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Vol. 36 No. 1, 1997
Variations of Reproductive Traits of Two Semi-terrestrial
Isopods, Ligia exotica and L. taiwanensis (Crustacea:
Ligiidae), in Southern Taiwan
Min-Li
Tsai* and Han-Cheng Chen
Dept.
of Zoology, National Taiwan Univ., Taipei, Taiwan 106
Min-Li
Tsai and Han-Cheng Chen (1997) Both inter- and
intraspecific reproductive traits of 2 semiterrestrial isopods were
examined and compared in an attempt to provide insights into the
adaptive strategies of reproduction. Gravid
females of Ligia exotica
(Roux) from the littoral zone and Ligia taiwanensis (Lee) from
mountain brooks show differences in repro- ductive allocation per brood
(F1,198 = 706, p
< 0.001), weight-specific egg weight (F1,198 = 166, p < 0.001), and weight-specific
fecundity (F1,198 = 120, p
< 0.001), but they also display similarities in the
interrelation- ships between reproductive traits.
The reproductive traits of L.
taiwanensis, such as larger weight-specific egg size and lower
reproductive allocation, seem more in accordance with theoretical
predictions for K-selected traits than those of L. exotica. When theeffects of body
size are removed,both species show a significant positive
correlation between fecundity and brood weight (L. exotica: r = + 0.49, t = 5.50, p < 0.001; L. taiwanensis: r = + 0.96, t = 36.09, p < 0.001), and a negative
correlation between fecundity and egg size (L. exotica: r = - 0.77, t = 11.78, p < 0.001; L. taiwanensis: r =
- 0.32, t = 3.41, p < 0.001) intraspecifically.
The reciprocal rela- tionships between egg size and
fecunidity in L. exotica
and L. taiwanensis seem
to match the assumption of optimality theories of
life-history evolution.
Key words: Ligia,
Reciprocal relationship, Life-history evolution.
*Correspondence: Tel: 886-2-363-0231 ext. 3324, Fax:
886-2-3638554. E-mail: D1205001@ccms.ntu.edu.tw
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