scholarly journals The effect of landscape on Cucurbita pepo-pollinator interaction networks varies depending on plants’ genetic diversity

2021 ◽  
Author(s):  
Patricia Landaverde-González ◽  
Eunice Enríquez ◽  
Juan Núñez-Farfán
Keyword(s):  
Genetic Diversity ◽  
Land Use ◽  
Network Structure ◽  
Cucurbita Pepo ◽  
Interaction Network ◽  
Network Evolution ◽  
Interaction Networks ◽  
Pollinator Community ◽  
Male Flowers ◽  
Plant Pollinator

AbstractIn recent years, evidence has been found that plant-pollinator interactions are altered by land-use and that genetic diversity also plays a role. However, how land-use and genetic diversity influence plant–pollinator interactions, particularly in the Neotropics, where many endemic plants exist is still an open question. Cucurbita pepo is a monoecious plant and traditional crop wide distributed, with high rates of molecular evolution, landraces associated with human cultural management and a history of coevolution with bees, which makes this species a promising model for studying the effect of landscape and genetic diversity on plant-pollinator interactions. Here, we assess (1) whether female and male flowers differences have an effect on the interaction network, (2) how C. pepo genetic diversity affects flower-bee visitation network structure, and (3) what is the effect that land-use, accounting for C. pepo genetic variability, has on pumpkin-bee interaction network structure. Our results indicate that female and male flowers presented the same pollinator community composition and interaction network structure suggesting that female/male differences do not have a significant effect on network evolution. Genetic diversity has a positive effect on modularity, nestedness and number of interactions. Further, the effect of semi-natural areas on nestedness could be buffered when genetic diversity is high. Our results suggest that considering genetic diversity is relevant for a better understanding of the effect of land-use on interaction networks. Additionally, this understanding has great value in conserving biodiversity and enhancing the stability of interaction networks in a world facing great challenges of habitat and diversity loss.

scholarly journals A novel perspective on the meaning of nestedness with conceptual and methodological solutions

2021 ◽  
Author(s):  
Rafael Barros Pereira Pinheiro ◽  
Carsten F. Dormann ◽  
Gabriel Moreira Felix ◽  
Marco A. R. Mello
Keyword(s):  
Null Model ◽  
Interaction Network ◽  
Species Interaction ◽  
Null Models ◽  
Interaction Networks ◽  
Common Pattern ◽  
Expected Values ◽  
New Perspective ◽  
Test Outcomes ◽  
Plant Pollinator

Aim: Nestedness is a common pattern in metacommunities and interaction networks, whose causes are still discussed. Nestedness inference is challenging because, beyond calculating an index, we need to compare observed values with values generated with a null model. There are different null models and the choice between them affects test outcomes. Furthermore, there is no established theoretical basis to guide this choice. Here, we propose a different look at the meaning of nestedness that improves our understanding of its causes and unveils the link between null models and hypotheses. Innovation: Nestedness of a matrix is a combination of marginal sum inequality and high overlap. The higher the overlap, the more predictable the cell values by marginal sums. Here, we show that nestedness actually measures how better one can predict cell values by marginal sums than by matrix dimensions and total sum alone. From this, we propose that two null models can be used to test for different topological hypotheses. The equiprobable model excludes all nestedness-generating mechanisms and provides the distribution of expected values for nestedness significance tests. The proportional model conserves nestedness-generating mechanisms and excludes nestedness-disrupting mechanisms, and thus, produces highly nested matrices. The proportional model provides the distribution of expected nestedness for nested matrices. Additionally, we evaluate the efficiency of several indices within this new perspective and illustrate our approach using an empirical plant-pollinator network. Main conclusions: Through a shift of perspective, our approach reconciliates contradictions in null model analysis and delimits the range of possible explanations for nestedness. The only way a process can increase nestedness in a matrix is by promoting marginal sum inequalities, without concomitantly introducing preferences. Consequently, in a species interaction network, explanations for nestedness should explain why some species interact more frequently than others.

scholarly journals Temporal dynamics of the hummingbird-plant interaction network of a dry forest in Chamela, Mexico: a 30-year follow-up after two hurricanes

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8338
Author(s):  
Sergio Díaz Infante ◽  
Carlos Lara ◽  
Maria del Coro Arizmendi
Keyword(s):  
Plant Species ◽  
Network Structure ◽  
Temporal Dynamics ◽  
Interaction Network ◽  
Dry Forest ◽  
Interaction Networks ◽  
Severe Drought ◽  
Plant Interactions ◽  
Temporal Perspective ◽  
Plant Interaction

Background Interactions among species are a driving force of community structure. The species composition of animal-plant interaction networks can be highly dynamic on a temporal scale, even though the general network structure is usually not altered. However, few studies have examined how interaction networks change over long periods of time, particularly after extreme natural events. We analyzed herein the structure of the hummingbird-plant interaction network in a dry forest of Chamela, Mexico, comparing the structure in 1985–1986 with that in 2016–2017 following the passage of two hurricanes (category 2 Jova in 2011 and category 4 Patricia in 2015). Methods The fieldwork was carried out in the Chamela-Cuixmala Biosphere Reserve in Jalisco, Mexico. In the last 30 years, three severe drought events and two hurricanes have affected this region. Previously, from 1985–1986, hummingbird-plant interactions were recorded monthly for one year in the study area. Then, from 2016–2017, we replicated the sampling in the same localities. We compared the network parameters describing the plant-hummingbird interactions of each period using adjacency matrices. Results We found differences in the number and identity of interacting species, especially plants. The plant species missing in 2016–2017 were either the least connected in the original network (1985–1986) or belonged to groups such as cacti, epiphytes, or trees. The new plant species incorporated in the 2016–2017 network were herbs, vines, and shrubs, or other species barely connected. These changes in the composition are consistent with reports on vegetation damage after strong hurricanes at other study sites. Conversely, all hummingbird species remained in the network, with the exception of Heliomaster constantii, which was primarily connected to a plant species absent in the 2016–2017 network. Migratory and habitat generalist species (i.e., Archilochus spp.) showed higher abundances following the disturbance events. Conclusions Most of the parameters describing the hummingbird-plant network structure remained unchanged after 30 years, with the exception of an increase in plant robustness and hummingbird niche overlap. However, the network’s generalist core was affected by the loss of some species. Also, core plant species such as Ipomoea bracteata, Combretum farinosum, and Justicia candicans were found to be important for maintaining the hummingbird-plant interaction network. The temporal perspective of this study provides unique insights into the conservation of plant-hummingbird networks across time and extreme natural events.

scholarly journals Invasive plants as novel food resources, the pollinators' perspective

2015 ◽  
Author(s):  
Ignasi Bartomeus ◽  
Jochen Fründ ◽  
Neal M. Williams
Keyword(s):  
Behavioral Flexibility ◽  
Plant Invasions ◽  
Interaction Networks ◽  
Exotic Plant ◽  
Native Plant ◽  
Exotic Plant Species ◽  
Plant Invaders ◽  
Pollinator Community ◽  
Species Specific ◽  
Plant Pollinator

Entomophilous exotic plant species not only compete directly for space and light with other plants, but also offer resource opportunities for the native pollinator community. Most research on this topic to date has taken the plant perspective, focusing on how successful plant invaders integrate into the native plant-pollinator interaction networks. However, species specific responses of pollinators to the addition of exotic plants are rarely taken into account. We show here that while some bumble bees and other trophic generalist bees can benefit from exotic plant invasions, other species can be negatively affected. Behavioral flexibility may be the key to persist in a changing world.

scholarly journals Changes in plant-herbivore network structure and robustness along land-use intensity gradients in grasslands and forests

2021 ◽  
Vol 7 (20) ◽  
pp. eabf3985
Author(s):  
Felix Neff ◽  
Martin Brändle ◽  
Didem Ambarlı ◽  
Christian Ammer ◽  
Jürgen Bauhus ◽  
...  
Keyword(s):  
Land Use ◽  
Network Structure ◽  
Interaction Network ◽  
Plant Species Richness ◽  
Network Size ◽  
Network Robustness ◽  
Land Use Intensity ◽  
The Stability ◽  
Plant Herbivore ◽  
Herbivore Communities

Land-use intensification poses major threats to biodiversity, such as to insect herbivore communities. The stability of these communities depends on interactions linking herbivores and host plants. How interaction network structure begets robustness, and thus stability, in different ecosystems and how network structure and robustness are altered along land-use intensity gradients are unclear. We analyzed plant-herbivore networks based on literature-derived interactions and long-term sampling from 289 grasslands and forests in three regions of Germany. Network size and nestedness were the most important determinants of network robustness in both ecosystems. Along land-use intensity gradients, networks in moderately grazed grasslands were more robust than in those managed by frequent mowing or fertilization. In forests, changes of network robustness along land-use intensity gradients relied on changes in plant species richness. Our results expand our knowledge of the stability of plant-herbivore networks and indicate options for management aimed at stabilizing herbivore communities.

scholarly journals Using Matching Traits to Study the Impacts of Land-Use Intensification on Plant–Pollinator Interactions in European Grasslands: A Review

Insects ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 680
Author(s):  
Jérémie Goulnik ◽  
Sylvain Plantureux ◽  
Isabelle Dajoz ◽  
Alice Michelot-Antalik
Keyword(s):  
Land Use ◽  
Flower Colour ◽  
Floral Traits ◽  
Knowledge Gaps ◽  
Land Use Intensification ◽  
Pollinator Community ◽  
Wide Range ◽  
Suitable Habitats ◽  
Underlying Mechanisms ◽  
Plant Pollinator

Permanent grasslands are suitable habitats for many plant and animal species, among which are pollinating insects that provide a wide range of ecosystem services. A global crisis in pollination ecosystem service has been highlighted in recent decades, partly the result of land-use intensification. At the grassland scale, however, the underlying mechanisms of land-use intensification that affect plant–pollinator interactions and pollination remain understudied. In this review, we first synthesise the literature to provide new insights into the relationships between land-use intensification and pollination by using matching community and interaction traits. We then identify knowledge gaps and summarise how land-use intensification of grassland influences floral traits that may in turn be associated with modifications to pollinator matching traits. Last, we summarise how these modifications may affect pollination function on permanent grasslands. Overall, land-use intensification may lead to a shift in flower colour, a decrease in mean nectar tube depth and a decrease in reward production and pollen quality at the community level. This, in turn, may generate a decrease in pollinator mouthparts length and body size, that may favour pollinators that require a low amount of floral reward. We found no study citing the effect of land-use intensification on volatile organic compounds emitted by flowers despite the importance of these molecules in pollinator community composition. Overall, our review highlighted major knowledge gaps about the effects of land-use intensification on plant–pollinator interactions, and suggests that land-use intensification could favour plants with generalised floral traits that adversely affect pollination.

scholarly journals Persistent variation in spatial behavior affects the structure and function of interaction networks

2015 ◽  
Vol 61 (1) ◽  
pp. 98-106 ◽  
Author(s):  
Noa Pinter-Wollman
Keyword(s):  
Network Structure ◽  
Interaction Network ◽  
Structure And Function ◽  
Spatial Behavior ◽  
Interaction Networks ◽  
Harvester Ants ◽  
Spatial Features ◽  
Physical Barriers ◽  
And Function ◽  
Animal Personalities

Abstract The function of a network is affected by its structure. For example, the presence of highly interactive individuals, or hubs, influences the extent and rate of information spread across a network. In a network of interactions, the duration over which individual variation in interactions persists may affect how the network operates. Individuals may persist in their behavior over time and across situations, often referred to as personality. Colonies of social insects are an example of a biological system in which the structure of the coordinated networks of interacting workers may greatly influence information flow within the colony, and therefore its collective behavior. Here I investigate the effects of persistence in walking patterns on interaction networks using computer simulations that are parameterized using observed behavior of harvester ants. I examine how the duration of persistence in spatial behavior influences network structure. Furthermore, I explore how spatial features of the environment affect the relationship between persistent behavior and network structure. I show that as persistence increases, the skewness of the weighted degree distribution of the interaction network increases. However, this relationship holds only when ants are confined in a space with boundaries, but not when physical barriers are absent. These findings suggest that the influence of animal personalities on network structure and function depends on the environment in which the animals reside.

scholarly journals Effects of habitat structure and land-use intensity on the genetic structure of the grasshopper species Chorthippus parallelus

2014 ◽  
Vol 1 (2) ◽  
pp. 140133 ◽  
Author(s):  
Kerstin R. Wiesner ◽  
Jan Christian Habel ◽  
Martin M. Gossner ◽  
Hugh D. Loxdale ◽  
Günter Köhler ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Land Use ◽  
Genetic Structure ◽  
Sampling Site ◽  
Land Use Intensity ◽  
Habitat Size ◽  
Grasshopper Species ◽  
Chorthippus Parallelus ◽  
Landscape Characteristics ◽  
Local Populations

Land-use intensity (LUI) is assumed to impact the genetic structure of organisms. While effects of landscape structure on the genetics of local populations have frequently been analysed, potential effects of variation in LUI on the genetic diversity of local populations have mostly been neglected. In this study, we used six polymorphic microsatellites to analyse the genetic effects of variation in land use in the highly abundant grasshopper Chorthippus parallelus . We sampled a total of 610 individuals at 22 heterogeneous grassland sites in the Hainich-Dün region of Central Germany. For each of these grassland sites we assessed habitat size, LUI (combined index of mowing, grazing and fertilization), and the proportion of grassland adjoining the sampling site and the landscape heterogeneity (the latter two factors within a 500 m buffer zone surrounding each focal site). We found only marginal genetic differentiation among all local populations and no correlation between geographical and genetic distance. Habitat size, LUI and landscape characteristics had only weak effects on most of the parameters of genetic diversity of C. parallelus ; only expected heterozygosity and the grasshopper abundances were affected by interacting effects of LUI, habitat size and landscape characteristics. The lack of any strong relationships between LUI, abundance and the genetic structure might be due to large local populations of the species in the landscape, counteracting local differentiation and potential genetic drift effects.

scholarly journals Genetic diversity in Cucurbita pepo landraces from northern KwaZulu-Natal, South Africa, revealed by random amplified polymorphic DNA (RAPD) markers

2013 ◽  
Vol 12 (44) ◽  
pp. 6253-6261
Author(s):  
R Ntuli Nontuthuko ◽  
M Zobolo Alpheus ◽  
B Tongoona Pangirayi ◽  
W Kunene Nokuthula
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Rapd Markers ◽  
Cucurbita Pepo ◽  
Random Amplified Polymorphic Dna ◽  
Kwazulu Natal
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