Interactions in Ecosystems Biology

Habitat and Niche- Every organism has one! Habitat- the area where an organism lives. Niche- ecological role an organism plays in its environment. Includes the food, abiotic conditions, and behavior. A habitat is where a species lives and a niche is how it lives within its habitat.

A Niche Includes Food- the type of food, how the organism competes with others for food, and where it fits into the food web. Abiotic factors- temperature, amount of water, etc. that a species can tolerate. Behavior- active time of day, when it reproduces, interactions with others, etc

What if two species are competing over limited resources? We know that organisms need food, water, and a place to live in order to survive. If an organism has these resources they are more likely to live and reproduce. What if two species are competing over limited resources?

Competitive Exclusion States that when two species are competing for the same resources, one species will be better suited to the niche, and the other species will be pushed out into another niche or eventually become extinct. Same community.

Competitive exclusion has different outcomes. Evolutionary response- species could have evolved differently or diverged / separated. Ex-One squirrel may have had teeth better for cracking large nuts, while the other may have teeth better for opening small nuts. Niche partitioning- niche is divided. Ex- two squirrel species live in the same tree. If one type of squirrel ate nuts from the tops of trees while others ate nuts from the ground, the niche would be divided.

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Ecological equivalents are species that occupy similar niches but live in different geographical regions. Madagascar South America

Community Interactions Predation Competition Mutualism Commensalism Parasitism

Competition Defined as: Two organisms fight for the same limited resources. Intraspecific- competition between the same species. Interspecific- competition between different species. Ex- Male elephant seals fighting over mates. https://www.youtube.com/watch?v=bpb7Oks5kWI

Predation When one organism captures and feeds upon another organism. Ex- Snake hunting and killing a mouse.

Symbiosis Relationship between two or more organisms. Three types Mutualism Parasitism Commensalism https://www.youtube.com/watch?v=zSmL2F1t81Q https://www.youtube.com/watch?v=Qqa0OPbdvjw

Mutualism Both organisms benefit. Ex- Clownfish and a sea anemone: clownfish brings in food and the anemone protects the clownfish. Remora on a shark. Remora hitches a ride and a free meal, as well as eats parasites from the sharks mouth and body.

Commensalism One organism benefits and the other is unharmed. Ex- Barnacle on a whale. The barnacle gets a free ride, as well as a plethora of nutrients as the whale travels.

Parasitism One organism benefits the other is harmed. Ex- Flea on a dog.

Another Example of Parasitism The pearlfish and the sea cucumber. https://www.youtube.com/watch?v=giA16BoH_no

Identify the Type of Symbiosis Read each example and decide if the scenario represents mutualism, parasitism, or commensalism.

Populations are always changing! 1. Immigration- movement of individuals into a population from another population. 2. Births- Increases the number of individuals in a population. 3. Emigration- movement of individuals out of a population and into another population. 4. Deaths- individuals die, population goes down.

Population growth is based on available resources. Exponential growth is a rapid population increase due to an abundance of resources. J- Shaped May occur when a species moves to an uninhabitated area.

Logistic growth – a population begins with a period of slow growth followed by a brief period of exponential growth before leveling off at a stable size. S- shaped Initially growth and resources are abundant. Over time, resources begin to deplete, growth slows, and population levels off.

Carrying capacity is the maximum number of individuals in a population that the environment can support. Changes when the environment changes.

There are many factors that can affect the carrying capacity of an ecosystem. Limiting factor- the factor that has the greatest effect in keeping down the size of a population. Density dependent limiting factors- factors that are affected by the number of individuals in a given area. Density independent limiting factors- aspects of the environment that limit a population’s growth regardless of the density of the population. 1. Competition- fighting for resources. Ex- food and shelter 1.Unusual weather Ex- Lack of wind can cause nutrient poor water from being replaced. 2. Predation- predator /prey relationships. Ex- Moose / Wolf of Isle Royale in Michigan. 2. Natural disasters-volcanoes, tsunamis, hurricanes, etc can wipe out populations. 3. Parasitism & Disease- the more crowded the area , the higher number of parasites and disease. 3. Human activities- Deforestation, urbanization, destruction of wetlands, etc.

Succession When an ecosystem goes through a disturbance or a devastating catastrophe, the area begins to re-grow and re-form itself. Defined as- the sequence of biotic changes that regenerate a damaged community or create a community in a previously uninhabited area.

EXAMPLE The Hawaiian Islands began forming 70 MYA. Volcanic eruptions created the islands. The bare volcanic rock eventually began to break down into the soil, which allowed plants to grow. Over time, a tropical ecosystem was created.

There are two types of succession. Primary succession Establishment and development of an uninhabited ecosystem. Started by pioneer species, which are the first species to live in an area that was uninhabited by breaking down solid rock into smaller pieces. Often lichens and some mosses. 0-15 years- moss, lichens, grass 15-80 years- shrubs, cottonwoods, thickets 80-115 years- transition to forest 115-200 years- mature forest

Pioneer Species: Lichens and Mosses

2. Secondary Succession Occurs after a disturbance, such as a hurricane or a fire; something that destroys the progression of an already established community. S is for SOIL- soil is intact, which allows the remaining plants and other organisms to start re-growing.

Video https://www.youtube.com/watch?v=uqEUzgVAF6g