Maternal Determinants of Seed Dispersal in Cakile edentula: Fruit, Plant, and Site Traits

Donohue, Kathleen

doi:10.2307/176516

Cited by 42 publications

(70 citation statements)

References 54 publications

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“…This result agrees with previous results (Barbour 1970, 1972, Rodman 1974, Keddy 1980, Payne & Maun 1981 and reflects the property of the lower fruit segment (which remains attached in the parent) to remain in the proven and productive habitat (Donohue 1998). The upper fruit segments can be dispersed by wind for long distances, even though they do not possess any accessory structure (such as a sail) for wind dispersal.…”

Section: Discussionsupporting

confidence: 92%

Seed characteristics and dispersal of dimorphic fruit segments of Cakile maritima Scopoli (Brassicaceae) population of southern Brazilian coastal dunes

Cordazzo¹

2006

Rev. bras. Bot.

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-(Seed characteristics and dispersal of dimorphic fruits segments of Cakile maritima Scopoli (Brassicaceae) population of southern Brazilian coastal dunes). Cakile maritima occurs sporadically along the southern Brazilian coast, where it is restricted to more protected sites at the base of foredunes. Somatic dimorphism in C. maritima is manifested as morphologically distinct upper and lower fruit segments (silicules). The two morphs were tested for differences in size, number of seeds, dispersal ability and natural establishment. In the C. maritima population of southern Brazil, the lower silicule has more seeds than upper silicule, and lower seeds are more likely to abort than the upper ones. Seeds from upper segments were significantly larger than those from lower ones; however, their mass ranges overlap. The mean silicule mass was not significantly different from both segments, but the silicule/seed mass ratio from upper and lower segments was significantly different. Both segments had high ability to float in sea water, more than 50% were still afloat after 70 days. Nevertheless, dispersal occurs mainly to landward due to dominant wind action. Most of the seedlings were restricted to within a one-metre radius of the mother plant, and were principally derived from lower fruit segments.Key words -Cakile, dimorphic fruits, dispersal, seed production RESUMO -(Características das sementes e dispersão dos segmentos de frutos dimórficos de uma população de Cakile maritima Scopoli (Brassicaceae) nas dunas costeiras do Sul do Brasil). Cakile maritima ocorre esporadicamente ao longo da costa Sul do Brasil, onde é encontrada restrita aos locais mais protegidos na base das dunas frontais. O dimorfismo somático é manifestado como segmentos de frutos (silículas) superior e inferior, morfologicamente distintos. As sementes dos dois tipos de segmentos foram avaliadas quanto ao tamanho, número, capacidade de dispersão e estabelecimento em condições naturais. Na população de C. maritima no Sul do Brasil as silículas inferiores apresentaram maior número de sementes do que as siliculas superiores, e as sementes das silículas inferiores foram mais abortadas que as das superiores. As sementes dos segmentos superiores foram significativamente maiores do que aquelas dos segmentos inferiores; entretanto ocorreu uma sobreposição nos pesos entre elas. O peso médio das silículas dos dois segmentos não difere significativamente, mas a razão peso das silículas / peso das sementes foi significativamente diferente para os segmentos superior e inferior. Ambos segmentos apresentaram grande habilidade de flutuar em água salgada, superior a 50% após 70 dias. Todavia, a dispersão dos segmentos dos frutos ocorre principalmente em direção ao continente através da ação do vento. A maioria das plântulas encontradas no ambiente natural se encontrava restrita num raio de um metro da planta-mãe, e era originada principalmente de sementes dos segmentos inferiores dos frutos.Palavras-chave -Cakile, dimorfismo de frutos, dispersão, produção de s...

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Section: Discussionsupporting

confidence: 92%

Seed characteristics and dispersal of dimorphic fruit segments of Cakile maritima Scopoli (Brassicaceae) population of southern Brazilian coastal dunes

Cordazzo¹

2006

Rev. bras. Bot.

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“…Mobile organisms can increase their dispersal distance with increasing density by altering behavioral responses (39). Alternatively, dispersal distances can decrease with density when crowding decreases reproductive and dispersal ability (39,51,52) or in animals (notably small mammals) with strong group behavior (39,53,54).…”

Section: Discussionmentioning

confidence: 99%

Density dependence in demography and dispersal generates fluctuating invasion speeds

Sullivan

Miller

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Density dependence plays an important role in population regulation and is known to generate temporal fluctuations in population density. However, the ways in which density dependence affects spatial population processes, such as species invasions, are less understood. Although classical ecological theory suggests that invasions should advance at a constant speed, empirical work is illuminating the highly variable nature of biological invasions, which often exhibit nonconstant spreading speeds, even in simple, controlled settings. Here, we explore endogenous density dependence as a mechanism for inducing variability in biological invasions with a set of population models that incorporate density dependence in demographic and dispersal parameters. We show that density dependence in demography at low population densities-i.e., an Allee effect-combined with spatiotemporal variability in population density behind the invasion front can produce fluctuations in spreading speed. The density fluctuations behind the front can arise from either overcompensatory population growth or density-dependent dispersal, both of which are common in nature. Our results show that simple rules can generate complex spread dynamics and highlight a source of variability in biological invasions that may aid in ecological forecasting.Allee effects | biological invasion | density-dependent dispersal | integrodifference equations | invasive species F luctuations in population size have long fascinated ecologists and fueled a now-classic debate over whether populations are governed by extrinsic environmental factors or intrinsic selflimitation (1). One of the most important advances of 20th century ecology was the discovery that intrinsic density feedbacks can cause population densities to fluctuate, even in constant environments (2-4). This discovery helped resolve the important role of density dependence in population regulation, revealing that strong regulating forces can generate dynamics superficially consistent with no regulation at all. Our understanding of temporal fluctuations in population size stands in sharp contrast with our relatively poor understanding of fluctuations in the spatial dimension of population growth: spread across landscapes.Understanding the dynamics of population spread takes on urgency in the current era of human-mediated biological invasions and range shifts in response to climate change. The velocity of spread or "invasion speed" is a key summary statistic of an expanding population and an important tool for ecological forecasting (5). Estimates of invasion speed are often derived from regression methods that describe change in spatial extent with respect to time (6-8). Implicit in this approach is the assumption that the true spreading speed is constant and that deviations from it represent "error" in the underlying process or human observation of the process. This assumption is reinforced by longstanding theoretical predictions that, under a wide range of conditions, a population will asymptotically spread w...

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“…Similarly, in plants, maternally determined seed architecture often determines where and how long after dispersal a seed germinates (Chambers & MacMahon 1994;Galloway 2005), even in those cases where seeds are animal distributed. Some plant species have maternally determined alternative seed morphs (Donohue 1998) as well as alternative life histories (Boyd et al 2007). In such cases, the influence on the offspring phenotype could be attributed to the maternal oviposition site choice behaviour or seed architecture, where the ultimate effect of mothers on their offspring is mediated via the ecological environment.…”

Section: Introductionmentioning

confidence: 99%

What are maternal effects (and what are they not)?

Wolf

Wade

2009

Phil. Trans. R. Soc. B

461

392

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Maternal effects can play an important role in a diversity of ecological and evolutionary processes such as population dynamics, phenotypic plasticity, niche construction, life-history evolution and the evolutionary response to selection. However, although maternal effects were defined by quantitative geneticists well over half a century ago, there remains some confusion over exactly what phenomena should be characterized as maternal effects and, more importantly, why it matters and how they are defined. We suggest a definition of maternal effects as the causal influence of the maternal genotype or phenotype on the offspring phenotype. This definition differs from some definitions in that it treats maternal effects as a phenomenon, not as a statistical construct. The causal link to maternal genotype or phenotype is the critical component of this definition providing the link between maternal effects and evolutionary and ecological processes. We show why phenomena such as maternal cytoplasmic inheritance and genomic imprinting are distinct genetically from and have different evolutionary consequences than true maternal effects. We also argue that one should consider cases where the maternal effect is conditional on offspring genotype as a class of maternal effects.

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Maternal Determinants of Seed Dispersal in Cakile edentula: Fruit, Plant, and Site Traits

Cited by 42 publications

References 54 publications

Seed characteristics and dispersal of dimorphic fruit segments of Cakile maritima Scopoli (Brassicaceae) population of southern Brazilian coastal dunes

Seed characteristics and dispersal of dimorphic fruit segments of Cakile maritima Scopoli (Brassicaceae) population of southern Brazilian coastal dunes

Density dependence in demography and dispersal generates fluctuating invasion speeds

What are maternal effects (and what are they not)?

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