Oikos: An introduction to ecology

Sometime in the 19th century, Ernest Haeckel, a naturalist, came up with the word ‘ecology’ to draw attention to something that he thought was important: the ‘entire relations’ of an organism. By this, he meant that it was not enough to study one plant or animal species at a time. He believed it was important to study not only the organism but also its relationships with other living organisms and how it interacts with non-living things like climate, water, soil and light.

This came from the idea that an organism’s home (habitat or surroundings) has a great influence on its form (what a plant or animal looks like) and its behaviour (how it grows, moves, communicates and so on).

Tropical rainforest trees have shallow roots access nutrients found closer to the surface, unlike temperate trees that have deeps roots for nutrients found deeper in the soil.

Ecology is derived from the Greek ‘oikos’ which means home or household. It is the study of the relationships that exist among living things and between living things and their environment. This includes both non-living things like water, soil, climate and minerals, and other organisms that are of the same or different species.

All plants, animals, fungi and microorganisms form a complex web of relationships—an ecosystem—that supports their survival. Interactions occur at many levels and there are different types of relationships.

A group of the same species living in an area make up a population. Think, for example, of the myna birds you see anywhere near your home: together they make up your neigbourhood’s myna population.

Photo by Bishnu Sarangi from Pixabay

Ecologists can study populations of organisms, examining their behaviours, their adaptations to their habitats, and how their numbers change over time and geographic regions. Some ecologists will spend years studying individuals in a population. They will record their births and deaths, diets, movements, and the impact they have on their surroundings.

Plants or animals also interact with other species in their habitats. A community is a set of several, different species that occupy a given area.

Take a simple house garden. Its trees, flowering shrubs, grass, worms, birds, bees, butterflies, snails, moss and mushrooms form a small community. As a community, they interact with each directly (bees feeding on flower nectar) and indirectly (worms dig through soil and this makes it better for plants to grow later).

Communities can be as small as that of a thinly-populated backyard garden or be found within huge national forests.

Interactions within communities involve processes like pollination, decomposition, and feeding. These benefit the organisms and also provide many services for us. Ecosystem services include:

  • food and fuel provision
  • fresh water supply
  • pest and pathogen control
  • soil improvement
  • climate regulation

Ecologists study such relationships and their outcomes, exploring how ecosystems are formed and how they are sustained. Thus, ecology studies contribute to a wide range of fields and practices including agriculture, conservation, natural resource management and sustainable development.

Here are some of the questions that ecologists try to answer:

  • How do behaviour and physiology change in response to the physical environment?
  • How do organisms use the resources in their habitats?
  • How will ecosystems respond to human activities?
  • How can we restore degraded ecosystems?

As the world deals with changing environmental conditions, pollution, food security and species loss, ecology helps us understand ecosystems and how to protect them—for our own well-being and that of the planet.


References

Egerton, F.N. (2013), History of Ecological Sciences, Part 47: Ernst Haeckel’s Ecology. The Bulletin of the Ecological Society of America, 94: 222-244. doi:10.1890/0012-9623-94.3.222

https://www.britannica.com/science/ecology


You can learn more about ecology and ecosystems closer to home here:

Rewilding, the case of urban Birdwing butterflies

Here I explain how you can think about ecosystems and how to restore them. The case study of the Golden Birdwing Butterfly, which can be found in the urban forest patch that is Rimba Ilmu Botanic Garden located inside the University of Malaya.

Merely reintroducing a species does not produce long lasting results. Butterfly farms all over the country constantly have to restock wild caught butterflies due to captive butterflies dying and not reproducing. When an animal is placed in a system that does not meet its needs, there’s nothing much that it can do except go extinct.

The secret to the birdwings survival is the fact that it has a functioning ecosystem that produces resources can satisfy its ecological requirements.

In a butterfly farm, the basic requirements for survival are met; the temperatures are suitable and there is enough food supplied through cut flowers and fruit. The ecosystem in a butterfly farm looks like this:

To be more sustainable and reduce the cost of having to feed the birdwings, you could plant food plants for the birdwings, so they can feed on the nectar. Birdwings prefer flowers that grow on in large clusters like Saraca, Ixora and Bauhinia kockiana so they can walk along and feed. The ecosystem would look this this:

As mentioned before, once the end of the lifespan of the butterfly is reached the ecosystem collapses. This is because all butterflies require a host to develop on as a caterpillar, in this case the Birdwings are breeding on a climbing plant known as Pipevine (Aristolochia tagala). If supplied with a host plant, the butterflies can lay their eggs and reproduce and create a new generation. This ecosystem would look like this:

However, Birdwing caterpillars damage the stem once they are about to pupate into a butterfly. This behaviour is believed to increase the nutrient density of the leaves while reducing the water content. Because of that, the above ecosystem will also eventually collapse after enough caterpillars damage and kill off all their hosts.

The special thing about the Rimba Ilmu ecosystem is that it has pollinators for the Pipevine, so the Pipevine can reproduce and replace the population that is lost to caterpillars. What is the pollinator of the pipevine? Tiny flies (Drosophilla spp., Megaselia spp.), which get caught in trap chambers in the flower of the Pipevine and forced to become pollinators without any reward. So a more viable ecosystem looks like this:

Of course since the Pipevine doesn’t feed them for the service of pollination, the fruit flies require their own food source, which is often rotten fruit, decomposing materials or fungus. These decomposition systems happen when there is enough fallen fruit, mulch and rotting logs in the overall ecosystem. This is supplied by leaves, fruit and branches falling off the plants in the system (which is an important reason to always leave some decomposition around). This results in this ecosystem:

The example above is a functioning, self sustaining ecosystem. As long as it gets enough sun it can keep going without any human interference. But the most interesting thing about this ecosystem is the fact that it assembled itself. While this “let nature find a way” approach is possible, we can help it along by being aware of the different parts and the needs of each part of the system. If you want butterflies in your garden, you need to think about more than butterflies.

References:

http://rainforest-australia.com/birdwing.html


This article is supported by The Habitat Foundation Conservation Grant