Mixed effect of habitat fragmentation on pollinator visitation rates but not on seed production in renosterveld of South Africa

2022 ◽  
Vol 146 ◽  
pp. 48-57
Author(s):  
Sina Juliana Hauber ◽  
Simone Lucia Maier ◽  
Opeyemi Adedoja ◽  
Mirijam Gaertner ◽  
Sjirk Geerts
Keyword(s):  
South Africa ◽  
Habitat Fragmentation ◽  
Seed Production ◽  
Pollinator Visitation ◽  
Mixed Effect ◽  
Visitation Rates

Pollinator visitation, pollen limitation, and selection on flower size through female function in contrasting habitats within a population of Campanula persicifolia

2006 ◽  
Vol 84 (3) ◽  
pp. 412-420 ◽  
Author(s):  
Vivi-Irèn Hansen ◽  
Ørjan Totland
Keyword(s):  
Seed Production ◽  
Structural Equation ◽  
Pollen Limitation ◽  
Phenotypic Selection ◽  
Flower Size ◽  
Pollinator Visitation ◽  
Pollinator Attraction ◽  
Female Function ◽  
Flower Visitation ◽  
Visitation Rates

We looked at whether flower visitation rates, pollen limitation on seed production, and phenotypic selection on flower size through female function varied across a sharp gradient in light intensity (open meadow vs. forest) within a population of the perennial plant Campanula persicifolia L. (Campanulaceae). Flower visitation rates of putative pollinators were similar in both habitats. Seed number per fruit was strongly pollen limited, with no difference in the magnitude of pollen limitation between the two habitats. This strong pollen limitation set the basis for significant phenotypic selection, through female function, on a trait that probably is important for pollinator attraction: flower size. This was revealed by path analysis and structural equation modelling. The lack of difference in pollen limitation on seed production in the two habitats may be explained by the similarity in flower visitation rates in the two habitats. Moreover, the similarity in pollen limitation in the two habitats probably resulted in a similar magnitude and direction of selection on flower size through female function. Our results suggest that pollen limitation and selection through female function may vary little across space within a popualtion despite large variation in the environmental conditions experienced by plants.

scholarly journals The factors influencing the pollinators visitation of the oilseed rape cultivars

2019 ◽  
Vol 65 (No. 12) ◽  
pp. 574-580
Author(s):  
Jan Kazda ◽  
Aneta Bokšová ◽  
Martina Stejskalová ◽  
Tomáš Šubrt ◽  
Jan Bartoška ◽  
...  
Keyword(s):  
Apis Mellifera ◽  
Oilseed Rape ◽  
Honey Bees ◽  
Bumble Bees ◽  
Major Influence ◽  
Winter Oilseed Rape ◽  
Pollinator Visitation ◽  
Factors Influencing ◽  
Visitation Rates ◽  
The Individual

Currently, the hybrid cultivars are predominant in the cultivation of winter oilseed rape in Europe. Cultivation of hybrid cultivars instead of the traditional line can affect the visitation of pollinators. Beekeepers and farmers claim that hybrid cultivars are not visited by pollinators as much as the line. Ten yellow and one white flowering oilseed rape cultivars were used to compare the visitation rates of pollinators (Apis mellifera L. and Bombus sp.) during flowering in the years 2015–2017. At the same time, the visitation of hybrid and line cultivars by pollinators was evaluated. Visitation of pollinators on each cultivar was calculated from observed visitations to flowering oilseed rape plants in an area 2.1 m<sup>2</sup> from the edge of single plots for 20 s. The results from this study clearly show that the individual cultivars, whether hybrids or lines, did not have a major influence on the pollinators’ visitation, either by honey bees or bumble bees. It is thus proved that hybrid cultivars do not affect the pollinator visitation and there is no need to worry about the prevalence of these cultivars in the Czech fields. However, a more significant effect for both pollinator groups appears to have been the color of the flower.

scholarly journals Experimental Test of the Combined Effects of Water Availability and Flowering Time on Pollinator Visitation and Seed Set

2021 ◽  
Vol 9 ◽  
Author(s):  
M. Kate Gallagher ◽  
Diane R. Campbell
Keyword(s):  
Climate Change ◽  
Reproductive Success ◽  
Seed Production ◽  
Water Availability ◽  
Seed Mass ◽  
Single Species ◽  
Flowering Phenology ◽  
Abiotic Factor ◽  
Pollinator Visitation ◽  
Plant Reproductive Success

Climate change is likely to alter both flowering phenology and water availability for plants. Either of these changes alone can affect pollinator visitation and plant reproductive success. The relative impacts of phenology and water, and whether they interact in their impacts on plant reproductive success remain, however, largely unexplored. We manipulated flowering phenology and soil moisture in a factorial experiment with the subalpine perennial Mertensia ciliata (Boraginaceae). We examined responses of floral traits, floral abundance, pollinator visitation, and composition of visits by bumblebees vs. other pollinators. To determine the net effects on plant reproductive success, we also measured seed production and seed mass. Reduced water led to shorter, narrower flowers that produced less nectar. Late flowering plants produced fewer and shorter flowers. Both flowering phenology and water availability influenced pollination and reproductive success. Differences in flowering phenology had greater effects on pollinator visitation than did changes in water availability, but the reverse was true for seed production and mass, which were enhanced by greater water availability. The probability of receiving a flower visit declined over the season, coinciding with a decline in floral abundance in the arrays. Among plants receiving visits, both the visitation rate and percent of non-bumblebee visitors declined after the first week and remained low until the final week. We detected interactions of phenology and water on pollinator visitor composition, in which plants subject to drought were the only group to experience a late-season resurgence in visits by solitary bees and flies. Despite that interaction, net reproductive success measured as seed production responded additively to the two manipulations of water and phenology. Commonly observed declines in flower size and reward due to drought or shifts in phenology may not necessarily result in reduced plant reproductive success, which in M. ciliata responded more directly to water availability. The results highlight the need to go beyond studying single responses to climate changes, such as either phenology of a single species or how it experiences an abiotic factor, in order to understand how climate change may affect plant reproductive success.

scholarly journals The karst ecology of the Bakwena Cave (Gauteng)

2012 ◽  
Vol 31 (1) ◽  
Author(s):  
François Durand ◽  
Antoinette Swart ◽  
Werner Marais ◽  
Candice Jansen van Rensburg ◽  
Johan Habig ◽  
...  
Keyword(s):  
South Africa ◽  
Habitat Fragmentation ◽  
Urban Development ◽  
Plant Material ◽  
Food Source ◽  
Foraging Area ◽  
Freshwater Amphipods ◽  
Bacteria And Fungi ◽  
Predatory Arthropods ◽  
Bat Guano

The Bakwena Cave houses a variety of organisms that form an intricate and interdependent food web. This cave is utilised as a permanent roost by a colony of Natal clinging bats. The bat guano and allochthonous plant material that fall into the cave from outside, form the basis of the ecology inside the cave which may be considered a typical example of a detritus ecosystem. Decomposers such as bacteria and fungi are responsible for the decay of the guano and plant detritus which, in turn, are utilised by several organisms, including nematodes and mites, as food source. These animals form the next trophic level which is utilised by predatory arthropods as food source. The Bakwena Cave is one of the few dolomitic caves in South Africa that provide access to the water table. The groundwater houses several types of organisms, including bacteria, fungi and animals – primarily nematodes and crustaceans. The Bakwena Cave is also the type locality for freshwater amphipods in Southern Africa. This unique and sensitive ecosystem is primarily dependent on bat guano. The grassland surrounding the cave is utilised by the bats as foraging area and is currently threatened by urban development and the resulting habitat fragmentation and destruction. A cascade of extinctions of the cave-dwelling organisms will follow if the bats abandon the cave.

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