福山魚怪的生活史及性轉變 (II)
Date Issued
2001
Date
2001
Author(s)
DOI
892311B002081
Abstract
Two types of inter-sexual cannibalism,
based on the sex victim, were detected
between heterosexual pairs of the
parasitic isopod, Ichthyoxenus fushanensis,
residing in the body cavity of the
freshwater fish, Varicorhinus bacbatulus.
One type was regarded as sexual
cannibalism in which the male was
consumed by the female before or after
mating. Another was a reversed type
in which the female was eaten by her
mate during or after breeding. Both
types of cannibalism occurred during the
breeding season from April to November,
with the female-on-male cannibalism
occurring at earlier stages, and the
reversed type occurring later. The
availability of juveniles in the breeding
season may ensure that a mating pair is
formed immediately after the cannibalism
occurs. Both types of cannibalism
occurred in those pairs inhabiting
smaller hosts (< 10 cm in body size)
suggesting that resource limitation is
possibly an important factor triggering
the cannibalism. Cannibalism may
lead to rapid growth or sex change of the
cannibal. Both types of cannibalism
occurred in mating pairs with a smaller
size ratio (below 1.6, female to male),
and both resulted in a great departure of
female size from its mate. The
increase in size ratio between paired
individuals ultimately leads to an
increase of clutch size. Since an
individual of I. fushanensis may
potentially display both male and female
functions by undergoing protandrous sex
change, the cannibalistic behavior would
not have evolved in response to
selection on either male or female.
Both types of cannibalism may be
regarded as the result of competition
between paired individuals, which is a
by-product in the evolution of a
reproductive strategy rather than the
consequence of sexual selection.
Subjects
Ichthyoxenus fushanensis
parasitism
sex change
selection
Publisher
臺北市：國立臺灣大學海洋研究所
Type
report
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