1. Matter cycles and energy dissipates through the biosphere and its component ecosystems. The concept of an ecosystem is used to explain energy flow and nutrient recycling and to quantify large-scale and long-term processes. Students will study habitat destruction, ecological succession and changes to populations, focusing on the need to balance the interests of a growing human population with sustainable ecosystems.

2. OBJECTIVES: UNIT D: OUTCOMES ● analyze ecosystems and ecological succession in the local area and describe the relationships and interactions among subsystems and components ● analyze and investigate the cycling of matter and the flow of energy through the biosphere and ecosystems as well as the interrelationship of society and the environment ● analyze and describe the adaptation of organisms to their environments, factors limiting natural populations, and evolutionary change in an ecological context.

3. OBJECTIVES: Water: An Essential Abiotic Factor ● investigate and analyze an aquatic or a terrestrial local ecosystem, distinguish between biotic and abiotic factors, describe how these factors affect population size and infer the abiotic effects on life; e.g., light, nutrients, water, temperature infer biotic interactions; e.g., predator-prey relationships, competition, symbiotic relationships infer the influence of biota on the local environment; e.g., microclimates, soil, nutrients ● describe the potential impact of habitat destruction on an ecosystem

4. Abiotic vs. Biotic Factors  In any part of the biosphere, there are abiotic and biotic factors: Abiotic factors are physical, non-living parts of an ecosystem. Biotic factors are living organisms found an ecosystem. NOTE: “abiotic” is not the same as “dead.” Dead things were once living and are therefore still considered biotic parts of an ecosystem.

5. Abiotic vs. Biotic Factors AbioticBiotic  Wind  Water  Temperature  Nutrients found in soil  Sunlight  Mammals  Trees  Fish  Plants/ flowers  insects

6. Ecosystems

7.  This is the MOST IMPORTANT fact: All life is connected. Organisms are connected to each other and the abiotic factors they rely on or interact with. Therefore, ecosystems are what connects all life. Ecosystems are connected by the organisms that leave or enter them and by the abiotic factors that leave or enter them. Everything on Earth exists in a closed system.

8. Habitat  Habitat is all the biotic and abiotic factors present in an area that encourage the reproduction and survival of an organism.  Every organism has a preferred habitat.  Every living thing has certain biotic and abiotic requirements of its habitat. If those minimum requirements are not met, the organism will struggle to survive.  Nutrients are some abiotic examples of these requirements.they are any element or compound that an organism needs for growth or other functioning.

9. Water: An Essential Abiotic Factor  Water is perhaps the most important abiotic factor in any ecosystem.  A few facts about water: 75-90% of all cells are made up of water. Somewhere between 70-75% if the Earth’s surface is covered in water. Pure water (only H 2 O(l)) has a pH of 7 and is neither acidic nor basic. The same water that existed on the earth millions of years ago is still present today. Of all the water on the earth, humans can used only use about three tenths of a percent of this water. Such usable water is found in groundwater aquifers, rivers, and freshwater lakes.

10. Water: An Essential Abiotic Factor  Water is the solvent for life. Many ionic components are dissolved in water and are transported between living cells in fluids such as blood and tree sap.  Water is a finite resource. There is only a certain amount that is useable to use as humans. When we remove water from the environment (an ecosystem), it is no longer available to other organisms for their use. This is becoming a major problem in the world.

11. OBJECTIVES: Biotic Factors: The Influence of Living Things ● investigate and analyze an aquatic or a terrestrial local ecosystem, distinguish between biotic and abiotic factors, describe how these factors affect population size and infer the abiotic effects on life; e.g., light, nutrients, water, temperature infer biotic interactions; e.g., predator-prey relationships, competition, symbiotic relationships infer the influence of biota on the local environment; e.g., microclimates, soil, nutrients ● describe the potential impact of habitat destruction on an ecosystem

12. Ecology  If ecosystems are built on the interactions of biotic and abiotic factors in an area, then ecology is the study of those interactions.  Ecologists are scientists who specialize in the study of interactions within ecosystems.  The study of ecology takes on many forms and is a difficult and challenging discipline. Remember, organisms interact with each other and the abiotic factors that surround them. This forms a complex web of connections between all components of an ecosystem. It is an ecologist’s job to make sense of that web.

13. Ecosystems We have mentioned that ecosystems, are based on the complex interactions between all the biotic and abiotic factors within an area. As a rule, ecosystems cover a larger geographic area than do communities. For ecologist, studying an entire ecosystem is difficult – they are made up of many communities that first need to be studied before a more complete picture of the ecosystem is made.

14. Biomass  Biomass is the dry mass of all the living things occupying a habitat or ecosystem.  It is generally accepted that biomass is a good measure as to how many of each organism are present in a habitat or ecosystem.

15. Organization of Biotic Factors  Within ecosystems, it is possible to organize biotic factors (living things) into categories.  Populations A group of organisms, all of the same species, which interbreed and live in the same area at the same time. For example, all the deer mice occupying a particular meadow in the month of June are a population. Ecologists often study ecosystems at the population level in order to better understand that organism’s role in the ecosystem.

16. Organization of Biotic Factors  Communities A community is more complex than a population. It is the interacting populations living in a certain area at a certain time. Therefore, a community is made up of more than one group of organisms that interact with each other. For example, a meadow in the month of June could be considered a community. There are plants, insects, birds and mammals that all interact with each other. Studying communities is much more difficult to do. Ecologists struggle with the complexity of the connections between all the populations within that community.

17. Interactions in Ecosystems – Symbiosis  Symbiosis is a type of interaction between biotic factors in an ecosystem. Symbiosis is a long-lasting, ecological relationship that benefits at least one organism of two different species that live in close contact. One of the important things to remember about symbiosis is that it NEEDS to be long-lasting. If the interaction is momentary (like a bear attacking something) then it is not symbiosis. There are three types of symbiosis that are recognized by ecologists.

18. Interactions in Ecosystems – Symbiosis  Mutualism Mutualism This is a type of symbiosis where both organisms involved benefit from the relationship. Nitrogen-fixing bacteria on the roots of some plants use the nutrients in the roots to sustain themselves (a benefit). The roots benefit from the relationship because the bacteria provide roots with a good source of nitrogen  Commensalism This is a type of symbiosis where one organism benefits and the other is neither benefitted nor harmed. For example, brown-headed cowbirds follow herds of bison around. The cowbirds eat flies that harass the bison (a benefit) and the bison are largely unaffected by the interaction.

19. Interactions in Ecosystems – Symbiosis  Parasitism Parasitism This type of symbiosis involves one organism that benefits from the relationship and another which is harmed. For example, yellow-bellied sapsuckers (a woodpecker) create small, square-shaped holes in the sides of trees. Sap leaks out of those holes, attracting ants which get caught in the sap. The sapsucker benefit by feeding on the trapped ants, the tree, however is harmed by the interaction (it loses sap).

20. Interactions in Ecosystems – Predator-Prey Interactions  A predator is an organism that hunts another organism for the purpose of killing and eating it.  A prey animal is an organism that is hunted by a predator.  A predator-prey relationship is an interaction between two organisms where one organism (the predator) hunts, kills and eats the other organism (the prey).  Predator-prey relationships are common in all ecosystems. It is important, however, to note that parasitism is NOT predation, nor is a consumer eating a plant (there is no hunting taking place)

21. Interactions in Ecosystems – Competition  The interesting thing about ecosystems is that resources are limited. A prey species is not usually a prey species for only ONE organism. In many cases competition for resources (for example a prey species) is a significant problem for organisms to overcome in order to be successful. ○ If an organism isn’t well-suited to compete for a resource, then it will struggle to survive. The resources that organisms compete for can be either biotic factors (plants, meat, etc.) or abiotic factors (water, air, sunlight, etc.) In many cases, competition for resources drives evolution.

22. OBJECTIVES: The Web of Life ● analyze and describe how energy flows in an ecosystem, using the concepts of conservation of energy (second law of thermodynamics); energy input and output through trophic levels, food webs, chains and pyramids; and specific examples of autotrophs and heterotrophs ● explain why population size and biomass are both directly related to the trophic level of the species and explain how trophic levels can be described in terms of pyramids of numbers, biomass or energy.

23. Ecological Niches  Within an ecosystem, each organism plays a particular role. Some organisms may fill a number of niches depending on how they are connected to the ecosystem.  An ecological niche is a specific role an organism plays in its ecosystem.  American Ecologist Eugene Odum used the analogy that, “ If an organisms habitat is it’s “address”, the niche is the organism’s “profession”.

24. Ecological Niches  Producer: an organism that uses light energy to synthesize sugars and other organic compounds through the process of photosynthesis[ the conversion of light energy to chemical energy in the forms of sugars and organic molecules] (in most ecosystems, these are plants).  Consumer: a broad definition referring to any organism that uses other organisms as a source of energy (i.e. they eat other organisms). Primary consumer (herbivore): an organism that east green plants, algae or phytoplanktons. Secondary consumer: an organism that eats herbivores. Tertiary consumer: an organism that eats secondary consumers.

25. Ecological Niches  Carnivore: an organism that kills and eats other animals.  Omnivore: an organism that eats both plants and animals.  Scavenger: a bird or animal that feeds on dead and decaying animals that it did not kill itself.  Decomposer: (or detritivore) an organism that breaks down complex organic molecules into simpler molecules.

26. Energy Flow in Ecosystems  Ecosystems are all about energy and matter. As you will learn, energy flows and matter cycles.  Energy flow starts with the ultimate source of energy in our solar system – the Sun. From the Sun, energy flows through the producers and into the consumers at different levels.  Energy flows in steps and each step in the energy pathway is referred to as a trophic level:  Trophic comes from the greek word Trophikos, which means “to nourish”. A tropic level is the division of species within an ecosystem based upon its energy source. Producers are the lowest trophic level, followed by primary consumers, secondary consumers, etc. Energy is lost as we move up trophic levels.

27. Energy Flow in Ecosystems  The reason that energy is lost as we move up in trophic levels of the energy pyramid is because the higher up you go the more energy is used to survive, thus less is passed on.  There are numerous ways we can represent the flow of energy in ecosystems. We’ll explore a few of these: Pyramids of numbers, energy and biomass. Food chains Food webs

28. Pyramid of Energy  Amount of energy at each trophic level can be represented by a pyramid of energy.  Tertiary consumers have a larger mass and expend large amounts of energy hunting, which is why the energy levels drop significantly.  Each level will obtain 1/10 or 10% of the energy their prey started out with.

29. Pyramid of Numbers  Represents the number of organisms at each trophic level.  The pyramid is not always the same, producers can be very large, while others are small.  What if we had a large number of top-level consumers and a small number of producers?

30. Pyramid of Biomass  Represents the biomass of each trophic level in an ecosystem.  Ex. Rainforest ecosystem would store large amounts of solar energy and would contains lots of organic matter = large amount of biomass  Tundra gets a lot less energy and would contain less organic matter = smaller amount of biomass

31. The Pyramids  Pyramids are a great way to represent the flow of energy in an ecosystem (as well as, in some cases the numbers of individuals of each species in the population). The problem is that they are often difficult to construct: The pyramid of energy requires us to measure the energy stored by plants and then what is passed on to the next trophic level – a difficult task. The pyramid of biomass requires us to take the dry mass of all organisms (or at least a portion of them) in order to get the masses correct.

32. Food Chains  Food Chain - a diagram of “who eats who” in the ecosystem, with one organism at each trophic level. This is a very simple representation of the flow of energy in an ecosystem. We trace energy from when it enters the ecosystem through the producer and as it passes from one trophic level to the next.

33. Food Chain 1 2 3 4 5 1 2 3 45

34. Food Webs  Food webs – a diagram made up of interconnecting food chains with many organisms at each trophic level More accurate because organisms eat more than 1 kind of food and can occupy more than one trophic level Food webs are quite complex, but give a more complete picture of how energy flows within an ecosystem.

35. Food Webs

36. Food Chains and Food Webs  You’ll notice that the food chains and food webs both have arrows. Those arrows represent the flow of energy. For example, energy flows from the fish to the osprey when the osprey eats the fish. THIS IS IMPORTANT TO REMEMBER!

37. OBJECTIVES: The Recycling of Matter ● outline the biogeochemical cycles of nitrogen, carbon, oxygen and water and, in general terms, describe their interconnectedness, building on knowledge of the hydrologic cycle from Science 10, Unit D ● describe artificial and natural factors that affect the biogeochemical cycles: nitrogen cycle; e.g., automobile, agricultural and industrial contributions to NOx combining with water to produce nitric acid, nitrogen in manure and fertilizers carbon cycle; e.g., emissions of carbon oxides from extraction, distribution and combustion of fossil fuels, releases associated with deforestation and cement industries water cycle; e.g., extraction of ground water, dams for hydro-electricity and irrigation

38. Matter Cycles  In the last lesson, we described that energy flows through ecosystems. It originates with the sun (in most cases) and flows up the trophic levels.  In ecosystems, matter does the opposite: it cycles.  Matter cycles because the Earth is a closed system – energy is allowed to enter and leave, but matter is not. Therefore, we have a finite amount of matter to use in our biosphere, therefore it must be cycled (think recycling).

39. The Biogeochemical Cycles  Matter within our biosphere cycles through biogeochemical cycles. “Bio” means living, therefore these cycles are connected to living things. “Geo” means Earth or rock, therefore these cycles are also connected to the rock/Earth. “Chemical” is obvious – these cycles are linked with chemical reactions.  Each cycle has a living, Earth and chemical reaction connection.

40. Hydrological (Water) Cycle  Involves the cycling of water in the atmosphere and on the surface of the earth.  driven by solar energy evaporation condensation precipitation

41. Purposes of the Hydrological Cycle  serves to stabilize the temperature of the surrounding air and land due to the high latent heat of vaporization required for evaporation and the latent heat of fusion for freezing  serves as a purification process as the water percolates through the soil, it is filtered “distillation” process – when water evaporates, it leaves potentially harmful substances behind.

42. Hydrological Cycle

43. Carbon and Oxygen Cycles  Involves the cycling of carbon (usually in CO 2 (g) form) and oxygen in the atmosphere or as a part of organisms or the land.  photosynthesis and cellular respiration maintain a balance of concentrations of carbon and oxygen in the atmosphere 6 CO 2 (g) + 6 H 2 O(l)  C 6 H 12 O 6 (s) + 6 O 2 (g) (Photosynthesis) C 6 H 12 O 6 (s) + 6 O 2 (g)  6 CO 2 (g) + 6 H 2 O(l) (Cellular respiration)  Atmospheric concentrations of oxygen and CO 2 (g) O 2 – 20.95% CO 2 – 0.033%  Oceans and forests serve as a sink for CO 2 either absorbing or releasing CO 2 to the atmosphere

44. What if CO 2 /O 2 isn’t balanced?  What would happen if, for some reason, the equilibrium maintained by cellular respiration and photosynthesis is disrupted?

45. Carbon Cycle  When carbon is not in its organic form it is stored in 3 main areas: the atmosphere (gas), the ocean in sediments, and the Earth’s crust.  Under some conditions carbon is converted to rocks and fossils (coal, petroleum, natural gas) rather than going into immediate circulation.  Organic carbon is also stored in bogs. There is little oxygen in bogs, decomposition is very slow, and carbon atoms become locked away (formation of coal).

46. Carbon Cycle

47. Oxygen Cycle  The oxygen cycle is a mirror image (mostly) of the carbon cycle. Since both are tied in to cellular respiration and photosynthesis, they mirror each other

48. Nitrogen Cycle  Nitrogen cycling is connected to the atmosphere, the soil and organisms.  Essential for the formation of amino acids (proteins)  Composes 78.08% of atmosphere but cannot be used in its atmospheric form (N 2 (g)) except for a few cases of nitrifying bacteria  In order to have usable nitrogen, we must convert it first to nitrates. This is done through lightning or nitrogen fixation (by bacteria)

49. Nitrogen Cycle

50. Disturbances to the Cycles  Humans are really good at disturbing the natural cycling of water, carbon, oxygen and nitrogen. Each time one of these cycles is messed with, it affects the ecosystems connected to the cycles. In most cases, the effects of “messing” with the cycles are negative, but in some cases, we can have positive effects.

51. OBJECTIVES: Biodiversity ● describe the potential impact of habitat destruction on an ecosystem ● describe the effects of introducing a new species into, or largely removing an established species from, an environment; e.g., zebra mussel, carp and the Eurasian milfoil in Canada’s lakes, purple loosestrife in Alberta, the horse or the buffalo in the plains region of Alberta.

52. Biodiversity  The International Union for the Conservation of Nature (IUCN) defines biodiversity as:biodiversity Biological diversity - or biodiversity - is a term we use to describe the variety of life on Earth. It refers to the wide variety of ecosystems and living organisms: animals, plants, their habitats and their genes.  Biodiversity is everywhere. It occurs both on land and in water, from high altitudes to deep ocean trenches and it includes all organisms, from microscopic bacteria to more complex plants. Although many tools and data sources have been developed, biodiversity remains difficult to measure precisely. According to the Millenium Ecosystem Assessment, the total number of species on Earth ranges from five to 30 million and only 1.7–2 million species have been formally identified. IUCN – 2010 – www.iucn.org

53. Biodiversity  But we do not need precise figures and answers to devise an effective understanding of where biodiversity is, how it is changing over space and time, what are the drivers responsible for this change, its consequences for ecosystem services and human well-being, and the available response options.  There are many measures of biodiversity. Species richness (the number of species in a given area) represents a single but important metric that is valuable as the common currency of the diversity of life—but to fully capture biodiversity, it must be integrated with other metrics. IUCN – 2010 – www.iucn.org

54. Biodiversity  Our food and energy security strongly depend on biodiversity and so does our vulnerability to natural hazards such as fires and flooding. Biodiversity loss has negative effects on our health, material wealth and it largely limits our freedom of choice. As all cultures gain inspiration from or attach spiritual and religious values to ecosystems or their components – e.g. landscapes, trees, hills, rivers or particular species - biodiversity loss also strongly influences our social relations. IUCN – 2010 – www.iucn.org

55. Biodiversity  Biodiversity is essential to global food security and nutrition and also serves as a safety-net to poor households during times of crisis.  More than 70,000 plant species are used in traditional and modern medicine.  The value of global ecosystem services is estimated at $16-$64 trillion. IUCN – 2010 – www.iucn.org

56. Habitat Fragmentation  Habitat fragmentation is the conversion of formerly continuous habitat into patches separated by non-habitat areas.  Some causes of habitat fragmentation common to Alberta are: Roads – usually oil and gas (seismic exploration or access) or forestry access Well sites

57. Habitat Fragmentation

58. Habitat Destruction  Habitat destruction is the permanent alteration of vital characteristics in an organism’s habitat. In other words, the habitat is no longer viable – it will no revert to what it was before. Organisms are no longer able to use that habitat.  Habitat fragmentation will cause problems that can usually be avoided by organisms (e.g. they move to another location nearby).  Habitat destruction can be more devastating for organisms. Because the habitat is destroyed (lost), it is not something that can be used anymore, they must relocate.

59. Invasive Species  An invasive species is a species that does not normally occur in an area, is introduced by human action, and then expands to become a breeding population that threatens the area’s biodiversity. Zebra mussels, seven-spot ladybugs, purple loosestrife and even house sparrows can be considered invasive species. Quite often invasive species are better suited to adapting to their environment than the native species are. This means they are better able to compete for resources. This competition can stress the native organisms, causing them major problems. In extreme cases, invasive species have forced native species to go extinct.

60. Invasive Species

61.  What role do humans have to play with respect to invasive species? Take a few minutes to think about how humans might be making invasive species more of a problem. ○ Share your thoughts with a partner.

62. Species at Risk  When an organism’s population (usually on a provincial-scale) is significantly reduced, often they are deemed a species at risk. What this designation means is that there is concern that their population has fallen for many consecutive years and it is not looking like the population will recover unless we step in. In nearly all cases of species at risk, humans are the central factor for the population’s decline.

63. Species at Risk CategoryDescriptionExamples ExtinctSpecies no longer exists anywhere (in the world). Banff longnose dace (fish), passenger pigeon, dodo bird ExtirpatedSpecies no longer exists in Alberta (or any region), but lives elsewhere. Black-footed ferret, prairie dog EndangeredSpecies threatened with imminent extinction or extirpation through their range. Woodland caribou, swift fox, burrowing owl ThreatenedSpecies likely to become endangered if the factors that cause its vulnerability are not reversed. Peregrine falcon VulnerableSpecies likely to become threatened or endangered Wolverine

64. Species at Risk  What role do humans have to play when it comes to species at risk? Take a few moments to think about how humans contribute to species becoming at risk. ○ Share your thoughts with a partner.

65. Biodiversity How is biodiversity being impacted? Name and describe 2 sources that are causing biodiversity to be impacted. Explain what could be done to minimize the impact of these sources. Introduce one species at risk in your ecosystem. What is it? Where does it live? Why is it at risk?

66. OBJECTIVES: Primary Succession ● describe the key stages of primary succession in a specific ecosystem and the nature of its climax community; e.g., spruce bog, sand dune, pond, prairie ● differentiate between primary and secondary succession in a specific aquatic and a specific terrestrial ecosystem, e.g., pond, river, lake, forest, parkland, and compare natural and artificial means to initiate secondary succession in an ecosystem, e.g., reforestation or regrowth after a forest fire, flood or other natural disaster, strip mining, clearcutting, controlled burns by some Aboriginal groups promoting grassland biome regeneration

67. Ecosystems Change  Every ecosystem undergoes change over time… trees die and are decomposed, wind damages large parts of forest; fire, flooding and drought will all affect an ecosystem.  Even if an ecosystem were not to undergo a drastic, rapid change like those mentioned above, they still change gradually over time. The gradual change in ecosystems over time is succession. It is NATURAL for ecosystems to change over their lifetimes. Most ecosystems change so slowly that it’s difficult for us to see the changes within our lifetimes. Some might evolve over hundreds of years. The next two lessons will be devoted to discussing two types of succession: primary and secondary.

68. Primary Succession  Primary succession is the process of changing – in successive, gradual stages – an ecosystem from an area of bare rock and few or no species to a complex community. Primary succession begins in places where soil has been removed or has never existed. ○ For example, bare land such as cooled lava, sand dunes and mountain slopes. Primary succession is a SLOW process because life must spring forth from “nothing” (bare rock). Let’s examine the stages of primary succession.

69. Primary Succession 1. Primary succession begins with a clean slate (bare rock, sand, lava, etc.) 2. A soil must then be developed (by wearing down rock and collecting some organic matter) before plants will grow. 3. Pioneer species (lichen and hardy plants) then populate the newly-formed, very sparse soil. When these organisms die, they add humus (organic matter) to the soil. 4. Once enough humus-rich soil is produced, larger plants can begin to grow. This will also start to attract more animals – starting with the smaller ones and moving on up. 5. Eventually forest will grow (if the climate allows) and this brings even more diverse plants and animals. 6. Ultimately a stable community results – forming what we call a climax community.

70. Primary Succession

71.  Climax communities are different depending on where you go in Alberta or the world. The type of community you find depends on the climate and accessibility to abiotic resources like water and sunlight. For example: ○ Due to the large amounts of rainfall, mild climate and many days of sunlight, large cedar and fir dominated rainforest are climax communities on the west coast of BC. ○ In the Arctic, a climax community might be a vast area of shrubs and grasslands, limited by short growing seasons and a harsh climate.

72. Aquatic Succession  In aquatic systems, we can encounter succession as well.  For example when water collects in a basin (likely rocky), it is poor in nutrients. Runoff and other organisms that die in that basin begin to add to a “soil” created at its bottom Eventually, enough soil collects to provide habitat for aquatic plants and aquatic invertebrates. This will attract frogs, salamanders and other insects and eventually fish may even find their way into the ecosystem. Once a vibrant community of organisms is thriving in this body of water, we have created a climax community yet again.

73. OBJECTIVES: Secondary Succession ● describe the key stages of primary succession in a specific ecosystem and the nature of its climax community; e.g., spruce bog, sand dune, pond, prairie ● differentiate between primary and secondary succession in a specific aquatic and a specific terrestrial ecosystem, e.g., pond, river, lake, forest, parkland, and compare natural and artificial means to initiate secondary succession in an ecosystem, e.g., reforestation or regrowth after a forest fire, flood or other natural disaster, strip mining, clearcutting, controlled burns by some Aboriginal groups promoting grassland biome regeneration

74. Secondary Succession  Secondary succession follows many of the same general steps as in primary succession, but with one very important difference: secondary succession does not start from bare rock. It is the return to a stable climax community from an area that has had its vegetation – but not its soil – removed.  This means that secondary succession proceeds much faster than primary succession because a soil is already developed.

75. Secondary Succession 1. Secondary succession begins a major event that eliminates all of the vegetation in an ecosystem, but not its soil. Major events could include fires, clear cuts, floods, etc. 2. Pioneer species (quite often grasses or fireweed) then populate the barren ground. 3. This attracts new, larger plants and of course more animals. 4. Eventually forest will grow (if the climate allows) and this brings even more diverse plants and animals. 5. Ultimately a stable community results – forming what we call a climax community.

76. Secondary Succession

77. Causes of Disturbances  Secondary succession starts with a disturbance that wipes out the vegetation in an ecosystem. This disturbance can originate naturally or can be manmade. Here are some examples: ○ Forest fire (most are natural, but some can be manmade). ○ Flooding ○ Clear-cutting ○ Reclamation of developed land.

78. Forest Fires  Quite often, society associates forest fires with being terrible catastrophes. This is only true, usually, when property or even lives are lost.  Forest fires are part of the natural cycle of forests (this could include grass fires on the prairies). A forest fire helps to regenerate the forest, returning many nutrients that were locked up in the trees, back to the soil. It opens the canopy allowing more light to the forest floor. Many species of coniferous trees (namely pines) require fire to open their cones and release the seeds stored in side.

79. Forest Fires  In many of our national parks (and even some of our provincial parks), forest fires are set on purpose to burn areas of forest. These are called prescribed burns. Their goal is to mimic what nature does naturally (i.e. setting fires by lightning). It is natural for a forest, when it reaches climax community status, to burn sometime afterwards. It renews and regenerates the forest, forcing secondary succession to begin again.

80. OBJECTIVES: Populations ● describe how factors including space, accumulation of wastes (e.g., salinization of soil), competition, technological innovations, irrigation practices (e.g., Hohokam farmers) and the availability of food impact the size of populations ● compare the growth pattern of the human population to that of other species.

81. A Population  Recall that a population is the total number of individuals of a certain species living in an area at a particular time. Human populations are determined based on geographic area and so are other organisms’. Understanding populations of other organisms has helped us understand human populations and vice versa.

82. Bacteria  One of the best populations to study are bacterial populations. Bacteria reproduce by dividing into two cells after they have reached a certain size. Their populations experience exponential growth: the rapid growth in population caused by a constant increase. This constant increase is achieved through the population doubling very quickly. Bacterial populations, when graphed, create an exponential curve.

83. Bacteria

84. Factors Affecting Population Size  The number of individuals in a population is affected by four major factors: Number of births (natality): how many organisms are born compared to the population size as a whole. Number of deaths (mortality): how many organisms die compared to the population size as a whole. Immigration: how many organisms move into (or join) the population’s area. Emigration: how many organisms leave the population’s area.

85. Factors Affecting Population Size  Open and closed populations have their numbers change differently because different factors are at play: Open population is a group of organisms that exists in a natural setting where births, deaths, immigration and emigration affect population size (most common in natural settings). Closed population is a group of organisms that exist in a natural or artificial setting where immigration and emigration do not occur, and population size is only affected by births and deaths (think about a zoo, for example).

86. Limiting Factors  Births, deaths, immigration and emigration are simple, broad factors used to determine a population’s size.  Limiting factors are specific parts of an organism’s habitat that affect population size In other words, these are the factors that will causes increases or decreases in births, deaths, immigration and emigration.

87. Limiting Factors  Space The amount of space available to a population will affect how it grows. Generally, the more space the better, so long as the space available includes suitable habitat.  Accumulation of wastes If too many wastes accumulate in an ecosystem (without being broken down or removed), a population’s size will decrease. ○ For example if the soil is to saline (salty) plant populations will struggle to grow, affecting other populations that rely on them.

88. Limiting Factors  Competition Competition between individuals of a species can significantly affect population size. Too much competition means resources are limited (food, water, shelter), therefore population size will decrease.  Availability of Food As food supplies become more scarce, population size will decrease and vice versa. ○ Scarcity of food can be cause by a population being too large (not enough food to feed all the hungry mouths) or it could be caused by an external factor (for example a change in the climate of their ecosystem).

89. Carrying Capacity  Each ecosystem has a specific carrying capacity for each organism that inhabits the ecosystem. Carrying capacity is the maximum number of individuals that can be sustained for an indefinite period of time in a given ecosystem. If carrying capacity is exceeded, a population will likely experience a crash (especially if its growth was exponential). This crash will be due to a lack of resources. For example an ecosystem is only able to support 3 grizzly bears because there are only enough resources within it to keep 3 grizzly bears alive. One more grizzly bear entering that ecosystem would put it over its carrying capacity. Something would have to give… a bear would need to die or leave.

90. Human Populations  Like bacteria, human population has been increasing exponentially. Human population has been able to grow exponentially because of technological innovations: ○ As we have developed better ways to stay alive in our ecosystems, our life expectancy has increased, so has our natality. This has kept more of us alive longer, allowing us to reproduce. ○ Some innovations that have aided in this include: central heating, refrigerators, medicine, guns, and the list goes on…

91. Human Populations  Many scientists and anthropologists believe that Earth is nearing its carrying capacity for humans. In other words, we are getting close to not being able to support any more humans. When we reach our carrying capacity for humans, like in the example with grizzly bears, something is going to have to give…

92. OBJECTIVES: Adaptations ● describe mutation as the principal cause for variation of genes in species and populations, identify the role of sexual reproduction in generating variability among individuals and describe the forces that drive evolution ● describe the adaptation of species over time due to variation in a population, population size and environmental change; e.g., bacterial resistance to antibiotics, giraffe neck length, gazelle speed ● describe evidence for evolution by natural selection; e.g., fossils, biogeography, embryology, homologous and vestigial structures, biochemical research

93. Changes in Populations  Populations are changing all the time, not only in size, but also in behaviour and appearance. What we mean by this is that what the species looks like and how it behaves changes over time.  There are two types of changes in populations: Gradualism: changes to the organisms in a populations occur slowly and steadily over the Earth’s history. Punctuated equilibrium: changes to the organisms in a population occur in rapid spurts, followed by long periods of little change.

94. Changes in Populations  These changes bring about changes in appearance and behaviour of the species that makes up the population. The rapid changes can be caused by major events in the population’s ecosystem. Gradual changes are usually caused by minor, slow changes to the population’s ecosystem.  How do these changes cause a change in the whole population?

95. Inheritance  All living things have DNA (deoxyribonucleic acid). DNA contains all the information necessary to make a particular kind of organism. DNA is passed from one generation (parents) to the next (offspring/kids). ○ Another way to say this is that you inherit DNA from your parents.  The DNA contains information that gives you some of the traits of your parents (e.g. eye colour, hair colour, facial features, etc.). Segments of DNA that “code” for particular traits are called genes.

96. Inheritance  In order to keep the genetic material changing in a species (which keeps a population healthy), there is a mix of genes. This “mix” occurs during sexual reproduction. When organisms sexually reproduce, the male donates half of the DNA needed, while the female donates the other half. This creates genetically diverse offspring. So, we can say that we inherit our genetics from our parents – half from our mom and half from our dad.

97. Variation in Populations  Every individual in a population is different (usually only slightly) – think about hair colour, eye colour, etc.  Where does this variation come from? Sexual reproduction – the mixing of DNA from your parents creates variation. Mutation – a change in the DNA sequence which results (sometimes) in a change in the traits expressed by your genes.

98. Mutations  Not all mutations are bad… Mutations that help an organism to better survive in its environment are good mutations. ○ These will make it more likely for the organism to be healthy enough to reproduce and pass on their DNA. Mutations that make it more difficult for an organism to survive are bad mutations. ○ These will make it less likely for the organism to be healthy enough to reproduce and pass on their DNA.

99. Adaptations  An adaptation is a structural (part of the body) or behavioural (what it does) trait that improves an organism’s success at surviving and reproducing in a particular environment. Structural: sharp claws, long neck, etc. Behavioural: migration, stalking, etc.  Adaptations are brought about by good mutations and are passed down to the next generation through DNA. Quite often these mutations are driven by changes in the organisms environment. Sometimes these mutations occur at random – bringing on a beneficial change.

100. A thought about inheritance and population change…  In order for a population to change, a mutation MUST be passed on to the next generation. If the change in DNA (mutation) is not passed on in the genetic information from the parents to the offspring, the population will not change.

101. OBJECTIVES: Evolutionary Theory ● describe evidence for evolution by natural selection; e.g., fossils, biogeography, embryology, homologous and vestigial structures, biochemical research ● compare gradual evolution with punctuated equilibrium

102. What is Evolution?  Evolution is the progressive change in organisms over time.

103. The Age of Earth  based on the rates of decay of radioactive isotopes the earth is over 4.5 billion years old

104. Evidence for Evolution  Comparative Anatomy Homologous – structures that are similar origin but have different functions (dolphin fin, dog leg) Analogous- structures that are similar in use but have different origins (bird wing and butterfly wing)

105. Evidence for Evolution  Fossil Evidence When we begin to compare fossils of organisms of different times, we can see the progression of evolution. Evolution of birds from dinosaurs is a great example.

106. Evidence for Evolution  Biochemistry (Genetics) The more closely related two organisms are, the more similar their genetic structures are DNA similarities – when we begin to compare the genomes (genetic material) in organisms, we can see that organisms who are closely related share much of the DNA sequence, while distant relatives have few similarities.

107. Evolutionary Theories  Evolution has not always been widely accepted as the way to explain how organisms have changed over time.  It wasn’t until Charles Darwin published his book “On the Origin of Species” in November of 1859 that the scientific community started to come together on this matter.  Darwin’s theory was contested by another theory – that of Lamarck.

108. Jean Baptiste Lamarck  Argued for the idea of spontaneous generation: species are continually being created spontaneously from non-living matter.  We now refer to this as inheritance of acquired characteristics: environmental changes bring about changes in individuals, and these changes are passed on to their offspring. We know this to not be true.

109. Lamarck: an Example  Lamarck would suggest that a giraffe used to be a short-necked animal, but due to the need to reach higher food sources, their necks stretched. This stretching would be passed on to their offspring.

110. Charles Darwin  In 1831, at the age of twenty- two, Charles Darwin set off from England on a voyage around the world. He was serving as the ship's naturalist aboard the H.M.S. Beagle.  The observations that he made on this voyage were the first step toward his formulation of the theory of evolution by natural selection. WHY DID SOME SPECIES SURVIVE WHILE OTHERS BECAME EXTINCT? NATURAL SELECTION

111. Charles Darwin  Following his voyage on the Beagle, Darwin came up with 3 inferences: 1. Individuals of the same species are in a constant struggle for survival. With each other and with the environment. 2. Individuals with more favourable variations are more likely to survive and pass these variations on. Survival is not random. THIS is natural selection. Think about a tiger that can move faster or a mouse with better camouflage.

112. Charles Darwin 3. Since individuals with more favourable variations contribute proportionately more offspring to succeeding generations, their favourable inherited variations (genetic information) will become more common. THIS IS EVOLUTION. A mouse that is better able to evade prey will survive longer and thus pass its inherited superior speed/camouflage/instincts on to its offspring. We are evolving a better mouse.

113. Charles Darwin  Initially, Darwin’s inferences were met with much resistance. Over time, though his theory of natural selection was accepted and has become the way we explain evolution.