Reproductive modes

Some cockroach species exhibit obligatory or facultative parthenogenesis, but most species reproduce sexually with reproductive modes that include oviparity, ovo-viviparity, and viviparity (Roth, 1970). Oviparous females oviposit their eggs inside a protective egg case (ootheca), which is either deposited soon after being produced or carried by the mother until the nymphs hatch. In ovoviviparous and viviparous species, the egg case is reduced and remains unsclerotized it is incubated within a brood sac or uterus and live nymphs hatch from the female. At least one species, Diploptera punctata (Eschscholtz), is viviparous and the embryos receive nutrients directly from the mother in the form of milk (Evans and Stay, 1995). 

Beukeboom, L.W., Sharbel, T.F. and Michiels, N.K. (1998) Reproductive modes, ploidy distribution, and supernumerary chromosome frequencies of the flatworm Polycelis nigra (Platyhelminthes Tricladida). Hydrobiologia 383, 277-285. 

The demosponge subclasses Tetractinomorpha and Ceractinomorpha are primarily defined by oviparous or viviparous larval development, respectively. This division is the subject of some dispute as there have been indications that the reproductive mode may be ecologically dependent and thus not a stable character for classification. There are 12 orders in the subclasses Tetractinomorpha and Ceractinomorpha, with the largest number of metabolites reported from the orders Halichondrida (424), Haplosclerida (489), and Dictyoceratida (663). 

Taxon Reproductive Phase Reproductive Mode Predator(s) Deterred References... 

Such a population will approach equilibrium where F = (1 — a)/(l + ) (2). The parameter a defines the binomial frequency for cross-fertilization, and (1 — a) defines the frequency for self-fertilization. The population can now be described in terms of its reproductive mode (3)—viz.,... 

Artemia have two modes of reproduction ovoviviparous (producing free-swimming nauplii released from egg sacs when conditions are stable) and oviparous (producing dormant cysts in diapause when conditions are unfavourable). All strains of Artemia possess both reproduction modes and can switch from one mode to the other in a respraise to changing environmental craiditions [35]. In early summer, all the Aral Artemia females produce ovoviviparously. In mid-summer,... 

In early spring, the first offspring appears from the overwintered cysts. Adults of the first generation consist of ovoviviparous females and small numbers (less than 1 %) of males. Males exist only for a very short period and then disappear. As the temperature rises and food conditimis worsen, females switch reproduction mode from ovoviviparity to oviparity. In autunm all females reproduce only cysts. In winter time, Artemia disappear from the sea. 

Kroken, S., Taylor, J.W. (2000). Phylogenetic species, reproductive mode, and specificity of the green alga Trebouxia forming lichens with the fungal genus Letharia. The Bryologist 103,645-660. 

FIGURE 10.8 Head-shields of cynipid wasps from the species Andricus gallaeumaeformis (Cynipidae) showing facial dimorphism related to reproductive mode sexually produced female (left) and parthenogeni-cally produced female (right). 

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