Pollinator shifts drive petal epidermal evolution on the Macaronesian Islands bird-flowered species.
Pollinator shifts are considered to drive floral trait evolution, yet little is still known about the modifications of petal epidermal surface at a biogeographic region scale. Here we investigated how independent shifts from insects to passerine birds in the Macaronesian Islands consistently modified this floral trait (i.e. absence of papillate cells). Using current phylogenies and extensive evidence from field observations, we selected a total of 81 plant species and subspecies for petal microscopy and comparative analysis, including 19 of the 23 insular species pollinated by opportunistic passerine birds (Macaronesian bird-flowered element). Species relying on passerine birds as the most effective pollinators (bird-pollinated) independently evolved at least five times and in all instances associated with a loss of papillate cells, whereas species with a mixed pollination system (birds plus insects and/or other vertebrates) evolved at least five times in Macaronesia and papillate cells were lost in only 25% of these transitions. Our findings suggest that petal micromorphology is a labile trait during pollinator shifts and that papillate cells tend to be absent on those species where pollinators have limited mechanical interaction with flowers, including opportunistic passerine birds that forage by hovering or from the ground.
Department of Evolutionary Biology and Ecology, Université Libre de Bruxelles, Avenue F.D Roosevelt 50, 1050, Belgium dario.alayon@gmail.com.
Dario I
http://orcid.org/0000-0001-8181-4804
DI
Ojeda
Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), C/Américo Vespucio s/n, La Cartuja, Sevilla 41092, Spain.
Alfredo
A
Valido
Real Jardín Botánico, RJB-CSIC, Plaza de Murillo 2, Madrid 28014, Spain.
Alejandro G
AG
Fernández de Castro
Área de Botánica, Facultad de Ciencias, Universidad de Extremadura, Avenida de Elvas s.n., Badajoz 06006, Spain.
Ana
A
Ortega-Olivencia
Real Jardín Botánico, RJB-CSIC, Plaza de Murillo 2, Madrid 28014, Spain.
Javier
J
Fuertes-Aguilar
Jardim Botânico da Madeira Eng. Rui Vieira, Caminho do Meio, 9064-512 Funchal, Madeira, Portugal.
José A
JA
Carvalho
Calle Guaidil No. 16, CP. 38280, Tenerife, Islas Canarias, Spain.
Arnoldo
A
Santos-Guerra
D000818:Animals; D005075:Biological Evolution; D035264:Flowers / Q000033:anatomy & histology* / Q000648:ultrastructure; D007313:Insecta; D062312:Islands; D019684:Magnoliopsida / Q000033:anatomy & histology* / Q000648:ultrastructure; D046109:Passeriformes; D010802:Phylogeny; D019441:Plant Epidermis / Q000033:anatomy & histology* / Q000648:ultrastructure; D054817:Pollination; D011174:Portugal; D013030:Spain
Islands; conical cells; mixed pollination; opportunistic passerine birds; pollinator shift