Do polyembryonic seeds of Carapa surinamensis (Meliaceae) have advantages for seedling development?

Abstract

Polyembryony is the differentiation and development of multiple embryos in a single seed. This characteristic can provide advantages, as more than one embryo is produced with the same amount of resources, and the probability of establishment of at least one seedling increases. However, sibling seedlings may also increase competition, affecting development and survival. In the present study, the possible advantages and disadvantages of polyembryony were analyzed in the initial establishment of seedlings of Carapa surinamensis (Meliaceae), a tree species that produces monoembryonic or polyembryonic seeds. In this regard, the development of single seedlings was compared with a pair of seedlings emerging from polyembryonic seeds. We compared the development of seedlings attached to or detached from each other and to the seed resources. We observed two levels of competition: (a) for the seed reserves during germination and initial development, as multiple embryos of C. surinamensis share the same reserves, and (b) for external factors, mostly space for root and shoot development, and also for light. Reducing the competition for external factors by separating the siblings was not enough to reduce the effects of competition for seed reserves in the first six months of development. Nevertheless, viable seedlings were produced in all treatments. Thus, depending on sprout management in the nursery, the number of seedlings per seed can be significantly increased by detaching the seedlings, or more vigorous seedlings can be obtained when only one seedling is maintained. Sementes poliembriônicas de Carapa surinamensis (Meliaceae) tem vantagens para o desenvolvimento das plântulas?RESUMO Poliembrionia é a diferenciação e o desenvolvimento de múltiplos embriões em uma única semente. Esta característica pode proporcionar diversas vantagens, como aumentar o número de embriões produzidos com a mesma quantidade de recursos, e aumentar a probabilidade de estabelecimento de pelo menos uma plântula de uma única semente. Por outro lado, a competição entre plântulas pode aumentar, afetando seu desenvolvimento e sobrevivência. Neste estudo, foram analisadas as possíveis vantagens e desvantagens da poliembrionia em sementes de andiroba, Carapa surinamensis (Meliaceae), uma espécie arbórea que produz sementes monoembriônicas ou poliembriônicas. Comparamos o desenvolvimento de plântulas únicas com o de pares de plântulas provenientes de sementes poliembriônicas. As plântulas foram mantidas unidas ou separadas entre si e ligadas à ou destacadas da semente. Os resultados revelaram dois níveis de competição: (a) pelas reservas da semente durante a germinação e desenvolvimento inicial da plântula, quando embriões múltiplos de C. surinamensis compartilham as mesmas reservas, e (b) por fatores externos, principalmente espaço para o desenvolvimento da raiz e da parte aérea, e luz. A redução da competição por fatores externos, através da separação das plântulas, não foi suficiente para reduzir os efeitos da competição pelas reservas das sementes no...

Reproductive compensation and selection among viable embryos drive the evolution of polyembryony

“…We develop a population genomic model to both test the two major advantages of simple polyembryony described by Kärkkäinen and Savolainen (1993), reproductive compensation (akin to egret mothers hedging their bets), and fitter offspring (akin to egret mothers preferentially raising high-fitness offspring) theories for the evolution of polyembryony, and to investigate how polyembryony changes embryonic and post-embryonic fitness and the genetic architecture of these complex traits. While these benefits of polyembryony have been acknowledged for some time, they have rarely been discussed together and their theoretical contributions to the evolution of polyembryony have not been disentangled (but see Ferreira et al 2019, for an empirical study of the influences of these processes on seedling establishment in a population of Carapa surinamensis that produces mono- and polyembryonic seeds).…”

Diaspore dispersal season influences root growth and seed traits, but not germination responses, of sympatric Piper species in a seasonal forest

“…2011; Ferreira et al . 2019). Although extra seedlings may increase the chances of survival per seed (Hotchkiss et al .…”

“…The lower germination of P. malacophyllum under water deficit and the lower viability of polyembryonic seeds may be related to competition between siblings (Cheplick 1992). In polyembryonic seeds, this competition among siblings occurs from the beginning of their development (Uma Shaanker& Ganeshaiah 1997) and may extend after germination, during the period of seedling establishment (Hotchkiss et al 2008;Mendes-Rodrigues et al 2011;Ferreira et al 2019). Although extra seedlings may increase the chances of survival per seed (Hotchkiss et al 2008), the analysed population of P. malacophyllum likely originated mainly from monoembryonic seeds, which are more frequent and remain viable for longer.…”