Local extinctions have cascading effects on ecosystem functions, yet little is known about the potential for the rapid evolutionary change of species in human-modified scenarios. We show that the functional extinction of large-gape seed dispersers in the Brazilian Atlantic forest is associated with the consistent reduction of the seed size of a keystone palm species. Among 22 palm populations, areas deprived of large avian frugivores for several decades present smaller seeds than nondefaunated forests, with negative consequences for palm regeneration. Coalescence and phenotypic selection models indicate that seed size reduction most likely occurred within the past 100 years, associated with human-driven fragmentation. The fast-paced defaunation of large vertebrates is most likely causing unprecedented changes in the evolutionary trajectories and community composition of tropical forests.

https://science.sciencemag.org/content/sci/340/6136/1086.full.pdf

Functional extinction of birds drives rapid evolutionary changes in seed size

From Avicennia to Zizania: seed recalcitrance in perspective.

Seed structure and histochemistry in the palm Euterpe edulis

The Brazilian biomes (Amazon, Atlantic Forest, Cerrado, Caatinga, Pantanal, and Pampa) comprise one of the highest levels of plant diversity in the world; however, non-sustainable practices, deforestation, and land use have resulted in significant losses and fragmentation of the native forests. These ecosystems are now threatened and protection of their native plants through ex situ conservation is an urgent necessity. Cryopreservation and in vitro conservation are complementary options for securing and protecting Brazil’s native plant species because their potential economic value is critically important to develop strategies that will (1) support their sustainable utilization, (2) protect against the over-exploitation of species growing in natural habitats, and (3) conserve the genetic diversity of germplasm from species of different provenances. Biotechnological approaches will help to address future economic and environmental demands placed upon already at-risk species. Conserving seed germplasm ex situ provides an additional safeguard against the risks (e.g., loss due to disease, climate change) of field conservation. Moreover, seed banks and cryobanks permit the long-term conservation of a wider genetic base; this offsets the labor and space intensive costs of conserving in the active growing state. This paper is a compilation of the current status of strategies applied for conserving Brazilian native plant species.

In vitro and cryogenic preservation of plant biodiversity in Brazil

Dehydration effects on germination and vigor of four pejibayeseed lots The dessication tolerance of four seed lots of spineless pejibaye( Bactris gasipaes Kunth) harvested at Yurimaguas (Peru); Camamuand Pirai do Norte (Bahia State, Brazil) and Pindorama (Sao PauloState, Brazil) was identified. The seeds were dried in a dryingchamber starting with undried controls. Samples were drawn every24 hours. Dessication effects were evaluated by means of germinationtest (until 184 days, vermiculite, 20-30 o C), germination first counting(36 days), germination speed and seed water content. It was verifiedthat seeds from that species are susceptible to dehydration, withhigher initial germination percentage (59 to 84%) when undried (47to 38% of water content). Water contents lower than 28 to 23%reduced significantly seed germination and vigor. All seeds died whenthe seed water content was lower than 15% (seed lots 2 and 4) and13% (seed lots 1 and 3). Keywords : Bactris gasipaes , peach palm, seed deterioration,recalcitrance, critical water content, lethal water content.

https://www.scielo.br/pdf/hb/v22n1/a23v22n1.pdf

Desidratação de sementes de quatro lotes de pupunheira: efeitos sobre a germinação e o vigor

In order to identify the desiccation tolerance of E. edulis seeds, four fruitlots were collected from the Campinas Agronomic Institute Palmae collection, located at Ubatuba, state of Sao Paulo, Brazil, and taken in moisture-proof containers to the College of Agriculture in Botucatu, state of Sao Paulo, There, the fruits were shelled and the seeds were dried, either under siliea gel conditions or in a drying chamber. The effects of dehydration were evaluated by measurements of the germination, embryo protrusion, germinative button plumule, speed of emergence, seedling length, seed dry matter and water content. Differences among seedlots and between harvest season for most of the traits were observed. Euterpe edulis seedlots seem to tolerate water content reductions until 39% without significant reduction in germination and vigor. Below this value, most of the evaluated traits were negatively affected. Total loss of germination was observed whenever seed water content was reduced to values below 21%.

J. Nakagawa

Papers

Desiccation tolerance of four seedlots from Euterpe edulis Mart.