Is Specialization a Dead End? Effects of Specialization on Evolutionary Success

Fernandez-Mazuecos et al. (2013) uses bifid toadflaxes (Linaria sect. Versicolores) for their study of specialization. Linaria, commonly known as toadflaxes, are the most species-rich genus of the snapdragon lineage (tribe Antirrhineae in the family Plantaginaceae), made up of 150 species, and show remarkably diverse floral traits. Several traits of Linaria flowers are potentially linked to pollinator specialization: they have a zygomorphic, bilabiate, usually personate corolla in which a spur of variable length is formed at the base of the lower lip. The spur contains nectar dripping down from a nectary located at the base of the ovary. The two pairs of anthers are placed at slightly different heights, with the stigma in the space between. The well-developed palates displayed by most species of Linaria suggest a specialization to bee pollination. This is because the palates prevent access to the corolla throat for most pollinators, while bees are heavy enough to push through