Analytical biogeography of land snails of Mount Kinabalu
This study examined the biogeography of land snail in Kinabalu Park (emphasised on Mt. Kinabalu) from the aspects of space (environmental factors) and time (historical factors). Sampling (land snails and environmental parameter) were done in 142 plots along the elevation gradient of Mt. Kinabalu...
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Format: | Thesis |
Language: | English |
Published: |
2006
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Subjects: | |
Online Access: | https://eprints.ums.edu.my/id/eprint/17638/1/Analytical%20biogeography.pdf |
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Summary: | This study examined the biogeography of land snail in Kinabalu Park (emphasised on
Mt. Kinabalu) from the aspects of space (environmental factors) and time (historical
factors). Sampling (land snails and environmental parameter) were done in 142 plots
along the elevation gradient of Mt. Kinabalu and Mt. Tambuyokon. Both mountains
support more than one-third (126 species) of the total number land snail species that
were recorded in Sabah. The assemblage of land snails exhibited zonation along the
elevation belts (500 - 1500 m; 1500 - 2600 m; 2600 - 3500 m; and 3500 - 4000
m). Each zone support its unique fauna and most of the Mt. Kinabalu's endemic were
found at the zone above 2600 m. The species richness, diversity, evenness and
shell's size decreased with increasing elevation. The species-area relationship
between log number of species and log area of elevation zone was described by the
z-value (0.193). The distribution ranges (elevation range) for the land snail of Mt.
Kinabalu and Mt. Tambuyokon were not complied with the Rapoport's rule. The high
elevation with relative younger age (of the area), smaller area and harsher
environment than the lower elevation caused the low diversity, richness and
evenness of the land snail at the top of the mountains. The small snails were better
adapted to high elevation habitat than the large snails. For the ecogeography
analysis, land snail from genus Everettia; and slugs were used to explore the
relationships between environmental parameter with their distribution. From all the
parameters that had been examined, elevation was the main factor that determined
the distribution of the snail and slug. Also, vegetation was related to the slug
distribution. However, the environment was not the sole factor that was determining
their distribution. Thus, phylogeny of Everettia (snail) and Meghimatium (slug) were
constructed by using the 16S mt DNA. Both genus' phylogenetic trees were
compatible, where the highland (above 2600 m) endemics (Everettia corrugata and
Meghimatium uniforme) diverged from first from their middle and lower elevation
congeners during the first upward move of Kinabalu batholith during the late Pliocene
(ca. 1.5 mya). The Everettia spi and Meghimatium striatum that are endemic to Mt.
Kinabalu (2000 - 2500 m) were split from the lowland congeners at middle
Pleistocene (1 mya) during intrusion of ultrabasic rocks which caused by the second
intensive upward movement of Kinabalu batholith. The glaciation and deglaciation
during the middle to late Pleistocene also separated the population with the ice-flow
(i. e. Meghimatium uniforme uniforme and Meghimatium uniforme 'kotal'). Besides,
the boundaries between species were clear, which have been maintained by the
isolating mechanisms that lie in the genitalia differences (i. e. Meghimatium spp. ) and
possible environment (elevation = climates). Results from this study suggested that
the biogeographical patterns of land snail of the Mt. Kinabalu and Tambuyokon had
resulted from the geology activities during the middle Miocene - Holocene, and have
been maintained by the present-day environment (climates, vegetation and etc.).
Therefore, the whole elevation ranges of the mountains need to be protected for
their remarkable diversity and evolutionary process of land snails |
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