ESC 301.01 - II-A-Ecology - Evolution of life, Biodiversity and Extinction PDF

ESc 301.01 The Environmental Dimension II-ECOLOGY Evolution of Life, Biodiversity and Extinction Ferhan Çeçen  Learning objectives In the ECOLOGY part, you will learn ❖ What ecology is about ❖ Why we should have an idea about biological evolution and how it relates to some of...

ESc 301.01 The Environmental Dimension II-ECOLOGY Evolution of Life, Biodiversity and Extinction Ferhan Çeçen  Learning objectives In the ECOLOGY part, you will learn ❖ What ecology is about ❖ Why we should have an idea about biological evolution and how it relates to some of the environmental problems. ❖ How chemical evolution affected the evolution of life forms ❖ How chemical evolution has lead to ozone formation ❖ About the behavior of populations and communities in ecosystems ❖ Why we need to understand the principles of ecology to understand and/or solve environmental problems.  Ecology Understanding environmental issues, be they historical or contemporary, requires a firm grasp of the science of ecology. It has been noted that ecology is to environmental sciences and resource management what anatomy, biochemistry, genetics, and physiology are to the practice of medicine (Wali 1992). The word ecology is derived from “Ökologie,” a term first coined by the German zoologist, Ernst Haeckel. The term has the Greek roots oikos, meaning house, and logos, study of. Ecology is the scientific study of relationships in the natural world. It includes relationships between organisms and their physical environments (physiological ecology); between organisms of the same species (population ecology); between organisms of different species (community ecology); and between organisms and the fluxes of matter and energy through biological systems (ecosystem ecology). Applied ecology uses information about these relationships to address issues such as developing effective vaccination strategies, managing fisheries without over- harvesting, designing land and marine conservation reserves for threatened species, and modeling how natural ecosystems may respond to global climate change. ORGANIZATION OF LIFE LEVELS OF ORGANIZATION IN ECOLOGY Evolution of Earth and Life EVOLUTION OF EARTH EVOLUTION OF LIFE The evolution of life is linked to the physical and chemical evolution of the Earth. primitive bacteria (3.5 billion years ago) evolution of photosynthetic prokaryotes (2.3 billion years ago) release of oxygen into ocean and atmosphere evolution of oxygen-using organisms evolution of more complex organisms including humans. RISE OF OXYGEN AND FORMATION OF OZONE Early aquatic organisms called blue- green algae began using energy from the Sun to split molecules of H2O and CO2 and recombine them into organic compounds and molecular oxygen (O2). This solar energy conversion process is known as photosynthesis. As oxygen in the atmosphere increased, CO2 decreased. High in the atmosphere, some oxygen (O2) molecules absorbed energy from the Sun's ultraviolet (UV) rays and split to form single oxygen atoms. These atoms combining with remaining oxygen (O2) to form ozone (O3) molecules, which are very effective at absorbing UV rays. The thin layer of ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light.  Early Earth Major events and trends in Earth’s surface environment during the first 4.0 b.y.: Ocean forms, 4.4 b.y. Oldest bacteria, 3.8 b.y. Blue-green algae, 3.0 b.y. Iron formations, 2.2 b.y. Oxygen buildup, 2.0 b.y. Eukaryotes, 2.0 b.y. Abundant multicelled fossils, 0.6 b.y. N. Lindsley-Griffin, 1999  How does biological evolution actually work? Natural Selection Some individuals may be better suited to the environment than others. Those better able to survive and reproduce leave more offspring. Their descendants form a larger proportion of the next generation. Mutation Natural Mutation caused by X-rays and mutagenic chemicals  Mechanisms of Species Adaptation Change through natural selection – Selective pressure determines which organisms survive and reproduce and which are eliminated.  Survival of the Fittest In his Origin of Species, published in 1859, Darwin proposed how one species might give rise to another. Where food was limited, competition meant that only the fittest would survive. This would lead to the natural selection of the best adapted individuals and eventually the evolution of a new species.  Natural Selection Galápagos Finches Darwin observed that the Galápagos species differed from each other in beak size and shape. He also noted that the beak varieties were associated with diets based on different foods. He concluded that when the original South American finches reached the islands, they dispersed to different environments where they had to adapt to different conditions. Over many generations, they changed anatomically in ways that allowed them to get enough food and survive to reproduce.  VARIATION IN A POPULATION Within a species there are always slight differences between individuals. Some individuals may have characteristics which make them better able to survive than others (they are better adapted). NATURAL SELECTION EXAMPLE OF RESISTANCE DEVELOPMENT IN INSECTS  NATURAL SELECTION EXAMPLE OF MOTH " Peppered" moths living near English industrial cities: During the 19th century, sooty smoke from coal burning furnaces killed the lichen on trees and darkened the bark. On these trees and other blackened surfaces, the dark colored ones were harder to spot by birds who ate them. Subsequently, they more often lived long enough to reproduce. Over generations, the environment continued to favor darker moths. By 1895, 98% of the moths in the vicinity of English cities like Manchester were mostly black. Since the 1950's, air pollution controls have significantly reduced the amount of heavy particulate air pollutants reaching the trees, buildings, and other objects in the environment. As a result, lichen has grown back, making trees lighter in color. In addition, once blackened buildings were cleaned making them lighter in color. Now, natural selection favors lighter moth varieties so they have become the most common. NATURAL SELECTION EXAMPLE OF MOTH Vulnerability of different organisms to environmental changes Biodiversity = Speciation- Extinction Biodiversity  Why do we value biodiversity? A species or group of species provides a product that is of direct value to people. Nature and its diversity provide some service, such as taking up carbon dioxide. Species have roles in their ecosystems, some of these are necessary for the persistence of their ecosystems, perhaps even for the persistence of all life. Species have a right to exist, independent of their value to people. Some religions value nature and its diversity. Nature provides us with healthful activities that we enjoy.  Why do we value biodiversity? Vinblastine (VBL), sold under the brand name Velban among others, is a chemotherapy medication, typically used with other medications, to treat a number of types of cancer. Vinblastine was isolated in 1958. An example of a natural herbal remedy that has since been developed into a conventional medicine, vinblastine was originally obtained from the Madagascar periwinkle. It is on the World Health Organization's List of Essential Medicines. Benefits of Biodiversity Number of described species  Threats to Biodiversity Overharvesting-Hunting Humans are harvesting many plants and animals at faster rates than the populations can maintain themselves (harvesting includes the use of animals and plants for food as well as other applications like medicines, trophies, and clothing). The declining yield from world fisheries shows how overharvesting threatens biodiversity on a large scale. Habitat loss Habitat loss is generally viewed as the largest single cause of biodiversity loss worldwide. When humans convert wild areas for agriculture, forestry, urban development, or water projects (including dams, hydropower, and irrigation), they reduce or eliminate its usefulness as a habitat for the other species that live there. Example of Habitat Loss Palm oil plantations in the tropical regions of Africa, Latin America, and Asia have led the large scale destruction of important habitat for many species. The largest growth of palm oil plantations has been in Malaysia and Indonesia where large tracts of rainforest are cleared to grow palm oil crops. Orangutans, tigers, elephants, rhinos, and many other species are increasingly isolated and their sources of food and shelter are in decline. Human-wildlife conflict also increases because without sufficient natural habitat these species come into contact with humans and are often killed or captured. Pollution Pollution reduces biodiversity by either changing organisms' biological functions or altering the environmental conditions that they need to survive. For example, pesticides can affect the health and reproductive patterns of many species. Climate change Global climate change threatens biodiversity worldwide because it is modifying average temperatures and rainfall patterns, and thereby shifting climate zones. Ecologists have documented changes in the geographic ranges and breeding cycles of many species. Invasive Species Thousands of exotic species have been introduced to new habitats worldwide as a result of human trade and travel, but they all have something in common: the potential to thrive and multiply beyond all expectations in their new environments. These invasive species are major threats to biodiversity because local species are not adapted to compete with them. Threats to Biodiversity  EXAMPLE TO BIODIVERSITY: AMAZON Not only does the Amazon encompass the single largest remaining tropical rainforest in the world, it also houses at least 10% of the world’s known biodiversity, including endemic and endangered flora and fauna, and its river accounts for 15-16% of the world’s total river discharge into the oceans. The Amazon River flows for more than 6,600 km, and with its hundreds of tributaries and streams contains the largest number of freshwater fish species in the world. Rainforests have a very high biodiversity. The Amazon Rainforest has been described as the "Lungs of our planet" because it provides the essential environmental world service of continually recycling carbon dioxide into oxygen. More than 20% of the world's oxygen is produced by the Amazon Rainforest and one fifth of the world's fresh water comes from the Amazon Basin. Rainforests are being destroyed because of the lands value of timber, by the governments, national logging companies, and land owners.  Biodiversity hotspots Biodiversity “hotspots”: Earth’s biologically richest places with high numbers of species.  Categories of Concern: Critically Endangered, Endangered, Vulnerable International Union for the Conservation of Nature (IUCN) maintains a database of threatened species and subgroups and publishes the Red List, which catalogues species most at risk. For species in the highest risk groups, Critically Endangered, Endangered, and Vulnerable, IUCN weighs criteria including population size, geographic range, and how individuals are distributed, especially if the population is very small. To determine whether a species is endangered or might become so, scientists collect data about their population (growing, shrinking, or at a steady state, and why?). They also study how it is it being affected by competitors, parasites, harvesting etc., its geographic range, the external impacts on its habitat, such as pollution and development. Risk of extinction Extinction of species since the 19th century