Unit 1: Summary Notes for Ecology, Conservation and Evolution IB Biology – Higher Level Topic 5 and Option G Campbell Text References: Chapter 50: Introduction to Ecology and Biosphere Chapter 52: Population Ecology Chapter 53: Community Ecology Chapter 54: Ecosystems Chapter 55: Conservation Biology Chapter 1: Taxonomy, Evolution and Natural Selection Chapter 50 – Introduction to Ecology and Biosphere Vocabulary: • Habitat: the environment in which a species normally lives or the location of a living organism. • Ecology : The Scientific Study of the Interactions between organisms and the environment • Abiotic : Non-living (ex. Temp, light, water, nutrients) • Biotic: Living organisms (called biota) • Population: A group of individuals of the same species living in a particular geographic area. • Population ecology: Concentrates mainly on factors that affect how many individuals of a particular species live in an area. • Community : Consists of all the organisms of all the species that inhabit a particular area; it is an assemblage of populations of many different species. • Community ecology: Deals with the whole array of interacting species in a community. This area of research focuses on how interactions such as predation, competition, and disease, as well as abiotic factors such as disturbance, affect community structure and organization.
Transcript
Unit 1: Summary Notes for Ecology, Conservation and Evolution IB Biology – Higher Level Topic 5 and Option G
Campbell Text References: Chapter 50: Introduction to Ecology and Biosphere Chapter 52: Population Ecology Chapter 53: Community Ecology Chapter 54: Ecosystems Chapter 55: Conservation Biology Chapter 1: Taxonomy, Evolution and Natural Selection
Chapter 50 – Introduction to Ecology and Biosphere Vocabulary:
• Habitat: the environment in which a species normally lives or the location of a living
organism. • Ecology: The Scientific Study of the Interactions between organisms and the
environment • Abiotic: Non-living (ex. Temp, light, water, nutrients) • Biotic: Living organisms (called biota) • Population: A group of individuals of the same species living in a particular geographic
area. • Population ecology: Concentrates mainly on factors that affect how many individuals of
a particular species live in an area. • Community: Consists of all the organisms of all the species that inhabit a particular
area; it is an assemblage of populations of many different species. • Community ecology: Deals with the whole array of interacting species in a community.
This area of research focuses on how interactions such as predation, competition, and disease, as well as abiotic factors such as disturbance, affect community structure and organization.
• Ecosystem: Consists of all the abiotic factors in addition to the entire community of species that exist in a certain area. An ecosystem—a lake, for example—may contain many different communities.
• Ecosystem ecology: The emphasis is on energy flow and chemical cycling among the various biotic and abiotic components.
• Biome: Any of the world’s major ecosystems, classified according to the predominant vegetation and characterized by by adaptations of organisms to that environment
• Biosphere: The global ecosystem—the sum of all the planet′s ecosystems. This broadest area of ecology includes the entire portion of Earth inhabited by life: the atmosphere to an altitude of several kilometers, the land down to and including water–bearing rocks at least 3 kilometers below–ground, lakes and streams, caves, and the oceans to a depth of several kilometers. An example of research at the biosphere level is the analysis of how changes in atmospheric CO2 concentration may affect Earth′s climate and, in turn, all life.
Activity: Science, technology, and society: DDT
DISCUSS how the science of ecology can help in the process of making difficult and complicated decisions such as whether or not to use DDT.
Relationship between Ecology and Evolutionary Biology Ecology and evolutionary biology are closely related sciences. Darwin′s extensive observations of the distribution of organisms and their adaptation to specific environments led him to propose that environmental factors interacting with variation within populations could cause evolutionary change. Today, we have ample evidence that events that occur in the framework of ecological time (minutes, months, and years) translate into effects over the longer scale of evolutionary time (decades, centuries, millennia, and longer). For instance, hawks feeding on field mice have an immediate impact on the prey population by killing certain individuals, thereby reducing population size (an ecological effect) and altering the gene pool (an evolutionary effect). One long–term evolutionary effect of this predator–prey interaction may be selection for mice with fur coloration that camouflages the animal The Figure Below is a good summary of the different factors that can limit the geographic distribution of a particular species
Concept Check 50.1: How can an event that occurs on the ecological time scale affect events that occur on an evolutionary time scale? Precautionary Principle
Although our ecological information is always incomplete, we cannot abstain from making decisions about environmental issues until all the answers are known. But given what we do know about the interconnectedness of the biosphere, it is probably wise to follow the precautionary principle, which can be expressed simply as “An ounce of prevention is worth a pound of cure.” Aldo Leopold, the famous wildlife conservationist, expressed the precautionary principle well when he wrote, “To keep every cog and wheel is the first precaution to intelligent t **An example of the Precautionary Principle is Global Warming. (ie. Even though we don’t know all the mechanisms by which humans increase the rate of global warming, the negative consequences of it should lead us to take action to reduce our production of greenhouse gases. Flowchart of factors limiting geographic distribution of a species.
CD Activity 50.2: Adaptations to Biotic and Abiotic factors CD Investigation 50.2: How do abiotic factors affect distribution of organisms
Describe which plant species’ at Wissahickon Creek Park were restricted to the floodplane and which were restricted to the hilltop and which seemed to range between both extremes. Outline some of the abiotic factors that produce these differences in distribution.
Explain why stiltgrass is a potentially damaging plant in the Wissahickon Creek Ecossystem. Include an assessment of its potential impact on animal populations.
Explain how abiotic factors such as fertilizer chemical pollutants (nitrogen, phosphorus, potassium) can affect the distribution of benthic macroinvertebrate communities in Wissahickon Creek. (Hint: Eutrophicaton)
Summary of the World’s Biomes
BY THE END OF CHAPTER 50 YOU SHOULD BE ABLE TO ANSWER THE FOLLOWING IB ASSESSMENT STATEMENTS A.S. 5.1.1, 5.2.4, 5.2.5, G.1.1, G.1.2, G.2.9, G.2.10, G.2.11, G.3.8 Chapter 52- Population Ecology Vocabulary
• Species: a group of organisms that can interbreed and produce fertile offspring. • Density: Number of individuals per unit area or volume. Ex. White Oak trees per
square kilometer in Potter County Pennsylvania or E.coli bacteria per milliliter in a testtube
• Demography: The study of the rise and fall of population sizes over time • Natality: Rate of Birth (# of individuals in a given period of time –usually a year) • Mortality Rate of Death (# of individuals in a given period of time –usually a year) • Immigration: The movement of individuals into a population • Emmigration: The movement of individuals out of a population • Carrying Capacity: The maximum population size that can be supported by the available
resources, symbolized by K. • Exponential Growth: The geometric (larger the quantity gets, the faster it grows)
increase of a population as it grows in an ideal, unlimited environment • Sigmoid (Logistic Growth): A model describing population growth that levels off as
population size approaches carrying capacity
Biome Moisture Temperature Vegetation
Tropical Rainforest ample rainfall very humid very hot jungle, trees
and vines
Tropical Savanna wet season dry season very hot tall grasses
• Life History: The series of events from birth through reproduction and death • r-Strategy Growth: The concept that in certain (r-selected) populations, a high
reproductive rate is the chief determinant of life history and survival • K-Strategy Growth: The concept that in certain (K-selected) populations, life history is
centered around producing relatively few offspring that have a good chance of survival Methods for Estimating Populations Sizes 1) For Animals (mostly)-------Mark-Recapture Method (Lincoln Index) Population size = n1 x n2 n3 n1 = number of individuals initially caught, marked and released n2 = total number of individuals caught in the second sample n3 = number of marked individuals in the second sample 2) For Plants (mostly) -----Quadrat Transect method
Key Aspects of Quadrat Method
• Transects are distributed evenly across the site (for full coverage so you don’t miss any “pockets” of a plant species.
• Each Quadrat is spaced evenly along the transects (for same reason as above) • The percent area of each plant species is estimated within each quadrat which is 1 meter 2 in size. • All the quadrat percentages are added up for each plant species • Each of these total species percentages is divided by the total quadrat percentages to get
the relative percentage of each plant species. As shown below
Survivorship Curves:
Type I: Low death rates during early and middle life, then high death rates in later life Type II Constant death rate over life of the organism Type III: High death rates during early life, then declining death rates in later years
Life history traits are products of natural selection
Natural selection favors traits that improve an organism′s chances of survival and reproductive success. In every species, there are trade–offs between survival and traits such as frequency of reproduction, the number of offspring produced (the number of seeds produced by plants and litter or clutch size for animals), and investment in parental care. The traits that affect an organism′s schedule of reproduction and survival (from birth through reproduction to death) make up its life history. Life histories entail three basic variables: when reproduction begins (the age at first reproduction or age at maturity), how often the organism reproduces, and how many offspring are produced during each reproductive episode. Keep in mind that, with the important exception of humans, organisms do not choose consciously when to reproduce or how many offspring to have. Life history traits are the products of evolution through natural selection. Population Dynamics To understand why populations increase and decrease, we must understand the definition of some terms like mortality, natality, immigration and emigration. We must also understand that these terms are usually expressed as a rate over a specified time interval – usually one year. Mortality rate = number deaths per year in a species in a specified area Natality rate = number of births per year in a species in a specified area *Immigration rate = number of individual of the species entering a specified area *Emmigration rate = number of individuals of a species leaving a specified area * unlike mortality and natality which are cumulative, these factors are measure at the end of the year or some other specific time.
To Calculate the Yearly Change in Population
Change in population size = births/yr – deaths/yr + immigration - emmigration Now: Imagine that on January 1, 2005 we had a population of 1000 monitor lizards on the Yucatan Peninsula in Mexico. During the course of the year, the following data is confirm: • 103 births • 85 deaths • 15 immigrants (as of Dec 31, 2005) • 8 emmigrants (as of Dec 31, 2005)
Using the equation above and the original population size, calculate the population size on January 1, 2006 (one year later) Show your work Often however, due to the difficulty in measuring immigration and emigration, we assume them to offset one another and deal only with mortality and natality. When we do this, these rates are expresses as Per Capita Rates of Increase. For Example: If there are 34 births per year in a population of 1000 individuals, the annual per capita natality rate is 34/1000 or 0.034 If there are 16 deaths per year in the same population of 1000, the annual per capita mortality rate is 16/1000 or 0.016 Now for a specific example using different numbers
• Annual Per Capita Natality Rate = 0.18 • Annual Per Capita Mortality Rate = 0.10 • Population Size = 450
What is the population at the end of the year? (Show your Work)
Sigmoid and Exponential Population growth
Populations cannot grow forever because limiting factors slow and eventually stop population growth. Populations typically follow a growth curve with three phases: exponential phase, transitional phase and plateau phase.
Population growth is the result of the interaction of four factors: natality, mortality, immigration and emigration
Carrying capacity
"K" is the carrying capacity, or the maximum stable population any environment can support. This is determined by the available resources.
Two different “Life History Stategies”
K-species and r-species
K-species are characterised by a low reproductive rate, large investment in offspring, long lives and large size.
r-species are characterised by a high reproductive rate, little or no investment in offspring, short lives and small size.
The growth curve for K-species flattens out as the carrying capacity ("K") of the environment is reached. This is because population growth is density-dependent.
The growth curve for r-species shoots through the carrying capacity ('boom') and then falls below it ('bust') once there are more organisms than the environment can support. This is because population growth is determined more by the reproductive rate ("r") than population density.
What are the environmental conditons that favor either r-stategists or K-strategists?
Predictable Envionment- K-strategies favored
Unstable Environment - r-strategis favored
Why are K strategies favored in a predicable env. And r strategies favored in an unpredictable environment??
Are humans a K-species or an r-species?
In traditional societies, high birth rates have always been balanced by high infant mortality. Now that modern medicine has sharply reduced mortality, the high natality has created a 'boom' in the world human population. The question is: will the human population exceed the carrying capacity of the planet, with a subsequent 'bust' phase?
http://www.unfpa.org/index.htm
Website for Populus Population Computer Model
www.cbs.umn.edu/populus/
Commercial Fishing and Fish Populations Some methods used to estimate the size of commercial fish stocks
• Catch-Mark-Release (Lincoln Index) clip a fin to mark • Sonar methods (possibly the ships would run transects across the ocean-then they would
multiply this number by the area they didn’t cover) • Gill nets (nets are set in areas known to be inhabited by certain species. The net has a
certain cross-sectional area and is laid out for a certain time period. The number of fish caught should be proportional to the total population.
Maximum Sustainable Yield: The maximum number of fish that can be caught by commercial fishing fleets per year and still sustain a relatively large population. In other words, if you exceed the maximum sustainable yield of a certain species, the population would “crash” and become locally rare or possibly even extinct. (ex. Chilean Sea Bass became very rare after they became popular in restaurants-this led to increased fishing pressure (because they became more valuable) and their maximum sustainable yield was exceeded. Another example is the fate of the North Atlantic bluefin tuna . Until the past few decades, this big tuna was considered a sport fish of little commercial value—just a few cents per pound for cat food. Then, in the 1980s, wholesalers began airfreighting fresh, iced bluefin to Japan for sushi and sashimi. In that market, the fish now brings up to $100 per pound . With that kind of demand, it took just ten years to reduce the North American bluefin population to less than 20% of its 1980 size. The collapse of the northern cod fishery off Newfoundland in the 1990s is a more recent example of how it is possible to overharvest what was formerly a very common species. International Measures that would promote the conservation of fish
• International agreements on quotas (maximum # caught) for specific species • Increased scientific research on the life histories of fish species • Increased efforts to monitor the populations of specific fish species
BY THE END OF CHAPTER 52 YOU SHOULD BE ABLE TO ANSWER THE FOLLOWING IB ASSESSMENT STATEMENTS A.S. 5.3.1, 5.3.2, 5.3.3, 5.3.4, G.1.3, G.1.4, G.5.1, G.5.2, G.5.3, G.5.4, G.5.5, G.5.6
Chapter 53 – Community Ecology Vocabulary
• Habitat : A particular environment, the typical location of a particular species. Habitat is a place = an organism's 'address'
• Ecological niche: The totality of an organism's relationships with all the biotic and abiotic factors which make up the organism's habitat.
• Interspecific Competition: When two species compete for a resource, the result is detrimental to both species (−/−) such as when two different species compete for a particular resource that is in short supply ex1 When bison and grasshoppers compete for grass on the Great Plains ex2: When a red oak seedling and a white ash seedling compete for sunlight
• Competitive exclusion: . Strong competition can lead to the local elimination of one of the two competing species, a process called competitive exclusion
• Symbiosis: is a special type of interaction, where one organism lives on or in another • Biomass: The total mass of all individuals in a population • Biodiversity: The number of different species in a given geographical area
Concept 53.1 Interspecific Interactions
Ecological niche is an idea = an organism's 'profession'
Actual descriptions of ecological niches are always approximations, since the list of abiotic and biotic factors is necessarily incomplete.
An ecological niche can be thought of as existing in a multi-dimensional ecological conceptual 'space', in which all possible 'professions' can be located.
For example, to see how the ecological niche of a squirrel fits into this ecological conceptual 'space', we could reduce ecological space to just three dimensions: temperature, food size and branch density. The niche occupied by a squirrel is then defined by the upper and lower limits on each of these three axes.
The result is a cube, the volume of ecological space which corresponds to the 'profession' of the squirrel.
The volume of ecological space occupied by any species may overlap with that occupied by some other species (niche overlap).
Fundamental niche: The niche potentially occupied by that species
Realized niche: The niche it actually occupies in a particular environment.
• Competition, co-existence and niche specialization
Different species in the same habitat are in competition for at least some of the resources of that habitat.
Two species in different habitats=no competition
co-existence
co-existence
co-existence
Not Possible*
* 'No two species can occupy the same niche'
Where only some of the resources are competed for, species can co-exist in the same habitat. Increasing specialization limits niche overlap by exploiting different food supplies, and by separation in time (night-hunters or day-hunters) or space (ground-living or tree-iving).
Interspecific Interactions
Species 1 Species 2 Example
Competition - - Red Squirrels and Gray Squirrels for
acorns
Herbivory - + Clover/Rabbits
Predation - + White tailed deer/Mt. Lion
Symbiosis Host Symbiont
Commensalism 0 +
Cattle egrets (birds) feeding on insects flushed by
moving cattle
Mutualism + +
Lichen (green algae and fungi) Fungi provide
algae with environment for growth and algae provide carbon
compounds through photosyn.
Parasitism + Tapeworm/human
0 No Affect, either negative or positive
+ Positive Affec
- Negative affect
Coevolution
Reciprocal evolutionary adaptations of two interacting species. A change in one species acts as a selective force on another species, whose adaptation in turn acts as a selective force on the first species. This linkage of adaptations requires that genetic change in one of the interacting populations of the two species be tied to genetic change in the other population. An example of this might be how specific butterflies have evolved alongside the specific flowers that they help to pollinate
Concept Check 53.1: According to the competitive exclusion principle, what outcome is expected when two species compete for a resource? Why?
• Predator-prey relationships
The interaction between primary and secondary consumers, and between secondary and tertiary consumers, comes under the special category of predator-prey relationships.
The inter-relationship between two animals where one animal, the prey, is food for the other, the predator. The size of the first population depends upon the number of predators; the size of the second population depends on the availability of the prey. Both populations are locked into a cycle of mutually dependent population fluctuations.
• Food Chain
A food chain is the simplest way of conceptualising the movement of matter and energy from organism to organism.
diatoms > copepods > 'krill' > whales
Diatoms are phytoplankton. Copepods and 'krill' are zooplankton. Plankton are small creatures in the sea which swim without direction (kinesis).
Diatoms are microscopic one-celled algae. They are the producers in the food chain. Sometimes called 'the grass of the sea'.
Copepods are small crustaceans which feed on the phytoplankton (i.e. they are herbivores).
'Krill' are a mix of larger crustaceans which feed on the copepods. Plankton-feeding whales feed on 'krill' by straining the water with special modified mouthparts.
• Food Web
A food web is a more realistic conceptualisation, as it recognises that a predator may have more than one prey, and prey may have more than one predator.
Biodiversity
Biodiversity: Generally speaking, higher biodiversity in a given ecosystem is a good thing because it leads to more stable food webs.
Why?
Biodiversity in an ecosystem can be estimated using the Simpson’s Diversity Index
Simpson’s Diversity Index = 1-D
where
D = Sum of n(n-1) (the greater the #, the N(N-1) greater the sample diversity) Where n = Total # of organisms of a particular species N = Total # of organisms of all species
Concept 53.2: Food Web Activity
Disturbance Influences Species Diversity and Composition
A disturbance is an event, such as a storm, fire, flood, drought, overgrazing, or human activity, that changes a community, removes organisms from it, and alters resource availability.
After Disturbance, plant and animal communities gradually re-colonize the disturbed area
When this process begins in a virtually lifeless area where soil has not yet formed, such as on a new volcanic island or on the rubble (moraine) left behind by a retreating glacier, it is called primary succession. Often the only life–forms initially present are autotrophic prokaryotes. Lichens and mosses, which grow from windblown spores, are commonly the first macroscopic photosynthesizers to colonize such areas. Soil develops gradually, as rocks weather and organic matter accumulates from the decomposed remains of the early colonizers. Once soil is present, the lichens and mosses are usually overgrown by grasses, shrubs, and trees that sprout from seeds blown in from nearby areas or carried in by animals. Eventually, an area is colonized by plants that become the community′s prevalent form of vegetation. Producing such a community through primary succession may take hundreds or thousands of years.
Concept 53.3 Succession
Secondary succession occurs when an existing community has been cleared by some disturbance that leaves the soil intact, as in Yellowstone following the 1988 fires (see Figure 53.22). Often the area begins to return to something like its original state. For instance, in a forested area that has been cleared for farming and later abandoned, the earliest plants to recolonize are often herbaceous species that grow from windblown or animal–borne seeds. If the area has not been burned or heavily grazed, woody shrubs may in time replace most of the herbaceous species, and forest trees may eventually replace most of the shrubs.
Concept Check 53.3
How do primary and secondary succession differ?
BY THE END OF CHAPTER 53 YOU SHOULD BE ABLE TO ANSWER THE FOLLOWING IB ASSESSMENT STATEMENTS 5.1.4, 5.1.5, 5.1.6, 5.1.7, 5.1.8, 5.1.9, 5.1.10, G.1.5, G.1.6, G.1.7, G.1.8, G.1.9, G.1.10, G.2.6, G.2.7, G.2.8, G.3.1, G.3.2, G.3.3 Chapter 54 – Ecosystems Vocabulary • Ecosystem: All organisms (species) living in a community as well as the abiotic factors
they interact with. (As you might imagine, this can get complicated!!!!) • Autotrophs. Most autotrophs make food by photosynthesis, a few by chemosynthesis. • Heterotrophs.: Heterotrophs cannot make their own food, so they have to feed on other
organisms, either autotrophs or each other. • Trophic Level: Producers, consumers, and decomposers • Herbivores: primary consumers, feed directly on producers • Carnivores: secondary, tertiary consumers which feed on herbivores or each other • Top Carnivores: animals that eat other animals, but no other animals eat them (top of the
food chain • Omnivores: animals which eat both plants and other animals, e.g. humans • Detritivores: animals which feed on the dead remains of other organisms
There are Two major concepts involved with Ecosystems
1. Energy Flow (Continual Supply to Earth’s Ecosystems from Sun) 2. Chemical Cycling (Finite Supply – What we have is What we Have!!!)
Producers Consumers DecomposersHerbivores Carnivores Top
Carnivores Detritivores e.g. green plants,
phytoplankton e.g. sheep, zooplankton
e.g. wolves
e.g. tigers, sharks
e.g. dung beetles
e.g. bacteria & fungi
An ecosystem must always include producers and decomposers in order to be self-sustaining. Most ecosystems have consumers, but an ecosystem can be self-sustaining without them.
• Energy flow
The ultimate source of energy for almost all organisms is the sun. As organisms eat each other the energy passes up the food chain.
Each population of organisms corresponds to a certain amount of energy. Energy is recorded as
kJ m¯2 yr ¯1
The transfer of energy between trophic levels can be represented as a pyramid of energy, in which the width of each block represents the energy.
The transfer of energy from one organism to another in a food chain is only 10% - 20% efficient. This explains why the blocks in a pyramid of energy get smaller as they go up.
*Net Primary Production = Gross Primary Production – Respiration (of Producers) Where: Gross Primary Production (KiloJoules/m2/yr) is all the solar energy plants convert to chemical energy through photosynthesis and Respiration is the energy used by the plants to carry on their life process (that is unavailable to 1st order consumers) Therefore, the Net Primary Production is the bottom of the energy pyr
Pyramids of Production Concept 54.3
Note: A Biomass Pyramid would be very similar in shape the Energy Pyramid because the Energy represented in the Energy Pyramid is really locked up in the bodies of all the animals represented at each trophic level. Therefore, these two pyramids are, in a sense, reflections of each other. Biological Magnification. One tangible consequence of the biomass pyramid is called biological magnification and occurs because the biomass at any given trophic level is produced from a much larger biomass ingested from the level below. In addition to ingesting the larger biomass, these animals are also ingesting any contaminants that are contained in that food. This leads to toxins becoming more concentrated in successively higher trophic levels of a food web. Thus, top–level carnivores tend to be the organisms most severely affected by toxic compounds in the environment.
This occurs because many toxins cannot be degraded (broken down) by microorganisms and consequently persist in the environment for years or even decades.. For example, mercury, a by–product of plastic production and coal–fired power generation, has been routinely expelled into rivers and the sea.. Bacteria in the bottom mud convert the waste to methyl mercury, an extremely toxic soluble compound that accumulates in the tissues of organisms as you move up the food chain/biomass pyramid, including humans who consume fish from the contaminated waters.
Activity: Science, technology, and society: DDT
Why are there limits to Food chain Length based on the Concept of Energy Flow through the Ecosystem described above?
How does this explain why there are relatively few top-level carnivores in any given ecosystem”
• Recycling of inorganic elements
An ecosytem must have decomposers, because otherwise the inorganic materials (carbon, nitrogen, phosphorus etc.) would be trapped inside the bodies of dead organisms for ever. Eventually there would be no inorganic materials available for the producers to use and the ecosystem would fail.
The result of the activity of decomposers is that inorganic materials get recycled. e.g. the carbon cycle
Website about Carbon Cycle http://mvhs.shodor.org/coresims/carboncycle/index.php
Carbon Cycle Concept 54.4
2 Problems: The Human Population is disrupting chemical processes throughout the Biosphere. Examples of this are increased combustion of
greenhouse gases and depletion of the earth’s ozone layer/ 1) Increased Global Warming Gases from Human Combustion (coal, oil, gas) First, you need to understand that the Greenhouse Effect is a Good Thing!!! Without it, our world would be a frozen wasteland!!!
However, since the Industrial Revolution, the concentration of CO2,, Methane, and Nitrogen Oxide in the atmosphere has been increasing as a result of the combustion of fossil fuels and the burning of enormous quantities of wood removed by deforestation.
This has increased the natural Greenhouse Effect to Produce a rapid and dangerous rise in global temperature In 1958, a monitoring station began taking very accurate measurements on Hawaii′s Mauna Loa peak, where the air is free from the variable short–term effects that occur near large urban areas. The result are shown below and indicate a steadily increasing concentration of carbon dioxide in the world’s atmosphere.
375
370
365
360
355
350
345
335
330
325
320
1970
1975
1980
1985
1990
1995
2000
COconcentration
/ ppm
2
Negative Outcomes of Rapid Global Warming • Negative impact on plant and animal populations such as the Polar Bear and
Caribou • Increased range of human diseases caused by pathogens which formerly restricted
to tropical climates establishing in cooler temperate climates • Increased ocean levels, causing inundation of coastal communities
Question to Answer: Based on the Carbon Cycle Diagram, what effect will the following activities have on atmospheric Carbon Dioxide levels
• Combustion of Fossil Fuels • Deforestation • Increased rates of decomposition • Planting more trees
2) Depletion of Atmospheric Ozone: Read pages 1205-1206 The basic deals is this: Ozone (O3) is formed when one atom of oxygen is added to atmospheric oxygen (O2) The role of Ozone is to filter Ultraviolet (UV) Radiation from sunlight. Without this filtering, living things would be exposed to lethal doses of radiation and life would not be possible. Chloroflourocarbons (CFC’s) from aerosol cans, refrigeration chemicals etc. released in the atmosphere can destroy the Ozone layer and reduce the filtering capacity of the atmosphere. Since world governments have decreased or eliminated production of CFC’s, there are signes that the ozone layer is replenishing itself. Yeah!!! BY THE END OF CHAPTER 54 YOU SHOULD BE ABLE TO ANSWER THE FOLLOWING IB ASSESSMENT STATEMENTS
• Restoration Ecology: a branch of biology that applies ecological principles in an effort to return degraded (damaged) ecosystems to conditions as similar as possible to their natural, predegraded state
• Introduced/Invasive Species: Species that humans move, either intentionally or accidentally, from the species’ native locations to new geographic locations.
Introduced/Invasive Species Invasive species outcompete “native” species because their populations are not limited as much (think carrying capacity and sigmoid population growth) by predation or the impacts of disease. They left their natural predators or diseases back in their old ecosystem!! This could explain the high biomass that invasive species can attain in environments lacking their natural predators and pathogens. Three examples of Invasive species and their impact on local ecosystems
• Stiltgrass: outcompetes native plants upon which native animals depend.\ • Ducth Elm disease Fungus: Has killed almost all American Elm trees • Gypsy Moth: Has killed many forest trees throughout the eastern U.S.
Biological Control of Invasive species: One example of this is the use of a small insect called the purple loostrife weevil that has been used to some success in contolling the spread of the purple loostrife plant in the eastern U.S.
Active Role of Management Techniques in Conservation: 1) Installing fence at Wissahickon Creek to keep out the deer and allow native species to
grow 2) Pulling out stiltgrass or other invasive plant to allow native species to grow
Indicator Species: Some species in an ecosystem are more sensitive to environmental changes and are therefore used to “indicate” changes. An example of this is the caddis fly from our Wissahickon Creek Benthic Macroinvertebrate sampling. These aquatic insects are “Very Sensitive” to pollution. Species Extinction About 20% of the known freshwater fishes in the world have either become extinct during historical times or are seriously threatened. One of the largest rapid extinction events yet recorded is the ongoing loss of freshwater fishes in East Africa′s Lake Victoria. About 200 of the more than 500 species of cichlids in the lake have been lost, mainly as a result of the introduction of a nonnative predator species, the Nile perch, in the 1960s. Anothr example is the hunting of the Passenger pidgeon to extinction in the 19th century. Endangered species can be protected in two ways 1) In-situ Conservation of Endangered Species- Preserving large terrestrial (land) or aquatic reserves (tracts of land) from being developed or otherwise damaged. This basically protects the organisms habitat for future generations. This is the most effective way of protecting endangered species Large Nature Reserves Better: Generally, large nature reserves are better than small ones and promost biodiversity better than small reserves because they contain “interior” habitat as well as “edge” habitat. Different animals are adapted to edge vs. interior habitat, so having both available will mean that the habitat will be acceptable to a larger range of species. Habitat “Corridors” are good These are strips of habitat that connect tracts of land that are separated from each other. Many times, they are riparian (river) corridors which allow the passage of animals from one large tract of habitat to another and thereby increase the amount of habitat available to them. 2) Ex.-situ Conservation on Endangered Species: Captive breeding of animals in zoos, keeping rare plants in botanical gardens. This method is not as effective but still can play a role in being a source of animals and plants to reintroduce to the nature preserves described above BY THE END OF CHAPTER 55 YOU SHOULD BE ABLE TO ANSWER THE FOLLOWING IB ASSESSMENT STATEMENTS
Chapter 1- Classification and Evolution through Natural Selection Vocablulary
• Taxonomy: The branch of biology concerned with the naming and classifying of the diverse forms of life.
• Binomial Nomenclature: The identification of a species using its Genus (capitalized) and species (lower case). Always written in italics. Example: Red Oak is Quercus rubra. And White Oak is Quercus alba
• Dichotamous Key: a method of identifying a species using a series of Yes/no decisions. After successfully answering these, the species is identified.
• Evolution: All the changes that have transformed life on earth from its earliest beginnings to the diversity that characterizes it today
• Natural Selection: The mechanism (method) by which evolution occurs. It involves differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in the relative frequency of alleles in the gene pool
• Allele: Alternative versions of a gene that produce distinguishable phenotypic traits. New alleles are produce by the genetic mutation of specific nucleotide sequences during DNA copying at cell division.
• Gene Pool: The total aggregate of genes in a population at any given time Classification (Taxonomy) Levels of Biological Organization Biosphere>>Ecosystems>>Communities>>Populations>>Organisms>>Organs>>Organ Systems>>Tissues>>Cells>>Organelles>>Molecules>>Atoms
Do CD Activity: Levels of Life Card Game
Concept Check Question 1. For each biological level in Figure 1.3, write a sentence that includes the next “lower”
level. Example: “A community consists of populations of the various species inhabiting a specific area.”
5 Basic Kingdoms of Living Things Multicellular Unicellular Prokaryote Eukaryote Photosynthesis Plantae Yes No No Yes Yes (573) Animalia Yes No No Yes No (626) Protoctista Some colonial* mostly No Yes some (549) Fungi Most a few No Yes No (608) Prokaryotae No Yes Yes No some (537) *Ex. Volvox page 568
At the kingdom level, these above characteristics are used to separate living groups, but at lower taxonomic levels (phyla, class, order, family, genus) some of the characteristics used to separate groups are:
• Morphology What they look like • Reproduction How they reproduce • Energy/Food How they obtain or process it
****However, the “best” way to separate groups is according to their genetics, because this is the most reliable measure of how closely 2 groups are related
Classifying life. The taxonomic scheme classifies species into groups that are then combined into even broader groups. Species that are very closely related, such as polar bears and brown bears, are placed in the same genus, genera (plural) are grouped into families, and so on. This example classifies the species Ursus americanus, the American black bear.
Cilia structure illustrates the evolutionary relationship among all living Review Page 15 The cilia of paramecium are indistinguishable from human cilia in the human windpipe. Once a structure was “developed” through evolution, it was used in many different ways!!!!
An example from two different kingdoms for each level
Use Pneumonic Device for Taxonomic Groups King Phillip Can Operate For Good Spines
Remember, the example from class. You can live in the same Kingdom (country) but not live in the same state (phyla). However, if you live in the same genus (street), you automatically live in the same Neighborhood!!!! Major Plant Phyla: Bryophyta: (moss, liverworts, hornworts) Low to the ground, No Vascular System, No Seeds Filicinophyta: (Ferns, club mosses, Horsetails) Vascular System, No Seeds Coniferophyta (Pines, Spruce, Fir) Evergreen Foliage, Vascular System, “Naked” Seeds Angiospermophyta (Decidious Plants) Decidious Foliage, Vascular System, Covered Seeds/ Major Animal Phyla Porifera: (Sponges) Cnidaria (Jellyfish, Corals) Platyhelminthes (Flatworms) Annelida (Round Worms) Mollusca (Clams, Muscles) Hard Shell Covering Arthropoda (Insects, Crustaceans) Segmented Body, Jointed legs, Exoskeleton
Do CD Activity: Classification Schemes
Evolution through Natural Selection
Key Elements of Natural Selection It works at the intraspecies level (within a species). A few key elements are necessary for evolution to occur through natural selection
1. Variation within the species is necessary (caused by genetic mutations and meiosis)
Why this is important: There have to be differences (sometimes undetectable or at the cellular level) which give one member of a species a slight advantage over its fellow species member)
2. There has to be overproduction and a struggle for existence
Why this is important: The variation between individuals would be unimportant and would not lead to individual “advantages” if there were enough “resources” to go around. Ie. There have to be “winners and losers” in evolution.
3. Some members (the “winners” of the species have to survive and reproduce at a higher rate. Over years and years, the phenotypic traits (and their underlying genes) that led to their success will become more common in the “gene pool.
The Effects of Natural Selection on Populations The pressures of natural selection can affect the distribution of phenotypes in a population in several ways.
Stabilizing Selection
Natural selection often works to weed out individuals at both extremes of a range of phenotypes resulting in the reproductive success of those near the mean. In such cases, the result is to maintain the status quo.
It is not always easy to see why both extremes should be handicapped; perhaps sexual selection or liability to predation is at work. In any case, stabilizing selection is common. In humans, for example, the incidence of infant mortality is higher for very heavy as well as for very light babies.
Directional Selection
A population may find itself in circumstances where individuals occupying one extreme in the range of phenotypes are favored over the others.
Since 1973, Peter and Rosemary Grant — aided by a succession of colleagues — have studied Darwin's finches in the Galapagos Islands.
Investigation: Concept 1.4 How do environmental changes affect a population
Website about Evolution http://nsm1.nsm.iup.edu/rgendron/EvolutionOnTheWeb.shtml
Which type of species is most vulnerable to environmental changes in an ecosystem (wheter human-caused or otherwise), species that are highly adapted to a specific niche (called ecological specialists) or species which have a broad range of acceptable ecological conditions (called ecological generalists)??
BY THE END OF CHAPTER 1 YOU SHOULD BE ABLE TO ANSWER THE FOLLOWING IB ASSESSMENT STATEMENTS A.S. 5.4 (all assessment statements) and A.S. 5.5 (all assessment statements)
