Biotic factors associated with the spatial distribution of the mistletoe Psittacanthus calyculatus in a tropical deciduous forest of central Mexico

Abstract

Abstract:Psittacanthus calyculatus (Loranthaceae) is a neotropical hemiparasitic mistletoe and one of the most abundant and widely distributed species of the genus. Like most mistletoes, the interaction with its hosts and dispersers are directly related with its distribution and community dynamics. For the last decade, the infested areas in central México have increased, becoming a potential plant health problem. The aim of this study was to investigate three main biotic factors associated with the distribution of P. calyculatus in a tropical deciduous forest: (1) the plant community structure, (2) the host spatial distribution and level of association with P. calyculatus, and (3) bird consumers. Modified Whittaker plots were used to analyze the structure and composition of the plant community, comparing a highly infected mistletoe sites with non-infected sites. The spatial distribution and association of P. calyculatus with its most frequent hosts were calculated through a spatial analysis by distance indices. Study sites differed in plant diversity and species composition, showing a positive relation of mistletoe abundance with low diversity sites. The distance indices analysis presented a clumped distribution of P. calyculatus and Acacia hosts, as well as a high association with leguminous species such as A. farnesiana (X = 0.31, P = 0.0041) and A. schaffneri (X = 0.3977, P = 0.001). Three species consumed P. calyculatus' berries: the Northern mockingbird, the Silky-Flycatcher and the Scott's Oriole. Keywords: dispersers, distance indices, host association, Psittacanthus calyculatus, spatial distribution.Resumen: Psittacanthus calyculatus (Loranthaceae) es un hemiparásito neotropical y uno de los más abundantes y con mayor distribución del género. Como la mayoría de los muérdagos, las interacciones con sus hospederos y dispersores están directamente relacionadas con su distribución y dinámica en la comunidad. En la última década las áreas infectadas se han incrementado, llegando a ser un problema potencial de salud forestal. Los objetivos de este estudio fueron investigar los tres factores bióticos principales asociados a la distribución de P. calyculatus en un bosque tropical caducifolio en la periferia de la ciudad de Querétaro: (1) la estructura de la comunidad vegetal, (2) la distribución espacial y el nivel de asociación de P. calyculatus para con sus hospederos y (3) las aves que consumen los frutos del muérdago Para analizar la estructura y composición de la comunidad vegetal, se comparó un área sin muérdago con un área con numerosos individuos de P. calyculatus con la ayuda de cuadrantes Whittaker. La distribución espacial y los valores de asociación fueron calculados mediante un análisis espacial por índices de distancia. Los sitios difirieron en composición de especies, mostrando una relación entre el muérdago y la importancia de sus hospederos en la comunidad. Se establecieron puntos de observación para registrar a las aves que se alimentaran de los frutos del muérdago. Se observó una distribución ...

The influence of climatic niche preferences on the population genetic structure of a mistletoe species complex

“…S2). Finally, host specificity might be obscured by other nonbiological factors affecting mistletoe incidence and infection on different host species (Norton & Carpenter, ; Lavorel et al ., ), such as landscape fragmentation (Arce‐Acosta et al ., ; Barbosa et al ., ).…”

“…Climatic niche preferences may not be as important for localscale mistletoe abundance on specific hosts, which probably relies not only on host-parasite interactions, but also on other factors associated with seed dispersal agents, host demographics and community composition (Norton & Carpenter, 1998;Lavorel et al, 1999;L opez de Buen & Ornelas, 1999Norton & Lange, 1999;Okubamichael et al, 2014;Arce-Acosta et al, 2016;Griffiths et al, 2016). The co-occurrence of different mistletoe species may have a strong effect on the infectivity and prevalence on different hosts.…”

“…Although parasite-host interaction becomes relevant in later stages of the life cycle, mistletoes need to control their water loss in coordination with their hosts in order to obtain water and nutrients. More specifically, mistletoes have been shown to control their transpiration rates relative to their host in order to obtain an effective transport of water and nutrients (Ehleringer et al, 1985;Stewart & Press, 1990;Arce-Acosta et al, 2016;Cocoletzi et al, 2016).…”

“…The prevalent view of population differentiation, genetic structuring and host-race formation in parasitic plants is that of the accumulation of genetic differences as a result of varying degrees of host specificity (Dr es & Mallet, 2002;Jerome & Ford, 2002;Zuber & Widmer, 2009;Yule et al, 2016). However, the role of host specificity in the evolution of host-races is often more complex because the life cycle of many parasitic angiosperms involves specialized interactions with pollination and seed dispersal vectors, which are often scale dependent (Watson, 2001;Mathiasen et al, 2008;Arce-Acosta et al, 2016). Thus, host specificity is a difficult concept to interpret in natural populations and its importance to population genetic structure is debatable (Kuijt, 2009).…”

Hybridization and differential introgression associated with environmental shifts in a mistletoe species complex

“…In parasitic plants the colonization of a new environment and further differentiation could be associated to adaptations to biotic factors such as new host associations, pollinators and dispersers or through adaptations to abiotic factors (like the parasite’s own niche) or both 41 , 69 . In mistletoes, controversial evidence exists about the role of host race formation as the main diversifying force.…”