Host specificity and aggregation for a widespread mistletoe in Campo Rupestre vegetation

Abstract

Assessment of host infection and distribution patterns are crucial to understand the underling mechanisms that shape parasitic plant spread in natural ecosystems. However, such data remain scarce for mistletoes inhabiting Brazilian campo rupestre vegetation, old-growth montane fire-prone grasslands. We evaluated the host range and distribution patterns of the mistletoe Psittacanthus robustus (Loranthaceae) at seven 1-ha plots located at in Serra do Cipó, southeastern Brazil. We investigate if the frequency of parasitism by P. robustus is directly related to the relative abundance of host tree species in the community, and how prevalence and intensity of infection vary among different host tree species. Average mistletoe density was 120 individuals ha −1 , which parasitized eight host species, including trees and shrubs in five families. Four tree species, Vochysia thyrsoidea, Qualea cordata (Vochysiaceae), Trembleya laniflora and Miconia ferruginata (Melastomataceae), comprised 95% of infected individuals. Twenty two percent of 1,108 trees sampled were parasitized by P. robustus, with host specificity within species in Myrtales Clade. Prevalence increased with host height for all tree species, with a highly aggregated distribution in few taller host trees within rocky outcrop patches in campo rupestre. The unveiling patterns of host infection and mistletoe distribution, support future studies addressing plant-plant, bird-plant and fire-plant interactions that might shape infection dynamics of this widespread mistletoe species in campo rupestre.

Root parasitism by Scybalium fungiforme Schott & Endl. is not random among host species in seasonal tropical forest

“…Classical studies about parasitism in plants indicate that parasitic species rarely infect just one host species (Kuijt 1969;Norton & Lange 1999). Despite other studies indicating that the existence of a preferential host is common, other species are often complementarily parasitized (Marvier & Smith 1997;Guerra et al 2018). In our study, we observed that the preference by hosts at species level was sharply different between fragments.…”

“…There is a wide variety in host specificity among parasitic plants at species or genus level (Kuijt 1969;Norton & Lange 1999;Su et al 2012;Guerra et al 2018), and this diversity is essential to understanding historical and ecological aspects that determine the associations between parasite and host (Stireman & Singer 2003). Some studies suggest the existence of functional patterns of parasitism (Ward 1992;Arruda et al 2006) and evolutionary adaptations that increase the reliance of the parasite on the host (Schneeweiss 2007;Conn et al 2015;Těšitel 2016).…”

Plant life in campo rupestre : New lessons from an ancient biodiversity hotspot

“…Its buzz-pollinated flowers with poricidal anthers, heterostemony, and pollen as the only reward are dependent on interbreeding; the large, crepuscular bees promote outcrossing within and among patches of naturally-isolated populations on rocky outcrops. Guerra et al (2018) explore the host range and distribution patterns of the mistletoe Psittacanthus robustus (Loranthaceae). Four species of trees (all within Myrtales) comprised 95% of infested individuals, with prevalence increasing with host height for all species and a highly-aggregated distribution in few taller host trees.…”

Color signals of bee‐pollinated flowers: the significance of natural leaf background

“…We selected bee‐pollinated Fabaceae species (Dafni and O’Toole, 1994; Potts et al, 2005; Gottsberger and Silberbauer‐Gottsberger, 2006; Guerra et al, 2018) of three seasonally dry vegetation types: the tropical campo rupestre and cerrado and a temperate Mediterranean shrubland (Appendix S1). The studied species were identified by specialized bibliography, herbarium collections, or based on previous studies developed at the same study sites (Blanca et al, 2009; Rocha et al, 2016; Camargo et al, 2019; Appendix S1).…”

“…Fabaceae is an important family with high species diversity (770 genera and 19500 species) and a cosmopolitan distribution in a huge variety of habitats (Koenen et al, 2013; Lewis et al, 2013; Azani et al, 2017). Most Fabaceae species rely on bee as pollinators (Potts et al, 2005; Gottsberger and Silberbauer‐Gottsberger, 2006; Guerra et al, 2018); thus, differences in the evolution of specific color signals to attract bees across different environmental conditions are expected.…”