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Male mating history in relation to monandrous and polyandrous lepidopteran species. M2 Aye Thanda Win

2011/11/04 17:07 に Takashi Matsuo が投稿

2011/11/11- (10:00 A.M.) 

Male reproductive success can be determined by the number of females he can re-mate throughout his lifetime. Male re-mate capacities and male reproductive investment vary in the degree of monandrous and polyandrous species (2). In lepidopteran species, male transfers a spermatophore containing sperm and accessory gland nutrients to female during copulation. These accessory gland nutrients not only increase female’s egg laying rate but also influence female’s re-mate period (1). Male lifetime reproductive investment declines with increasing number of matings, resulting in a limiting factor to male fitness. Males in highly polyandrous species are capable of producing larger and nutritious spermatophore in successive matings than males in intermediate polyandrous and monandrous species (2). It was found that in most lepidopteran species, males transfer a larger first spermatophore than successive ones in most species. Male mating experiences on female fecundity vary widely in monandry and polyandry (1). In this seminar, I reviewed papers related to male mating history in relation to monandrous and polyandrous lepidopteran species.

When given a chance to re-mate, majority of Pieris rapae (highly polyandry) species mated three times whereas relatively few of Aporia crataegi (intermediate polyandry) and P. brassicae (monandry) performed three matings. P. rapae produced three successive ejaculate of similar mass and protein content. Aporia crataegi and P. brassicae never produced another large ejaculate as large as transferred by males in first time although protein content did not differ in second and third ejaculate. These results suggest that male ability to produce large, nutritious ejaculate is limited in monandrous species (2). 

 However, the interval between successive copulations has a strong effect on the size of spermatophore and nutritious content. When P. rapae males were permitted to mate twice in same day, males could not produce another ejaculate as large as first one (3).The relative protein content did not differ between first and second ejaculates when males were remated one, two or three days after their first mating. However, second ejaculate transferred by males mating twice in the same day contained a significantly higher percentage of protein. It takes time (2days) for P.rapae males to recover for producing ejaculate of the same mass and the same amount of proteins as spermatophores produced by males mating for the first time. Before recovery time, males were likely to immediately assess to accessory gland nutrients, such as protein (4). Although the number of eupyrene sperm bundles did not differ between first and successive matings, sperm density became increased after first mating. It has been suggested that P. rapae seem to maintain sperm numbers to be able to succeed in sperm competition because as polyandrous females mate multiply, sperm from different males can be in direct competition to fertilize eggs (3 &5).

In monandrous speckled wood butterfly, Pararge aegeria , males transferred significantly smaller spermatophore after first mating but spermatophore mass did not decrease further with subsequent matings. Although male mating history did not affect female fecundity, a female’s pattern of oviposition (hatching rate); producing fewer offsprings was influenced (6). Interestingly, the number of eupyrene sperm bundles relative to spermatophore mass decreased linearly but the ratio of the number of eupyrene bundles on the spermatophore mass was significantly higher during second mating. Such a pattern has been found in polyandrous P. rapae. It has been known that differences in sperm allocation strategy between polyandrous and monandrous species may be quantitative rather than qualitative. The spermatophore mass and the number of eupyrene sperm of this monandrous species did not recovery even though there was 48hr between subsequent matings. Female’s remate after receiving a small spermatophore can be occurred not only in polyandry but also in monandry species. Nevertheless, females (P. aegeria) did not remate despite receiving a small spermatophore (7).

In conclusion, male investment in successive matings can have important consequences for female fitness but the magnitude of this fitness may vary with mating system (monandry or polyandry).

 

 

 

References

1.       Torres-Vila, L. M. & Jennions, M. D. 2005. Male mating history and female fecundity in the Lepidoptera: do male virgins make better partners? Behav Ecol Sociobiol 57:318-326.

2.       Bissoondath, C. J. & Wilklund, C. 1996. Male butterfly investment in successive ejaculates in relation to mating system. Behav Ecol Sociobiol 39:285-292.

3.       Watanabe, M., Wiklund, C. & Bon’no, M. 1998. The effect of repeated matings on sperm numbers in successive ejaculates of the cabbage white butterfly Pieris rapae (Lepidoptera: Pieridae). J Insect behav 11:559-569.

4.       Bissoondath, C. J. & Wilklund, C. 1996. Effect of male mating history and body size on ejaculate size and quality in two polyandrous butterflies, Pieris napi and Pieris rapae (Lepidoptera: Pieridae). Funct Ecol 10:457-464.

5.       Parker, G. A. 1970. Sperm competition and its evolutionary consequences in the insects. Biol Rev 45:525-567.

6.       Lauwers, K. & Dyck, H. V. 2006. The cost of mating with a non-virgin male in a monandrous butterfly: experimental evidence from the speckled wood, Pararge aegeria. Behav Ecol Sociobiol 60:69-76.

7.       Velde, L. V., Damiens, D. & Dyck, H. V. 2011. Spermatophore and sperm allocation in males of the monandrous butterfly Pararge aegeria: the female’s perspective. Ethol 117:645-654.

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