An official website of the United States government
ABSTRACT AimStudies assessing large‐scale patterns of microbial diversity have predominantly focused on free‐living microorganisms, often failing to link observed patterns to established theories regarding the maintenance of global diversity patterns. We aimed to determine whether foliar fungi on two closely related grass hosts—Heteropogon contortusandThemeda triandra—display a commonly observed latitudinal gradient in species richness and determine whether host identity, energy (temperature and precipitation), climate seasonality, fire frequency and grass evolutionary history drive the observed patterns in species richness and composition. LocationPaleotropical. Time PeriodContemporary. Major Taxa StudiedFoliar fungi. MethodsFoliar fungal diversity was quantified from 201 leaf samples ofT. triandraandH. contortuscollected across the distributional range of these species. Mixed effects models were used to quantify patterns of diversity and their correlates among and within continents. Ordinations were used to assess drivers of composition. ResultsFoliar fungi displayed consistent latitudinal diversity gradients in richness. Energy was a strong driver of richness at inter‐continental and continental scales, while other factors had inconsistent impacts on richness among scales, hosts and guilds. Globally, richness was higher in regions of higher growing season temperatures and where hosts were present for longer periods. Composition was primarily structured by geographic region at the global scale, indicating that distance was a dominant driver of community composition. Within Australia, temperature and rainfall seasonality and the amount of growing season rainfall, were the dominant drivers of both richness and composition. Main ConclusionsWe find some support for the idea that foliar fungal species diversity is governed by the same factors as many macro‐organisms (energy availability and evolutionary history) at inter‐continental scales, but also that fungal diversity and composition in the highly seasonal continent of Australia were driven by factors that shape tropical grassy ecosystems, namely climate seasonality and fire.
more »
« less
Environmental variables drive spatial patterns of trophic diversity in mammals
Abstract Understanding environmental drivers of species diversity has become increasingly important under climate change. Different trophic groups (predators, omnivores and herbivores) interact with their environments in fundamentally different ways and may therefore be influenced by different environmental drivers. Using random forest models, we identified drivers of terrestrial mammals' total and proportional species richness within trophic groups at a global scale. Precipitation seasonality was the most important predictor of richness for all trophic groups. Richness peaked at intermediate precipitation seasonality, indicating that moderate levels of environmental heterogeneity promote mammal richness. Gross primary production (GPP) was the most important correlate of the relative contribution of each trophic group to total species richness. The strong relationship with GPP demonstrates that basal‐level resource availability influences how diversity is structured among trophic groups. Our findings suggest that environmental characteristics that influence resource temporal variability and abundance are important predictors of terrestrial mammal richness at a global scale.
more »
« less
- Award ID(s):
- 1932889
- PAR ID:
- 10519443
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Ecology Letters
- Volume:
- 26
- Issue:
- 11
- ISSN:
- 1461-023X
- Page Range / eLocation ID:
- 1940 to 1950
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Functional diversity is an important aspect of biodiversity, but its relationship to species diversity in time and space is poorly understood. Here we compare spatial patterns of functional and taxonomic diversity across marine and terrestrial systems to identify commonalities in their respective ecological and evolutionary drivers. We placed species-level ecological traits into comparable multi-dimensional frameworks for two model systems, marine bivalves and terrestrial birds, and used global speciesoccurrence data to examine the distribution of functional diversity with latitude and longitude. In both systems, tropical faunas show high total functional richness (FR) but low functional evenness (FE) (i.e. the tropics contain a highly skewed distribution of species among functional groups). Functional groups that persist toward the poles become more uniform in species richness, such that FR declines and FE rises with latitude in both systems. Temperate assemblages are more functionally even than tropical assemblages subsampled to temperate levels of species richness, suggesting that high species richness in the tropics reflects a high degree of ecological specialization within a few functional groups and/or factors that favour high recent speciation or reduced extinction rates in those groups.more » « less
-
Mean annual temperature and mean annual precipitation drive much of the variation in productivity across Earth's terrestrial ecosystems but do not explain variation in gross primary productivity (GPP) or ecosystem respiration (ER) in flowing waters. We document substantial variation in the magnitude and seasonality of GPP and ER across 222 US rivers. In contrast to their terrestrial counterparts, most river ecosystems respire far more carbon than they fix and have less pronounced and consistent seasonality in their metabolic rates. We find that variation in annual solar energy inputs and stability of flows are the primary drivers of GPP and ER across rivers. A classification schema based on these drivers advances river science and informs management.more » « less
-
ABSTRACT Assemblages in seasonal ecosystems undergo striking changes in species composition and diversity across the annual cycle. Despite a long‐standing recognition that seasonality structures biogeographic gradients in taxonomic diversity (e.g., species richness), our understanding of how seasonality structures other aspects of biodiversity (e.g., functional diversity) has lagged. Integrating seasonal species distributions with comprehensive data on key morphological traits for bird assemblages across North America, we find that seasonal turnover in functional diversity increases with the magnitude and predictability of seasonality. Furthermore, seasonal increases in bird species richness led to a denser packing of functional trait space, but functional expansion was important, especially in regions with higher seasonality. Our results suggest that the magnitude and predictability of seasonality and total productivity can explain the geography of changes in functional diversity with broader implications for understanding species redistribution, community assembly and ecosystem functioning.more » « less
-
Abstract Plant phenology is affected by both abiotic conditions (i.e., temperature, nitrogen enrichment, and drought) and biotic conditions (i.e., species diversity). The degree of spatial heterogeneity in soil resources is known to influence community assembly and dynamics, but the relationship between resource heterogeneity and phenology or the potentially interactive effects of soil resources on phenology are less understood. We leveraged a tallgrass prairie restoration experiment that has manipulated soil nitrogen availability and soil depth over 20 years to test the effects of environmental heterogeneity, nutrient enrichment, and potentially interactive effects of global change drivers (nutrient enrichment and a drought manipulation) on the phenology of a highly dominant prairie grass (Andropogon gerardii). We recorded the timing of major developmental stages ofA. gerardiiin plots containing four soil heterogeneity treatments (control, soil depth heterogeneity, nutrient/depth heterogeneity, and nutrient/precipitation heterogeneity). We found that the boot, first spikelet, and emerged spikelet stages ofA. gerardiioccurred earlier in treatments with greater heterogeneity of soil nitrogen, and this effect was driven by the accelerative effect of nitrogen enrichment on phenology. Reduced precipitation increased the flowering length ofA. gerardiibut did not otherwise affect developmental phenology. There were no interactive effects among any soil resource treatments on phenology. These results advance our understanding of the relationship between plant phenology and global change drivers, which is important for understanding and predicting the timing of plant resource use and the provision of resources to higher trophic levels by plants under varying levels of resource availability.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1111/ele.14306
