Species Interaction

• Five types of interactions among species— interspecific competition, predation, parasitism, mutualism, and commensalism —affect the resource use and population sizes of species.
• Competition occurs when members of one or more species interact to use the same limited resources such as food, water, light, and space
• Intraspecific can occur between individuals of the same species
• Interspecific can occur between different species
• Interference Competition, organisms interact directly by fighting for scarce resources
• Exploitative Competition Organisms interact indirectly by consuming scarce resources. The use of the resource by one individual will decrease the amount available for other individuals. For example, plants consume nitrogen by absorbing it into their roots, making nitrogen unavailable to nearby plants.
• Resource Partitioning occurs when species competing for similar scarce resources evolve specialized traits that allow them to share resources by using parts of them, using them at different times, or using them in different ways.
• Competitive Exclusion Principle, sometimes one species will eliminate another species through competition for limited resources
• Predation is a member of one species (the predator, or hunter) feeds directly on all or part of a living organism (the prey, or hunted) as part of a food web. 
• Prey species have evolved many ways to avoid predators, including

  • camouflage
  • Chemical warfare
• Warning Coloration is a brightly colored advertising that helps experienced predators to recognize and avoid them.
• Mimicry is a species gain protection by looking and acting like other, more dangerous species, a protective device
• Behavioral Strategies, such as deceptive looks and deceptive behavior
• Parasitism occurs when one species (the parasite) feeds on another organism (the host), usually by living on or inside the host. In this relationship, the parasite benefits and the host is often harmed
• In mutualism, two species behave in ways that benefit both by providing each with food, shelter or some other resource.
• Commensalism is an interaction that benefits one species but has little if any, beneficial or harmful effect on the other.
• Herbivory is a special case of predation in which the prey species is a plant
• TYPES OF ECOLOGICAL SUCCESSION

  • Primary Ecological Succesion
  • Secondary Ecological Succesion
• Primary Ecological Succession involves the gradual establishment of communities of different species in lifeless areas where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic ecosystem.
• Secondary Ecological Succession is series of communities or ecosystems with different species develop in places containing soil or bottom sediment. This type of succession begins in an area where an ecosystem has been disturbed, removed, or destroyed, but some soil or bottom sediment remains.
• Four variables— births, deaths, immigration (arrival of individuals from outside the population), and emigration (departure of individuals from the population)— govern changes in population size.
• Population's Age Structure is a distribution of individuals among various age groups
• Prereproductive Stage, are organisms not mature enough to reproduce
• Reproductive Stage, those capable of reproduction
• Postreproductive Stage, those too old to reproduce
• Terrestrial ecosystem is a temperature and precipitation
• Aquatic Systems is a water temperature, water depth and clarity (allowing for more or less sunlight), nutrient availability, acidity, salinity, and the level of oxygen gas in the water.
• Population Density is the number of individuals in a population found within a defined area or volume
• Density-Dependent (become more important as a population’s density increases)
• Density-Independent (they can affect population sizes regardless of density)
• Exponential Curve (J-curve), members of such populations typically reproduce at an early age, have many offspring each time they reproduce, and reproduce many times, with short intervals between successive generations.
• Logistic Growth (S-SHAPED), limiting factors largely determine any area’s carrying capacity: the maximum population of a given species that a particular habitat can sustain indefinitely. As a population approaches the carrying capacity of its habitat, the J-shaped curve of its exponential growth is converted to an S-shaped curve
• R-Selected Species those that have a capacity for a high rate of population increase
• K-Selected Species they tend to reproduce later in life and have a small number of offspring with fairly long life spans.