🌱Option C ecology n conservation

• • Species is a group of organisms that can potentially interbreed with one another to produce fertile offspring 
  • A community is a group of populations of different species living and interacting with one another
• REASONS FOR EXTINCTION OF SPECIES + IMPORTANCE OF WILDLIFE CONSERVATION 

  • Humans and human activities - human population growth, overhunting, toxic pollution, climate change and overconsumption 
  • Wildlife conservation should be a concern for us as all countries and communities will be negatively impacted by consequences of species extinction (environmental degradation, species loss, increase in disease, lack of pollination, proliferation of pests, environmental imbalances, etc). It is in the interest of the governments and citizens to work to conserve ecosystems and all species living there.
• INTERACTION BETWEEN SPECIES 

  • Interactions between species in a community can be classified according to their effects 

  
• COMPETITION:

  • Competition refers to the rivalry between living things for territory, resources, food, mates, etc 
  • Competition is greater between members of the same species as they are competing for the same resources
• Predator-Prey Cycle:

  • Predators kill and eat prey 
  • There is a cycle of increases and decreases for both predator and prey 
  • The changes in the predator population lag behind the prey population 
  • Large predator populations kill large numbers of prey, causing a decrease in the prey 
  • The decrease in the prey results in a shortage of food for the predator 
  • The shortage of food is going to cause a decrease in predator numbers 
  • Low predator numbers cause an increase in prey numbers, which also causes an increase in predator numbers 
• SYMBIOSIS 

  • Symbiosis refers to the interaction between two different organisms living in close physical association

  
• APPLICATION: ZOOXANTHELLAE+REEF-BUILDING CORAL REEF SPECIES 

  • Mutualistic relationship, because the coral and algae both gain from the relationship 
  • The photosynthetic zooxanthellae algae produce nutrients like glucose used by the corals. They also remove waste and produce oxygen 
  • The coral polyps protect the zooxanthellae, as well as providing them with carbon dioxide for photosynthesis 
• CORAL BLEACHING

  • Increasing ocean temperatures caused by global warming is causing the corals to expel the zooxanthellae 
  • The corals thus lose their color and become bleached 
  • If ocean temperatures remain high, the zooxanthellae do not return and the corals die 
• KEYSTONE SPECIES 

  • Species that have a disproportionate effect on the structure of a community 
  • If the keystone species is removed from the ecosystem it will result in a significant decrease in biodiversity (number of organisms) of the ecosystem 
• INFLUENCE OF KEYSTONE SPECIES

  • They can influence the community in many ways: 
  • PREDATORS: They exert pressure on lower trophic levels to prevent them from monopolizing certain resources. E.g: Wolves of Yellowstone Park 
  • MUTUALISM: They support the life cycle of a variety of species within a community. E.g: Pollinators 
  • BUILDERS: They can support the life cycle of a variety of species within a community. E.g: Beavers building dams on rivers 
• NICHES 

  • A niche is the particular environment and lifestyle that is adopted by a species 
  • A niche includes habitat, food, mode of nutrition, time of year for reproduction, interactions with other species, interactions with own species, interactions with abiotic factors
• COMPETITIVE EXCLUSION 

  1. A smaller yellow species of bird forages across the whole tree 
  2. A larger red bird species compete for resources 
  3. Red birds dominate in the middle of the tree where resources are most abundant 

  →Yellow birds are competitively excluded from the middle of the tree to avoid competition
• Competitive exclusion

  No two species can occupy the same niche
• One species will be more successful and will out-compete and exclude the other
• Fundamental niche

  The niche that an organism could potentially occupy, assuming there is no competition for resources
• Realized niche


  The niche that an organism does occupy due to competition with other species for resources
• Birds


  • Yellow birds' fundamental niche was the whole tree, but their realized niche is the top and bottom of the tree because of competition with the red birds
• APPLICATION: FUNDAMENTAL AND REALIZED NICHE OF CTHAMALUS BARNACLES 

  • Balanus barnacles grow faster and outcompete Cthamalus barnacles. The Balanus barnacles can only survive in tidal zones where they are covered by seawater for most of the day
  • This prevents Cthamalus from surviving in all areas of its fundamental niche. 
  • Thus, Cthamalus continues to survive in its realized niche as the Balanus barnacles cannot survive being above water for so long when the tide goes out
• LABORATORY EXPERIMENTS ON COMPETITIVE EXCLUSION 

  • George Gause carried out experiments on competitive exclusion using two unicellular Paramecia species 
  • Paramecia aurelia outcompetes Paramecia caudatum. Paramecia caudatum is competitively excluded

  
• SHELFORD’S LAW OF TOLERANCE 

  • The law of tolerance was proposed by Shelford in 1911 
  • According to the law:

  1. Organisms have optimal survival rates for abiotic factors 
  2. As an organism moves from areas with optimum conditions, there is a decrease in survival rates 

  • The law proposes a normal distribution of a species in response to a limiting factor
• SHELFORD'S LAW OF TOLERANCE GRAPH

  • There are distinct sections in the graph:

  1. Optimum range with maximum survival rates 
  2. Zones of stress with reduced survival rates 
  3. Zone of intolerance where organisms cannot survive

  
• There are certain abiotic factors that can affect an organism’s distribution 

  • Temperature 
  • pH
  • Available minerals
  • Available light
  • Latitude
  • Altitude 
  • Humidity
  • Soil content 
  • Breeding sites 
  • Aeration of soil 
  • Climate
• APPLICATION: DISTRIBUTION OF SAGUARO CACTUS. PART 1

  • Can only be found in the Sonoran desert in the US (wet desert w/ two rainy seasons)
  • Thrive best at high temperatures where water is relatively scarce for most of the year
  • Cold temperatures and frost kill Saguora. Thus, not found above altitude of 1300m
• APPLICATION: DISTRIBUTION OF SAGUARO CACTUS. PART 2

  • Survive best in coarse soils of south-facing rocky slopes
  • Grow very slowly as they use CAM physiology for photosynthesis, so outcompeted in areas with faster-growing plants when water is plentiful 
  • Often begin life in the shelter of a nurse tree or shrub which can provide shaded, moist habitat for germination
• APPLICATION: DISTRIBUTION OF STAGHORN CORAL

  • Found in warm, sunny, clear tropical waters 
  • Found to a depth of 30m with gentle wave action. In coral reefs located within latitudes of 25 deg N to 25 deg S
  • Requires temperature range between 23C and 29C
  • Requires salinity range of 32% to 40%
  • Decrease in ocean pH affects staghorn coral adversely 
  • Require presence of zooxanthellae to provide most nutrients 
  • High turbidity (murkiness) reduces photosynthesis in zooxanthellae, meaning corals need clear water to thrive 
• BELT TRANSECTS 

  • Use of a transect to correlate the distribution of plant or animal species with an abiotic variable 
  • Can be used to investigate the changes of species distribution when an abiotic factor changes, like change in altitude or change in light intensity 
  • It is used when there is a gradual change from one side of a habitat to another 
  • A transect is a path along which one counts and records occurrences of species of study within quadrats 
  • Requires observer to move along a fixed path and count occurrences along the path
• Ecosystems are biological communities of interacting organisms and their abiotic environment
• BIOSPHERE 

  • The biosphere is the zone of air, land, and water where organisms exist
  • It is commonly known as the global sum of all ecosystems, and consists of several layers including the atmosphere, the lithosphere, and the hydrosphere 
  • In closed ecosystems energy but NOT matter is exchanged with the surroundings 
  • Mesocosms are closed ecosystems as no material is added to the ecosystem 
  • Earth is a closed system as matter doesn’t enter the Earth from outside the atmosphere, nor does it leave. ENERGY does enter in the form of sunlight. Heat energy is lost from atmosphere
• ECOLOGICAL SUCCESSION 

  •  It is the process of change in a particular area over a time period, caused by complex interactions between organisms and the environment 

  COMPARING AND CONTRASTING PRIMARY + SECONDARY SUCCESSION 

  • A succession of organisms replace each other 
  • Both are slow processes 
  • Both result in a climax community 
  • Primary succession begins in an area where plants have not been before
  • Secondary succession begins in an area where an ecological community has been destroyed 
  • Secondary succession is faster than primary succession 
• • Pioneer species are the first organisms to colonize an area. Often mosses and lichens. They help break down rock and when they die they decompose and form soil. The soil then allows other species to colonize the area 
• CHARACTERISTIC CHANGES DURING SUCCESSION 

  • Species diversity increases but some species replace earlier species 
  • Producers are more productive, increasing plant density 
  • Organic matter in soil increases as more organisms grow, die, and are decomposed 
  • Water-holding capacity of soil increases due to organic matter
  • Soil depth increases 
  • Soil erosion reduced due to roots 
  • Nutrients are recycled 
• • Primary succession begins when an area of ground or bare rock with no existing soil is colonized for the first time 
  • Secondary succession is a process started by a disturbance like a forest fire, hurricane, etc. that reduces an already established ecosystem to a smaller community of species 
• SUCCESSION AT GLACIER BAY NATIONAL PARK PART 1

  • Disturbances influence structure + rate of change within ecosystems 
  • As the glaciers retreat, bare land is exposed 
  • Primary succession can begin 
  • Pioneer species are first to colonize the land as the glacier retreats 
  • As first plants die, soil quality improves in depth + nitrogen content 
• SUCCESSION AT GLACIER BAY NATIONAL PARK PART 2

  • Pioneer species are replaced by successive communities, where more leaf litter adds to quality and soil depth 
  • Woodland of alder trees present after 60 years 
  • However, they are replaced by climax community which includes spruce and hemlock woodlands 
  • Climax community reduces soil pH, becomes acidic 
• CLIMAX COMMUNITY 

  • A climax community is an ecological community in which populations of organisms remain stable and exist in balance with each other and their environment 
  • It is the final stage of succession, remaining relatively unchanged until destroyed by an event, like fire or human interference 
  • An extensive and identifiable climax community is a biome
• WHITTAKER’S CLIMOGRAPH 

  • It predicts the climax community aka biome found according to mean annual temperatures and mean annual precipitation

  
• BIOMES 

  • Biomes are naturally occurring climax communities of plants and animals occupying a major habitat
• PRODUCTIVITY IN ECOSYSTEMS 

  • Productivity refers to the rate of generation of biomass in an ecosystem 
  • Biomass is the dry mass (not incl. water) of living organisms in an ecosystem 
  • Productivity can be classified as:

  Primary production: producers synthesize organic compounds by photosynthesis to increase their biomass

  • Secondary production: heterotrophs increase biomass by using organic matter obtained through feeding
• ENERGY CONVERSION RATES 

  • Gross production of energy is the total amount of energy in food synthesized by producers, or amount of energy in food eaten by an animal 
  • Net production of energy is amount of energy in food converted to biomass in an organism. Always less than gross production 
  • Some food is used in cell respiration and the energy from it is lost as heat from the organism and the ecosystem 

  NET PRODUCTION OF ENERGY = GROSS PRODUCTION OF ENERGY - LOSS OF ENERGY BY RESPIRATION 

  • Percentage of ingested energy converted to biomass is dependent on respiration rate of organisms
• PRODUCTIVITY AND ECOSYSTEMS 

  • The productivity of ecosystems varies and depends on:

  PRIMARY PRODUCTIVITY OF PLANTS & FEED CONVERSION RATES OF CONSUMERS

  % OF ENERGY LOST = GROSS PRODUCTIVITY - NET PRODUCTIVITY / GROSS PRODUCTIVITY X 100  = %