scholarly journals Detecting the ecological footprint of selection

2021 ◽  
Author(s):  
Juliette Luiselli ◽  
Isaac Overcast ◽  
Andrew Rominger ◽  
Megan Ruffley ◽  
Helene Morlon ◽  
...  
Keyword(s):  
Population Genetic ◽  
Ecological Footprint ◽  
Mechanistic Model ◽  
Species Traits ◽  
Species Identity ◽  
Trait Variation ◽  
Inference Mechanism ◽  
Structure Of Communities ◽  
New Form ◽  
Species Richness And Abundance

The structure of communities is influenced by many processes, both ecological and evolutionary, but these processes are hard to distinguish from available data. The aim of this work is to distinguish the ecological footprint of selection from that of neutral processes that are invariant to species identity. To do this, we build on existing theory to produce a new mechanistic model of community structure incorporating ecology and evolution. We base our work on "massive eco-evolutionary synthesis simulations" (or MESS), which uses information from three biodiversity axes - species richness and abundance; population genetic diversity; and trait variation - to distinguish between processes with a mechanistic model. We added a new form of competition to MESS that explicitly compares the traits of each pair of individuals and allows us to distinguish between inter- and intra-specific competition. We find that this addition is essential to properly detect and characterise selection and it yields different results to the existing simpler model that only compares species' traits to the community mean. Neutral forces receive much less support from systems where trait data is incorporated into the inference mechanism.

scholarly journals An Assessment of Multiple Drivers Determining Woody Species Composition and Structure: A Case Study from the Kalahari, Botswana

Land ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 122 ◽  
Author(s):  
Meyer ◽  
Holloway ◽  
Christiansen ◽  
Miller ◽  
D’Odorico ◽  
...  
Keyword(s):  
Species Abundance ◽  
Woody Species ◽  
Environmental Variable ◽  
Woody Vegetation ◽  
Tobit Regression ◽  
Species Identity ◽  
Rainfall Gradient ◽  
Composition And Structure ◽  
Species Richness And Abundance ◽  
The Impact

Savannas are extremely important socio-economic landscapes, with pastoralist societies relying on these ecosystems to sustain their livelihoods and economy. Globally, there is an increase of woody vegetation in these ecosystems, degrading the potential of these multi-functional landscapes to sustain societies and wildlife. Several mechanisms have been invoked to explain the processes responsible for woody vegetation composition; however, these are often investigated separately at scales not best suited to land-managers, thereby impeding the evaluation of their relative importance. We ran six transects at 15 sites along the Kalahari transect, collecting data on species identity, diversity, and abundance. We used Poisson and Tobit regression models to investigate the relationship among woody vegetation, precipitation, grazing, borehole density, and fire. We identified 44 species across 78 transects, with the highest species richness and abundance occurring at Kuke (middle of the rainfall gradient). Precipitation was the most important environmental variable across all species and various morphological groups, while increased borehole density and livestock resulted in lower bipinnate species abundance, contradicting the consensus that these managed features increase the presence of such species. Rotating cattle between boreholes subsequently reduces the impact of trampling and grazing on the soil and maintains and/or reduces woody vegetation abundance.

scholarly journals Influence of Isolation Method on Recovery of Pythium Species from Forest Nursery Soils in Oregon and Washington

Plant Disease ◽  
2011 ◽  
Vol 95 (5) ◽  
pp. 547-553 ◽  
Author(s):  
Jerry E. Weiland
Keyword(s):  
Pacific Northwest ◽  
The United States ◽  
Pythium Species ◽  
Forest Nursery ◽  
Isolation Method ◽  
Species Identity ◽  
The Pacific ◽  
Forest Nurseries ◽  
Species Richness And Abundance ◽  
Isolated Species

Pythium species are common damping-off pathogens that can cause stunting, chlorosis, and death of conifer seedlings in the Pacific Northwest (PNW) region of the United States. Despite the prevalence and importance of these pathogens in forest nurseries, relatively little is known about the identity of Pythium species associated with forest nursery soils in Washington and Oregon. A limited number of studies have reported P. aphanidermatum, P. irregulare, P. mamillatum, and P. ultimum as the predominant species in the PNW, but most studies of this genus in forest nurseries have not reported Pythium species identity. In an attempt to identify Pythium species associated with forest nursery soils, field surveys were conducted at three forest nurseries (two in Oregon and one in Washington) in 2008 using three isolation methods. Pythium species were isolated by plating soil onto a semiselective medium or by baiting soil with rhododendron leaf disks and Douglas-fir needle segments. One hundred isolates were randomly selected from each isolation method at each nursery (900 isolates total) and identified on the basis of the internal transcribed spacer (ITS) sequence. Nineteen Pythium species were identified during the survey. Species richness and abundance were strongly influenced by both nursery and isolation method. Of the 300 isolates obtained from each nursery, P. irregulare was the most commonly isolated species from nursery A in Washington (65% incidence). P. ‘vipa’ and P. dissotocum were the most commonly isolated species from nurseries B and C in Oregon, respectively (53 and 47% incidence, respectively).

scholarly journals Response of fish species to river restoration – the role of species traits

2016 ◽  
Author(s):  
Stefanie Höckendorff ◽  
Jonathan D Tonkin ◽  
Peter Haase ◽  
Margret Bunzel-Drüke ◽  
Olaf Zimball ◽  
...  
Keyword(s):  
Species Richness ◽  
Fish Species ◽  
River Restoration ◽  
Species Traits ◽  
Functional Ecology ◽  
Response Patterns ◽  
Transfer Of Knowledge ◽  
Species Identity ◽  
Species Response ◽  
Repeated Sampling

Species are known to respond differently to restoration efforts, but we still lack a clear conceptual understanding of these differences. We analyzed the development of an entire fish community as well as the relationship between multi-metric response patterns of fish species and their ecological species traits at a comprehensively monitored river restoration project, the Lippe River in Germany. Using electrofishing data from 21 consecutive years (4 years pre- and 17 years post-restoration) from multiple restored and unrestored control reaches, we demonstrated that this restoration fully reached its targets, approximately doubling both species richness and abundance. Species richness continuously increased while fish density exhibited an overshooting response in the first years post restoration. Both richness and abundances stabilized approximately seven years after the restoration, although interannual variability remained considerable. The response of each species to the restoration was characterized using a set of six parameters. Relating the dissimilarity in species response to their ecological dissimilarity, based on 13 species traits, we found life-history and reproduction-related traits were the most important for species’ responses to restoration. Short-lived species with early female maturity and multiple spawning runs per year exhibited the strongest response, reflecting the ability of fast reproducers to rapidly colonize new habitats. Fusiform-bodied species also responded more positively than deep-bodied species, reflecting the success of this restoration to reform appropriate hydromorphological conditions (riffles and shallow bays), for which these species depend. Our results demonstrate that repeated sampling over periods longer than seven years are necessary to reliably assess river restoration outcomes. Furthermore, this study emphasizes the utility of species traits for examining restoration outcomes, particularly the metapopulation and metacommunity processes driving recovery dynamics. Focusing on species traits instead of species identity also allows for easier transfer of knowledge to other biogeographic areas and promotes coupling to functional ecology.

scholarly journals A unified model of species abundance, genetic diversity, and functional diversity reveals the mechanisms structuring ecological communities

2020 ◽  
Author(s):  
Isaac Overcast ◽  
Megan Ruffley ◽  
James Rosindell ◽  
Luke Harmon ◽  
Paulo A. V. Borges ◽  
...  
Keyword(s):  
Community Assembly ◽  
Island Biogeography ◽  
Spatial Scales ◽  
Mechanistic Model ◽  
Species Abundance ◽  
Real Data ◽  
Current Theory ◽  
Supervised Machine Learning ◽  
Ecological Communities ◽  
Trait Variation

AbstractBiodiversity accumulates hierarchically by means of ecological and evolutionary processes and feedbacks. Reconciling the relative importance of these processes is hindered by current theory, which tends to focus on a single spatial, temporal or taxonomic scale. We introduce a mechanistic model of community assembly, rooted in classic island biogeography theory, which makes temporally explicit joint predictions across three biodiversity data axes: i) species richness and abundances; ii) population genetic diversities; and iii) trait variation in a phylogenetic context. We demonstrate that each data axis captures information at different timescales, and that integrating these axes enables discriminating among previously unidentifiable community assembly models. We combine our massive eco-evolutionary synthesis simulations (MESS) with supervised machine learning to fit the parameters of the model to real data and infer processes underlying how biodiversity accumulates, using communities of tropical trees, arthropods, and gastropods as case studies that span a range of spatial scales.

scholarly journals Species interactions and environmental context affect intraspecific behavioural trait variation and ecosystem function

2020 ◽  
Vol 287 (1919) ◽  
pp. 20192143 ◽  
Author(s):  
Camilla Cassidy ◽  
Laura J. Grange ◽  
Clement Garcia ◽  
Stefan G. Bolam ◽  
Jasmin A. Godbold
Keyword(s):  
Environmental History ◽  
Ecosystem Functioning ◽  
Species Interactions ◽  
Nutrient Release ◽  
Functional Trait ◽  
Benthic Invertebrate ◽  
Species Identity ◽  
Trait Variation ◽  
Amphiura Filiformis ◽  
Morphological Differences

Functional trait-based approaches are increasingly adopted to understand and project ecological responses to environmental change; however, most assume trait expression is constant between conspecifics irrespective of context. Using two species of benthic invertebrate (brittlestars Amphiura filiformis and Amphiura chiajei ), we demonstrate that trait expression at individual and community levels differs with biotic and abiotic context. We use PERMANOVA to test the effect of species identity, density and local environmental history on individual (righting and burrowing) and community (particle reworking and burrow ventilation) trait expression, as well as associated effects on ecosystem functioning (sediment nutrient release). Trait expression differs with context, with repercussions for the faunal mediation of ecosystem processes; we find increased rates of righting and burial behaviour and greater particle reworking with increasing density that are reflected in nutrient generation. However, the magnitude of effects differed within and between species, arising from site-specific environmental and morphological differences. Our results indicate that traits and processes influencing change in ecosystem functioning are products of both prevailing and historic conditions that cannot be constrained within typologies. Trait-based study must incorporate context-dependent variation, including intraspecific differences from individual to ecosystem scales, to avoid jeopardizing projections of ecosystem functioning and service delivery.

scholarly journals The Effect of nest Size and Species Identity on Plant Selection in Acromyrmex Leaf-Cutting Ants

Sociobiology ◽  
2018 ◽  
Vol 65 (3) ◽  
pp. 456 ◽  
Author(s):  
Laura Elizabeth Jofre ◽  
Ana Irene Medina ◽  
Alejandro Gustavo Farji-Brener ◽  
Marta Matilde Moglia
Keyword(s):  
Plant Species ◽  
Foraging Ecology ◽  
Species Traits ◽  
Colony Growth ◽  
Nest Size ◽  
Agricultural Pests ◽  
Species Identity ◽  
Extrinsic Factors ◽  
Intrinsic Factors ◽  
Leaf Cutting

Leaf-cutting ants are key organisms because their role as primary consumers and potential agricultural pests. However, their foraging ecology was mostly studied as response of extrinsic factors such as climate and plant species traits. We evaluated the effects of intrinsic factors (i. e., nest size and species identity) on the foraging behavior in two species of Acromyrmex Mayr leaf-cutting ants. While large and small nests of A. lobicornis Emery showed similar feeding behavior, small nests of A. striatus Roger harvested a greater percent of the plant species available in their foraging area and showed a higher level of selectivity than larger nests. We discussed some probable reasons for this pattern. Our results highlight the relevance of intrinsic factors and species characteristics to explain changes in the foraging ecology of leaf-cutting ants as colony growth.

scholarly journals Trait-based responses to cessation of nutrient enrichment in a tundra plant community

Oecologia ◽  
2021 ◽  
Author(s):  
Chhaya M. Werner ◽  
Maria Tuomi ◽  
Anu Eskelinen
Keyword(s):  
Plant Communities ◽  
Nutrient Enrichment ◽  
Nutrient Use Efficiency ◽  
Species Traits ◽  
Functional Trait ◽  
Nutrient Addition ◽  
Species Identity ◽  
Community Recovery ◽  
Plant Resource ◽  
Fertilization Effects

AbstractPlant communities worldwide show varied responses to nutrient enrichment—including shifts in species identity, decreased diversity, and changes in functional trait composition—but the factors determining community recovery after the cessation of nutrient addition remain uncertain. We manipulated nutrient levels in a tundra community for 6 years of nutrient addition followed by 8 years of recovery. We examined how community recovery was mediated by traits related to plant resource-use strategy and plant ability to modify their environment. Overall, we observed persistent effects of fertilization on plant communities. We found that plants with fast-growing traits, including higher specific leaf area, taller stature and lower foliar C:N, were more likely to show a persistent increase in fertilized plots than control plots, maintaining significantly higher cover in fertilized plots 8 years after cessation of fertilization. Additionally, although graminoids responded most strongly to the initial fertilization treatment, forb species were more vulnerable to fertilization effects in the long-term, showing persistent decline and no recovery in 8 years. Finally, these persistent fertilization effects were accompanied by modified environmental conditions, including persistent increases in litter depth and soil phosphorous and lower soil C:N. Our results demonstrate the potential for lasting effects of nutrient enrichment in nutrient-limited systems and identify species traits related to rapid growth and nutrient-use efficiency as the main predictors of the persistence of nutrient enrichment effects. These findings highlight the usefulness of trait-based approach for understanding the persistent feedbacks of nutrient enrichment, plant dynamics, and niche construction via litter and nutrient build-up.

scholarly journals Just how big is intraspecific trait variation in basidiomycete wood fungal fruit bodies?

2019 ◽  
Author(s):  
Samantha K. Dawson ◽  
Mari Jönsson
Keyword(s):  
Intraspecific Variation ◽  
Community Dynamics ◽  
Niche Partitioning ◽  
Fruit Body ◽  
Interspecific Variation ◽  
Functional Trait ◽  
Species Level ◽  
Fungal Ecology ◽  
Species Identity ◽  
Trait Variation

AbstractAs the use of functional trait approaches is growing in fungal ecology, there is a corresponding need to understand trait variation. Much of trait theory and statistical techniques are built on the assumption that interspecific variation is larger than intraspecific variation. This allows the use of mean trait values for species, which the vast majority of trait studies adopt. We examined the size of intra- vs. inter-specific variation in two wood fungal fruit body traits: size and density. Both coefficients of variation (CV) and Trait Probability Density analyses were used to quantify trait variation. We found that intraspecific variation in fruit body density was more than twice as variable as interspecific variation, and fruit body size was hugely variable (CVs averaged 190%), although interspecific variation was larger. Further, there was a very high degree of overlap in the trait space of species, indicating that there may be little niche partitioning at the species level. These findings show that intraspecific variation is highly important and should be accounted for when using trait approaches to understand fungal ecology. More data on variation of other fungal traits is also desperately needed to ascertain whether the high level of variation found here is typical for fungi. While the need to measure individuals does reduce the ability to generalise at the species level, it does not negate the usefulness of fungal trait measurements. There are two reasons for this: first, the ecology of most fungal species remains poorly known and trait measurements address this gap; and secondly, if trait overlap between species more generally is as much as we found here, then individual measurements may be more helpful than species identity for untangling fungal community dynamics.

scholarly journals Species specificity and intraspecific variation in the chemical profiles of Heliconius butterflies across a large geographic range

2019 ◽  
Author(s):  
Kathy Darragh ◽  
Gabriela Montejo-Kovacevich ◽  
Krzysztof M. Kozak ◽  
Colin R. Morrison ◽  
Clarisse M. E. Figueiredo ◽  
...  
Keyword(s):  
Mate Choice ◽  
Strong Correlation ◽  
Species Recognition ◽  
Population Level ◽  
Species Traits ◽  
Geographic Range ◽  
Biologically Active ◽  
Species Identity ◽  
Strong Signal ◽  
Chemical Profiles

AbstractIn many animals, mate choice is important for the maintenance of reproductive isolation between species. Traits important for mate choice and behavioural isolation are predicted to be under strong stabilising selection within species, however such traits can also exhibit variation at the population level driven by neutral and adaptive evolutionary processes. Here, we describe patterns of divergence among androconial and genital chemical profiles at inter- and intra-specific levels in mimetic Heliconius butterflies. Most variation in chemical bouquets was found between species, but there were also quantitative differences at the population level. We found a strong correlation between interspecific chemical and genetic divergence, however, this correlation varied in intraspecific comparisons. We identified ‘indicator’ compounds characteristic of particular species that included known biologically active compounds, suggesting an approach for identification of candidate compounds for future behavioural studies in novel systems. Overall, the strong signal of species identity suggests a role for these compounds in species recognition, but with additional potentially neutral variation at the population level.

scholarly journals Effects of species traits and abiotic factors during the stages of plant invasions

2020 ◽  
Author(s):  
Daniel Vedder ◽  
Ludwig Leidinger ◽  
Juliano Sarmento Cabral
Keyword(s):  
Propagule Pressure ◽  
Management Practice ◽  
Mechanistic Model ◽  
Abiotic Factors ◽  
Species Traits ◽  
Influential Factors ◽  
Invasion Success ◽  
List Type ◽  
Species Invasions ◽  
Dispersal Abilities

AbstractThe success of species invasions depends on multiple factors acting over the four invasion stages transport, colonisation, establishment, and landscape spread. Each of these stages is influenced simultaneously by particular species traits and abiotic factors. While the importance of many of these determinants has already been investigated in relative isolation, they are rarely studied in combination and even then mostly ignore the final phase, i.e., landscape spread.Here we address this shortcoming by exploring the effect of both species traits and abiotic factors on the success of invasions using an individual-based mechanistic model, and relate those factors to the stages of invasion. This approach enables us to explicitly control abiotic factors (temperature as surrogate for productivity, disturbance and propagule pressure) as well as to monitor whole-community trait distributions of environmental adaptation, mass and dispersal abilities. We simulated introductions of plant individuals to an oceanic island to assess which abiotic factors and species traits contribute to invasion success.We found that the most influential factors were higher propagule pressure and a particular set of traits. This invasion trait syndrome was characterized by a relative similarity in functional traits of invasive species to natives, while invasives had on average higher environmental tolerances, higher body mass and increased dispersal abilities, i.e., were more generalist and dispersive.Our results highlight the importance in management practice of reducing the import of alien species, especially from similar habitats.

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