Climate niches of milkweeds with plesiomorphic traits (Secamonoideae; Apocynaceae) and the milkweed sister group link ancient African climates and floral evolution.

Premise Of The Study: Climate change that increases mortality of plants and pollinators can create mate-finding Allee effects and thus act as a strong selective force on floral morphology. Milkweeds (Secamonoideae and Asclepiadoideae; Apocynaceae) are typically small plants of seasonally dry habitats, with pollinia and high pollen-transfer efficiency. Their sister group (tribe Baisseeae and Dewevrella) is mostly comprised of giant lianas of African rainforests, with pollen in monads.