Buoyancy, salt tolerance and germination of coastal seeds: implications for oceanic hydrochorous dispersal

2010 ◽  
Vol 37 (12) ◽  
pp. 1175 ◽  
Author(s):  
Lydia K. Guja ◽  
David J. Merritt ◽  
Kingsley W. Dixon
Keyword(s):  
Salt Tolerance ◽  
Saline Water ◽  
Long Distance Dispersal ◽  
Single Factor ◽  
Long Distance ◽  
Plant Dispersal ◽  
Salt Response ◽  
Coastal Plant ◽  
Dispersal Unit ◽  
Adverse Environmental Conditions

Many coastal plant species are widely distributed, including several pan-global species. Long-distance dispersal and physiological resilience of diaspores (i.e. the plant dispersal unit encompassing the seed and any additional surrounding or attached tissues at dispersal) to adverse environmental conditions are possible contributors to the presence of species over hundreds of kilometres of coastline. Dispersal by water (hydrochory) may occur in coastal habitats. This study investigated diaspore traits considered important for oceanic hydrochorous dispersal, including morphology, buoyancy and survival in seawater, and germination under saline conditions for 13 species common to Holocene dune communities in Western Australia. Of the diaspores of 13 species dominant in this coastal community, 11 floated in seawater, with 7 having >50% of diaspores buoyant after 14 days and some diaspores remaining buoyant for 70 days. Of the 10 species that germinated, diaspores of 9 survived exposure to seawater for up to 70 days. Germination of physiologically dormant seeds contained within indehiscent woody fruits and physically dormant seeds was least affected by time in seawater. The effects of varying concentrations of NaCl (0–500 mM) on germination differed between species, but most were able to recover and germinate when transferred to non-saline water. Three different patterns of salt response were observed. It appears likely a combination of diaspore traits, rather than a single factor, facilitate oceanic hydrochorous dispersal.

The angiosperm flora of the Archipelago Juan Fernandez (Chile): origin and dispersal

2006 ◽  
Vol 84 (8) ◽  
pp. 1266-1281 ◽  
Author(s):  
Gabriel Bernardello ◽  
Gregory J. Anderson ◽  
Tod F. Stuessy ◽  
Daniel J. Crawford
Keyword(s):  
New Zealand ◽  
Unit Length ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Dioecious Species ◽  
Dispersal Capability ◽  
Dispersal Unit ◽  
Unisexual Flowers ◽  
Dispersal Agents ◽  
Seeds And Fruits

We review the hypothesized origin and the methods of arrival of the angiosperm colonists to the Juan Fernandez Islands. We also summarize the dispersal capabilities of the current flora, including data on fruit type, fruit length, and dispersal unit length, correlating these features with dispersal and establishment. Most species originated from South America, followed by Pantropical, Australian, New Zealand, and Pacific colonizers. Sea and land birds were the most important initial long-distance dispersal agents. Most colonizing species are hermaphroditic flowered, and thus all dispersal methods are represented among them. Monoecious, andromonoecious and gynomonoecious, dioecious, and polygamous species were mainly carried by birds. Most wind- and bird-pollinated colonizing genera arrived with birds as did most annual herbs and species with bright-colored flowers. In the current flora, the majority of the species have dry fruits. In monoecious, andromonoecious and gynomonoecious, and dioecious species, achenes predominate. Fleshy fruits are limited to perennials. Most species have medium to small dispersal units, and generally, the larger the flower, the larger the fruit. Large- and medium-sized dispersal units are common in shrubs and trees. Abiotic dispersal is common in the current flora, which may reflect the ancestral dispersal capability of the colonizers, or adaptation to the absence of a fauna to disperse seeds and fruits. Anemochorous and autochorous species are mainly perennial and have medium to large, unisexual flowers. Anemochorous species have small dispersal units and dull-colored flowers, whereas large dispersal units and brightly colored flowers are frequent in autochorous species. Medium-sized dispersal units are represented in autochorous or ornithochorous species. The establishment and evolution of this flora was previously discussed to have occurred with very few pollination and (or) reproductive options. This study suggests that elements associated with dispersal are also analogously limited.

scholarly journals Spatial structure of natural boxwood and the invasive box tree moth can promote coexistence

2020 ◽  
Author(s):  
Léo Ledru ◽  
Jimmy Garnier ◽  
Christiane Gallet ◽  
Camille Noûs ◽  
Sébastien Ibanez
Keyword(s):  
Spatial Structure ◽  
Spatial Dynamics ◽  
Field Measurements ◽  
Global Scale ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
Moth Population ◽  
Plant Dispersal ◽  
Local Plant ◽  
Parameter Values

AbstractIn the absence of top-down and bottom-up controls, herbivores eventually exhaust their host plants driving them-selves to extinction. Poorly mobile herbivores may nevertheless go extinct only locally; then recolonize intact plant patches elsewhere, leaving time to previously over-exploited patches to regrow. However most herbivores such as winged insects are highly mobile, which may prevent the formation of spatial heterogeneity.We test if long-distance dispersal can preclude coexistence using the invasion of box tree moth (Cydalima perspectalis) in Europe as a model system. We build a lattice model and estimate the parameters with a combination of field measurements, experimental data and literature sources. Space corresponds either to a realistic boxwood landscape in the Alps, or to theoretical landscapes of various sizes.We find that both species persist under a large range of realistic parameter values, despite a severe reduction in boxwood biomass, with an alternation of outbreaks and near-to-extinction moth densities. Large landscapes are necessary for coexistence, allowing the formation of spatial structure. Low plant regrowth combined with long-distance dispersal could drive moths to extinction, because of resources depletion at the global scale even without a complete synchronization of the local dynamics. The spatial dynamics leads to formation of small plant patches evenly distributed in the landscape, because of a combination of local plant dispersal and global indirect competition between plants through their positive effect on moth population size. Coexistence is favored by such heterogeneous landscapes, because empty patches increase moth mortality during dispersal: the system thus creates its own stability conditions.

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