Pollen quantity and quality as explanations for low seed set in small populations exemplified by Eupatorium (Asteraceae )

1995 ◽  
Vol 82 (8) ◽  
pp. 1000-1006 ◽  
Author(s):  
Diane L. Byers
Keyword(s):  
Seed Set ◽  
Small Populations ◽  
Pollen Quantity

Plant-level fecundity and andromonoecy in three common (Melaleuca styphelioides, M. thymifolia, M. nodosa) and one rare (M. deanei) Melaleuca (Myrtaceae) species of the Sydney region

2014 ◽  
Vol 62 (4) ◽  
pp. 276 ◽  
Author(s):  
Alison Hewitt ◽  
Paul Holford ◽  
Adrian Renshaw ◽  
Anthony Haigh ◽  
E. Charles Morris
Keyword(s):  
Reproductive Performance ◽  
Fruit Set ◽  
Seed Set ◽  
Low Frequency ◽  
Common Species ◽  
Flowering Plants ◽  
Breeding Systems ◽  
Small Populations ◽  
Small Field ◽  
Plant Level

This paper reports plant-level measures of reproductive performance from large and small field populations of the vulnerable species Melaleuca deanei F.Meull. compared with three common species within the genus: Melaleuca nodosa (Sol. ex Gaertn.) Sm., Melaleuca thymifolia Sm. and Melaleuca styphelioides Sm. Measures reported include average seed numbers per capsule and per plant; average fruit loads per plant; the proportion of buds that become flowers and thence fruits (fruit set); the number of ovules per flower and seed : ovule ratios (seed set); and floral morphologies. Results indicate that when M. deanei flowers, bud to flower ratios and flower to fruit ratios are not reduced compared with the congeners or between large and small populations. Seed loads per plant held by fruiting plants were comparable between the species and between large and small populations of M. deanei. Seed to ovule ratios were in the order of 5–9% in M. nodosa; 5–7% in M. styphelioides; 7–10% in M. deanei; and 12–15% in M. thymifolia. Larval herbivory of ovules was recorded in M. nodosa and pre-dispersal seed predation noted in M. thymifolia. Andromonoecy was recorded in two of the species at rates of 0.9–3.1% (M. deanei) and 2.9–7% (M. thymifolia). Results suggest that seed production within smaller populations of M. deanei is poor because of a low frequency of flowering and a low proportion of flowering plants per population, rather than plant-level pollination, fruit- or seed-set barriers. Further study is needed to determine the triggers to flowering, the breeding systems, the extent of clonality and the germination and establishment requirements in these species.

scholarly journals Inbreeding and inbreeding depression of Paeonia decomposita (Paeoniaceae), a threatened endemic plant to China

2019 ◽  
Vol 60 (1) ◽  
Author(s):  
Shi-Quan Wang
Keyword(s):  
Seed Production ◽  
Inbreeding Depression ◽  
Evolutionary Biology ◽  
Seed Set ◽  
Extinction Risk ◽  
Small Populations ◽  
Endemic Plant ◽  
Pollinator Limitation ◽  
Potential Threat ◽  
Selfed Progeny

Abstract Background Small populations are predominantly vulnerable to inbreeding and inbreeding depression (ID). Owing to increased levels of inbreeding on individuals in small populations, ID could decrease the population growth rate, as well as its effective size, and exacerbate the extinction risk. Inbreeding depression remains a crucial area of research in conservation biology, ecology, and evolutionary biology. This study aims to elucidate the reproductive biology, inbreeding, and ID of Paeonia decomposita and to conserve, manage, and improve them better in the future. Results Paeonia decomposita belongs to a xenogamous category and is partially self-compatible; moreover, it requires pollinators for seed production. Lately, the occurrence of pollination and pollinator limitations has affected the seed set. Low seed set primarily correlated with an abnormality of meiosis in the pollen mother cell, moderate to low genetic diversity, drought and extreme weather, pollinator limitation, or carpel space limit. One of the primary reasons for endangered mechanism in P. decomposita is the low seed set under natural conditions. The cumulative value of ID was positive, and outcrossed progeny outperformed selfed progeny. Conclusions Paeonia decomposita requires pollinators to ensure seed production either through autogamy, geitonogamy, or allogamy. It is both allogamous and partially self-compatible, as well as a successful outcrosser. Inbreeding occurs frequently and results in ID, which imposes a potential threat to the survival of populations. Besides, it needs conservation via in situ and natural return methods.

Pollen limitation and reproduction varies with population size in experimental populations of Sabatia angularis (Gentianaceae)

Botany ◽  
2009 ◽  
Vol 87 (3) ◽  
pp. 330-338 ◽  
Author(s):  
Rachel B. Spigler ◽  
Shu-Mei Chang
Keyword(s):  
Reproductive Success ◽  
Population Size ◽  
Intraspecific Competition ◽  
Seed Set ◽  
Pollen Limitation ◽  
Small Populations ◽  
Plant Populations ◽  
Large Populations ◽  
Fruit And Seed Set ◽  
Supplemental Pollination

Individuals in large plant populations are expected to benefit from increased reproductive success relative to those in small populations because of the facilitative effects of large aggregations on pollination. As populations become small, the inability to attract sufficient numbers of pollinators can reduce reproduction via pollen limitation. This study experimentally tested whether such trends occur for the herbaceous biennial Sabatia angularis (L.) Pursh (Gentianaceae). We created artificial populations of varying size consisting of potted S. angularis plants in two field sites to determine whether population size affected mean fruit and seed set. We also examined whether population size affected the degree of pollen limitation using a supplemental pollination design in one of the sites. Our results showed that, on average, seed set was lower in large populations, not small populations, of S. angularis and that this result may be due to increased pollen limitation in large populations. We suggest that in certain contexts, small populations may enjoy reproductive advantages over large populations by escaping intraspecific competition for pollinators.

scholarly journals Spatiotemporal Variations in Seed Set and Pollen Limitation in Populations of the Rare Generalist Species Polemonium caeruleum in Poland

2022 ◽  
Vol 12 ◽  
Author(s):  
Justyna Ryniewicz ◽  
Katarzyna Roguz ◽  
Paweł Mirski ◽  
Emilia Brzosko ◽  
Mateusz Skłodowski ◽  
...  
Keyword(s):  
Reproductive Success ◽  
Population Size ◽  
Seed Production ◽  
Seed Set ◽  
Pollen Limitation ◽  
Monthly Precipitation ◽  
Small Populations ◽  
Flower Visitors ◽  
Visitation Frequency ◽  
Average Monthly Precipitation

A vast majority of angiosperms are pollinated by animals, and a decline in the number and diversity of insects often affects plant reproduction through pollen limitation. This phenomenon may be particularly severe in rare plant species, whose populations are shrinking. Here, we examined the variability in factors shaping reproductive success and pollen limitation in red-listed Polemonium caeruleum L. During a 5-year study in several populations of P. caeruleum (7–15, depending on year), we assessed the degree of pollen limitation based on differences in seed set between open-pollinated (control) and hand-pollinated flowers. We analysed the effects of flower visitors, population size, and meteorological data on plant reproductive success and pollen limitation. Our study showed that pollen limitation rarely affected P. caeruleum populations, and was present mainly in small populations. Pollen limitation index was negatively affected by the size of population, visitation frequency of all insects, and when considering the visitation frequency of individual groups, also by honeybee visits. Seed production in control treatment was positively influenced by the population size, average monthly precipitation in June and visits of hoverflies, while visits of honeybees, average monthly temperature in September, and average monthly precipitation in August influenced seed production negatively. As generalist plant P. caeruleum can be pollinated by diverse insect groups, however, in small populations their main visitors, the honeybees and bumblebees, may be less attracted, eventually leading to the disappearance of these populations. In pollination of P. caeruleum managed honeybees may play a dual role: while they are the most frequent and efficient flower visitors, their presence decreases seed set in open-pollinated flowers, which is most probably related to efficient pollen collection by these insects.

Pollen quantity and quality affect fruit abortion in small populations of a rare fleshy-fruited shrub

2002 ◽  
Vol 3 (4) ◽  
pp. 319-327 ◽  
Author(s):  
Kaspar Pflugshaupt ◽  
Johannes Kollmann ◽  
Markus Fischer ◽  
Barbara Roy
Keyword(s):  
Small Populations ◽  
Pollen Quantity ◽  
Fruit Abortion

BEHAVIOUR AND EFFECTIVENESS OF BEES IN POLLINATING LEGUMES

1974 ◽  
pp. 105-110
Author(s):  
I.W. Forster
Keyword(s):  
White Clover ◽  
Seed Set ◽  
Red Clover ◽  
Potential Maximum ◽  
Open Fields

One honeybee or bumblebee working on each square metre of white clover or red clover gave adequate pollination. This could be obtained with one hive of honeybees to each three hectares of flowering clover. Lucerne seeding averaged only 10% of the potential maximum in open fields with honey- or bumblebees. In cages where honeybees were forced to gather pollen, this was raised to 30% but it was not possible to increase seed set significantly in the fields.

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