干旱区生态环境知识资源中心

The reproductive strategies of seven oniscid isopod species were studied: Hemilepistus reaumuri, Porcellio olivieri, Agabiformius sp., and Armadillo albomarginatus inhabiting the arid Negev desert; Porcellio ficulneus, Schizidium tiberianum, and Armadillo officinalis inhabiting xeric habitats in the Mediterranean region; and Porcellio chuldaensis and Armadillo sp. (’’brown’’) inhabiting mesic habitats in the Mediterranean region. Females were collected once or twice monthly, and changes in their ovaries’ and oocyte dimensions were followed. These changes were associated with the onset of oogenesis and vitellogenesis, as were changes in oocyte numbers. Likewise, marsupial egg, embryo, and manca numbers were counted. Due to the fact that some females were kept individually, the onset and course of oogenesis, extent of the marsupial period, and onset and duration of manca release could be obtained. Any artificial change in ambient photophase and temperature caused disruption of the normal reproductive pattern. The number of oocytes, eggs, and mancas enabled calculating both oocyte and marsupial egg loss, as well as reproductive allocation, parental investment, and reproductive potential. The species have shown wide variation in respect to these criteria. No positive relationship could be found between the reproductive patterns in these isopods and their anatomy, taxonomy, or ecological conditions within their habitat. This suggests that the reproductive patterns in isopods must have evolved irrespective of environmental conditions.