The role of pollination effectiveness on the attributes of interaction networks: from floral visitation to plant fitness 
Hesajim de Santiago‐Hernández, 2019.

Network analysis is a powerful tool to understand community‐level plant‐pollinator interactions. We evaluate the role of floral visitors on plant fitness through a series of pollination exclusion experiments to test the effectiveness of pollinators of an Ipomoea community in the Pacific coast of México, including: (1) all flower visitors, (2) visitors that contact the reproductive organs, (3) visitors that deposit pollen on stigmas, and (4) visitors that mediate fruit and seed production. Our results show that networks built from effective pollination interactions are smaller, less connected, more specialized and modular than floral visitor networks. Modules are associated with pollinator functional groups and they provide strong support for pollination syndromes only when non‐effective interactions are excluded. In contrast to other studies, the analyzed networks are not nested. Our results also show that only 59% of floral visitors were legitimate pollinators that contribute to seed production. Furthermore, only 27% of the links in visitation network resulted in seed production. Our study shows that plant‐pollination networks that consider effectiveness measures of pollination in addition to floral visitation provide insightful information about the different role floral visitors play in a community, encompassing a large number of commensalistic/antagonistic interactions and the more restricted set of mutualistic relationships that underlie the evolution of convergent floral phenotypes in plants.

 .

https://bit.ly/2LwWnRL

.

.
A white lotus,
and pondering whether to cut it--
the priest´s dilemma
  
Yosa Buson (1716 – 1784)
.

Dormancy in Metacommunities 
Nathan I. Wisnoski, Mathew A. Leibold, and Jay T. Lennon

Although metacommunity ecology has improved our understanding of how dispersal affects community structure and dynamics across spatial scales, it has yet to adequately account for dormancy. Dormancy is a reversible state of reduced metabolic activity that enables temporal dispersal within the metacommunity. Dormancy is also a metacommunity-level process because it can covary with spatial dispersal and affect diversity across spatial scales. We develop a framework to integrate dispersal and dormancy, focusing on the covariation they exhibit, to predict how dormancy modifies the importance of species interactions, dispersal, and historical contingencies in metacommunities. We used empirical and modeling approaches to demonstrate the utility of this framework. We examined case studies of microcrustaceans in ephemeral ponds, where dormancy underlies metacommunity dynamics, and identified constraints on the dispersal and dormancy strategies of bromeliad-dwelling invertebrates. Using simulations, we showed that dormancy can alter classic metacommunity patterns of diversity in ways that depend on dispersal-dormancy covariation and spatiotemporal environmental variability. We propose that dormancy may also facilitate evolution-mediated priority effects if locally adapted seed banks prevent colonization by more dispersal-limited species. Last, we present testable predictions for the implications of dormancy in metacommunities, some of which may fundamentally alter our understanding of metacommunity ecology.

 

https://www.journals.uchicago.edu/doi/10.1086/704168

.

Transverse section of an ostrich fern (250x)
Anatoly Mikhaltsov
.

Focus rural land policies on ecosystem services, not agriculture      

David Gawith & Ian Hodge, 2019

Land policies around the world tend to focus on support for agricultural output. We argue that this leads to ineffective public expenditure, environmental harm and missed opportunities for the use of rural resources. Applying thinking centred on ecosystems services to the governance of rural land would secure greater social value.

https://go.nature.com/2IGyYLz

.

Onagadori 
Japanese breed of chicken with an exceptionally long tail

Synergies between mycorrhizal fungi and soil microbial communities increase plant nitrogen acquisition     
Hestrin et al., 2019

Nitrogen availability often restricts primary productivity in terrestrial ecosystems. Arbuscular mycorrhizal (AM) fungi are ubiquitous symbionts of terrestrial plants and can improve plant nitrogen acquisition, but have a limited ability to access organic nitrogen. Although other soil biota mineralize organic nitrogen into bioavailable forms, they may simultaneously compete for nitrogen, with unknown consequences for plant nutrition. Here, we show that synergies between the mycorrhizal fungus Rhizophagus irregularis and soil microbial communities have a highly non-additive effect on nitrogen acquisition by the model grass Brachypodium distachyon. These multipartite microbial synergies result in a doubling of the nitrogen that mycorrhizal plants acquire from organic matter and a tenfold increase in nitrogen acquisition compared to non-mycorrhizal plants grown in the absence of soil microbial communities. This previously unquantified multipartite relationship may contribute to more than 70 Tg of annually assimilated plant nitrogen, thereby playing a critical role in global nutrient cycling and ecosystem function.

 

Multipartite synergies between AM fungi and soil microbial communities increase plant biomass and N acquisition from organic matter. a Mesocosm design. b Plants acquired more N from organic matter in the presence of AM fungi and soil microbial communities. c Plants grown with both AM fungi and soil microbes acquired more N than expected based on the sum of N acquired by control plants and those grown with AM fungi or soil microbes alone. d AM colonization is associated with greater plant biomass. e AM plants grown with soil microbes derived a greater proportion of their total N from organic matter than control plants and plants grown with AM fungi or soil microbial communities alone. Significance levels are indicated with the following symbols: ·p < 0.1, *p < 0.05, **p < 0.01, ***p < 0.001 and denote the results of a Tukey’s HSD test performed on log-transformed data (b, d), an unpaired t test (c), and a Tukey’s HSD test performed on untransformed data (e). Error bars represent the standard error (n = 7 biologically independent samples)

https://www.nature.com/articles/s42003-019-0481-8

.
Sustainability is living on nature's income rather than living on its capital.

Murray Gell-Mann
.

The Beast of Gévaudan was a mysterious man-eating animal (most likely a wolf or series of wolves) that terrorized a region in in south-central France between 1764 and 1767.

https://bit.ly/2J7UQPh
.

.
The Language of Flowers: An Alphabet of Floral Emblems (1857)

From Abatina (fickleness) to Zinnia (thoughts of absent friends), and from Absence (wormwood) to Zest (Lemon), the marvellous Language of Flowers: An Alphabet of Floral Emblems (1857) pairs up hundreds of flowers with hundreds of emotions.

https://bit.ly/2WZL86g
.

Holobiont Evolution: Model with Vertical vs. Horizontal Microbiome Transmission with Remarks on Lineal vs. Collective Inheritance

Joan Roughgarden, 2019.

A holobiont is a composite organism consisting of a host together with its microbiome, such  as a coral with its zooxanthellae. Some investigators contend that selection operates on entire holobionts and view the microbiome’s genes as extending the host’s nuclear genome to jointly comprise a hologenome.

Holobiont selection then operates on entire hologenomes by analogy to  how ordinary natural selection operates on genes in a Mendelian population. Other investigators argue that vertical transmission of microbiomes is uncommon. Therefore, holobiont selection cannot be evolutionarily important because the microbiome is an acquired condition rather than  an inherited trait.

The conceptual disagreement between these positions invites a simple mathematical model to see how holobiont selection might operate and to assess the plausibility of holobiont selection as an evolutionary force.

Here I present two variants of such a model. In one variant, juvenile hosts obtain microbiomes from their parents (vertical transmission). In the other variant, microbiomes of juvenile hosts are assembled from source pools containing the combined microbiomes of all parents (horizontal transmission). According to both variants, holobiont selection indeed causes evolutionary change in holobiont traits. Therefore, holobiont selection is plausibly an important evolutionary force with either mode of microbiome transmission.

Furthermore, a new concept of inheritance emerges from the modeling: collective inheritance whereby juveniles inherit a sample of the collected genomes from all parents as contrasted with traditional lineal inheritance whereby juveniles inherit the genomes only from their own parents. This new concept of collective inheritance may apply to the evolution of soil and other microbes that feature large amounts of horizontal gene transfer and may underlie cultural evolution wherein each generation inherits a sample of knowledge from the collected knowledge of the preceding generation.

Sequence of processes with vertical transmission of mutualistic microbiome.

Results with vertical transmission of mutualistic microbiome. Top left and middle graphs show log of total holobiont and microbe numbers through time and top right graph shows holobiont fitness as function of number of microbes in host. Histograms show distribution of hologenotype frequencies through time. The horizontal axis in the histograms is number of microbes per host and vertical axis is fraction of holobiont population.

Sequence of processes with horizontal transmission of mutualistic microbiome.

Results with horizontal transmission of mutualistic microbiome.Top left and middle graphs show log of total holobiont and microbe numbers through time and top right graph shows holobiont fitness as function of number of microbes in host. Histograms show distribution of hologenotype frequencies through time. The horizontal axis in the histograms is number of microbes per host and vertical axis is fraction of holobiont population.

https://www.biorxiv.org/content/10.1101/465310v4

.

Individual and Population Differences Shape Species Interactions and Natural Selection 
Start, 2019.

Trait variation is central to our understanding of species interactions, and trait variation arising within species is increasingly recognized as an important component of community ecology. Ecologists generally consider intraspecific variation either among or within populations, yet these differences can interact to create patterns of species interactions. These differences can also affect species interactions by altering processes occurring at distinct scales. Specifically, intraspecific variation may shape species interactions simply by shifting a population’s position along a trait-function map or by shifting the relationship between traits and their ecological function. I test these ideas by manipulating within- and among-population intraspecific variation in wild populations of a gall-forming insect before quantifying species interactions and phenotypic selection. Within- and among-population differences in gall size interact to affect attack rates by an enemy community, but among-population differences were far more consequential. Intraspecific differences shaped species interactions by both shifting the position of populations along the trait-function map and altering the relationship between traits and their function, with ultimate consequences for patterns of natural selection. I suggest that intraspecific variation can affect communities and natural selection by acting through individual- and population-level mechanisms.

 .

https://www.journals.uchicago.edu/doi/pdfplus/10.1086/704060

.

.
Maruyama Ōkyo's Sketchbooks, late 18th century.
.

Pollen from multiple sunflower cultivars and species reduces a common bumblebee gut pathogen

LoCascio et al., 2019.

Pathogens are one of the factors driving pollinator declines. Diet can play an important role in mediating pollinator health and resistance to pathogens. Sunflower pollen (Helianthus annuus) dramatically reduced a gut pathogen (Crithidia bombi) of Bombus impatiens previously, but the breadth of this effect was unknown. We tested whether pollen from nine H. annuus cultivars, four wild H. annuus populations, H. petiolarus, H. argophyllus and two Solidago spp., reduced Crithidia in B. impatiens compared to mixed wildflower pollen and buckwheat pollen (Fagopyrum esculentum) as controls. We also compared hand- and honeybee-collected pollen (which contains nectar) to assess whether diet effects on pathogens were due to pollen or nectar. All Helianthus and Solidago pollen reduced Crithidia by 20-40-fold compared to buckwheat pollen, and all but three taxa reduced Crithidia compared to wildflower pollen. We found no consistent differences between hand- and bee-collected pollen, suggesting that pollen alone can reduce Crithidia infection. Our results indicate an important role of pollen diet for bee health and potentially broad options within the Asteraceae for pollinator plantings to manage bee disease.

https://bit.ly/2KeSxNi
.

.
A cow, in a group of cattle being herded across a relief in the tomb of Kheruef at Luxor around 3500 years ago.
.
https://bit.ly/2I7vgZZ
.

.
Plants: 82.4% of global biomass 
Bacteria: 12.8% 
Fungi: 2.2% 
Single-cell microbes: 1.5% 
Protists: 0.7% 
Animal biomass: 0.4% (of which humans are 2.5%, or 0.1% of global biomass) 
Viruses: 0.04%
.
https://bit.ly/2I2DGC6
.

Subsidy type and quality determine direction and strength of trophic cascades in arthropod food web in agro‐ecosystems 

Laura G.A. Riggi and Riccardo Bommarco

1.The subsidy hypothesis states that communities receiving nutrient subsidies will demonstrate top‐down trophic cascades where predators indirectly increase plant biomass. This has been both confirmed and refuted, which might depend on whether the subsidy has mainly targeted the plant or the detrital food‐web compartment, and on the subsidy quality. This is particularly poorly understood for terrestrial communities such as heavily subsidized agroecosystems.

2.Using cages covering 4 m² of ground in a long‐term agricultural fertilisation experiment, we tested whether subsidies targeting the detrital soil meso‐fauna compartment with organic fertilisers, or the plants with mineral fertiliser, impacted the direction and strength of trophic cascades in an arthropod‐plant food web. We expected top‐down controls of generalist arthropod predators (spiders, ground and rove beetles) on aphid densities to be stronger in organically fertilised plots due to enhanced alternative prey availability in the soil. Bottom‐up control from barley quality on aphids was anticipated to be stronger in the mineral treatments. We examined how the quality (decomposability) of the organic subsidy governed the cascades by comparing treatments with labile (manure) and recalcitrant (hay) organic matter.

3.Top‐down forces dominated in food webs receiving organic subsidies, while bottom‐up forces dominated under mineral fertilisation. A high quality, easily degradable organic subsidy propagated faster through the food chain, leading to a top‐down trophic cascade with generalist predators having a positive effect on plant biomass in the labile but not in the recalcitrant organic treatment.

4.Synthesis and applications. Management of agricultural soils that bolster the soil meso‐fauna, e.g. adding organic fertilisers, has potential to increase top‐down biological control by naturally occurring generalist arthropod predators. Our research demonstrates how barley biomass can be enhanced in manure treatment in the presence of arthropod predators to a level comparable to that of mineral fertiliser.

 .

https://bit.ly/2KcBVWj

.