Biological Interactions How species interact with each other and with the world around them Ecology Standards: 6c ~ Students know how fluctuations in population size in an ecosystem are determined by the relative rates of birth, immigration, emigration, and death.

Habitat & Niche habitat The habitat of an organism is considered all of the biotic and abiotic factors where an organism lives Leopards are graceful and powerful big cats closely related to lions, tigers, and jaguars. They live in sub-Saharan Africa, northeast Africa, Central Asia, India, and China. However, many of their populations are endangered, especially outside of Africa. (National Geographic)

Habitat & Niche ecologicalniche The ecological niche of a species is made up of all the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce Native to the Central Asian mountains, the snow leopard is a rare sight, with only about 6,000 left in the wild. They are hunted for their beautiful, warm fur and for their organs, which are used in traditional Chinese medicine. (National Geographic)

Habitat & Niche habitat niche Think of a habitat as where a species lives and the niche as how it lives within its habitat A niche includes: Food – type of food, how it competes for food, and where it finds its food Abiotic conditions – air temp., amount of water, etc. Behavior – the time of day a species is active as well as where and when a species reproduces

Habitat & Competition When two species live in the same habitat it is possible that they may require the same resources One species will always be better adapted to obtain a resource over another competitive exclusion The competitive exclusion principle states that when two species compete for the same resources, one will “win” and the other will be ‘forced’ into a new niche or become extinct

Habitat & Competition competitive exclusion3 Effects: When two or more species compete for resources (competitive exclusion) it can have 3 Effects: Extinction Extinction – one species puts so much pressure on the other that it dies out Niche partitioning Niche partitioning – the two species could occupy different niches near each other not overlapping Evolutionary response Evolutionary response – one species may evolve or be ‘selected for’ different traits and evolve away from the original form

Habitat & Competition ecological equivalent An ecological equivalent would be a case where two species occupy the same niche in different parts of the world

Community Interactions Competition Competition happens when two organisms fight for similar resources such as food, space, or water Interspecific competition Interspecific competition – happens when two different species compete Intraspecific competition Intraspecific competition – occurs when the same species compete

Community Interactions Predation Predation – the process by which one organism captures and eats another organism

Community Interactions Symbiosis Symbiosis – an interaction between two or more organisms that live in direct contact with one another (Sym = same) (Bio = life) (Sis = together) There are 3 Types of Symbiosis: There are 3 Types of Symbiosis: Mutualism Mutualism Commensalism Commensalism Parasitism Parasitism

Mutualism Mutualism both species benefit Mutualism – a symbiotic relationship where both species benefit from the interaction A cleaner shrimp reaches into a moray eel's mouth. The shrimp uses its claws to pick stuff off the eel's body. That can include dead skin, tiny pieces of food, and even little creatures that can hurt the fish. (National Geographic)

Commensalism Commensalism Commensalism – an interaction between organisms where one species benefits and the other does not benefit nor is it harmed The clown fish swims among the stinging tentacles of the sea anemone for protection and safety. The sea anemone does not benefit from this relationship nor is it harmed. The clown fish is safe in its anemone home!

Parasitism Parasitism Parasitism – a relationship where one organism benefits while the other is harmed host Parasites keep their host alive for days or even years while predation kills immediately

Organism Population One of the main goals of all living things is to reproduce population distribution growth Studying organism population distribution and growth is an important part of Ecology Population density Population density – is a measurement of the number of individuals living in a defined space

Organism Population population dispersion (aka) distribution Organism populations have varying types of population dispersion (aka) distribution Clumped Clumped – living close together Uniform Uniform – living at regular intervals in relation to one another Random Random – living in random places and distances from one another Each of these types has its own advantages and disadvantages

Organism Population Four Factors Population Growth and the Four Factors: Migration Migration (two types) Immigration Immigration – moving “in to” an area Emigration Emigration – moving “out of” an area Birth & Death Birth & Death Birth rates Birth rates – new organisms born cause an increase in population Death rates Death rates – organisms dying cause a population to decrease

Organism Population factors To calculate an overall population increase or decrease, you must know all four factors Population Change Births + Immigration Deaths + Emigration –=

Population Growth Two Main Types There are Two Main Types: Exponential Exponential – a population increases quickly over a short period of time Logistic Logistic – a population begins with slow growth followed by rapid growth before leveling off or slower growth A carrying capacity occurs here

Limits to Growth Most populations have a limit to how large they can get limiting factor A limiting factor is any factor that causes population growth to decrease or stop carrying capacity A carrying capacity is the maximum number of individuals a given area can support Carrying capacity

Limits to Growth Two Types of Limiting Factors There are Two Types of Limiting Factors: Density-dependentaffects a population differently depending on the size of the population Density-dependent – affects a population differently depending on the size of the population Example: a disease can have a greater effect on a larger population versus a small population that is spread out (diseases, predation, competition, & parasitism) Density-independentaffects a population in similar ways regardless of its size Density-independent – affects a population in similar ways regardless of its size Example: an earthquake will happen regardless of the size of the population of groundhogs in a certain area (natural disasters, seasons, & unusual weather)

Ecological Succession Occasionally an ecosystem suffers a tragic event that kills all life Succession Succession – the sequence of biotic changes that regenerate a damaged community or a ‘new’ area

Ecological Succession Primary successiona new area is available for colonization of species Primary succession occurs when a new area is available for colonization of species pioneer species The pioneer species is the first species to colonize an area of primary succession Mosses, lichens, and other primitive plants take root into rock and break it down over a long period of time into the first soil

Ecological Succession Secondary succession Secondary succession – regenerates a community quicker than primary and usually follows a natural disaster

Yet, another reason not to smoke

Sample Test Question Many lakes in the U.S. have received large amounts of nutrients, such as nitrogen and phosphorus, as a result of pollution from farms and industry. This pollution causes rapid and massive increases in some lakes’ algae population. This gradually depletes oxygen supply, killing many organisms. What is the most logical explanation for the rapid growth of algae? Many lakes in the U.S. have received large amounts of nutrients, such as nitrogen and phosphorus, as a result of pollution from farms and industry. This pollution causes rapid and massive increases in some lakes’ algae population. This gradually depletes oxygen supply, killing many organisms. What is the most logical explanation for the rapid growth of algae?

Sample Test Question (answers) A) The increased nutrients led many organisms to emigrate A) The increased nutrients led many organisms to emigrate B) The increased nutrients supported the population growth of algae B) The increased nutrients supported the population growth of algae C) The increased nutrients allowed algae to outcompete other species C) The increased nutrients allowed algae to outcompete other species D) The increased nutrients caused algae to immigrate D) The increased nutrients caused algae to immigrate