Marina Wolowski1 & Leandro Freitas2,3
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Rodriguésia 66(2): 329-336. 2015 http://rodriguesia.jbrj.gov.br DOI: 10.1590/2175-7860201566204 An overview on pollination of the Neotropical Poales Marina Wolowski1 & Leandro Freitas2,3 Abstract Current phylogenetic hypotheses support that ancestral Poales were animal-pollinated and that subsequent shifts to wind pollination have occurred. Ten of the 16 Poales families are widely distributed in the Neotro- pics, however a comprehensive understanding of their pollination systems’ diversity is still lacking. Here we surveyed studies on pollination biology of Neotropical species of Poales. Poaceae, Cyperaceae and Juncaceae are predominantly wind-pollinated but insect pollination also occurs. Thurniaceae and Thyphaceae fit on anemophily but empirical data are missing. Pollen flowers with poricidal anthers have evolved independently in Mayacaeae and Rapateaceae. Pollen- and nectar-flowers occur in Xyridaceae, which are mainly pollinated by bees. Eriocaulaceae flowers secrete minute quantity of nectar and are pollinated by “diverse small insects”. Pollination of Bromeliaceae is carried out by a great variety of animal groups, mainly hummingbirds, and includes anemophily. The diversity in floral forms is very high within the order but more constant within the families. This trend indicates that many events of species diversification may have occurred without divergence in the pollination mode. Still, parallel shifts in pollination modes are found, including possible reversals to wind- or animal-pollination, changes in the type of pollinators (e.g. from hummingbirds to bee or bats) and the arising of ambophily. Key words: ambophily, ecology, evolution, floral biology, monocots. Introduction over the literature among studies of one or few The order Poales represents about one species and concentrated in Bromeliaceae. third of the monocots, with ca. 20,000 species A first overview about the evolution of distributed in 16 families (APG III 2009), and pollination modes in the light of the current has one of the highest diversification rates among phylogenetic hypotheses within the order indicated the angiosperm orders (Magallón & Castillo that ancestral Poales were animal pollinated and 2009). The order probably originated in the late that five subsequent shifts to wind pollination have Cretaceous in wet nutrient-poor sunny habitats occurred, which were correlated with shift to open and diversified into distinct habitat conditions habitats and small, inconspicuous, unisexual, and (wetlands, forest understory, epiphytic habitats) nectarless flowers (Givnish et al. 2010). However during the Paleogene, with major diversification a comprehensive understanding of the diversity into fire-adapted vegetation in seasonal climates of pollination systems in the families of Poales is still lacking (but see Benzing 2000; Givnish et al. and low atmospheric CO2 in the Neogene (Linder & Rudall 2005). Thus, diversification into these 2010; Oriani 2011). Ten of the Poales families are widely distributed in the Neotropical region (see habitats was associated with CO2-concentrating mechanisms (Bouchenak-Khelladi et al. 2014). Stevens 2001). From these, Cyperaceae, Juncaceae, Despite the high diversity within Poales and Poaceae and Typhaceae are worldwide distributed, several morphological and molecular studies Eriocaulaceae is pantropical (to temperate, but that established well-supported phylogenetic especially at Guayana Shield and Southeastern relationships within the order (Givnish et al. Brazil) and Xyridaceae is pantropical (to warm 2010; Bouchenak-Khelladi et al. 2014), empirical temperate). While Bromeliaceae, Mayacaceae, knowledge on its pollination ecology is dispersed Rapateaeceae and Thurniaceae are almost exclusive 1 Universidade Estadual de Campinas, Depto. Biologia Vegetal, C.P. 6109, 13083-970, Campinas, SP, Brazil. 2 Jardim Botânico do Rio de Janeiro, R. Pacheco Leão 915, 22460-040, Rio de Janeiro, RJ, Brazil. 3 Author for correspondence: [email protected] 330 Wolowski, M. & Freitas, L. distributed in the Neotropics, and one species of vectors - wind; animal; ambophily - sensu Culley each family in Africa. Although Restionaceae is et al. 2002); pollinator taxa (scientific names and distributed within the Indo-Pacific region, there taxonomic group); sexual system (hermaphrodite; are representatives in Chile. monoecy; andromonoecy); mating system (self- Here, we surveyed published studies, compatible; self-incompatible); floral reward dissertations and theses with information on pollination (nectar; pollen); floral attractiveness (floral scents; biology and breeding system of Neotropical species colour). We obtained the phylogenetic hypothesis of Poales. Specifically, we aimed to evaluate if family for the Neotropical families of Poales using the diversity is associated with biotic pollination. Besides, angiosperm APG III (APG III 2009) consensus tree we provided an overview on the pollination modes (R20120829) from Phylomatic (Webb & Donogue in Poales families. 2004). Then, we plot the predominant pollination mode as wind, animal, ambophily for each family Methods on the phylogenetic hypothesis and the secondary We reviewed published studies primarily using pollination mode (i.e. other systems restricted for the databases ‘Institute for Scientific Information some species or genera of the family) (Fig. 1). Web of Science®’ and ‘Scientific Electronic Library We estimated the Neotropical species’ richness Online - SciELO’, without date limit. We used the of each family following Smith et al. (2004), and following keyword combination: “family name performed t-Test to evaluate if biotic pollination AND pollinat*” and “family name AND reproduc*”. increases diversity (species richness was log- Then, we sought for dissertations and theses from the transformed to achieve parametric assumptions). online collection of Coordination of Improvement of Higher Education Personnel (CAPES), and Results and Discussion from personal library collections of the authors, Animal pollination stands as the ancestral which also included books and papers. We did pollination mode of Poales evidenced by the earliest not include the keyword “Neotrop*” in the search diverging lineage of Bromeliaceae (Givnish et al. because the quantity of results were low. Then, we 2010). Birds are by far the main group of pollinators used as criterion the selection of studies conducted of the bromeliads (131 of surveyed species, 72.5%), on native species of Poales from the Neotropics followed by bats (10.7%) and bees (7.6%). Within (Olson et al. 2001). Other criteria were the studies the birds, hummingbirds pollinated most of the containing data, or descriptive information, on species (97.9%), and passerine birds pollinated pollination biology and/or breeding system, e.g., exclusively only two species of Puya. Mixed empirical data on biotic or abiotic pollen vectors, pollination systems, i.e. pollination by different pollination experiments as fruit set after hand self or functional groups of pollinators, count for 9.2% cross-pollination and natural pollination. Our search of the bromeliads. For instance, hummingbirds, resulted in studies available from 1971 through 2014. bees and butterflies were recorded in flowers of In total our dataset was composed of 79 studies Dyckia pseudococcinea (= Dyckia martinellii (two book chapters, five unpublished dissertations B.R. Silva & Forzza) (Martinelli 1994), bats, and theses, and 72 papers) that described features hummingbirds, bees and moths in Encholirium of pollination biology of the native Poales species horridum L.B.Sm. (Hmeljevski 2013); and bats, from the Neotropics. These studies counted 227 bees and moths in Pitcairnia albiflos Herb. (Wendt species. Bromeliaceae had strong representation in et al. 2001). Further examples include pollination the studies of the Neotropical Poales with 78.4% by hummingbirds (Canela 2006) and bats (Sazima of the records, while other families were under et al. 1995) in Vriesea longicaulis Mez, and flowers represented (11.9% in Poaceae, 4.4% in Cyperaceae, of Aechmea nudicaulis (L.) Griseb. that were 2.2% in Eriocaulaceae, 1.8% in Xyridaceae, and mainly pollinated by hummingbirds (Sazima et 1.3% in Rapateaceae), while no studies were al. 1996; Buzato et al. 2000; Araujo et al. 2004; recorded for Juncaceae, Mayacaceae, Thurniaceae, Canela 2006; Machado & Semir 2006; Piacentini and Typhaceae. & Varassin 2007), but were also visited by bees For each study/species, we compiled data on (Schmid et al. 2011). Indeed hummingbirds and pollination syndrome (based on floral morphology bees was the most frequent combination (58.3%) sensu Faegri & van der Pijl 1979), pollination of mixed pollination systems in Bromeliaceae, system (based on empirical observation of pollen recorded in Aechmea nudicaulis (Schmid et al. Rodriguésia 66(2): 329-336. 2015 Pollination of the Neotropical Poales 331 Figure 1 – Distribution of the predominant pollination mode (abiotic or biotic) in each family and the likely secondary pollination mode in Bromeliaceae, Cyperaceae, and Poaceae along the phylogenetic hypotheses of the Neotropical Poales. Families denoted with asterisk have no empirical data on pollination biology. Illustrations from: Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 1: 475. (Juncaceae); Hooker, Joseph Dalton. 1883. Hooker’s Icones Plantarum v 15, plates 1407–1408 in Watson, L. and Dallwitz M.J. 1992 onwards. The families of flowering