Ecology

The Biosphere What is Ecology?

Ecology Definition - the study of interactions among organisms and between organisms in their environment

Levels of organization A single member of a species is known as an individual Populations are groups of individuals Communities are grouping of different populations An ecosystem includes a community and its surroundings A biome is a group of ecosystems with the same type of climate A biosphere would be the entire planet

The Biosphere Energy Flow

Producers Q: What do we call organisms that make their own food? A: Autotrophs Q: What process do plants undergo to make their own food? A: Photosynthesis Q: What’s the equation for photosynthesis? A: 6CO2 + 6H2O + sunlight  C6H12O6 + 6O2

Consumers Q: What do we call an organism that consumes its food? A: Heterotroph There are four types of heterotrophs, depending on where the organism’s energy (i.e. food) comes from: Carnivores Herbivores Omnivores Decomposers

Consumers Q: Where does a carnivore get its energy? A: From meat only Q: What are some examples of carnivores? A: Lion, cheetah, jaguar, leopard

Consumers Q: Where does an herbivore get its energy? A: Only vegetables/grains/fruits, etc (i.e. non-meat eater) Q: What are some examples of herbivores? A: Deer, rabbits, horses, zebra

Consumers Q: Where does an omnivore get its energy? A: From both meat and vegetables/grains/fruit, etc Q: What are some examples of omnivores? A: Bears, chimpanzees, pigs, various birds

Consumers Q: Where does a decomposer get its energy? A: From breaking down dead organic matter Q: What are some examples of decomposers? A: Bacteria, fungi (mushrooms), earthworms

Food Chains The levels of a food chain include: First level – producer – autotroph that makes food Second level – primary consumer – herbivore that eats producer Third level – secondary consumer – carnivore that eats herbivore Fourth level – tertiary consumer – carnivore that eats secondary consumer

Food Chains Ex: Producer – grass that photosynthesizes Primary consumer – rabbit that eats the grass Secondary consumer – fox that eats the rabbit Tertiary consumer – wolf that eats the fox

Food Chains Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers) Energy is transferred by organisms eating and being eaten Energy transfer is represented by arrows going in the direction of the energy’s movement

Food webs A food web links all the food chains in a ecosystem together More complex interactions than unidirectional flow of food chains In reality, the interactions between predators and prey in an ecosystem’s exists as a food web instead of a food chain

Tertiary Consumer Secondary Consumer Primary Consumer Producer

Energy Pyramids Each step in the food chain is called a trophic level Producers are the first trophic level Consumers make up the second, third or higher trophic level

Energy Pyramid Amount of energy available in this tropic level Energy pyramid – only 10% of energy is transferred from one trophic level to the next Energy is used up by the organism’s metabolism and/or released as heat

Please do “Ecology Vocabulary” Crossword,

Ecosystems and Communities The Role of Climate

Biotic vs. Abiotic factors Biotic factor –influences/interactions of living organisms Abiotic factor – physical, non-living influence that affect an ecosystem Q: What are some biotic factors that affect a forest? A: Birds, insects, deer, grass, trees Q: What are some abiotic factors that affect a forest? A: Temperature, precipitation, wind, soil type

Biotic vs. Abiotic Factors Biotic + Abiotic Factors Together = Ecosystem

Community Interactions Competition Predation Symbiosis Mutualism Commensalism Parasitism

Competition Definition – organisms of the same or different species attempt to use the same ecological resource Competitive exclusion principle – no two species can occupy the same niche in the same habitat at the same time; one species will outcompete the other Niche – range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions

Predation Definition – one organism captures and feeds on another Predator benefits, prey does not

Symbiosis Definition – close, long-term relationship between two organisms There are 3 kinds: Mutualism Commensalism Parasitism *Notes on chart Examples: PowerPoint

Mutualism Definition – both species benefit, neither species is harmed Ex: flowers and pollinating insects Q: How do flowers benefit? A: Insects carry pollen to another plant Q: How to insects benefit? A: Consume nectar of flower

Commensalism Definition – one member benefits, the other is neither helped nor harmed Ex: barnacles on whales Q: How do the barnacles benefit? A: They get a place to live! The whale is neither helped nor harmed by the barnacles

Parasitism Definition – one organism benefits, the other organism is harmed The parasite normally lives on (tick) or in (tapeworm) the host Ex: mosquito on human Q: How does the mosquito benefit? A: Sucks the blood from human Human is harmed – transmission of disease

Populations How Populations Grow

Characteristics of Populations Growth can be Exponential growth Logistic characterized by represented by characterized by represented by Falling growth rate S-shaped curve Limits on growth No limits on J-shaped Constant Unlimited resources which cause a

Population Growth Three factors affect population size 1. Number of births 2. Number of deaths 3. Number of individuals that enter or leave pop. Immigration – into area Emigration – out of area

Exponential Growth Under ideal conditions with unlimited resources, a population will grow exponentially Population increases indefinitely without stopping Agriculture begins Plowing and irrigation Bubonic plague Industrial Revolution Human Population Growth

Logistic Growth As resources become limited, the growth of a population slows or stops Carrying capacity (K) – largest number of individuals a given environment can support Once the population reaches its carrying capacity, the population size stays the same

Practice Problem Q: What type of growth is depicted in this graph? A: Logistic Q: What’s a carrying capacity? A: Maximum number of organisms an environment can support

Practice Problem Q: What’s the carrying capacity of this population? A: Around 65 rabbits Q: When did this population reach its carrying capacity? A: Around August 1

Practice Problem Q: What should be the title for the x-axis? A: Months Q: What might be a good title for this graph? A: Logistic growth of a population of rabbits over 5 months

Practice Problem Q: Do you see a problem with the scale on the x-axis? A: July isn’t included!

Populations Limits to Growth

Imagine a small island that has a population of five rabbits Imagine a small island that has a population of five rabbits. Does how the factor affects the rabbits depend on the size of the population, or will the factor affect the rabbits in the same way, regardless of the population size? a. climate b. food supply c. predation Now imagine another small island that has a population of 500 rabbits. How would the same factors affect this population? Which of the factors depend on population size? Which factors do not depend on population size?

Limiting Factors Limits to Growth Density-Dependent Factors – limiting factor that depends on the populations size Predation (predator-prey relationships), food supply Disease Density-Independent Factors – limiting factor that affects all populations in a similar way, regardless of the population size Weather, natural disaster Seasonal cycles

Please do “Deer: Predation or Starvation” Lab

Density-Dependent Factor Predator-prey relationship Q: What happens to the wolf population (predators) with an increase in deer population (prey)? Why? A: Wolf population increases because their food source, deer, increased Q: What happens to the deer population in response to an increase in wolf population? Why? A: Deer population decreases because there are more wolves to hunt the deer

Density-Dependent Factor Predator-prey relationship Q: What happens when the deer population decreases? A: The wolf population decreases because they don’t have as much food (deer) Q: What happens when the wolf population decreases? A: The deer population increases because they don’t have as many predators (wolves) Cycle/relationship between predator (wolf) and prey (deer)

Density Independent Affect all populations in similar ways regardless of the population size Unusual weather, natural disasters, seasonal cycles Some human activities: cutting down forests, damming rivers etc.

Coevolution Definition- a long term change that takes place in two species because of their close interactions with one another. Examples: Acacia tree and ants Flowers and pollinators (e.g., hummingbirds long beak and nectar) Newts and garter snakes- see videos: Newt humor Newt versus garter snake