22 research outputs found
Temporal rarity is a better predictor of local extinction risk than spatial rarity
Spatial rarity is often used to predict extinction risk, but rarity can also occur temporally. Perhaps more relevant in the context of global change is whether a species is core to a community (persistent) or transient (intermittently present), with transient species often susceptible to human activities that reduce niche space. Using 5–12 yr of data on 1,447 plant species from 49 grasslands on five continents, we show that local abundance and species persistence under ambient conditions are both effective predictors of local extinction risk following experimental exclusion of grazers or addition of nutrients; persistence was a more powerful predictor than local abundance. While perturbations increased the risk of exclusion for low persistence and abundance species, transient but abundant species were also highly likely to be excluded from a perturbed plot relative to ambient conditions. Moreover, low persistence and low abundance species that were not excluded from perturbed plots tended to have a modest increase in abundance following perturbance. Last, even core species with high abundances had large decreases in persistence and increased losses in perturbed plots, threatening the long-term stability of these grasslands. Our results demonstrate that expanding the concept of rarity to include temporal dynamics, in addition to local abundance, more effectively predicts extinction risk in response to environmental change than either rarity axis predicts alone.Fil: Wilfahrt, Peter A.. University of Minnesota; Estados UnidosFil: Asmus, Ashley L.. University of Minnesota; Estados UnidosFil: Seabloom, Eric. University of Minnesota; Estados UnidosFil: Henning, Jeremiah A.. University of Minnesota; Estados UnidosFil: Adler, Peter. State University of Utah; Estados UnidosFil: Arnillas, Carlos A.. University of Toronto Scarborough; CanadáFil: Bakker, Jonathan. University of Washington; Estados UnidosFil: Biederman, Lori. University of Iowa; Estados UnidosFil: Brudvig, Lars A.. Michigan State University; Estados UnidosFil: Cadotte, Marc W.. University of Toronto Scarborough; CanadáFil: Daleo, Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Eskelinen, Anu. German Centre for Integrative Biodiversity Research; AlemaniaFil: Firn, Jennifer. University of Queensland; AustraliaFil: Harpole, W. Stanley. German Centre for Integrative Biodiversity Research; Alemania. Helmholtz Centre for Environmental Research; Alemania. Martin Luther University Halle-Wittenberg; AlemaniaFil: Hautier, Yann. Utrecht University; Países BajosFil: Kirkman, Kevin P.. University of KwaZulu-Natal; SudáfricaFil: Komatsu, Kimberly J.. Smithsonian Environmental Research Center; Estados UnidosFil: Laungani, Ramesh. Doane University; Estados UnidosFil: MacDougall, Andrew. University of Guelph; CanadáFil: McCulley, Rebecca L.. University of Kentucky; Estados UnidosFil: Moore, Joslin L.. Monash University; AustraliaFil: Morgan, John W.. La Trobe University; AustraliaFil: Mortensen, Brent. Benedictine College; Estados UnidosFil: Ochoa Hueso, Raul. Universidad de Cádiz; EspañaFil: Ohlert, Timothy. University of New Mexico; Estados UnidosFil: Power, Sally A.. University of Western Sydney; AustraliaFil: Price, Jodi. Charles Sturt University; AustraliaFil: Risch, Anita C.. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Schuetz, Martin. Swiss Federal Institute for Forest, Snow and Landscape Research; SuizaFil: Shoemaker, Lauren. University of Wyoming; Estados UnidosFil: Stevens, Carly. Lancaster University; Reino UnidoFil: Strauss, Alexander T.. University of Minnesota; Estados Unidos. University of Georgia; Estados UnidosFil: Tognetti, Pedro Maximiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Virtanen, Risto. University of Oulu; FinlandiaFil: Borer, Elizabeth. University of Minnesota; Estados Unido
Higher predation risk for insect prey at low latitudes and elevations
Biotic interactions underlie ecosystem structure and function, but predicting interaction outcomes is difficult. We tested the hypothesis that biotic interaction strength increases toward the equator, using a global experiment with model caterpillars to measure predation risk. Across an 11,660-kilometer latitudinal gradient spanning six continents, we found increasing predation toward the equator, with a parallel pattern of increasing predation toward lower elevations. Patterns across both latitude and elevation were driven by arthropod predators, with no systematic trend in attack rates by birds or mammals. These matching gradients at global and regional scales suggest consistent drivers of biotic interaction strength, a finding that needs to be integrated into general theories of herbivory, community organization, and life-history evolution
The Astropy Problem
The Astropy Project (http://astropy.org) is, in its own words, "a community
effort to develop a single core package for Astronomy in Python and foster
interoperability between Python astronomy packages." For five years this
project has been managed, written, and operated as a grassroots,
self-organized, almost entirely volunteer effort while the software is used by
the majority of the astronomical community. Despite this, the project has
always been and remains to this day effectively unfunded. Further, contributors
receive little or no formal recognition for creating and supporting what is now
critical software. This paper explores the problem in detail, outlines possible
solutions to correct this, and presents a few suggestions on how to address the
sustainability of general purpose astronomical software
Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome
Invertebrate
herbivores depend on external temperature for growth and metabolism.
Continued warming in tundra ecosystems is proposed to result in
increased invertebrate herbivory. However, empirical data about how
current levels of invertebrate herbivory vary across the Arctic is
limited and generally restricted to a single host plant or a small group
of species, so predicting future change remains challenging. We
investigated large-scale patterns of invertebrate herbivory across the
tundra biome at the community level and explored how these patterns are
related to long-term climatic conditions and year-of-sampling weather,
habitat characteristics, and aboveground biomass production. Utilizing a
standardized protocol, we collected samples from 92 plots nested within
20 tundra sites during summer 2015. We estimated the community-weighted
biomass lost based on the total leaf area consumed by invertebrates for
the most common plant species within each plot. Overall, invertebrate
herbivory was prevalent at low intensities across the tundra, with
estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant
biomass. Our results suggest that mid-summer temperature influences the
intensity of invertebrate herbivory at the community level, consistent
with the hypothesis that climate warming should increase plant losses to
invertebrates in the tundra. However, most of the observed variation in
herbivory was associated with other site level characteristics,
indicating that other local ecological factors also play an important
role. More details about the local drivers of invertebrate herbivory are
necessary to predict the consequences for rapidly changing tundra
ecosystems.KeywordsBackground herbivory Biomass loss Climate change Community-weighted average Invertebrate Insects Tundra </div
Breeding on the leading edge of a northward range expansion: differences in morphology and the stress response in the arctic Gambel's white-crowned sparrow
Individuals at the forefront of a range shift are likely to exhibit phenotypic traits that distinguish them from the population breeding within the historic range. Recent studies have examined morphological, physiological and behavioral phenotypes of individuals at the edge of their range. Several studies have found differences in the hypothalamic-pituitary-adrenal (HPA) axis activity in response to acute restraint stress in individuals at the range limits. HPA axis activation leads to elevations in glucocorticoids that regulate physiology and behavior. Here we compare the hormonal profiles and morphometrics from Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii) breeding at the northern limit of the population's range to those birds breeding within the historic population range. Birds breeding at the northern limit experienced a harsher environment with colder temperatures; however, we found no differences in arthropod prey biomass between the northern limit and more southern (historic) sites. Males at the northern limit had higher body condition scores (mass corrected for body size) compared to individuals within the historic range, but no differences were found in beak and tarsus lengths, wing chord, muscle profile or fat stores. In males during the pre-parental stage, before breeding commenced, HPA axis activity was elevated in birds at the northern limit of the range, but no differences were found during the parental or molt stages. Females showed no differences in HPA axis activity during the parental stage. This study suggests that "pioneering" individuals at the limits of their breeding range exhibit physiology and morphology that are distinct from individuals within the historic range
QTLs for Biomass and Developmental Traits in Switchgrass (Panicum virgatum)
Genetic and genomic resources have recently been developed for the bioenergy crop switchgrass (Panicum virgatum). Despite these advances, little research has been focused on identifying genetic loci involved in natural variation of important bioenergy traits, including biomass. Quantitative trait locus (QTL) mapping is typically used to discover loci that contribute to trait variation. Once identified, QTLs can be used to improve agronomically important traits through marker-assisted selection. In this study, we conducted QTL mapping in Austin, TX, USA, with a full-sib mapping population derived from a cross between tetraploid clones of two major switchgrass cultivars (Alamo-A4 and Kanlow-K5). We observed significant among-genotype variation for the vast majority of growth, morphological, and phenological traits measured on the mapping population. Overall, we discovered 27 significant QTLs across 23 traits. QTLs for biomass production colocalized on linkage group 9b across years, as well as with a major biomass QTL discovered in another recent switchgrass QTL study. The experiment was conducted under a rainout shelter, which allowed us to examine the effects of differential irrigation on trait values. We found very minimal effects of the reduced watering treatment on traits, with no significant effect on biomass production. Overall, the results of our study set the stage for future crop improvement through marker-assisted selection breeding
Serum levels of perfluorooctanoic acid and perfluorooctane sulfonic acid in pregnant women: Maternal predictors and associations with birth outcomes in the PIPA
Hiding in the background: community-level patterns in invertebrate herbivory across the tundra biome
Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and year-of-sampling weather, habitat characteristics, and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02 and 5.69% of plant biomass. Our results suggest that mid-summer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems