What does it mean to be interdependent?
Do species live alone, or do many live in communities with other organisms? All species rely on other species in some way in order to survive. They may rely on other species for food, shelter or to help them reproduce. Here the bee is helping the flower spread its pollen. Species are not independent, they are interdependent.
Interdependence of Living Things
Biological interactions are the interactions between different organisms in an environment. In the natural world, no organism is cut off from its surroundings. Organisms are a part of their environment which is rich in living and non-living elements that interact with each other in some way. The interactions of an organism with its environment are vital to its survival, and the functioning of the ecosystem as a whole.
These relationships can be categorized into many different classes. The interactions between two species do not necessarily need to be through direct contact. Due to the connected nature of ecosystems, species may affect each other through such relationships involving shared resources or common enemies.
The term symbiosis comes from a Greek word that means “living together.” Symbiosis can be used to describe various types of close relationships between organisms of different species, such as mutualism and commensalism, which are relationships in which neither organism is harmed. Sometimes the term symbiosis is used only for cases where both organisms benefit, sometimes it is used more generally to describe all kinds of close relationships, even when one organism is killed by another, as shown in Figure below. Symbiosis can also be used to describe relationships where one organism lives on or in another, called parasitism, or when one organism kills and eats another organism, called predation. These relationships will be further described in Concept Ecology (Advanced).
Competition is as an interaction between organisms or species, for the same resources such as water, food, or hunting grounds in an environment, shown in Figure below. Eventually, the species that is less able to compete for resources will either adapt or die out. According to evolutionary theory, competition for resources plays an important role in natural selection.
Animals that eat decomposing organic material also have an important interaction with the environment. They help to decompose dead matter and assist with the recycling of nutrients. By burying and eating dung, dung beetles, such as the one shown in Figure below, improve nutrient cycling and soil structure. They make the dead organic matter available to bacteria that break it down even further.
Organisms are not independent, they are interdependent. They cannot live alone; they need other organisms to survive. The same is true for species. All species need other species to survive.
Levels of Organization
In studying how organisms interact with each other, biologists often find it helpful to classify the organisms and interactions into levels of organization. Similar to the way an organism itself has different levels of organization, the ways in which organisms interact with their environment and each other can also be divided into levels of organization. For example:
The biosphere includes all living things within all of their environments. It includes every part of the environment where life exists, from the upper reaches of the atmosphere to the top few meters of soil, to the bottoms of the oceans. An ecosystem is made up of the relationships among smaller groups of organisms with each other, and with their environment. Scientists often speak of the interrelatedness of living things, because, according to evolutionary theory, organisms adapt to their environment, and they must also adapt to other organisms in that environment.
A community is made up of the relationships between groups of different species. For example, the desert communities consist of rabbits, coyotes, snakes, birds, mice and such plants as sahuaro cactus, ocotillo, and creosote bush. Community structure can be disturbed by such dynamics as fire, human activity, and over-population.
A population is a group of individuals of a single species that mate and interact with one another in a limited geographic area. For example, a field of flowers which is separated from another field by a hill or other area where none of these flowers occur.
It is thus possible to study biology at many levels, from collections of organisms or communities, to the inner workings of a cell (organelle). More about the interactions of organisms will be discussed in Concept Ecology (Advanced).
The Diversity of Life
Evolutionary theory and the cell theory give us the basis for how and why organisms relate to each other. The diversity of life found on Earth today is the result of 4 billion years of evolution. Some of this diversity is shown in Figure below. The origin of life is not completely understood by science, though limited evidence suggests that life may already have been well-established a few 100 million years after Earth formed. Until approximately 600 million years ago, all life was made up of single-celled organisms.
The level of biodiversity found in the fossil record suggests that the last few million years include the period of greatest biodiversity in the Earth's history. However, not all scientists support this view, since there is a lot of uncertainty as to how strongly the fossil record is biased by the greater availability and preservation of more recent fossil-containing rock layers. Some researchers argue that modern biodiversity is not much different from biodiversity 300 million years ago. Estimates of the present global species diversity vary from 5 million to 30 million species, with a best estimate of somewhere near 10 million species. All living organisms are classified into one of the six kingdoms: Archaebacteria (Archaea), Eubacteria (Bacteria), Protista (Protists), Fungi, Plantae (Plants), and Animalia (Animals).
New species are regularly discovered and many, though already discovered, are not yet classified. One estimate states that about 40 percent of freshwater fish from South America are noa few of the many members of the animal kingdom are shown in Figure below. The animal kingdom is just a tiny portion ot yet classified. Every year, scientists discover the existence of many hundreds more archaea and bacteria than were previously known. Just f the total diversity of life. More about the diversity of living creatures will be discussed throughout numerous concepts.
- The interactions of an organism with its environment are vital to its survival, and the functioning of the ecosystem as a whole.
- An ecosystem consists of the relationships among smaller groups of organisms with each other, and with their environment.
- Symbiosis can be used to describe various types of close relationships between organisms of different species.
- Competition is as an interaction between organisms or species for the same resources in an environment.
- What are biological interactions?
- What is the difference between mutualism and commensalism?
- What is predation?
- What are the levels of organization that organisms interact with their environment and explain them?
- Give an example of how you are interdependent with another organism.