| Project/Area Number |
16570012
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Ecology/Environment
|
|---|
| Research Institution | Tokyo Gakugei University |
|---|
Principal Investigator |
KARINO Kenji Tokyo Gakugei University, Department of Education, Associate Professor, 教育学部, 助教授 (40293005)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Project Status |
Completed (Fiscal Year 2006)
|
| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
|
|---|
| Keywords | Female mate choice / Sexual selection / Reproductive strategy / offspring manipulation / sex ratio / Behavioral ecology / Poecilia reticulata |
|---|
| Research Abstract |
This study aimed to examine the benefits and costs of female mate choice on the basis of each male trait and adaptive offspring manipulation by females depending on their mates using feral guppies Poecilia reticulata in Okinawa, Japan. The following results were obtained.
1. By using digitally modified video playbacks of stimulus male images, a significant female preference for the color saturation of male orange spots was confirmed. In addition, observations indicated that males possessing the high color saturation of orange spots exhibited a greater algal-foraging ability. Parent-offspring regression analysis demonstrated that the algal-foraging ability of male guppies was a heritable component. Males possessing higher algal-foraging ability exhibited faster growth and larger orange spots. These results suggest that females can acquire indirect benefits such as producing offspring possessing the high algal-foraging ability and thus a greater reproductive success via their mate choice on the basis of male orange spot coloration.
2. It has been reported that female guppies exhibited mate preference for males possessing large total lengths, however some males elongated their tails (caudal fins) to achieve large total lengths. Aquarium experiments in which a female physically contacted with two males exhibiting same total lengths but possessing different tail lengths indicated that the females preferred the short-tailed males over the long-tailed males. Females incurred costs of mating with long-tailed males, such as small body sizes and low reproductive efficiency of their daughters. However, when females mated with long-tailed males, they decreased the number of offspring and biased offspring sex ratio toward males in order to reduce the costs of mating with the long-tailed males. On the other hand, long tails of males affected their swimming performance and consequently limited their choice of habitats to those with slow water velocity in the wild.
|
