Biomedical Engineering Reference
In-Depth Information
intentionally interbred at most breeding facilities (with the
notable exception of the California National Primate
Research Center;
Kanthaswamy et al., 2008b
), the
subspecies affiliations of both regional varieties are typi-
cally unknown and ignored and does not correlated closely
with genetic differences (
Smith and McDonough, 2005;
Smith et al., 2006
).
Phenotypic differences between Indian and Chinese
rhesus macaques and their hybrid offspring (
Smith, 1994
)
that are of potential clinical significance and undoubtedly
result from genetic differences have also been noted.
Regional differences in the organization of behavior and
physiology that are detectable at an early age (
Capitanio,
1986
) and persist throughout life (
Capitanio et al., 1998
),
specific differences in temperament (
Champoux et al.,
1994
), blood chemistry (
Champoux et al., 1996
), body size
(
Clarke and O'Neil, 1999; Fooden, 2000
), body length
(
Smith and Scott, 1989
), tail length (
Hamada et al., 2005
),
and physiology (
Champoux et al., 1997
) have all been
reported.
Fooden (2000)
reported latitudinal clinal varia-
tion in size of rhesus macaques, which he attributed to
Bergman's Rule, and longitudinal variation in tail size
among western (Indian), eastern (Chinese), and southern
(Indochinese) rhesus macaques.
Feeroz et al. (2010)
have
shown that rhesus macaques from Bangladesh are
morphologically similar to those from India but distinct
from Chinese rhesus macaques. Thus, it is reasonable to
consider recognizing the eastern and western taxa of rhesus
macaques as different subspecies of Macaca mulatta.
Rhesus macaques of Chinese origin are more resistant to
infection with SIV than those of Indian origin (
Joag et al.,
1994; Ling et al., 2002; O'Conner, 2006
), but there is still
some contention over this matter (e.g. see
Burdo et al.,
2005
). Moreover, since the exact location of origin of
rhesus macaques used in any given study is seldom known,
regional differences among rhesus macaques from the same
country (e.g. eastern, western, or southern China or eastern
or western India) have not been studied because few
samples from well-documented regions of origin have been
available. For example, the Yangtze and Brahmaputra
Rivers might have provided formidable barriers to north-
ward expansion of Chinese rhesus macaques and admixture
between the eastern (Chinese) and western (Indian) rhesus
macaques, respectively, and the mountainous regions of
western China might have contributed to genetic differ-
ences between rhesus macaques from eastern and western
China.
Because breeding centers throughout China interbreed
rhesus macaques from different areas of China (
Satkoski
et al., 2008a
), and perhaps elsewhere as well, the domestic
supply of Chinese rhesus macaques is genetically sub-
divided. Consequentially, the phenotypic variance of clin-
ically significant biomedical traits of interest is
undoubtedly inflated, a circumstance that might influence
their suitability as animal models for the study of human
diseases.
Longtail Macaques
Longtail macaques are notable among the macaque species
for having tails at least as long as their bodies, crown to
rump.
Fooden and Albrecht (1999)
have described the
phenotypic variation in tail length among the species of the
fascicularis group of macaque species. In the zone of
hybridization between longtail and rhesus macaques in
northeastern Thailand, rhesus macaques exhibit the typical
rhesus color patterns but are smaller in size and have longer
tails than Indian and Chinese rhesus macaques (
Hamada
et al., 2006
), which suggests the introgression of longtail
macaque genes into rhesus macaques. Genetic evidence for
the introgression of Indochinese rhesus macaque genes into
Indochinese longtail macaques is now relatively abundant
(
Tosi et al., 2002; Kanthaswamy et al., 2008a; Stevison and
Kohn, 2008; Bonhomme et al., 2009
), but evidence for
introgression of Indochinese longtail macaque genes into
Indochinese rhesus macaques has not been reported,
primarily due to lack of genetic studies of the latter species.
Adult males and females have mustaches and beards,
respectively, and both exhibit cheek whiskers. Subspecies
vary in the color of the pelage on their backs, legs, and arms
from light brown or grayish to brown, but all are lighter on
their undersides and their head hair sweeps backward to
form a crest of hair.
Both
Fooden (1995)
and
Groves (2001)
divide M. fas-
cicularis into 10 subspecies, the most widespread of which,
M. f. fascicularis, is distributed from southern Thailand
south throughout most of the Indonesian islands to Timor
and east to western Mindanao. The only other broadly
distributed subspecies is M. f. aurea, which is found from
southern Bangladesh to the Thailand
Burma border and
intergrades with M. f. fascicularis at the Isthmus of Kra.
The Isthmus of Kra represents a biogeographical boundary
north of which longtail macaques exhibit shorter tail length
and a greater color contrast between the pelage of the back
and thigh (
Hamada et al., 2008
). M. f. philippinensis is
distributed throughout the Philippine islands, but the other
seven subspecies are all isolated on small islands or island
groups throughout Indonesia. The general agreement on
intraspecific taxonomy may be more related to the lack of
genetic data than to the strength of the morphological
evidence. For example, while the restricted insular
subspecies are differentiated by the ratio of tail to body
length, the observed variation in this trait in the subspecies
M. f. fascicularis encompasses the entire range of variation
for the species, at least in part due to the intermediate tail
length of longtail macaques that have interbred with rhesus
macaques in Indochina. While it is unknown whether or not
the subspecies defined on the basis of morphology exhibit
e
