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between the two species. Molecular phylogenetic study is necessary to assess
the genetic exchange between these two species.
The hybridization may have occurred through climate and environmental
changes during the Plio-Pleistocene epoch with alterations of glacial and
inter-glacial climates and accompanying temperature fluctuation, such as
in the hypsithermal period of the Holocene (i.e., 5,000-9,000 years ago).
Ancestors of long-tailed and rhesus macaques may have been confined to
refugia in the glacial period(s), which are thought to have been located in
Indochina Peninsula and other areas in Asia, such as southern China to Xay
Phou Louang mountainous area, northeast India (Kasi hill, Eudey, 1980 ),
Dawna Range (Eudey, 1980 ), the northeast Thai mountains, including the
present-day Phu Khieow Mountains (Koenig et al ., 2003 ), and in Sundaland
(Gathorne-Hardy et al ., 2002 ). Climate change could have influenced the
distribution of the two species, and genetic exchange would have occurred
between them.
Influences from human activity
Threats to long-tailed macaques appear incipient in southern Laos. It is because
the human population is still low and the economic development is limited.
However, threats are present and will accelerate in the near future. Several
macaque species, including the long-tailed macaque, are considered common
wildlife that are tolerant of habitat degradation and hunting and considered by
some to be a “weed” (Richard et al ., 1989 ). However, the scale of habitat deg-
radation in Laos may be beyond their ability to accommodate.
Apart from self-consumption cultivation, commodity crop cultivation con-
sisting of rubber, ginger, sugarcane, and corn is driven by capital from for-
eign countries. Wide areas of coffee and vegetable plantations were established
in the Bolaven Plateau. Wide areas of forest in the less steep lands near the
river and close to the roads (e.g., Attapeu), which are habitats for long-tailed
macaques, have been cut away and turned into large-scale farmlands for pro-
duction of commodity crops. Industrial afforestation of acacia, eucalyptus or
other trees, is expanding rapidly for the supply of paper materials and for the
control of carbon discharge (Clean Development Mechanism, Kyoto Protocol).
These plantations will be established in similar regions as the farmlands,
and will replace or block regeneration of natural forests, separating historic
macaque habitat into small patchy forests. These trends will be accelerated as
a result of the construction of corridor roads and bridges connecting Laos with
southern China, Thailand, Myanmar, Vietnam, and Cambodia. After the roads
are constructed or improved in less inhabited regions of southern Laos, human
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