Ecology, Part #1

Levels of Organization In Ecology 1. Organism – a single individual 2. Population – a group of the same species in the same place at the same time 3. Community – all living things; interacting populations 4. Ecosystem – all biotic and abiotic factors

1. Organism

2. Population

3. Community

4. Ecosystem

Habitat A HABITAT is the place where an organism lives its life Forest, bottom of the ocean, desert, coral reef

Niche A NICHE is an organism’s role in its environment; how it obtains energy What it eats, how it eats, where it lives, etc. Most of the time different species occupy different niches (reduced competition) When two species have the exact same niche, competition will eventually force one species to either die out or find a different niche

Lions kill prey and eat meat Monkeys climb trees and eat fruits and insects Whale sharks swim and eat plankton Trees use sunlight to make food

Where Does Earth’s Energy Come From? The ultimate source of energy for life is the SUN Plants use the sun’s energy to manufacture food in a process known as PHOTOSYNTHESIS

Autotroph An organism that can make its own food is called an AUTOTROPH Autotrophs are also called PRODUCERS because they provide the entire food chain with energy Plants and algae are the most common type of autotroph and they make their own food using photosynthesis

Heterotroph An organism that cannot make its own food is called a HETEROTROPH Heterotrophs obtain energy by eating other organisms Heterotrophs are also known as CONSUMERS because they get energy from other organisms.

Herbivore An HERBIVORE is a heterotroph that feeds only on PLANTS E.g. cows horses, zebras, squirrels

Carnivore A CARNIVORE is a heterotroph that feeds only on other heterotrophs (meat, insects, etc) E.g. Lions, sharks, wolves

Omnivore An OMNIVORE is a heterotroph that feeds on BOTH plants and animals E.g. Humans, bears, raccoons, skunks

Scavenger A SCAVENGER is a heterotroph that does not kill for food but eats already dead animals E.g. Vultures, insects, crabs

Decomposer DECOMPOSERS break down and release nutrients from dead organisms (recycle) E.g. Bacteria, fungus

Food Chain A FOOD CHAIN is a simple model that shows how matter and energy moves through an ecosystem producers  consumers  decomposers Arrows on a food chain show the direction ENERGY is moving

Trophic Levels Each step in a food chain is called a TROPHIC LEVEL Trophic levels include: Producers – autotrophs that produce their own food Primary Consumers – heterotrophs that eat autotrophs Secondary Consumers – heterotrophs that eat primary consumers Tertiary Consumers – heterotrophs that eat secondary consumers

Food Web Most of the time food chains are too simple and don’t show all of the feeding relationships in an ecosystem A FOOD WEB is a complex model of interconnected food chains that shows all of the feeding relationships in an ecosystem

10% Rule As energy moves up the food chain, 90% of it is lost as HEAT Only 10% of energy moves up to the next level The 90% that is lost is used up by the organism for metabolism and movement; only 10% is stored in its tissues Biomass – The total weight of living organisms at each trophic level 100 kg of grain  10 kg beef  1 kg of human tissue

Survival Relationships In biomes all animals are part of some type of survival relationship Predator-prey: predators are consumers that hunt and eat other organisms called prey Predators have no natural enemies

Survival Relationships Symbiosis: relationship in which one species lives on, in, or near another species and affects its survival Three types: (1) Mutualism (2) Commensalism (3) Parasitism

Mutualism Mutualism: type of symbiosis in which both species benefit Ants living in the tropical acacia trees- trees are protected when ants attack animals that try to feed on the tree and ants receive nectar and shelter from the tree.

Commensalism Commensalism: type of symbiosis in which one species benefits and the other species is neither harmed nor benefited Spanish moss grows on the branches of trees. The moss gets a habitat and the tree gets nothing. Whale have barnacles that live on them. The barnacles have somewhere to live, but do not affect the whale.

Parasitism Parasitism: type of symbiosis in which one species benefits and the other species is harmed Parasite: organism that harms but does not kill another organism Host: organism that is harmed by a parasite Ticks feed on dogs, people, etc. The ticks get food (blood) and the hosts lose blood and can be infected with disease. Best parasites do not kill their hosts…why?

Limiting Factors A limiting factor or limiting resource is a factor that controls a process, such as organism growth or species population size or distribution Examples of limiting factors include: availability of food, predation pressure, or availability of shelter

Carrying Capacity As a result of limiting factors (like food availability, disease, predation, etc) no population will continue to increase forever The carrying capacity is the largest number of individuals in a population that a given environment can support

Growth Rate The growth rate of a population is affected by three things: (1) the number of births (2) the number of deaths (3) the number of individuals that enter or leave the population Immigration – individuals that enter the population Emmigration – individuals that leave the population

Human Population Growth If birth rate is greater than death rate, population will grow If death rate is greater than birth rate, population will decrease Current human population growth is exponential Will the population continue to grow unchecked?

Human Population Growth Discussion Human (or any species) growth cannot continue unchecked-why? What resources do we need to survive as a population? Are we just concerned about longevity of life? Or do we also care about anything besides physical necessities? How does human population growth affect biodiversity?

Logistic Growth As resources become less available, the growth of a population slows or stops. An s-shaped curve of this growth pattern is called logistic growth

What can affect population size: Disease Competition for limited resources, predation, and disease can all affect the size of a population EX: Dutch Elm Disease – Elm trees are attacked by a fungus spread by a beetle. Result: many elm tree populations have been decimated by this fungus EX: Pfiesteria- a toxic heterotrophic dinoflagellate associated with fishkills and algal blooms.