Scales of Ecology Part 1: Organisms and Populations

In the introduction to this series we looked at all the tiers of complexity that an ecologist

may study, starting with an individual organism and zooming out to consider the entire biosphere.

Let’s now take a closer look at all of these tiers one at a time so that we can get a better

understanding of what ecologists study, starting at the most fundamental level, an organism. What

can an ecologist study when it comes to a single organism? First, they can study an organism’s

life history, or cycle. This pertains to how the organism grows, develops with time, reproduces

and, ultimately, survives. Life histories vary tremendously from one species to the next. For

example, some organisms die immediately after reproducing, such as salmon, many insects, and

all grain crops, while others live on to reproduce repeatedly, like most plants and vertebrates. Why

is there so much variation? Researchers who study ecology at the organism level ask this question

and many others, like: How have different life cycles developed? How do they serve

the organism? They also attempt to understand adaptations they observe in an organism. These

are beneficial features or behaviors arising by natural selection which allow organisms to thrive

in specific habitats. They range from varying body coverings, like fur, feathers, and scales;

to patterns of color and camouflage; to defenses like a skunk’s spray and a snake’s venom;

and finally, to body parts like beaks, claws, and antlers. Adaptations can take multiple forms,

including alterations to an organism’s morphology, which refers to a structural change which gives

an organism a greater chance of survival in its particular habitat. A great example is the Fennec

fox, which lives in the desert. It has large ears. You might think it’s so the fox can hear better,

but it’s actually to allow heat to radiate away from the body, helping to cool the

fox down in the intensely hot environment. Adaptations can be physiological in nature as

well: these are internal processes that regulate and maintain homeostasis, so that an organism is

able to survive in the environment in which it exists. Examples of this include temperature

regulation, release of toxins or poisons for protection, and even releasing natural antifreeze

in the form of proteins, to avoid freezing in cold environments. When it comes to humans, we can find

some familiar examples. Calluses on our hands can be considered physiological adaptations to

repeated contact or pressure, as can tanning or darkening of the skin after repeated

exposure to the sun. There are also behavioral adaptations, which are changes in behavior that

certain organisms or species use to survive in their environment. There are two types: learned

behaviors and instinctive behaviors. Learned behaviors include habituation, or getting used

to a particular stimulus after being exposed to it multiple times; and sensitization, or responding

to certain stimuli in an enhanced or more reactive manner. Think about becoming allergic

to something – like a certain type of food or pollen. Your body, by becoming more sensitive,

protects you from exposing yourself to these irritants in the future by producing a noticeable

and worsening response. Then there’s imprinting – an adaptive function that allows a young animal to

distinguish its own mother from other females of the same or different species – and to remain near

her for safety and protection. Learned behaviors can also come about from play and observation.

Crows, for example, are notorious for their knack for observation-based learned behaviors, including

solving puzzles and using tools. Instinctive behaviors are those behaviors that animals are