Presentation on theme: "ECOLOGY. Biosphere – the combined portions of the planet in which all of the life exists, including land, water, and air, or atmosphere. It extends from."— Presentation transcript:
Biosphere – the combined portions of the planet in which all of the life exists, including land, water, and air, or atmosphere. It extends from about 8 km above Earth’s surface to 11 km below the ocean surface. Ecology – the study of the interactions between organisms and the living and non-living components of their envronment.
Today’s Environment Exploding Human Population: the most significant environmental change is probably the rapid increase in the human population. The World’s human population has TRIPLED from 2 billion in 1930 to 6 billion in We just surpassed 7 billion. The World population is estimated to be between billion by 2050.
ESTIMATED Population of the World in Millions 1991 Information Please AlmanacLivi-Bacci Concise History of World Population, 2nd, 1997 Colin McEvedy Atlas of World Population History 1978 United Nations 1999 BCE CE
An increasing population requires increasing amounts of energy, food, space for wastes, and a greater share of resources. Mass Extinctions: Paleontologists have found evidence in the fossil record of FIVE major mass extinctions The SIXTH is believed to be occurring now because of habitat destructions (rain forest – etc.) Scientists estimate that about 1/5 of the species in the world now will disappear in the next century.
The Thinning Ozone Layer: The ozone (O 3 ) layer in the upper atmosphere protects the living organisms on Earth by absorbing UV radiation from the sun. In 1992, a treaty was signed that banned chlorofluorocarbons (CFCs) and other ozone-destroying chemicals. The ozone shield over Antarctica fluctuates in density seasonally, sometimes to a low of half the original density.
Climate Changes: since 1860, the average global temperature has risen about 0.6° C (1° F). Most scientists agree the increase in temperature is due to increasing levels of carbon dioxide (CO 2 ) in the atmosphere, resulting from the Greenhouse Effect. Some scientists project by the year 2100 the average global temperature will increase 1.5°C to 4.5°C (3° F to 8° F). This increase in average temperature may change global weather patterns and cause sea levels to rise.
What is Climate? Weather – the day-to-day condition of Earth’s atmosphere at a particular time and place. Climate – refers to the average, year-after-year conditions of temperature and precipitation in a particular region. The Effect of Latitude on Climate As a result of differences in latitude and thus the angle of heating. Earth has three main climate zones: polar, temperate, and tropical.
The Effect of Latitude on Climate Polar zones – cold areas where the sun’s rays strike Earth at very low angles. Temperate zones – sit between the polar zones and the tropics. Because temperate zones are more affected by the changing angle of the sun over the course of a year, the climate in these zones ranges from hot to cold, depending on the season. Tropical zone – or tropics, is near the equator, between 23.5° North and 23.5° South latitudes. Direct sunlight year-round, makes the climate almost always warm.
Interdependence – (interconnectedness) each ecosystem is a network in which organisms are linked to other organisms and to the nonliving environment. Habitat – the physical area in which an organisms lives. Biotic Factors – the living components of the environment. Abiotic Factors – nonliving factors in an organism’s environment. TemperatureHumiditypH SalinityOxygen ConcentrationAmount of Sun Availability of N 2 Precipitation These two factors vary w/ time impacting the environment.
Levels of Organization To understand relationships within the biosphere, ecologists ask questions about events and organisms that range in complexity from a single individual to the entire biosphere. Species - a group of organisms so similar to one another that they can interbreed and produce fertile offspring. Populations – groups of individuals that belong to the same species and live in the same area. Communities – different populations that live together in a defined area.
Ecosystem – a collection of all organisms that live in a particular place, together with their nonliving, or physical, environment. Biome – a group of ecosystems that have the same climate and similar dominant communities.
Population density – the number of individuals of a species that live in a given area. If the individuals are few and far apart, they may seldom encounter one another and reproduction may be rare.
Exponential Growth Curve – the rate of population growth remains the same and the pop. size increases exponentially.
Carrying capacity – the population size that an environment can sustain. This number is related to the resources available to the organism – food, water, space, oxygen, sunlight, etc.
Density dependent factors – resources that may become depleted and therefore limit the growth of the population (slow it down) – food and water are examples - the rate they are used up depends on the density of the population using them. Density independent factors – factors that may affect the growth pattern of a species but in return are not affected by the population size of the organisms. Weather and climate are examples. Mosquito populations increase in warm moist weather – but have no impact on the weather itself.
Patterns of Growth r-strategists – these are species whose populations grow rapidly when conditions are favorable. This strategy results in large populations that last for a short period of time. The population size will then decrease rapidly when conditions become unfavorable. Usually r-strategists have short life spans, reproduce early in their life, and produce large numbers of offspring. The offspring develop with little to no parent care.
Patterns of Growth k-strategists – these are organisms that grow slowly. They usually are near the carrying capacity for their environment. They have long life spans, produce relatively few young, mature slowly, and reproduce later in life. k-strategists often provide care for their young and live in stable environments.
Hardy-Weinberg Principle – the principle stating that the frequencies of alleles in a population do not change unless evolutionary forces act on the population. The Hardy-Weinberg Equation: p 2 +2pq+q 2 =1 frequency offrequency offrequency of individualsheterozygousindividuals that areindividualsthat are homozygouswith alleles Ahomozygous for allele Aand afor allele a
Factors affecting the Hardy-Weinberg Principle mutations - changes in genes - in nature they occur at a rate of 1-10 mutations per 100,000 cell divisions. gene flow - the movement of alleles into or out of a population nonrandom mating - when mating occurs by choosing mates based on location or characteristics rather than randomly - inbreeding is an example - as is self fertilization in plants - this increases homozygotes genetic drift - the random change in allele frequency in a population - this is sometimes caused by a chance event natural selection - individuals with less desirable traits will have trouble surviving and may not mate as often.
Normal distribution of traits -- bell curve - polygenic traits -- human height and skin color are examples
Directional selection - a natural selection process in which one genetic variation is selected that causes a change in the overall genetic make up of the population. Fruit flies raised in dark when exposed to light, some flew toward it others did not. If only those that flew toward light were allowed to reproduce, within 20 generations the tendency to fly toward light increases - insect pesticide resistance is another example
Stabilizing selection - a natural selection where the average form of a trait is favored and becomes more common - the extremes of the trait are eliminated.
Ecosystems Habitat – where a particular population of species lives. Community – the many different species that live together in a habitat. Ecosystem – includes the community and the non-living (abiotic) factors of that habitat. Biodiversity – the number of different species living within an ecosystem.
Succession – a somewhat regular progression of species replacement. Pioneer species – the first organism to live in a new habitat. These are typically small fast growing plants. Primary succession – progression of species that occurs where plants have not grown before. Secondary succession – progression of species that occurs on areas where plants have been before – such as after a forest fire, after land has been cleared, etc.
Producers - organisms that first capture energy - plants, some kinds of bacteria, and algae. Producers make energy storing molecules. Consumers - organisms that consume producers or other consumers. They do this to get the energy necessary to build molecules.
Chemosynthesis – when organisms use chemical energy to produce carbohydrates. Such as sulfur bacteria converting sulfur compounds into carbohydrates around thermal vents in the ocean.
Food chain - the path of energy through an ecosystem
Trophic level - each organism in a food chain fits into one of the trophic levels of the chain based upon what they consume to get energy. Most ecosystems can only support 3 or in some rare cases 4 trophic levels. First trophic level - producers Second trophic level - primary consumers - herbivores - organisms that feed on producers Third trophic level - secondary consumers - animals that eat the primary consumers -- May include carnivores - which are animals that eat other animals or other consumers OR omnivores - animals that are both herbivores and carnivores
Detritivores - these are the organisms which feed on organic wastes and dead bodies Decomposers are organisms that cause decay or break down of organic matter and feeds on it - fungus and bacteria are examples
Most ecosystems don't just follow a straight food chain, because organisms may feed on a diet of multiple things. Therefore an ecosystem usually is an interconnected group of food chains called a food web.
Energy pyramid - an illustration of energy flow through an ecosystem - usually only 1/10 (10%) of the energy in one level is available for use by the next level. Most of the rest of the energy is lost as heat.
Biomass - the dry weight of tissue and other organic matter found in an ecosystem - again, each level contains only about 10% of the biomass of the level below it.
Biogeochemical cycle - the circulation of substances through living organisms from and/or to the environment - Water cycle (hydrologic cycle), carbon cycle, nitrogen cycle, and phosphorus cycle are examples. Transpiration - water passing through a plant and into the atmosphere - this is a sun driven process
Nitrogen cycle - The atmosphere is about 78% nitrogen gas N 2 - however this form is not usable by most organisms - the two nitrogen atoms are held together by a triple covalent bond which is very strong and is not breakable by most organisms. Some bacteria are able to break these bonds with enzymes that they produce. Once these bonds are broken, the nitrogen atoms are bonded to hydrogen to form ammonia NH 3 - this process is called Nitrogen Fixation and makes the nitrogen usable by plants and other organisms. These nitrogen fixing bacteria live in the soil and are found in nodules of roots of certain plants.
Interaction of organisms Predation is the act of one organism killing another for food - Lions, spiders, and centipedes are examples of predators.
Studies show that predation can actually help maintain diversity. Gray wolves were killed out in many parts of North America. What happened to deer and herbivore populations? What happened to many plant species in North American ecosystems?
Symbiosis - two or more species living in a close association with one another. Examples of symbiosis include: Mutualism - a relationship in which BOTH organisms benefit. Ants & aphids - Termites & protozoa - Bacteria & humans Commensalism - one of the members of the relationship is helped the other is unaffected. - barnacles on whales, remora sharks, clown fish and sea anemones Parasitism - one member is helped, the other is harmed - lice, mosquitoes, ticks, fleas, hook worms, tape worms are all examples of parasites.
Competition - When two species use the same resource, such as food, nesting sites, living space, light, or water they must compete with one another for the resource. Often times this results in a winner and a loser - this is known as competitive exclusion.
Niche - how an organism lives, or the role it fills in an ecosystem. The habitat can be thought of as the neighborhood of the organism and the niche its occupation Fundamental niche - the entire range of resources available to an organism in its ecosystem. Realized niche - the niche the organism actually occupies in its ecosystem.
Community Interactions Mimicry – a harmless species resembles a poisonous or distasteful species. Batesian mimicry – a palatable or harmless species mimics an unpalatable or harmful species. Mimicry is a widespread mechanism to avoid predation: caterpillars and spiders resemble bird droppings, caterpillar butts look like snake heads, and so on.
Community Interactions Camouflage or cryptic coloration – a passive defense that makes potential prey difficult to spot against its background. Aposematic coloration – warning coloration; Seen in animals with Effective chemical defenses.
Tropical Rainforest The tropical rain forest is the most diverse ecosystem on Earth. Large-scale human destruction of tropical rain forests continues to endanger many species –It may also alter world climate
Tropical Savanna Grasslands with scattered trees. Drier, tropical areas and some nontropical areas are characterized by the savanna
Desert Biome Deserts are the driest of all terrestrial biomes – They are characterized by low and unpredictable rainfall – Desertification is a significant environmental problem
Temperate Woodland and Shrub-land (Chaparral) The chaparral biome is a shrub-land with cool, rainy winters and dry, hot summers Chaparral vegetation is adapted to periodic fires
Temperate Grassland Temperate grasslands are found in the interiors of the continents, winters are cold – Drought, fires, and grazing animals prevent trees from growing – Farms have replaced most of North America's temperate grasslands
Temperate (Deciduous) Forest Temperate deciduous forests grow where there is sufficient moisture to support the growth of large trees – Nearly all of the original deciduous forests in North America have been drastically altered by agriculture and urban development.
Coniferous Forest or Taiga The northern coniferous forest, or taiga, is the largest terrestrial biome on Earth. The taiga is characterized by long, cold winters and short, wet summers. Coastal coniferous forests of the Pacific Northwest are actually temperate rain forests.
Tundra The arctic tundra lies between the taiga and the permanently frozen polar regions – It is a treeless biome characterized by extreme cold, wind, and permafrost – Permafrost is continuously frozen subsoil.
Aquatic Biomes Some aquatic communities include: Freshwater communities Wetlands Estuaries Marine communities - Shallow ocean waters - Surface of the open ocean - Deep ocean
Acid rain – sulfur introduced into the atmosphere (from smokestacks) combined with water vapor produces sulfuric acid. Rain and snow carry the sulfuric acid to the Earth’s surface. The pH of pure water is Acid rain may have a pH of – this is over 10 times the acidity of typical pH values of rainfall in the US. Chemical pollution – putting chemicals or toxic agents into the environment.
Biological magnification – as chemicals pass up the food chain, they become more and more concentrated – one small fish may have little of the chemical in it, but after several are eaten by larger fish and then several of the larger fish eaten by an eagle – the eagle accumulates large amounts of the toxin.