Impact of mating system on range size and niche breadth inEpipactis(Orchidaceae)

Abstract

Background and Aims The geographical distribution of plant species is not only fundamentally linked to environmental variables, but also to key traits that affect the dispersal, establishment and evolutionary potential of a species. One of the key plant traits that can be expected to affect standing genetic variation, speed of adaptation and the capacity to colonize and establish in new habitats, and therefore niche breadth and range size, is the plant mating system. However, the precise role of mating system in shaping range size and niche breadth of plant species remains unclear and different studies have provided contrasting results. In this paper, we tested the hypothesis that range size and niche breadth differed with mating system in the orchid genus Epipactis. Methods We modelled the ecological niches of 14 Epipactis species in Europe using occurrence records and environmental satellite data in Maxent. Niche breadth and niche overlap in both geographic and environmental space were calculated from the resulting habitat suitability maps using ENMTools and geographic range was estimated using α-hull range definition. Habitat suitability, environmental variable contributions and niche metrics were compared among species with different mating systems. Key Results We did not detect significant differences in niche breadth, occurrence probability or geographical range between autogamous and allogamous Epipactis species, although autogamous species demonstrated notably low variation in niche parameters. We also found no significant differences in niche overlap between species with the same mating system or different mating systems. For all Epipactis species, occurrence was strongly associated with land-cover, particularly broad-leafed and coniferous forests, and with limestone bedrock. Conclusions These results suggest that the mating system does not necessarily contribute to niche breadth and differentiation, and that other factors (e.g. mycorrhizal specificity) may be more important drivers of range size and niche breadth in Epipactis and orchids in general.

Rules of Plant Species Ranges: Applications for Conservation Strategies

“…Questions concerning the relationship between range size and particular plant groups, or life histories, should be investigated. For example, as stated earlier, highly selfing species are expected to have larger geographic ranges and greater niche breadth, but this was not found for Epipactis (Orchidaceae) species in Europe (Evans and Jacquemyn, 2020).…”

The relationship between phylogeny, range size, niche breadth and niche overlap in European orchids (Orchidaceae)

“…Soil data were acquired from the European Soil Data Center (ESDAC) and consisted of two datasets, one with six physical measurement of soil texture and water availability (Hiederer, 2013) and the other with six biochemical levels and the pH of the soil (Ballabio et al., 2019). Each of the two sets of soil variables was summarized with a principal component analysis and the rasters of the resulting first two axes were used as predictor variables (Evans & Jacquemyn, 2020). Two categorical variables were obtained, the dominant bedrock from ESDAC (Van Liederkerke et al., 2006) and the Corine Land Cover type from the Copernicus program of the European Environmental Program (Heymann, 1994).…”

“…The resulting output includes the graphs from the jack‐knife procedures, the variable contribution of each environmental variable and the habitat suitability map for each species. Additionally, a heatmap was created using the ‘pheatmap’ package (Kolde & Kolde, 2019) to visualize the relative contribution of the environmental variables to the ecological niche model of each species and to see whether species could be grouped based on their habitat preferences (Evans & Jacquemyn, 2020).…”

“…Cypripedium guttatum and C. calceolus) have a very wide distribution across the entire Northern Hemisphere, including both North America and Eurasia, whereas other species have rather small distributions in Central America (C. molle and C. irapeanum) or Asia (C. yunnanense and C. bardolphianum). Similarly, Evans and Jacquemyn (2020) showed large variation in range size in the European orchid genus Epipactis, with some species (e.g. Epipactis helleborine and E. atrorubens) occurring across most of Europe, whereas others (e.g.…”

“…Third, the environmental conditions that affect the distribution of orchid species are relatively well known and include climatic variables (e.g. annual temperature and precipitation), soil and land use variables, and elevation (Djordjević et al, 2016;Evans & Jacquemyn, 2020;Hrivnák et al, 2020;Pfeifer et al, 2009;Štípková et al, 2022;Tsiftsis et al, 2011Tsiftsis et al, , 2019Tsiftsis & Djordjević, 2020).…”