No abstract

Conservation programs in urban ecosystems need to determine the genetic background in populations of urban dwellers. We examined the genetic diversity and structure of Pieris rapae and P. melete using AFLP markers, and compared them between species and between urban and rural environments. As a result: (i). in both species, there was no reduction in genetic diversity within urban populations by direct comparison of diversity measurements, although the analysis of molecular variance suggested significant reductions in the variance within seasonal subpopulations in urban populations; (ii). P. rapae retained greater genetic diversity within species and populations; (iii). populations of both species showed significant genetic differentiation, and P. melete was more strongly subdivided; (iv). in both species, geographically close populations did not cluster with one another in the upgma analysis; (v). there was no genetic isolation due to geographical distance in either species; (vi). the genetic composition of seasonal subpopulations differed in urban populations of both species, and the genetic distances among subpopulations were correlated with seasonal differences in P. rapae and with temporal differences in P. melete. These results indicate that the genetic diversity in urban populations of both species was reduced at times, but was maintained by dispersal from genetically differentiated populations. Differences in the ability and mode of dispersal in the two species may be reflected in the degree of population subdivision and patterns of seasonal change in the genetic composition.

-Mating behaviour and associated songs were compared between 2 sympatric congeneric species, Nezara antennata and N. viridula, between which interspecific mating was known to occur under natural conditions. The fundamental sequence of mating behaviour for these species was the same. Three kinds of songs were recorded from each sex of N. antennata. For N. viridula, 4 kinds of male songs and 3 kinds of female songs were recorded. The songs which corresponded with definite behavioural bouts were distinct between these species. Some consideration was made as to why interspecific differences in the songs did not sufficiently engender ethological isolation. In addition, some geographic variations in the songs were shown among Yugoslavian (~okl et al. 1972), American (Harris et al. 1982) and Japanese populations of N. viridula.These variations were relatively inconspicuous when compared with the interspecific differences from N. antennata.

Isaza, Chaenogobius isaza, is a small gobiid fish endemic to Lake Biwa. It lives offshore throughout almost the entire year, showing a remarkable diel vertical migration. In early spring, males and females migrate to lake shore to spawn under stones. Spawning season is limited to a very short span of time in early spring, late April to early May. During this short spawning season, the male is supposed to have only 2 brood cycles at maximum. At each brood cycle, the male is strictly monogynous, never accepting additional females. Males therefore show a marked mate choice, choosing a larger female regardless of the size of the male himself. Females also choose larger males. However, males are supposed to not waste time in male-male fighting in the natural spawning area. That this very short spawning season and its occurrence in early spring is primarily to avoid interspecffic competition with another littorally reproducing goby Yoshinobori, Rhinogobius brunneus, is experimentally demonstrated.Isaza, Chaenogobius isaza (Fig. 1), is a small

Sperm transfer in the aphidophagous ladybird beetle, Harmonia axyridis Pallas, is by a spermatophore (unpublished data). Although the utilization of spermatophores in insects has been considered to be a more primitive method of insemination than direct sperm transfer, males of many orders produce spermatophores (Chapman 1969; Gerber 1970; Leopold 1976). The remains of the spermatophore, after the sperm has migrated to the spermatheca, is ejected by the female in some species and dissolved within the female genital tract in others (Chapman 1969; Leopold 1976). In Coccinellidae, Fisher (1959) reported on spermatophore formation of Chilocorus spp. and indicated that the female ejected the empty spermatophore 18–24 h after copulation. In this paper evidence is presented that H. uxyridis females not only eject the empty spermatophore but also feed on it.