Alternative-reproductive-tactics
Guides
Centris
Oil-diggers
Centris is a genus of approximately 250 large apid bees distributed from the southern United States through South America. Females are specialized oil collectors, possessing morphological adaptations for gathering floral oils from plants, primarily in the family Malpighiaceae, which they use for larval nutrition and cell construction. The genus is sister to the corbiculate bees (honey bees, bumble bees, stingless bees) and represents an important lineage for understanding bee evolution and pollination ecology.
Centris pallida
Pallid Desert-Digger, digger bee, desert bee, pallid bee
Centris pallida is a solitary desert bee native to the Sonoran Desert region of North America. Males exhibit two distinct morphs associated with alternative reproductive tactics: large patrollers that use olfactory cues to locate buried virgin females near the ground, and small hoverers that use visual cues to find females above vegetation. The species has evolved remarkable thermal adaptations to survive extreme desert temperatures, including high thoracic conductance and dorsal solar reflectance in large-morph males. Long-term studies document a persistent decline in male body size since the 1970s, with potential consequences for the stability of alternative reproductive tactics.
Paracerceis
Paracerceis is a genus of marine isopod crustaceans in the family Sphaeromatidae, established by Hansen in 1905. The genus comprises at least 13 described species distributed across tropical and temperate coastal regions. The best-studied species, Paracerceis sculpta, has become a model organism for research on alternative reproductive tactics and sexual selection due to its unusual system of three discrete male morphs. Several species have been introduced outside their native ranges, including P. sculpta in Australia and Türkiye.