Syllabus Edition
First teaching 2015
Last exams 2025
Studying Ecosystems
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
Studying Ecosystems
Identifying an ecosystem
The study of an ecosystem first requires that it be named and located to provide a specific and clear reference point for the ecosystem being studied
Naming an ecosystem can include the identification of its physical characteristics, such as vegetation type, climate, and location
Location is important because it provides a specific geographic area for the ecosystem being studied, allowing for more accurate comparisons with other similar ecosystems
Examples of named ecosystems and their geographical locations include:
Amazon Rainforest, South America:
The Amazon rainforest is located in South America, covering approximately 2.7 million square miles
It is the largest rainforest in the world and is home to a diverse range of plant and animal species
Characteristic vegetation: dense evergreen trees, such as mahogany, Brazil nut, and rubber trees, and understory vegetation, such as ferns, palms, and lianas
The Serengeti is well known for its herds of wildebeest
Serengeti, Tanzania:
The Serengeti National Park is located in Tanzania, covering an area of over 5,700 square miles
It is known for its large herds of wildebeest, zebras, and gazelles, as well as predators such as lions and cheetahs
Characteristic vegetation: grasslands dominated by perennial grasses, with scattered trees, such as acacia and baobab
Naming and locating ecosystems not only provides a clear reference point for research, but it also helps to raise awareness about the unique characteristics and value of each ecosystem, encouraging conservation efforts
Identifying organisms in an ecosystem
Organisms in an ecosystem can be identified using various tools and techniques
These tools are important for understanding the biodiversity and ecological interactions within the ecosystem
By accurately identifying organisms, scientists can better understand the roles they play in the ecosystem and how they contribute to its functioning
Examples of these tools and techniques include:
1. Comparison to herbarium or specimen collections
Herbariums and specimen collections are archives of pressed and preserved plants, animals, and other organisms
These collections can be used to compare the characteristics of the organisms in question with the archived specimens to identify them
2. Technologies such as DNA profiling
DNA profiling involves the extraction of DNA from an organism, which is then amplified and sequenced
The resulting sequence can be compared to known sequences in databases to identify the organism
3. Scientific expertise
Scientists with specialised knowledge of a particular group of organisms can identify them based on their morphology, anatomy, and behaviour
4. Dichotomous keys
Dichotomous keys are tools used to identify organisms based on their characteristics
The keys consist of a series of questions with two possible answers, leading to the identification of the organism
Dichotomous Keys
A dichotomous key for animals in the Serengeti
Below is an example of a dichotomous identification key for eight named species in the Serengeti ecosystem:
1 | a | Animal covered in black and white stripes | Zebra (Equus quagga) |
| b | Animal not covered in black and white stripes | go to 2 |
2 | a | Animal is a large cat | go to 3 |
| b | Animal is not a large cat | go to 4 |
3 | a | Animal covered in spots | Cheetah (Acinonyx jubatus) |
| b | Animal not covered in spots | Lion (Panthera leo) |
4 | a | Animal has horns | go to 5 |
| b | Animal does not have horns | go to 7 |
5 | a | Horns meet in middle of head | Cape buffalo (Syncerus caffer) |
| b | Horns do not meet in middle of head | go to 6 |
6 | a | Horns are long and curved | Grant's gazelle (Nanger granti) |
| b | Horns are not long and curved | Oribi (Ourebia ourebi) |
7 | a | Animal has a long neck | Giraffe (Giraffa camelopardalis) |
| b | Animal does not have a long neck | African elephant (Loxodonta africana) |
There are several limitations of using a dichotomous identification key for identifying organisms:
1. Limited scope
Dichotomous keys are typically designed to identify a limited number of species and may not be comprehensive enough to identify all organisms in a given ecosystem
2. Inaccuracies
Dichotomous keys are only as accurate as the information provided
If the key is not designed properly or lacks important distinguishing characteristics, the identification may be inaccurate
3. Variability
Organisms can exhibit variability in their physical characteristics, which can make it difficult to accurately identify them using a dichotomous key
4. Time-consuming
Using a dichotomous key can be a time-consuming process, especially for beginners who are not familiar with the organisms in question
5. Expertise required
Dichotomous keys require a certain level of expertise and familiarity with the organisms in question
Beginners may find it difficult to use the key without assistance from an expert
6. Limited to physical characteristics
Dichotomous keys are limited to the physical characteristics of organisms and may not take into account other important factors, such as behaviour or habitat, which can be important in identifying certain species
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