The cosmopolitan bee genus Ceratina, often referred to as small carpenter bees, is the sole lineage of the tribe Ceratinini, and is not closely related to the more familiar carpenter bees. The genus presently contains over 300 species in 23 subgenera. They make nests in dead wood, stems, or pith, and while many are solitary, a number are subsocial, with mothers caring for their larvae, and in a few cases where multiple females are found in a single nest, daughters or sisters may form very small, weakly eusocial colonies. One species is unique for having both social and asocial populations, Ceratina australensis, which exhibits all of the pre-adaptations for successful group living. This species is socially polymorphic with both solitary and social nests collected in sympatry. Social colonies in that species consist of two foundresses, one contributing both foraging and reproductive effort and the second which remains at the nest as a passive guard. Cooperative nesting provides no overt reproductive benefits over solitary nesting in this population, although brood survival tends to be greater in social colonies. Maternal longevity, subsociality and bivoltine nesting phenology in this species favour colony formation, while dispersal habits and offspring longevity may inhibit more frequent social nesting in this and other ceratinines.
Ceratina
Typical interior structure of a small carpenter bee's nest, here built into a dry stem of fennel. The stem cavity is partitioned into cells, each one containing pollen bread and one offspring. In the lowermost cell (on the right), the larva has already hatched. The other two cells still contain eggs.
Ceratina chalcites
Ceratina smaragdula
Parthenogenesis
is a natural form of asexual reproduction in which growth and development of an embryo occur directly from an egg, without need for fertilization.
In animals, parthenogenesis means development of an embryo from an unfertilized egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg.
The asexual, all-female whiptail species Aspidoscelis neomexicanus (center), which reproduces via parthenogenesis, is shown flanked by two sexual species having males, A. inornatus (left) and A. tigris (right), which naturally hybridized to form A. neomexicanus.
A young Komodo dragon, Varanus komodoensis, produced through parthenogenesis. Komodo dragons are an example of a species which can produce offspring both through sexual reproduction and parthenogenesis.
Honey bee on a plum blossom
Komodo dragon, Varanus komodoensis, rarely reproduces offspring via parthenogenesis.