Ecology is an essential part of Environmental Studies as it is the branch that deals with the evolution of species, the how and why of the organisms alive today. Ecology is invested in the interaction between organisms, natural resources, and the environment. Because of this, it is very focused on making those interactions better and is very concerned with the status and state of each component in the natural environment. The relationship between ecology and environmental studies is that environmentalists use the research carried out by ecologists to improve the quality of the ecosystems for now and the distant future. Ecologists and Environmentalists are both intertwined in a social movement for the environment, and as such are both trying to protect and preserve the natural environment and the organisms that rely on it as best they can.
In the late 18th century, people were starting to realize that places and organisms looked different at different parts of the world. There were different species residing in different habitats, so in turn this lead to the discovery of thousands of different food webs, population cycles, and trophic levels. It was also discovered that each species has its own niche, or a requirement for temperature, humidity, food, and location where that species can exist. Questions like how the species affects its surrounding environment, what are the specific climates, habitats, and foods each individual needs to survive, why are there more species than their profits, and why do we even have so many species started to arise. These new findings and newfound curiosity eventually lead to the birth of ecology.
As the idea of ecology was a fairly new one, there were multiple theories and effects proposed that weren’t exactly correct, such as the idea of individualism in which an organisms simply reacts with the environments and has no care for other species. This theory was eventually regarded as false as community interactions, such as mutualism, commensalism, and parasitism, were observed and deemed necessary for the survival of all species. At this point, ecologists were wondering why tertiary level species, such as the lynx, were not dominating over the other weaker species in the area, as they were the top predator in the area. It wasn’t until they observed the interaction of both the lynx and its prey the hare that they found the answer to their question. Their findings basically showed that a population cannot explode in numbers because each species has a carrying capacity that factors in exactly how much the environment can give before it becomes overexposed. The rate of growth has to get smaller and eventually negative as it reaches its carrying capacity, and this became the theory of density dependence.
By now, niches had been discovered, community interactions were evaluated, and density dependence was theorized. Different branches of ecology were created, such as community ecology, and a community was described as all the individuals and all the species at one place and one time. However, the boundaries of what space each species had, where they could move in and out of, and what differences merited different species were still unclear. So now ecologists had the challenge of explaining organisms that looked too similar, but not similar enough to be considered the same species. One observation showed that in all situations, one species will always be better adapted and will out-compete the other; the winner was simply the species that survived. So if two species are fighting for the same resource, such as food items of a particular size, their resource curves will overlap and interspecific competition between the two is the most intense in the community.
Ultimately, species that depend on a single limiting resource cannot coexist. Instead it was found that overtime the organisms that are the most fit and evolve with their environment through natural selection would start to use other resources and find other niches in the same habitat to survive, an example being multiple species of warbler eating and residing using different parts of a single tree. The criterion for different species was finally created, it was not just based on the appearance of the individual, it was how that organism utilized the environment to survive. These new findings opened multiple doors for the field of ecology. Because it was noted that species that compete for the same limiting resource cannot coexist, ecologists were starting to realize that even species of similar size would coexist less frequently in local communities and overlap less in their geographic distributions than expected, suggesting that their theory of co-occurrence being precluded by interspecific competition was correct.
A new phenomenon went along with this, deemed character displacement, in which traits evolve in response to selection to actually lessen the resource competition or reproductive interactions between species, the offspring of two different species results in a hybrid that cannot reproduce so it is a waste of reproductive efforts. This meant that organisms were actually trying to diversify themselves and create multiple different species, the complete opposite of the previous theory that different species steer clear of each other.
A link between species richness and nutrient availability was found, in which more species arise and thrive when there are more nutrients available in the environment and the identity of the dominant functional group varies along the gradients of resource availability. However, functionally diverse communities were prone to composition shifts and increased dominance with nutrient addition because they were more likely to contain a species with functional traits suited to exploitation of the added resource. This showed how fragile the balance of equilibrium is in nature and how much each different species relies on one another.
An organism’s ability to cope with extremes in resource availability should be a reflection of its corresponding functional trait values. Therefore, understanding the correspondence between abiotic factors and particular functional traits, ecologists realized, would help predict which species from a regional pool could colonize and survive in the area, as these traits determine how an organisms extracts resources from its environment. In addition, the idea that certain species contribute disproportionately to ecosystem function rests on the premise that those species possess particular functional traits that allow the to capture a greater proportion of the total available resources that other species. It was at this point that they realized that species richness is incredibly important for an ecosystem, as greater differences in resource use lead to increased ecosystem function. Finally, ecologists were starting to uncover the true systems of ecology as they focused on what was different between species and how they adapt to changes rather than how similar they are.