Leaf Traits Within Communities: Context May Affect the Mapping of Traits to Function

The leaf economics spectrum (LES) has revolutionized the way many ecologists think about quantifying plant ecological trade-offs. In particular, the LES has connected a clear functional trade-off (long-lived leaves with slow carbon capture vs. short-lived leaves with fast carbon capture) to a handful of easily measured leaf traits. Building on this work, community ecologists are now able to quickly assess species carbon-capture strategies, which may have implications for community-level patterns such as competition or succession. However, there are a number of steps in this logic that require careful examination, and a potential danger arises when interpreting leaf-trait variation among species within communities where trait relationships are weak. Using data from 22 diverse communities, we show that relationships among three common functional traits (photosynthetic rate, leaf nitrogen concentration per mass, leaf mass per area) are weak in communities with low variation in leaf life span (LLS), especially communities dominated by herbaceous or deciduous woody species. However, globally there are few LLS data sets for communities dominated by herbaceous or deciduous species, and more data are needed to confirm this pattern. The context-dependent nature of trait relationships at the community level suggests that leaf-trait variation within communities, especially those dominated by herbaceous and deciduous woody species, should be interpreted with caution

Species Composition and Fire: Non-Additive Mixture Effects on Ground Fuel Flammability

Diversity effects on many aspects of ecosystem function have been well documented. However, fire is an exception: fire experiments have mainly included single species, bulk litter, or vegetation, and, as such, the role of diversity as a determinant of flammability, a crucial aspect of ecosystem function, is poorly understood. This study is the first to experimentally test whether flammability characteristics of two-species mixtures are non-additive, i.e., differ from expected flammability based on the component species in monospecific fuel. In standardized fire experiments on ground fuels, including monospecific fuels and mixtures of five contrasting subarctic plant fuel types in a controlled laboratory environment, we measured flame speed, flame duration, and maximum temperature. Broadly half of the mixture combinations showed non-additive effects for these flammability indicators; these were mainly enhanced dominance effects for temporal dynamics – fire speed and duration. Fuel types with the more flammable value for a characteristic determined the rate of fire speed and duration of the whole mixture; in contrast, maximum temperature of the fire was determined by the biomass-weighted mean of the mixture. These results suggest that ecological invasions by highly flammable species may have effects on ground-fire dynamics well out of proportion to their biomass

Neoliberal Redistributive Policy: The U.S. Net Social Wage in the 21st Century

In this paper, I examine the trends of fiscal transfers between the state and workers during 1959 - 2012 to understand the net impact of redistributive policy in the United States. This paper presents original net social wage data from and analysis based on the replication and extension of Shaikh and Tonak (2002). The paper investigates the appearance of a post-2001 variation in the net social wage data. The positive net social wage in the 21st century is the result of a combination of factors including the growth of income support, healthcare inflation, neoliberal tax reforms, and macroeconomic instability. Growing economic inequality does not appear to alter the results of the net social wage methodology

Experimental evidence that leaf litter decomposability and flammability are decoupled across gymnosperm species

Biological decomposition and wildfire are two predominant and alternative processes that can mineralize organic C in forest litter. Currently, the relationships between decomposition and fire are still poorly understood. We provide an empirical test of the hypothesized decoupling of surface litter bed decomposability and flammability, and the underlying traits and trait spectra. We employed a 41-species set of gymnosperms of very broad evolutionary and geographic spread, because of the wide range of (absent to frequent) fire regimes they are associated with. We found that the interspecific pattern of mass loss proportions in a "common garden" decomposition experiment was not correlated with any of the flammability parameters and an RDA analysis also showed that the decomposability and flammability of leaf litter in litter layers were decoupled across species. This decoupling originates from the former depending mostly on size and shape spectrum traits and the latter on PES traits and those trait spectra being virtually uncorrelated. Synthesis: Our results show that, indeed, leaf litter decomposability and flammability parameters are decoupled across species, and this decoupling can be explained by their different drivers in terms of trait spectra: chemical traits for decomposability and size-shape traits for litter layer flammability

Putting plant resistance traits on the map: a test of the idea that plants are better defended at lower latitudes

It has long been believed that plant species from the tropics have higher levels of traits associated with resistance to herbivores than do species from higher latitudes. A meta-analysis recently showed that the published literature does not support this theory. However, the idea has never been tested using data gathered with consistent methods from a wide range of latitudes. We quantified the relationship between latitude and a broad range of chemical and physical traits across 301 species from 75 sites world-wide. Six putative resistance traits, including tannins, the concentration of lipids (an indicator of oils, waxes and resins), and leaf toughness were greater in highlatitude species. Six traits, including cyanide production and the presence of spines, were unrelated to latitude. Only ash content (an indicator of inorganic substances such as calcium oxalates and phytoliths) and the properties of species with delayed greening were higher in the tropics. Our results do not support the hypothesis that tropical plants have higher levels of resistance traits than do plants from higher latitudes. If anything, plants have higher resistance toward the poles. The greater resistance traits of high-latitude species might be explained by the greater cost of losing a given amount of leaf tissue in low-productivity environments.EEA Santa CruzFil: Moles, Angela T. The University of New South Wales. School of Biological, Earth and Environmental Sciences. Evolution & Ecology Research Centre; Australia.Fil: Moles, Angela T. Victoria University of Wellington. School of Biological Sciences; Nueva ZelandiaFil: Moles, Angela T. Australian National University. Research School of Biology; Australia.Fil: Moles, Angela T. Macquarie University. Department of Biological Sciences; Australia.Fil: Wallis, Ian R. Australian National University. Research School of Biology; Australia.Fil: Foley, William J. Australian National University. Research School of Biology; Australia.Fil: Warton, David I. The University of New South Wales. School of Mathematics and Statistics and Evolution & Ecology Research Centre; Australia.Fil: Stegen, James C. University of North Carolina. Department of Biology; Estados UnidosFil: Bisigato, Alejandro J. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina.Fil: Cella-Pizarro, Lucrecia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; Argentina.Fil: Clark, Connie J. Woods Hole Research Center; Estados UnidosFil: Cohen, Philippe S. Stanford University. Jasper Ridge Biological Preserve; Estados UnidosFil: Cornwell, William K. University of British Columbia. Biodiversity Research Centre; Canadá.Fil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Prior, Lynda D. University of Tasmania. School of Plant Science; Australia

Symbiotic status alters fungal eco-evolutionary offspring trajectories

Despite host-fungal symbiotic interactions being ubiquitous in all ecosystems, understanding how symbiosis has shaped the ecology and evolution of fungal spores that are involved in dispersal and colonization of their hosts has been ignored in life-history studies. We assembled a spore morphology database covering over 26,000 species of free-living to symbiotic fungi of plants, insects and humans and found more than eight orders of variation in spore size. Evolutionary transitions in symbiotic status correlated with shifts in spore size, but the strength of this effect varied widely among phyla. Symbiotic status explained more variation than climatic variables in the current distribution of spore sizes of plant-associated fungi at a global scale while the dispersal potential of their spores is more restricted compared to free-living fungi. Our work advances life-history theory by highlighting how the interaction between symbiosis and offspring morphology shapes the reproductive and dispersal strategies among living forms

An Automatic Palindrome Generator

In 1984 Dan Hoey, a US naval mathematician, wrote a computer which he used to create a 540-word expansion of Leigh Mercer\u27s Panama palindrome (PD). It began A man, a plan, a caret, a ban, a myriad, a sum, a lac... and ended ...a calmus, a diaryman, a bater, a canal Panama. (For the full PD, plus additional information, see http://www2.vo.lu/homepages/phahn/anagrams/panama/htm.

Sexual dimorphism in trait variability and its eco-evolutionary and statistical implications

Biomedical and clinical sciences are experiencing a renewed interest in the fact that males and females differ in many anatomic, physiological, and behavioural traits. Sex differences in trait variability, however, are yet to receive similar recognition. In medical science, mammalian females are assumed to have higher trait variability due to estrous cycles (the ‘estrus-mediated variability hypothesis’); historically in biomedical research, females have been excluded for this reason. Contrastingly, evolutionary theory and associated data support the ‘greater male variability hypothesis’. Here, we test these competing hypotheses in 218 traits measured in >26,900 mice, using meta-analysis methods. Neither hypothesis could universally explain patterns in trait variability. Sex bias in variability was trait-dependent. While greater male variability was found in morphological traits, females were much more variable in immunological traits. Sex-specific variability has eco-evolutionary ramifications, including sex-dependent responses to climate change, as well as statistical implications including power analysis considering sex difference in variance.SRKZ and ML were supported by the Australian (ARC) Discovery Grant (DP180100818) awarded to SN. JM was supported by EMBL core funding and the NIH Common Fund (UM1-H G006370). AMS was supported by an ARC fellowship (DE180101520)