Genetic Diversity and Connectivity in Plant Species Differing in Clonality and Dispersal Mechanisms in Wetland Island Habitats

Abstract

In plants, long-distance dispersal is both attenuated and directed by specific movement vectors, including animals, wind, and/or water. Hence, movement vectors partly shape metapopulation genetic patterns that are, however, also influenced by other life-history traits such as clonal growth. We studied the relationship between area, isolation, plant-species richness, reproduction, and dispersal mechanisms with genetic diversity and divergence in 4 widespread wetland plant-species in a total of 20 island-like kettle-hole habitats surrounded by an intensive agricultural landscape. Our results showed that genetic parameters reflect the reproduction strategies with the highest genetic diversity being observed in the non-clonal, outcrossing Oenanthe aquatica compared to the clonal Lycopus europaeus, Typha latifolia, and Phragmites australis. Lycopus showed a positive relationship between genetic diversity and kettle-hole area, but a negative relationship with the number of neighboring kettle holes (less isolation). Genetic diversity increased with plant-species richness in the clonal species Phragmites and Lycopus; while it decreased in the non-clonal Oenanthe. Finally, genetic divergence and, therefore, connectivity differed between alternative dispersal strategies, where wind-dispersed Typha and Phragmites had a higher gene flow between the analyzed kettle holes compared with the insect-pollinated, hydrochorous Lycopus and Oenanthe. Our study provides information on genetic patterns related to reproduction and dispersal mechanisms of 4 common wetland species contributing to the understanding of the functioning of plant metacommunities occurring in kettle holes embedded in agricultural landscapes.

Exploring island syndromes: Variable matrix permeability in Phalaenopsis pulcherrima (Orchidaceae), a specialist lithophyte of tropical Asian inselbergs

“…Moreover, Nm estimates were significantly higher among populations belonging to each of the two genetic clusters ( Nm = 1.295 for HN group, Nm = 0.961 for IC group) than the mean for the species as a whole, suggesting greater gene flow at the scale of either landmass. Similarly, whilst our Fst estimate for P. pulcherrima is somewhat higher than the mean calculated for the orchid family as a whole (0.146; Philips et al., 2012 ), it is considerably lower than for many other terrestrial habitat island specialists (e.g., Pinheiro et al., 2014 ; Gao et al., 2015 ; Nistelberger et al., 2015 ; Lexer et al., 2016 ; Wanderley et al., 2018 ; Lozada-Gobilard et al., 2021 ), suggesting that the species is comparatively mobile in the context of habitat specificity.…”

“…Unifying these taxonomically disparate plants, and underlying their ecological specialisation, are a number of functional traits, including a variable combination of pollinator specificity, self-compatibility, a tendency towards selfing, frequent inbreeding among related individuals and/or short-range seed dispersal. In fact, these traits have been identified in a number of plants restricted to a variety of terrestrial island-like systems, and in some cases they have been linked to clonality and low reproductive success, too ( Lhuillier et al., 2006 ; Lozada-Gobilard et al., 2021 ). Combined with high habitat specificity, these attributes can render habitat island species prone to fixation and drift ( Pinheiro et al., 2014 ; Nistelberger et al., 2015 ).…”

“…Thus, the balance of vegetative growth versus sexual recruitment, and of selfing as opposed to outcrossing, will impact genetic diversity indices, and pollination and seed dispersal strategies will influence average gene flow distances and divergence ( Auffret et al., 2017 ). Indeed, studies of plants restricted to terrestrial island habitats have uncovered trade-offs between on-site persistence and genetic diversity ( Hmeljevski et al., 2014 ; Lozada-Gobilard et al., 2021 ), pollinator sharing and genetic differentiation ( Wanderley et al., 2018 ), pollen flow and genetic structuring ( Lexer et al., 2016 ), and seed dispersal and genetic divergence ( Rossetto et al., 2008 ; Gao et al., 2015 ). In some cases, these findings have been taken as evidence of the applicability of island biogeography theories to terrestrial habitat islands, with species that are more geographically isolated and more confined by habitat-specificity typically being found to exhibit an array of traits consistent with an island syndrome (e.g., fibrous fruits, gravity-dispersed seeds, strong resprouting behaviour, self-compatibility and pollinator specialisation).…”

Sex and Asex: A Clonal Lexicon

“…Although only a handful of studies have genotyped both haploid and diploid stages, Krueger-Hadfield et al (2021) found that available empirical data broadly support the theoretical predictions proposed by Stoeckel et al (2021). Lozada-Gobilard et al (2021) consider the importance of both reproductive mode (clonal versus nonclonal) and dispersal mechanism for shaping plant metacommunities occurring in island-like kettle-hole habitats. Ryan et al (2021) offers an intriguing look at how reproductive plasticity, in the form of temperature-dependent fission, may help shape the historical distribution of clones and genetic diversity in the non-native range of an invasive sea anemone.…”

Dispersal in Time- the role of seed banks in patchy population dynamics of an aquatic plant

“…The effect of patch size on local genetic diversity was negligible or even negative. This may be due to increased inter-speci c competition as the emergence of more competitive species in late successional stages may suppress seedling recruitment in O. aquatica, a process likely more pronounced in larger patches(Schöpke et al, 2019;Lozada-Gobilard et al, 2021) ultimately resulting in ephemeral population built-up. Hence, unlike in populations that are resulting from progressive fragmentation of continuous habitat, the extent of genetic variation and connectivity in our study system is less a matter of patch size(Plue et al, 2017) than a matter of small-scale environmental conditions and historical population establishment in the naturally scattered landscape.…”