Group 2 - GE ENVI SCI PDF

CHAPTER 3 EVOLUTION, BIODIVERSITY AND POPULATION Group 2  Where do SPECIES come from? The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations. Populations evolve when genes mutate and give some individuals...

CHAPTER 3 EVOLUTION, BIODIVERSITY AND POPULATION Group 2  Where do SPECIES come from? The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations. Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).  BIOLOGICAL EVOLUTION the process whereby earth’s life changes over time through changes in the genes of populations.  FACTORS AFFECTING BIOLOGICAL EVOLUTION TECTONIC PLATE VOLCANIC EARTHQUAKES CLIMATE CHANGE MOVEMENTS ERUPTIONS These factors have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.  Geological Processes Affect Natural Selection Scientists have discovered that huge flows of molten rock within the earth’s interior break its surface into a series of gigantic solid plates, called tectonic plates. For hundreds of millions of years, these plates have drifted slowly atop the planet’s mantle. The locations of continents and oceanic basins greatly influence the earth’s climate and thus help determine where plants and animals can live. The movement of continents has allowed species to move, adapt to new environments, and form new species through natural selection. When continents join together, populations can disperse to new areas and adapt to new environmental conditions. And when continents separate, populations either evolve under the new conditions or become extinct.  Geological Processes Affect Natural Selection Earthquakes can also affect biological evolution by causing fissures in the earth’s crust that can separate and isolate populations of species. Over long periods of time, this can lead to the formation of new species as each isolated population changes genetically in response to new environmental conditions. Volcanic eruptions affect biological evolution by destroying habitats and reducing or wiping out populations of species.  Climate Change and Catastrophes Affect Natural Selection Throughout its long history, the earth’s climate has changed drastically. Sometimes it has cooled and covered much of the earth with ice. At other times it has warmed, melted ice, and drastically raised sea levels. Such alternating periods of cooling and heating have led to advances and retreats of ice sheets at high latitudes over much of the northern hemisphere, most recently, about 18,000 years ago. These long-term climate changes have a major effect on biological evolution by determining where different types of plants and animals can survive and thrive and by changing the locations of different types of ecosystems such as deserts, grasslands, and forests.  Climate Change and Catastrophes Affect Natural Selection Some species became extinct because the climate changed too rapidly for them to survive, and new species evolved to fill their ecological roles. Another force affecting natural selection has been catastrophic events such as collisions between the earth and large asteroids. There have probably been many of these collisions during the earth’s 4.5 billion years. Such impacts have caused widespread destruction of eco systems and wiped out large numbers of species. But they have also caused shifts in the locations of ecosystems and created opportunities for the evolution of new species.  BIODIVERSITY, SPECIES INTERACTION AND POPULATION CONTROL WHAT IS BIODIVERSITY? Biodiversity or Biological diversity is a term that describes the variety of living beings on earth. In short, it is described as degree of variation of life. Biological diversity encompasses microorganism, plants, animals and ecosystems such as coral reefs, forests, rainforest, deserts etc. What is Biodiversity? is the variety of the earth’s species, the genes they contain, the ecosystems in which they live, and the ecosystem processes such as energy flow and Genetic Diversity nutrient cycling that sustain all life. Species Richness Ecosystem Diversity  The Importance of Biodiversity MAINTAINING BALANCE OF THE ECOSYSTEM Recycling and Storage Combating Stabilizing Climate Forming, Protecting Soil and of Nutrients Pollution Protecting Water Resources Maintaining Eco balance PROVISION OF BIOLOGICAL RESOURCES Provision of Medicines Food for Human Ornamental Plants and Breeding Stock and and Pharmaceuticals Population and Animals Wood Products Diversity of Species  The Importance of Biodiversity SOCIAL BENEFITS Recreation and Cultural Value and Research Tourism Education The role of biodiversity in the following areas will help make clear the importance of biodiversity in human life: BIODIVERSITY AND FOOD 80% of human food supply comes from 20 kinds of plants. But humans use 40,000 species for food, clothing and shelter. Biodiversity provides for variety of foods for the planet. The role of biodiversity in the following areas will help make clear the importance of biodiversity in human life: BIODIVERSITY AND HUMAN HEALTH The shortage of drinking water is expected to create a major global crisis. Biodiversity also plays an important role in drug discovery and medicinal resources. Medicines from nature account for usage by 80% of the world’s population. The role of biodiversity in the following areas will help make clear the importance of biodiversity in human life: BIODIVERSITY AND INDUSTRY Biological sources provide many industrial materials. These include fiber, oil, dyes, rubber, water, timber, paper and food. The role of biodiversity in the following areas will help make clear the importance of biodiversity in human life: BIODIVERSITY AND CULTURE Biodiversity enhances recreational activities like bird watching, fishing, trekking etc. It inspires musicians and artists. Biodiversity has three essential elements: ECOSYSTEM DIVERSITY GENETIC DIVERSITY SPECIES DIVERSITY ECOSYSTEM DIVERSITY It relates to variety of habitats, biotic communities and ecological processes in the biosphere, and is considered as complex level of diversity. Biodiversity has three essential elements: ECOSYSTEM DIVERSITY GENETIC DIVERSITY SPECIES DIVERSITY GENETIC DIVERSITY Refers to total genetic information contained in the genes of individuals of plants, animals and microorganisms. Genetic diversity is comparatively less obvious level of diversity as it represents variations within species Biodiversity has three essential elements: ECOSYSTEM DIVERSITY GENETIC DIVERSITY SPECIES DIVERSITY SPECIES DIVERSITY It is the most common level of diversity, and comprises the number of different species at a place.  SPECIES INTERACTION In nature, no species exists in total isolation – all organisms interact with both the abiotic environment and other organisms. If two species interact directly within a shared environment, they share a positive association (they co-exist). If interactions within an environment are mutually detrimental to both species, they share a negative association (do not co-exist).  SPECIES INTERACTION SPECIES INTERACT IN (5) MAJOR WAYS: Competition Predation Parasitism Mutualism Commensalism  POSITIVE ASSOCIATIONS 1. Predator - PREY RELATIONSHIP Predation is a biological interaction whereby one organism (predator) hunts and feeds on another organism (prey). Because the predator relies on the prey as a food source, their population levels are inextricably intertwined If the prey population drops (e.g. due to over-feeding), predator numbers will dwindle as intra-specific competition increases If the prey population rises, predator numbers will increase as a result of the over-abundance of a food source. POSITIVE ASSOCIATIONS  POSITIVE ASSOCIATIONS 2. SYMBIOTIC RELATIONSHIP Symbiosis describes the close and persistent (long-term) interaction between two species. Symbiotic relationships can be obligate (required for survival) or facultative (advantageous without being strictly necessary). Symbiotic relationships can be beneficial to either one or both organisms in the partnership:  POSITIVE ASSOCIATIONS MUTUALISM - Both species benefit from the interaction (anemone protects clownfish, clownfish provides fecal matter for food) COMMENSALISM - One species benefits, the other is unaffected (barnacles are transported to plankton-rich waters by whales) PARASITISM - One species benefits to the detriment of the other species (ticks and fleas feed on the blood of their canine host) POSITIVE ASSOCIATIONS  NEGATIVE ASSOCIATIONS COMPETITION Competition describes the interaction between two organisms whereby the fitness of one is lowered by the presence of the other. Competition can be intraspecific (between members of same species) or interspecific (between members of different species). Limited supplies of resources (e.g. food, water, territory) usually triggers one of two types of responses: 1. Competitive Exclusion - One species uses the resources more efficiently, driving the other species to local extinction. 2. Resource Partitioning - Both species alter their use of the environment to divide the resources between them. NEGATIVE ASSOCIATIONS  POPULATION DYNAMICS Population Dynamics is a study of how characteristics of populations change in response to changes in environmental conditions. Examples of such conditions are temperature, presence of disease organisms or harmful chemicals, resource availability, and arrival or disappearance of competing species. Populations Have Certain Characteristics Populations differ in factors such as their distribution, numbers, age structure (proportions of individuals in different age groups), and density (number of individuals in a certain space). WHAT LIMITS THE GROWTH OF POPULATION? no population can continue to grow indefinitely because of limitations on resources and because of competition among species for those resources. Most populations live together in clumps or patches. - Three general patterns of population distribution or dispersion in a habitat are clumping, uniform dispersion, and random dispersion. Populations can grow, shrink or remain stable. - Over time, the number of individuals in a population may increase, decrease, remain about the same, or go up and down in cycles in response to changes in environmental conditions.  Populations can grow, shrink or remain stable. - Four variables—births, deaths, immigration, and emigration—govern changes in population size. No population can grow indefinitely. - Species vary in their biotic potential or capacity for population growth under ideal conditions. - Generally, populations of species with large individuals, such as elephants and blue whales, have a low biotic potential. Those of small individuals, such as bacteria and insects, have a high biotic potential - Intrinsic Rate of Increase (r) is the rate at which the population of a species would grow if it had unlimited resources.  - Individuals in populations with a high intrinsic rate of growth typically reproduce early in life, have short generation times (the time between successive generations), can reproduce many times, and have many offspring each time they reproduce. - Environmental resistance is the combination of all factors that act to limit the growth of a population. - Together, biotic potential and environmental resistance determine the carrying capacity (K): the maximum population of a given species that a particular habitat can sustain indefinitely without being degraded. The Human Population and Urbanization Today, 55% of the world’s population lives in urban areas, a proportion that is expected to increase to 68% by 2050. Projections show that urbanization, the gradual shift in residence of the human population from rural to urban areas, combined with the overall growth of the world’s population could add another 2.5 billion people to urban areas by 2050, with close to 90% of this increase taking place in Asia and Africa, according to a new United Nations data. The Human Population and Urbanization The 2018 Revision of World Urbanization Prospects produced by the Population Division of the UN Department of Economic and Social Affairs (UN DESA) notes that future increases in the size of the world’s urban population are expected to be highly concentrated in just a few countries. By 2050, it is projected that India will have added 416 million urban dwellers, China 255 million and Nigeria 189 million. The Human Population and Urbanization The urban population of the world has grown rapidly from 751 million in 1950 to 4.2 billion in 2018. Asia, despite its relatively lower level of urbanization, is home to 54% of the world’s urban population, followed by Europe and Africa with 13% each. The Human Population and Urbanization Today, the most urbanized regions include Northern America (with 82% of its population living in urban areas in 2018), Latin America and the Caribbean (81%), Europe (74%) and Oceania (68%). The level of urbanization in Asia is now approximating 50%. In contrast, Africa remains mostly rural, with 43% of its population living in urban areas. REASONS FOR THIS INCREASE IN GROWTH RATE INCLUDE: Humans have expanded into almost all of the planet’s climate zones and habitats. The emergence of early and modern agriculture allowed us to grow more food for each unit of land area farmed. Death rates dropped sharply because of improved sanitation and health care. FACTORS THAT INFLUENCE THE SIZE OF THE HUMAN POPULATION: Birth rate, or crude birth rate, is the number of live births per 1,000 people in a population in a given year. Death rate, or crude death rate, is the number of deaths per 1,000 people in a population in a given year. Population change of an area = (births + immigration) - (deaths + emigration) Immigration (arrival of individuals from outside the population) Emigration (departure of individuals from the population)  “Protecting biodiversity is critical to maintaining healthy ecosystems and ensuring sustainable development. Let's work together to preserve the rich biodiversity of our planet.”  THANK YOU FOR LISTENING!