complex. Plate tectonic theory describes three basic end members: A) Divergent plate (rifts - spreading centers), B) A convergent plate (subduction zones - collisions) C) Transform faults. Tectonic Cycles A divergent plate boundary occurs at a spreading ocean ridge, where plates are moving away from one another and new lithosphere is produced. This process, known as seafloor spreading, produces ocean basins. A convergent plate boundary occurs when plates collide. When a plate composed of relatively heavy ocean-basin rocks dives (subducts) beneath the leading edge of a plate composed of lighter continental rocks, a subduction zone is present. Such a convergence may produce linear coastal mountain ranges, such as the Andes in South America. When two plates that areboth composed of lighter continental rocks collide, a continental mountain range may form, such as the Himalayas in Asia. 9

10 Tectonic Cycles A transform fault boundary occurs where one plate slides past another. An example is the San Andreas Fault in California, which is the boundary between the North American and Pacific plates. The Pacific plate is moving north, relative to the North American plate, at about 5 cm/year (2 in./year). As a result, Los Angeles is moving slowly toward San Francisco, about 500 km (300 mi) north. If this continues, in about 10 million years San Francisco will be a suburb of Los Angeles. Why Earth Science id4 10

11 Catastrophes and Natural Selection Volcanic eruptions E.g. Montserrat Cyclones E.g. Indian ocean islands Lightning strikes / severe fires Asteroids E.g. Meteor; Shehab; Luminary Floods E.g. tsunami Earthquakes Fires Volcanic eruptions 11

12 Cyclones Lightening 12

13 Asteroids Flooding 13

14 Earthquake Fire 14