A new seed coat water-impermeability mechanism in <i>Chaetostoma armatum</i> (Melastomataceae): evolutionary and biogeographical implications of physiophysical dormancy

Pereira

2019

Plants

Seeds of Cistus ladanifer experience bursts of germination following fires. The effects of heat shock from 10 °C to 150 °C on seed germination were investigated by final germination plus the number of days required for germination to start and finish, and symmetry of cumulative germination. The occurrence of physical dormancy in C. ladanifer seeds was investigated by a variety of methods, including imbibition, scanning electron microscopy (SEM) and light microscopy, and use of dyes. The significance of responses of C. ladanifer seeds to fires was investigated essentially by abstracting existing literature and by using fire effects models and simulations. Parameters of germination were variously affected by heat treatments—positively in the range 80–100 °C, negatively above 130 °C. Non-dormancy was consistently found in about 30% of seeds but no evidence was obtained to support the existence of physical dormancy in the dormant fraction of C. ladanifer seeds. Two complementary processes seem to be in place in seeds response to fire. A direct fire-driven increase in germination of virtually all seeds in response to the appropriate heat load produced by fire or, in the absence of such heat loads, the germination of the non-dormant fraction provided that above-ground vegetation burns.

Section: Discussioncontrasting

confidence: 62%

Seed Germination in Cistus ladanifer: Heat Shock, Physical Dormancy, Soil Temperatures and Significance to Natural Regeneration

Pereira

2019

Plants

“…microrefugia and climate change (Cooper et al 2011;Keppel et al 2012;Ashcroft and Gollan 2013;Brendonck et al 2014;Mee and Moore 2014;Barrett and Yates 2015), the evolution of trees (Raven and Andrews 2010;Cramer 2012), clonality (Binks et al 2015), the occurrence of OCBISs (old, climatically buffered, infertile seascapes - Langlois et al (2012), significant gaps in Darwinian evolutionary theory (Hopper and Lambers 2009), old salt lake systems (Bui et al 2014a, b), and evolution of novel aquatic traits (Tuckett et al 2010;Davies and Stewart 2014). Seed biological studies are beginning to explore the relevance of Ocbil theory to their discipline (Tuckett et al 2010;Hidayati et al 2012;Wilman et al 2014;Alvarado et al 2015b;Edwards et al 2015;Ribeiro et al 2015).…”

Section: Citation Review Areas Of Focus In the Literature And Summarmentioning

confidence: 99%

Biodiversity hotspots and Ocbil theory

Hopper

Silveira

Fiedler³

2015

Plant Soil

162

129

Background Ocbil theory aims to develop hypotheses explaining the evolution and ecology of, and best conservation practices for, biota on very old, climatically buffered, infertile landscapes (Ocbils). Scope This paper reviews recent multi-disciplinary literature inspired by or reacting to aspects of Ocbil theory and discusses how it can assist conservation in biodiversity hotspots. Conclusions Ocbils occur in at least 12 out of 35 known terrestrial hotspots, but also in other biologically significant sites. Most evidence comes from the Southwest Australian and Greater Cape Floristic Regions, South America's Pantepui, and the Campo Rupestre of Brazil, though predictions of the theory have been corroborated in 22 sites across South America, Western and Eastern Africa, Southern Asia, and Oceania. Most hypotheses have been corroborated, indicating that Ocbil theory has survived largely intact after 6 years of independent scientific critique, quantitative experimentation, and development. The theory also has been extended to allow identification and characterization of OCBISs (old, climatically-buffered, infertile seascapes), and OCFELs (old, climatically-buffered, fertile landscapes). We illustrate that the principles of Ocbil theory are key to conservation of biodiversity at global scale and provide new directions for research that can improve the theoretical and practical contributions of Ocbil theory.

“…Seeds of both species are probably dormant, but the type of dormancy is unknown. The dormancy types and metabolism in Melastomataceae are poorly known, although some studies have showed multiple dormancy [36], physiological dormancy [45] and water impermeability in seed coat [46]. The spreading of the germination through time, typical of seeds of several Melastomataceae, permits the inclusion of these seeds in the category of relative dormancy as proposed by Labouriau [47], but the type of dormancy is unclear because the spreading of the germination through time can be due to physical, morphological, physiological or combination of these causes.…”

Section: Discussionmentioning

confidence: 99%

Are the Alien Species of Melastomataceae and Bombacoideae a Potential Risk for Brazilian Cerrado?

Mendes‐Rodrigues¹,

Oliveira²,

Marinho³

et al. 2019

OALib

The cultivation of species in urban areas for landscaping or consumption has increased in cities surrounded by Cerrado, putting in risk the local flora. Thus, the objective of this paper was to describe seed germination and seedling emergence of five urban cultivated species of Melastomataceae and Bombacoideae and compare them with Cerrado native species to evaluate if they offer any risk to local vegetation. The seeds were collected in the urban area of Uberlândia, within the Brazilian Cerrado. We calculated germination and emergence measurements and compared them to literature data. Seeds of Bombax ceiba and Pachira aquatica had a germination and emergence pattern similar to other Bombacoideae. Tibouchina pulchra and Tibouchina granulosa also had a similar pattern to other Melastomataceae, with low germinability. In contrast, seed germination of Heterotis rotundifolia, an invasive African species, was similar to Clidemia hirta, also known as invasive, including the higher spreading of germination through time, a common character of invasive plants. Seed germination of H. rotundifolia was more similar to Cerrado species with dormant seeds, showing high germinability and germination spread through time. These features added to its fast-growing due to its decumbent herbaceous habit that forms dense mats could offer risks to local species. Thus, it is being recommended that its populations be monitored.