| Summit rat | |
|---|---|
 | |
| on a pitcher of Nepenthes rajah | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Muridae |
| Genus: | Rattus |
| Species: | R. baluensis |
| Binomial name | |
| Rattus baluensis (Thomas, 1894) | |
The summit rat (Rattus baluensis) is a species of rodent in the family Muridae. It is found only on Mount Kinabalu and Mount Tambuyukon, [2] Malaysia, and has been recorded at altitudes of 2,040 to 2,477 m on Mt. Tambuyukon and 2,670 to 3,426 m on Mt. Kinabalu. [1] [3] They are most abundant in higher altitude dwarf forest and montane scrubland. [4] The rat populations from these two peaks were connected in the Holocene. However, nowadays they are genetically isolated despite being 18 km apart. [5] With current predictions of Global warming, the suitable habitat for Rattus baluensis is expected to shift around 500 m upwards. This will put the population in Mount Tambuyukon at risk. However, the population in Mount Kinabalu will likely survive in its upper slopes. [5] Genetic analysis situate its origin in a local population of Rattus tiomanicus from northern Borneo at around 300-400 thousand years ago. [3]
The summit rat has a mutualistic relationship with a species of giant pitcher plant, Nepenthes rajah . Like the treeshrew Tupaia montana , it defecates into the plant's traps while visiting them to feed on sweet, fruity secretions from glands on the pitcher lids. [6] [7]
