biology

Southern white-cheeked gibbon

Southern white-cheeked gibbon is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Southern white-cheeked gibbon rather than just read about it. In short: The southern white-cheeked gibbon (Nomascus siki) is a species of gibbon, native to Vietnam and Laos. It is closely related to the northern white-cheeked gibbon (Nomascus leucogenys) and the yellow-cheeked gibbon (Nomascus gabriellae); it has previously been identified as a subspecies of each of these.

Key takeaways

Southern white-cheeked gibbon belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Southern white-cheeked gibbon to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Southern white-cheeked gibbon from memory before moving on to harder problems.

Reference excerpt

The southern white-cheeked gibbon (Nomascus siki) is a species of gibbon, native to Vietnam and Laos. It is closely related to the northern white-cheeked gibbon (Nomascus leucogenys) and the yellow-cheeked gibbon (Nomascus gabriellae); it has previously been identified as a subspecies of each of these.

Description and habitat Members of the species are not a uniform colour; unweaned juveniles are a light brown, turning to black after weaning. Adult males remain black, but adult females are brown. The name of the species is taken from the male's facial markings, a large patch of white fur around the edge of the mouth - this distinguishes it from a male of N. leucogenys, which has the white in a streak along the cheeks. Females have a thin edging of white around the face. The species lives in lowland broadleaf forest, with some populations living in forested mountainous areas. As with all gibbons, they are arboreal and frugivorous. The original distribution covered an area of central Vietnam and central Laos, ranging from the Nam Theun (Khading) and Rao Nay rivers in the north (approximately 19th parallel north) to the Banghiang and Thach Han rivers in the south (approximately 17th parallel north). Between 19 and 20 parallel there appears to be an area of overlap or intergradation between N. siki and N. leucogenys. Within its original distribution, the species is still common in the remaining large forest blocks in Laos, but in Vietnam the populations are scattered due to human encroachment on their habitat for logging and farming. Numbers are thought to have declined by 50% over the last 45 years, and the species is classed as endangered; it is legally protected in Vietnam, but this is not effectively enforced outside of protected areas. Hunting for food, traditional medicine and the pet trade is a serious threat to this species in both Laos and Vietnam.

Taxonomy The taxon was first formally identified in 1951 by Jean Théodore Delacour where he described siki as a subspecies of N. concolor (a species placed in Hylobates at that time). Since its description, it has been considered to be a subspecies of variously N. leucogenys, N. gabriellae, or N. concolor. The assignation of N. siki as a subspecies of N. gabriellae was due to the interpretation of a single baculum, but later research indicated that the specimen was part of a different species. It was then assigned to N. leucogenys due to similarities of its song, as well as strong visual similarities between the females of the two species. However, it has been considered a separate species since 2001. In the north of the range of N. siki, it overlaps or intergrades with N. leucogenys, and based on mtDNA and voices, these species are closer to each other than to the remaining Nomascus; some maintain that N. siki should be regarded as a subspecies of N. leucogenys. A southern population formerly associated with N. siki was described as a new species, N. annamensis in 2010.

References

External links Photograph gallery

Illustrations

Worked examples

Example 1 — a first encounter with Southern white-cheeked gibbon

Start with the simplest possible case. Write down what Southern white-cheeked gibbon claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Southern white-cheeked gibbon before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Southern white-cheeked gibbon ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Southern white-cheeked gibbon

In research: Southern white-cheeked gibbon appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Southern white-cheeked gibbon in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Southern white-cheeked gibbon is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arboreal mammals, Endangered fauna of Asia, Fauna listed on CITES Appendix I, so understanding it makes those chapters shorter.
In everyday life: Look for Southern white-cheeked gibbon outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Southern white-cheeked gibbon in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Southern white-cheeked gibbon means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Southern white-cheeked gibbon out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Southern white-cheeked gibbon in simple terms?

Why does Southern white-cheeked gibbon matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Southern white-cheeked gibbon?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Southern white-cheeked gibbon.