Seed Set and Seed Mass in Ipomopsis aggregata: Variance Partitioning and Inferences about Postpollination Selection

AbstractA straightforward way to explore variation between communities is to calculate dissimilarity indices and relate them with environmental and spatial variables. Communities are most often represented by the (relative) abundances of taxa they comprise; however, more recently, the distribution of traits of organisms included in the communities has been shown more strongly related to ecosystem properties. In this study, we test whether taxon- or trait-based dissimilarity is correlated more tightly with environmental difference and geographical distance and how the abundance scale influences this correlation. Our study system is grassland vegetation in Hungary, where we sampled vegetation plots spanning a long productivity gradient from open dry grasslands to marshes in three sites. We considered three traits for vascular plants: canopy height, specific leaf area and seed mass. We obtained field estimates of normalized vegetation difference index (NDVI) as proxy of productivity (water availability) for each plot. We calculated between-community dissimilarities using a taxon-based and a trait-based index, using raw and square-root transformed abundances and presence/absence data. We fitted distance-based redundancy analysis models with NDVI difference and geographical distance on the dissimilarity matrices and evaluated them using variance partitioning. Then, using the pooled data, we calculated non-metric multidimensional scaling ordinations (NMDS) from all types of dissimilarity matrices and made pairwise comparisons using Procrustes analysis. Data analysis was done separately for the three sites.We found that taxonomical dissimilarity matches environmental and spatial variables better when presence/absence data is used instead of abundance. This pattern was mainly determined by the increasing variation explained by space at the presence/absence scale. In contrast to this trend, with trait-based dissimilarity, accounting for abundance increased explained variation significantly due to the higher explanatory power of NDVI. With abundance data, considering traits improved environmental matching to a great extent in comparison with taxonomical information. However, with presence/absence data, traits brought no advantage over taxon-based dissimilarity in any respect. Changing the abundance scale caused larger difference between ordinations in the case of trait-based dissimilarity than with taxonomical dissimilarity.We conclude that considering relevant traits improves environmental matching only if abundances are also accounted for.Supporting informationAdditional graphs supporting the results are presented as appendix.Open researchData used in this research are publicly available from Dryad ###link to be supplied upon acceptance###

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Near-neighbour optimal outcrossing in the bird-pollinated Anigozanthos manglesii

Annals of Botany ◽

10.1093/aob/mcz091 ◽

2019 ◽

Vol 124 (3) ◽

pp. 423-436 ◽

Cited By ~ 2

Author(s):

Bronwyn M Ayre ◽

David G Roberts ◽

Ryan D Phillips ◽

Stephen D Hopper ◽

Siegfried L Krauss

Keyword(s):

Reproductive Success ◽

Seed Set ◽

Spatial Genetic Structure ◽

Seed Mass ◽

Nearest Neighbour ◽

Near Neighbour ◽

Nectar Feeding ◽

Hand Pollination ◽

Germination Success ◽

The Impact

Abstract Background and Aims In plants, the spatial and genetic distance between mates can influence reproductive success and offspring fitness. Negative fitness consequences associated with the extremes of inbreeding and outbreeding suggest that there will be an intermediate optimal outcrossing distance (OOD), the scale and drivers of which remain poorly understood. In the bird-pollinated Anigozanthos manglesii (Haemodoraceae) we tested (1) for the presence of within-population OOD, (2) over what scale it occurs, and (3) for OOD under biologically realistic scenarios of multi-donor deposition associated with pollination by nectar-feeding birds. Methods We measured the impact of mate distance (spatial and genetic) on seed set, fruit size, seed mass, seed viability and germination success following hand pollination from (1) single donors across 0 m (self), <1 m, 1–3 m, 7–15 m and 50 m, and (2) a mix of eight donors. Microsatellite loci were used to quantify spatial genetic structure and test for the presence of an OOD by paternity assignment after multi-donor deposition. Key results Inter-mate distance had a significant impact on single-donor reproductive success, with selfed and nearest-neighbour (<1 m) pollination resulting in only ~50 seeds per fruit, lower overall germination success and slower germination. Seed set was greatest for inter-mate distance of 1–3 m (148 seeds per fruit), thereafter plateauing at ~100 seeds per fruit. Lower seed set following nearest-neighbour mating was associated with significant spatial genetic autocorrelation at this scale. Paternal success following pollination with multiple sires showed a significantly negative association with increasing distance between mates. Conclusions Collectively, single- and multi-donor pollinations indicated evidence for a near-neighbour OOD within A. manglesii. A survey of the literature suggests that within-population OOD may be more characteristic of plants pollinated by birds than those pollinated by insects.

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Plant size, geitonogamy and seed set in Ipomopsis aggregata

Oecologia ◽

10.1007/bf00317407 ◽

1992 ◽

Vol 89 (3) ◽

pp. 310-315 ◽

Cited By ~ 77

Author(s):

Tom J. de Jong ◽

Nickolas M. Waser ◽

Mary V. Price ◽

Richard M. Ring

Keyword(s):

Seed Set ◽

Plant Size ◽

Ipomopsis Aggregata

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Growth, seed set and nitrogen fixation of 28 annual legume species on 3 Vertosol soils in southern New South Wales

Australian Journal of Experimental Agriculture ◽

10.1071/ea02141 ◽

2003 ◽

Vol 43 (9) ◽

pp. 1101 ◽

Cited By ~ 21

Author(s):

B. S. Dear ◽

G. A. Sandral ◽

M. B. Peoples ◽

B. C. D. Wilson ◽

J. N. Taylor ◽

...

Keyword(s):

Seed Set ◽

Seed Mass ◽

Individual Species ◽

Curvilinear Relationship ◽

First Year ◽

Legume Species ◽

South Wales ◽

Melilotus Albus ◽

Mass Size ◽

The Individual

The adaptation of 28 annual legume species to heavy clay cracking soils prone to waterlogging during winter was evaluated at 3 sites ranging in pH (CaCl2) from 4.6 to 5.4 in the wheatbelt of southern NSW. The 32 accessions and cultivars included Medicago arabica, M. polymorpha, Melilotus albus (syn. M. alba), Trigonella balansae, and 24 Trifolium species. Species identified as potentially valuable new plants for these environments included Trifolium hirtum, T. echinatum, T. glanduliferum and M. arabica for winter production, and M. albus, T. echinatum, T. glanduliferum, T. isthmocarpum, T. pauciflorum, and T. purpureum for spring production. Current cultivars of T. subterraneum subsp. brachycalycinum cv. Clare, and subsp. yanninicum, cv. Riverina, T. resupinatum cvv. Kyambro, Nitro and Prolific, and T. michelianum cvv. Bolta and Paradana, and M. polymorpha cv. Santiago, also proved well adapted. Average seed mass (size) of the legume species varied from 0.3 mg to 8.9 mg/seed with a negative curvilinear relationship between individual seed mass of a species and the number of seed set at all 3 sites (r2 = 0.59–0.89). Seed mass of a species did not influence winter productivity or seed yield. The percentage of nitrogen biologically fixed by the individual species in the first year averaged over the 3 sites varied from 30 to 75%. Species which fixed the highest proportion of their nitrogen requirement were T. subterraneum, M. arabica, T. isthmocarpum and T. resupinatum cv. Kyambro, all fixing >62% of their shoot nitrogen and having a nitrogen content >3.0%. In contrast, T. sylvaticum, T. cherleri, T. spumosum, T. stellatum and T. glomeratum performed poorly at most sites, and fixed <42% of their nitrogen requirements (averaged over 3 sites) with <2.5% nitrogen in their tissue in spring.

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Coat thickness and hard-seededness in some Medicago and Trifolium species

Seed Science Research ◽

10.1017/s0960258500001434 ◽

1992 ◽

Vol 2 (4) ◽

pp. 243-249 ◽

Cited By ~ 15

Author(s):

L. Russi ◽

P. S. Cocks ◽

E. H. Roberts

Keyword(s):

Electron Microscope ◽

Seed Coat ◽

Seed Set ◽

Morphological Changes ◽

Seed Mass ◽

Palisade Layer ◽

North West ◽

Morphology And Structure ◽

Cuticular Layer ◽

Scanning Electron

AbstractThe seeds of three medics (Medicago orbicularis, M. rigidula and M. rotata) and three clovers (Trifolium stellatum, T. campestre and T. tomentosum) were collected from a pasture in north-west Syria on three occasions: immediately after seed set, at the end of the dry season, i.e. 4 months after seed set, and 16 months after seed set. Complete and sectioned seeds were observed with a scanning electron microscope. Morphological changes and differences in thickness of the seed coat were related to the hard-seededness of the samples collected in the seed bank before the onset of the rainy season. The morphology and structure of the seed coat of all six species were typical of papilionoid legumes. The species with the softest seeds (T. stellatum) showed a very thin and discontinuous cuticular layer at seed maturation (0.16 μm), while a thick and continuous cuticle (4.24 μm) was characteristic of the hardest-seeded species (M. orbicularis). The lens region of seed of all species except T. campestre was weakened after a few months in the field. This weakening was also found in seeds which were certainly hard, but the cracks in the lens region were apparently not deep enough to allow imbibition. Even when large areas of the palisade layer were removed from the lens region of seeds of M. rotata, this was not sufficient to permit water uptake. Differences in the seed coat thickness of the six species accounted for differences in seed dormancy only when seed mass was taken into account.

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THE EFFECT OF DELPHINIUM NELSONII POLLEN ON SEED SET IN IPOMOPSIS AGGREGATA, A COMPETITOR FOR HUMMINGBIRD POLLINATION

American Journal of Botany ◽

10.1002/j.1537-2197.1985.tb08363.x ◽

1985 ◽

Vol 72 (7) ◽

pp. 1144-1148 ◽

Cited By ~ 36

Author(s):

Joshua R. Kohn ◽

Nickolas M. Waser

Keyword(s):

Seed Set ◽

Ipomopsis Aggregata ◽

Hummingbird Pollination

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Population structure effect on reproduction of a rare plant: beyond population size effect

Canadian Journal of Botany ◽

10.1139/b06-078 ◽

2006 ◽

Vol 84 (9) ◽

pp. 1371-1379 ◽

Cited By ~ 13

Author(s):

Arantzazu L. Luzuriaga ◽

Adrián Escudero ◽

María José Albert ◽

Luis Giménez-Benavides

Keyword(s):

Population Structure ◽

Population Size ◽

Reproductive Output ◽

Seed Set ◽

Plant Density ◽

Size Structure ◽

Seed Mass ◽

Plant Size ◽

Aggregation Index ◽

Negative Effect

Several studies have evaluated the effect of population size on plant reproductive output, but there are few studies concerning the effect of other population structure variables on plant reproduction. In this study, we went beyond population size effect and we tested the effect of some population spatial variables such as plant density, plant aggregation, population structure, and population identity on plant reproductive success and fitness in large populations (>1000 individuals) of Centaurea hyssopifolia Vahl., an endemic species of central Spain. We analysed the reproductive output (capitula, flowers, and seeds) and another two components of plant fitness (seed mass and germinability) in 350 individuals from seven populations in 2002 and 2003. All populations were similar in size but differed in other population spatial characteristics (density, plant aggregation pattern, population plant size structure). We used Morisita’s aggregation index to characterize the level of plant aggregation within populations. Population plant size structure variable determined the proportion of different sized plants in a population. We used generalized linear mixed models to model the contribution of these population spatial variables to several reproductive parameters. Our results showed that whereas the aggregation index exerted a positive control on plant seed set, plant density had a negative effect, and plant population size structure did not significantly influence any response variable. Density only exerted a negative effect on seed set. On the contrary, plant aggregation had a positive effect. Seed mass was also larger in more aggregated populations, although no differences in seed germinability were observed. We detected the effect of population attributes on reproduction in terms of seed set, but we did not detect any effect on other overall reproductive variables measured at plant level. To sum up, our results showed that if population fragments were large enough, spatial population attributes became crucial factors for plant reproductive output and fitness. These easily measurable population variables may improve the conservation management of rare plant species.

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Interspecific pollen transfer as a mechanism of competition: effect of Castilleja linariaefolia pollen on seed set of Ipomopsis aggregata

Canadian Journal of Botany ◽

10.1139/b00-034 ◽

2000 ◽

Vol 78 (5) ◽

pp. 600-606 ◽

Cited By ~ 20

Author(s):

Christina M Caruso ◽

Monica Alfaro

Keyword(s):

Seed Set ◽

Pollen Transfer ◽

Competition Effect ◽

Priority Effect ◽

Negative Effects ◽

Ipomopsis Aggregata ◽

Interspecific Pollen Transfer ◽

Hand Pollination ◽

Stigma Closure ◽

Pollen Flowers

We investigated whether the deposition of Castilleja linariaefolia (Pursh) V. Grant pollen on flowers of Ipomopsis aggregata (Benth.) in DC. reduced I. aggregata's seed set. Ipomopsis flowers were hand-pollinated with either pure conspecific pollen (the control) or with C. linariaefolia pollen applied prior to, simultaneously with, or following conspecific pollen. Flowers that were simultaneously given C. linariaefolia and I. aggregata pollen received 39% less conspecific pollen than flowers in the control, but did not set fewer seeds per fruit. Flowers that were given C. linariaefolia pollen first received 30% less conspecific pollen and set 38% fewer seeds per fruit than the control. These results suggest that there is a priority effect; deposition of C. linariaefolia pollen on I. aggregata flowers results in competition, but only when C. linariaefolia pollen is deposited first. Unlike pollen of another competitor of I. aggregata (Delphinium nelsonii Greene. Per.), C. linariaefolia pollen caused competition without inducing an increased rate of stigma closure. Only 12% of I. aggregata's stigmas closed when C. linariaefolia pollen was deposited, and seed set of I. aggregata was reduced relative to the control whether their stigmas closed or not. The low rate at which C. linariaefolia pollen induces closure of I. aggregata's stigmas could be an adaptation to reduce the negative effects of competition.Key words: Castilleja linariaefolia, competition, hand pollination, hummingbirds, Ipomopsis aggregata, pollination.

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Reproductive ecology of the Australian herb Trachymene incisa subsp.incisa (Apiaceae)

Australian Journal of Botany ◽

10.1071/bt02001 ◽

2002 ◽

Vol 50 (5) ◽

pp. 619 ◽

Cited By ~ 19

Author(s):

Yvonne C. Davila ◽

Glenda M. Wardle

Keyword(s):

Life Histories ◽

Seed Set ◽

Reproductive Ecology ◽

Seed Mass ◽

Perennial Herb ◽

Male And Female ◽

Pollen Presentation ◽

And Gender ◽

Diversity Of Life ◽

Reproductive Characters

Within the Apiaceae, subtle variation in reproductive characters such as dichogamy, pollinator specificity and umbel density may cause cryptic specialisation and be responsible for the diversity of life histories and gender expression in the family. To address the paucity of information for Australian species we investigated the reproductive ecology of the native perennial herb, Trachymene incisa Rudge subsp. incisa. T. incisa exhibits protandry within flowers and umbels; however, an overlap of 3 days in male and female phases among umbels of consecutive orders permits geitonogamous pollination. There are 72 ± 2.0 (n = 74) white flowers per umbel and nectar is presented during the male and female phases. Apis mellifera appears to be the main diurnal pollinator. The pollen : ovule ratio is 1902 : 1, indicating that T. incisa is a facultatively xenogamous species. The long phase of pollen presentation and the low natural seed set of about 45% implies that many flowers are functioning as pollen donors only. Controlled pollination experiments showed that self-pollen led to lower seed set than cross, open and supplemental applications. Early and late-produced cohorts differed in days to emergence but not in seed mass or final percentage emergence.

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