EQ: How do the biotic and abiotic factors of an ecosystem interact? Types of Interactions EQ: How do the biotic and abiotic factors of an ecosystem interact?

Part 1: Limiting Factors EQ: How do the biotic and abiotic factors of an ecosystem interact?

Types of Interactions Look at the seaweed forest on the left. How many fish do you count? How many seaweed plants can you see? Why do you think there are more members of the seaweed population than members of the fish population? Types of Interactions

Interactions with the Environment Most living things produce more offspring than will survive. A female frog will lay hundreds of eggs in a small pond In a few months, the frog population will not increase appreciably. T-P-S – Why? Organisms, such as frogs, interact with the biotic and abiotic factors in its environment. The environment will control the size of its population Interactions with the Environment

Populations cannot grow without stopping, because the environment has a limited amount of food, water, living space and other resources Limiting Factors

A resource that is so scarce that it limits the size of a population is called a limiting factor. Food Water Space Limiting Factors

Conditions that may limit the population of an ecosystem include, but are not limited to are: Disease Accidents Natural Factors (fires, floods, etc.) Starvation Hunting Predation Limiting Factors

The largest population that an environment can support is known as its carrying capacity. When a population grows larger than its carrying capacity, limiting factors in the environment cause individual organisms to die off and leave. This causes a decrease in population See What Limits Your Species PPT for lab Carrying Capacity

EQ: How do the biotic and abiotic factors of an ecosystem interact? Part 2: Interactions EQ: How do the biotic and abiotic factors of an ecosystem interact?

Nature is amazing! For the most part, it keeps itself balanced (homeostasis) without human interference. An ecosystem can only support a certain number of organisms (its carrying capacity). To keep this number in check, each organism within an ecosystem has a specific role, or niche to fill. As a result of the interactions between organisms as they carry out their roles, ecosystems generally stay balanced. Limiting factors! Interactions

Interactions Between Organisms Ecologists have described four main ways that species interact: Competition Predator/Prey Symbiotic Coevolution Interactions Between Organisms

When two or more individuals or populations try to use the same resource such as food, water, shelter, space or sunlight, it is called competition Ex: Buffalo competing for mates One wins, the other loses Competition

Because resources are in limited supply in the environment, their use by one individual or population decreases the amount of resources available to other organisms Competition

Many interactions between species consist of one organism eating another. The organism that is being eaten is the prey. The organism that eats the prey is called the predator. Ex: Lion and zebra Predator/Prey

Predator/Prey Result: To survive, predators must be able to catch their prey. To survive, prey must have methods and abilities to avoid capture. These methods and abilities are called adaptations. Predator/Prey

Some species have very close interactions with other species. Symbiosis (symbiotic) is a close, long-term association between two or more organisms or species. Symbiosis

In addition to the competitive relationships that help limit the population of an area, there are also cooperative relationships in an ecosystem that allow the habitat to function. Those examples are: Mutualism Commensalism Parasitism Result: Organisms working in cooperative relationships Symbiosis

The Earth is not static, meaning that it stays the same, but instead it is dynamic, or constantly and continuously changing. Because the Earth itself is dynamic, the organisms that inhabit the Earth must change as well, or they will evolve out. Another relationship is called coevolution, which is when two different species who are interdependent evolve together in order to perpetuate the species. Coevolution

The term coevolution is used to describe cases where two (or more) species reciprocally affect each other’s evolution. So for example, an evolutionary change in the structure of of a plant, might affect the structure of an herbivore that eats the plant This in turn might affect the evolution of the plant, which might affect the evolution of the herbivore...and so on. Example: Ant and acacia tree Coevolution

Some Central American Acacia species have hollow thorns and pores at the bases of their leaves that secrete nectar These hollow thorns are the exclusive nest-site of some species of ant that drink the nectar. But the ants are not just taking advantage of the plant—they also defend their acacia plant against herbivores. This system is probably the product of coevolution: The plants would not have evolved hollow thorns or nectar pores unless their evolution had been affected by the ants, And the ants would not have evolved herbivore defense behaviors unless their evolution had been affected by the plants. Coevolution

Mutualism is a symbiotic relationship in which both organisms benefit. Example: Insects and plants What each organism gets: Insects get the tasty nectar Flower gets pollinated Mutualism

A symbiotic relationship where one organism benefits, and the other is unaffected is called commensalism Example: Clownfish and sea anemone What each organism is getting: Clownfish: protection Anemone: doesn’t even notice Commensalism

A symbiotic association in which one organism benefits and the other is harmed is called parasitism. Example: Fleas and dogs What each organism gets: Fleas: food as it sucks blood from the dog Dog: harmed Parasitism