Biology Reference
In-Depth Information
Table 10.1.
Upper canine tooth diameters and skull lengths for the small Indian
mongoose in eastern India and Bangladesh versus on various islands to which the
species has been introduced in the absence of its congeners (Data from Simberloff
et al. 2000).
C
ANINE
T
OOTH
D
IAMETER
(
MM
)
S
KULL
L
ENGTH
(
MM
)
Locality
Male
Female
% difference*
Male
Female
% difference*
E. India and Bangladesh
2.65
2.39
9.8
61.9
58.0
4.7
St. Croix, U.S.Virgin Islands
3.26
2.89
11.3
65.7
61.1
7.0
Hawaii, HI, USA
3.11
2.70
13.2
65.7
60.5
7.9
Oahu, HI USA
3.09
2.73
11.6
66.5
62.0
6.8
Mauritius
3.15
2.77
12.1
65.5
60.5
7.6
Viti Levu, Fiji
3.14
2.86
8.9
65.5
61.4
6.2
Okinawa, Japan
3.14
2.81
10.2
65.5
60.0
8.4
* Difference from value for males.
and introduced insular range of the small Indian mongoose, however,
showed that males from the island areas have increased in size and that
sexual dimorphism has increased relative to Asian populations with sym-
patric congeners (Simberloff et al. 2000). Skull length of island population
males averages 5.7-7.4% longer and canine tooth diameter 17-23%
greater than for males from eastern India and Bangladesh (Table 10.1).
These differences are intermediate between those of animals in eastern
India and Bangladesh and those in easternmost Asia. Sexual dimorphism
of animals in island populations is similar to that in the easternmost Asian
populations.
That these patterns are consistent for mongoose populations on islands
in widely separated ocean areas suggests that the changes are evolution-
ary. For most of these island populations, the changes in morphology have
appeared over about 100-200 generations. It appears likely that these
changes have resulted from release of the small Indian mongoose from
competition for food, which consists largely of small animals, and an
increase in specialization of females for smaller prey and males for larger
prey.
Interactions of Predators, Parasites, and Prey
Natural selection favors characteristics of predators and parasites that
maximize the fitness of individuals of these species, that is, their contribu-
tion to gene pools of subsequent generations. For predators, characteris-
