Sex allocation is a crucial life-history parameter in all sexual organisms. Over the last decades
a body of evolutionary theory, sex allocation theory, was developed, which has yielded …

Recently, several authors have challenged the view that anisogamy, the defining feature of
the sexes, is an important determinant of the evolution of sex roles. Sex roles are instead …

Sex allocation theory for simultaneous hermaphrodites predicts an influence of the mating
group size on sex allocation. Mating group size may depend on the size of the group in which …

Macrostomum lignano n. sp. is a member of the Macrostomorpha, the basal‐most subtaxon
of the Platyhelminthes–Rhabditophora. This new species can be easily cultured in the …

Sperm are the most diverse of all animal cell types, and much of the diversity in sperm
design is thought to reflect adaptations to the highly variable conditions under which sperm …

Hermaphrodites combine the male and female sex functions into a single individual, either
sequentially or simultaneously. This simple fact means that they exhibit both similarities and …

There is a clear tendency in nature for males to compete more strongly for fertilizations than
females, yet the ultimate reasons for this are still unclear. Many researchers—dating back to …

The free-living flatworm, Macrostomum lignano has an impressive regenerative capacity.
Following injury, it can regenerate almost an entirely new organism because of the presence of …

Spermatogenesis is a long and complex process that, despite the shared overall goal of
producing the male gamete, displays striking amounts of interspecific diversity. In this review, we …

Larger testes are considered the quintessential adaptation to sperm competition. However,
the strong focus on testis size in evolutionary research risks ignoring other potentially …