[Space/Aliens] Reproductive Features: alien, exotic and weird ideas

[vicky_molokh]

Greetings, all!

For some reason I'm in the mood for making up and sharing, and seeking out some setting-building ideas. Not sure I'll make anything out of it, but they might be used in a re-haul of one of my settings. Anyway, recently I've read some wiki articles on the more unusual reproductive systems (marsupial anatomy, bee genetics, traumatic insemination etc.), and realized that I want to make a list of reproductive features useable in science-fiction settings (because the ones found in Celestial Ocean only fit fantasy worlds). So, here are some, for a start (but I'm willing to read other ones - whether yours or someone else's):

• Three sexes, as in the Player of Games by Iain M. Banks: the male, female, and the 'apex', whose function is basically the transit of spermatozoa. But that seems like a not-too-useful build from an evolutionary perspective.
• Parthenogenesis + use of some external event to create genetic diversity. Perhaps the Asari of Mass Effect are the most known example.
• Generation-linked dimorphism. I.e. generation 1 has the same traits as generation 3, 5 etc., while generation 2 has the same as 4, 6 and so on. Dimorphism itself might be either very or not very noticeable. If the species uses parthenogenesis, things are easy. If the species reproduces sexually, this can be set up with effectively 3 or 4 templates, depending on whether the male-equivalent has a single generation-based form or two.
• Normal insemination, cross-species gestation: males function pretty much like mammalian ones, but females lack a functional/meaningful uterus, and are hermaphromorphs instead. The ova are fertilized in the female organism, which then proceeds to hermaphromorph, and expel the germinated cells into a member of another species; the germinated cells pretend to belong to the gestating species. This seems like a good way for a physically weak or otherwise deficient species to put the expenses of pregnancy on a physically more fit one - if they can seduce the gestator-species.
• As above, but male actually takes/extracts ova from the female, and then does the seducing-other-species part.
• Parthenogenetic cross-species gestation + caste system: reproduction by implanting parthenogenetic ova into other species as above, but offspring can be of two castes: the fertile caste, with the prime function being introduction and hunting/warfare/etc., and the working caste, whose functions include more 'peaceful' work, as well as caring for any offspring that is not accepted by the cross-species surrogate-parents.
• Conditional parthenogenesis + conditional gender bias (probably pretty common in our world): unfertilized ova have a chance to start developing anyway, and always produce male offspring. Fertilized ova produce female offspring.

Comments and contributions welcome.
Thanks in advance!