scholarly journals Reproductive Biology, Seed Production, and Culture of the Hawaiian Limpet Cellana sandwicensis (Pease, 1861)

Author(s):  
Hua Thai Nhan ◽  
Harry Ako
2014 ◽  
Vol 44 (4) ◽  
pp. 427-434 ◽  
Author(s):  
Thays de Assis Schvinn ◽  
Anderson Fernandes de Miranda ◽  
Celice Alexandre Silva

Floral mechanisms that ensure seed production via autogamy are more likely to occur in species growing in environments where pollination is scarce. Amasonia obovata was studied in the State of Mato Grosso-Brazil, from 2009 to 2012, to analyze the morphological and reproductive characteristics, aside from investigating the association of the reproductive success with the pollinator frequency and identity. The flowering and fruiting of A. obovata was concentrated in a period of five months during the rainy season. The dichogamy in flowers of A. obovata is not clearly defined, since the sexual functions were overlapped in the male and female phases. The species is self-compatible and not apomictic. The fruiting percentage obtained by hand self-pollination did not differ from cross-breeding (F = 0.74, P =0.39). In the observations from 2010 to 2012, a hummingbird (Thalurania furcata) legitimate visited 20-100% of the flowers in the male and female phases on different A. obovata plants. Due to the high frequency, this hummingbird was considered the single potential pollinator of the species. These findings show that a limited availability of pollinators may select for floral traits and plant mating strategies that lead to a system of self-fertilization.


1998 ◽  
Vol 46 (4) ◽  
pp. 377 ◽  
Author(s):  
Byron B. Lamont ◽  
Jens M. Olesen ◽  
Peter J. Briffa

The reproductive biology of two species pairs was compared, one member of which (Dryandra sessilis (Knight) Domin, Hakea erinacea Meissner) is susceptible to severe stress and disturbance by fire (nonsprouter) and stores few seeds in its crown, while the other (D. lindleyana Meissner, H. cristata R.Br.) is resilient (resprouter) and also stores most of its seeds for some years. It was hypothesised that the nonsprouter would have a high annual seed production associated with a suite of attributes directed towards that end (forming a reproductive syndrome), and that the resprouter would have the reverse properties. Over 30 attributes were assessed, covering putative pollinators, pollinator attractants and rewards, flower phenology, breeding system, and flower, fruit and seed production. Dryandra sessilis produced far more seeds than D. lindleyana, due to prolific flower production and a high fruit : flower ratio (associated with an effective outcrossing breeding system). Hakea erinacea produced significantly more seeds than H. cristata, which was attributable to its smaller fruits and exceptionally high fruit : flower ratio (associated with highly effective selfing). The correlation of seed production and fruit : flower ratio with susceptibility to fire was not supported by any consistent pattern among the other reproductive attributes.


2021 ◽  
Vol 38 ◽  
pp. 00111
Author(s):  
Inessa Selyutina ◽  
Elena Konichenko ◽  
Natalia Igay ◽  
Davaajav Darikhand

The seed production of the rare species Gueldenstaedtia monophylla has been investigated in 19 coenotic populations in the territories of Russia (Central Altai) and Mongolia (the north-western part). G. monophylla reproduces exclusively by seeds and is characterized by the low number and density of the plants in the populations. Its populations have a high proportion of generative plants: from 31 to 84% from the total number of the plants. The plants of G. monophylla have a small number of generative shoots, varying from 1 to 6 per plant. The number of flowers on the plants is low, too, and varies in the populations on average from 1.2 to 15.3 per plant. The potential seed production (PSP) varies considerably from 13.5 to 308.6 ovules per plant. The real seed production is much lower, to constitute from 6.2 to 74.5 seeds per plant. The low seed production, fructification that occurs not every year, and scanty populations make the species vulnerable.


2003 ◽  
Vol 51 (2) ◽  
pp. 179 ◽  
Author(s):  
Manfred Jusaitis ◽  
Birgitte Sorensen ◽  
Lesley Polomka

The reproductive biology of Brachycome muelleri Sonder (Asteraceae) was studied from 1995 to 1997 by using nursery and field experiments. Reproductive development and seed dispersal occupied approximately half of the 4-month growth cycle. Flowers of B. muelleri did not have any obvious self-incompatibility systems and were readily selfed to produce viable seed. It appeared that B. muelleri may be preferentially cross-pollinated under ideal conditions of pollinator visitation, but could revert to self-pollination in the event of outcross failure. Seed dispersal was assisted by the epinastic curvature of peduncles as fruit matured, bringing capitula into contact with the soil a short distance away from the parent plant. Slight wind-stimulated movement of the capitulum was sufficient to dislodge seed directly onto the soil surface. Seed was shed in the immediate vicinity of parent plants and although some short-range movement facilitated by rain splash, water flow and gravity was observed, no long-distance dispersal mechanisms were apparent. Annual seed production of the single extant population of B. muelleri in South Australia was estimated at about 5 million seeds. Immediately after dispersal, the soil seed bank in the vicinity of B. muelleri plants contained, on average, over 1700 germinable seeds m–2. Many of these seeds germinated or died within a year, the remainder persisting into a second or third year. Seed viability under field-burial conditions declined to less than 10% over that time. Population size did not appear to be limited by seed production, but rather by seed dispersal syndrome.


2008 ◽  
Vol 70 (2) ◽  
pp. 145-154 ◽  
Author(s):  
BM Potts ◽  
MH McGowen ◽  
DR Williams ◽  
S Suitor ◽  
TH Jones ◽  
...  

Author(s):  
Alan N. Hodgson

The hermaphrodite duct of pulmonate snails connects the ovotestis to the fertilization pouch. The duct is typically divided into three zones; aproximal duct which leaves the ovotestis, the middle duct (seminal vesicle) and the distal ovotestis duct. The seminal vesicle forms the major portion of the duct and is thought to store sperm prior to copulation. In addition the duct may also play a role in sperm maturation and degredation. Although the structure of the seminal vesicle has been described for a number of snails at the light microscope level there appear to be only two descriptions of the ultrastructure of this tissue. Clearly if the role of the hermaphrodite duct in the reproductive biology of pulmonatesis to be understood, knowledge of its fine structure is required.Hermaphrodite ducts, both containing and lacking sperm, of species of the terrestrial pulmonate genera Sphincterochila, Levantina, and Helix and the marine pulmonate genus Siphonaria were prepared for transmission electron microscopy by standard techniques.


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