ECO - Responses to the Environment [LESSON]

Responses to the Environment

What is Ecology?

Ecology comes from the Greek words oikos (house or place where one lives) and logos (the study of). Ecology then means the study of the house in which we live (the study of our environment...where we live). Ecology can be defined more specifically as the study of the interactions between organisms and the nonliving components of their environment.

The Earth includes a tremendous variety of living things. Each organism depends in some way on other living and nonliving things in its environment. It involves collecting information about organisms and their environment, looking for patterns, and seeking to explain these patterns and interrelationships.

There are three basic approaches scientists use to conduct modern ecological research:

1. 1. Interactions within populations.
   2. Individual interaction within communities.
   3. Interactions among living things and abiotic factors.

This focus, along with the levels of organization, provides ecologists with a hierarchy within the scope of ecological research.

Levels of Ecology

Try the activity below to learn the Levels of Ecological Organization.

 

Ecological Factors

In examining what influences the relationships between organisms and their environments, ecologists began to research factors that seemed to determine species distribution. They discovered several important points: Ecosystems can contain hundreds or even thousands of interacting species. Ecosystems are very complex and can be large or small depending on the environment examined. Ecosystems are reliant on all the organisms and the nonliving environment found in a particular place, and those environmental factors can be categorized into two groups, biotic and abiotic factors.

Biotic factors are all of the living things, or organisms present in a particular environment. The other organisms living within that ecosystem may provide positive or negative interaction. For instance, two organisms may survive well with each other in the form of a mutually beneficial relationship such as flowers and bees. In contrast, two organisms may experience competition or even a predator-prey relationship.

Abiotic factors are the nonliving factors such as temperature, light, and water. These factors are either chemical or physical factors. Chemical factors include water, oxygen, salinity, pH, soil nutrients, etc. Physical factors include light, temperature, soil, fire, and moisture.

Behavioral Ecology

One goal of behavioral biology is to distinguish the innate behaviors, which have a strong genetic component and are largely independent of environmental influences, from the learned behaviors, which result from environmental conditioning.

Innate behavior, or instinct, is important because there is no risk of an incorrect behavior being learned. These behaviors are “hard wired” into the system. In contrast, learned behaviors are flexible, dynamic, and can be altered relative to changes in the environment. An example of an innate behavior is kinesis, which is the undirected movement in response to a stimulus such as increased or decreased speed of movement of an organism in response to a stimulus. Woodlice, for example, increase their speed of movement when exposed to high or low temperatures. This movement, although random, increases the probability that the insect spends less time in the unfavorable environment.

A similar, but more-directed version of kinesis is taxis: the directed movement towards or away from a stimulus. This movement can be in response to light (phototaxis), chemical signals (chemotaxis), or gravity (geotaxis). It can be directed toward (positive) or away (negative) from the source of the stimulus.

Behaviors that lower the fitness of the individual engaging in the behavior, but increase the fitness of another individual, are termed altruistic. Examples of such behaviors are seen widely across the animal kingdom. Social insects, such as worker bees, have no ability to reproduce, yet they maintain the queen so she can populate the hive with her offspring. Meerkats keep a sentry standing guard to warn the rest of the colony about intruders, even though the sentry is putting itself at risk. Wolves and wild dogs bring meat to pack members not present during a hunt. Lemurs take care of infants unrelated to them.

Learned behaviors, even though they may have instinctive components, allow an organism to adapt to changes in the environment and are modified by previous experiences. Simple learned behaviors include habituation and imprinting—both are important to the maturation process of young animals.

Habituation is a simple form of learning in which an animal stops responding to a stimulus after a period of repeated exposure. This is a form of non-associative learning as the stimulus is not associated with any punishment or reward. Prairie dogs typically sound an alarm call when threatened by a predator, but they become habituated to the sound of human footsteps when no harm is associated with this sound; therefore, they no longer respond to them with an alarm call. In this example, habituation is specific to the sound of human footsteps, as the animals still respond to the sounds of potential predators.

Imprinting is a type of learning that occurs at a particular age or a life stage that is rapid and independent of the species involved. Hatchling ducks recognize the first adult they see, their mother, and make a bond with her. A familiar sight is ducklings walking or swimming after their mothers. This type of non-associative learning is very important in the maturation process of these animals as it encourages them to stay near their mother in order to be protected, greatly increasing their chances of survival. However, if newborn ducks see a human before they see their mother, they will imprint on the human and follow it in just the same manner as they would follow their real mother.

What do you remember about the role of genetic variation in the ability of a population to evolve against environmental pressures?

Hopefully, you remember that the variation present in the population serves as the basis for traits that are selected FOR to become more common over time!  This allows populations to push back against environmental selective pressures.

Conditioning

Conditioned behaviors are types of associative learning where a stimulus becomes associated with a consequence. Two types of conditioning techniques include classical and operant conditioning.

In classical conditioning, a response called the conditioned response is associated with a stimulus that it had previously not been associated with, the conditioned stimulus. The response to the original, unconditioned stimulus is called the unconditioned response. The most cited example of classical conditioning is Ivan Pavlov's experiments with dogs. In Pavlov's experiments, the unconditioned response was the salivation of dogs in response to the unconditioned stimulus of seeing or smelling their food. The conditioning stimulus that researchers associated with the unconditioned response was the ringing of a bell. During conditioning, every time the animal was given food, the bell was rung. This was repeated during several trials. After some time, the dog learned to associate the ringing of the bell with food and to respond by salivating. After the conditioning period was finished, the dog would respond by salivating when the bell was rung, even when the unconditioned stimulus (the food) was absent. Thus, the ringing of the bell became the conditioned stimulus and the salivation became the conditioned response.

In operant conditioning, the conditioned behavior is gradually modified by its consequences as the animal responds to the stimulus. A major proponent of such conditioning was psychologist B.F. Skinner, the inventor of the Skinner Box. Skinner put rats in his boxes that contained a lever that would dispense food to the rat when depressed. While initially the rat would push the lever a few times by accident, it eventually associated pushing the lever with getting the food.  This is the type of conditioning that allows animals to be trained (typically with a food reward).

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