Is Mundulla Yellows really a threat to undisturbed native vegetation? A comment

The term Mundulla Yellows (MY) was coined in 1997 to refer to a dieback disorder involving leaf chlorosis which affects Eucalyptus and other native southern Australian vascular plants. It was thought to be a new, spreading, contagious biotic disease with the potential to devastate native vegetation. Since then, research has found no evidence to confirm any role of biotic agents and generally the disorder has been more convincingly attributed to abiotic soil factors. It has now been suggested that most or all of the reported cases of MY are simply the very well‐known nutrient disorder of alkaline soils, lime‐induced chlorosis. All of the well‐documented records of MY are from sites where acidic soils have become more alkaline because of the use of crushed limestone in road‐making or to the use of alkaline irrigation water; none are from undisturbed native vegetation. Despite this research and much circumstantial evidence, the view that MY poses a grave risk to undisturbed vegetation still persists and needs to be corrected accordingly.     

Effects of water temperature on freshwater macroinvertebrates: a systematic review

Water temperature is one of the main abiotic factors affecting the structure and functioning of aquatic ecosystems and its alteration can have important effects on biological communities. Macroinvertebrates are excellent bio-indicators and have been used for decades to assess the status of aquatic ecosystems as a result of environmental stresses; however, their responses to temperature are poorly documented and have not been systematically evaluated. The aims of this review are: (i) to collate and summarize responses of freshwater macroinvertebrates to different temperature conditions, comparing the results of experimental and theoretical studies; (ii) to understand how the focus of research on the effects of temperature on macroinvertebrates has changed during the last 51 years; and (iii) to identify research gaps regarding temperature responses, ecosystem types, organism groups, spatiotemporal scales, and geographical regions to suggest possible research directions. We performed a comparative assessment of 223 publications that specifically consider freshwater macroinvertebrates and address the effects of temperature. Short-term studies performed in the laboratory and focusing on insects exposed to a range of temperatures dominated. Field studies were carried out mainly in Europe, at catchment scale and almost exclusively in rivers; they mainly investigated responses to water thermal regime at the community scale. The most frequent biological responses tested were growth rate, fecundity and the time and length of emergence, whereas ecological responses mainly involved composition, richness, and distribution. Thermal research on freshwater macroinvertebrates has undergone a shift since the 2000s when studies involving extended spatiotemporal scales and investigating the effects of global warming first appeared. In addition, recent studies have considered the effects of temperature at genetic and evolutionary scales. Our review revealed that the effects of temperature on macroinvertebrates are manifold with implications at different levels, from genes to communities. However, community-level physiological, phenological and fitness responses tested on individuals or populations should be studied in more detail given their macroecological effects are likely to be enhanced by climate warming. In addition, most field studies at regional scales have used air temperature as a proxy for water temperature; obtaining accurate water temperature data in future studies will be important to allow proper consideration of the spatial thermal heterogeneity of water bodies and any effects on macroinvertebrate distribution patterns. Finally, we found an uneven number of studies across different ecosystems and geographic areas, with lentic bodies and regions outside the West underrepresented. It will also be crucial to include macroinvertebrates of high-altitude and tropical areas in future work because these groups are most vulnerable to climate warming for multiple reasons. Further studies on temperature–macroinvertebrate relationships are needed to fill the current gaps and facilitate appropriate conservation strategies for freshwater ecosystems in an anthropogenic-driven era.     

Towards diagnostic biotic indices for river macroinvertebrates

The construction of biotic indices that use macroinvertebratesto assess pollution and other anthropogenic disturbances ofrivers and streams often requires that each taxon be assigned anumber indicating its level of sensitivity. A problem inconstructing such indices is that individual taxa may varyquite widely in sensivity, depending on the nature of theparticular disturbance. One possible means of overcoming thisproblem is to construct a suite of indices, each assembledusing sensitivity numbers targeted to a particular impact.In order to test this idea, we sampled macroinvertebrates fromrivers in south-eastern Australia subjected to three differenttypes of anthropogenic disturbance: operation of large dams,discharge of effluent from municipal sewage treatment plants,and contamination by metals originating from historical mining.Using macroinvertebrate data from sampling sites with varyinglevels of exposure to disturbance, we developed sensitivitynumbers for macroinvertebrate families for individual riversand combinations of rivers with the same disturbance type.Sensitivity numbers calculated for individual families differedsignificantly according to disturbance type in several cases.Gastropod molluscs (family Thiaridae) were tolerant of dameffects but sensitive to sewage and metals, whereascoenagrionid damselfly nymphs, elmid beetles and ostracods weremost tolerant of sewage. Corydalid alderfly larvae,leptophlebiid mayfly nymphs, lestid damselfly nymphs,libellulid dragonfly nymphs and scirtid beetle larvae weremost tolerant of metals. Indices constructed using sensitivitynumbers for a particular disturbance were generally mostresponsive to that disturbance, but there was considerablegenerality in responses as well as substantial variabilitybetween different rivers with the same disturbance type. Inparticular, macroinvertebrate communities at sites downstreamof dams responded quite variably, probably because ofsubstantial differences in release regimes. We conclude thatthe approach has merit but requires considerable furtherdevelopment and testing, as well as consideration of the levelsof specificity and diagnostic strength that are appropriate orachievable.     

Villin Family Members Associated with Multiple Stress Responses in Cotton

Villin (VLN) is considered to be one of the most important actin-binding proteins, participates in modulating the actin cytoskeleton dynamics, plays essential role in plant development and resisting adverse environments. However, systematic studies of the VLN gene family have not been reported in cotton (Gossypium). In this study, 14 GhVLNs were identified in G. hirsutum. These GhVLN genes were distributed in 6 A-subgenome chromosomes and 6 D-subgenome chromosomes of the allotetraploid upland cotton and classified into three phylogenetical groups based on the classification model of AtVLNs. In addition, the 14 GhVLN genes have highly conserved gene structure and motif architecture. The number of introns was ranged from 18 to 22 and the length of protein sequences was varied from 901 to 1077. Six gelsolin homology domains, G1–G6, and villin headpiece domain, VHP, were existed in all GhVLNs with the exception of two VLNs (GhVLN6 and GhVLN13) which lacked VHP. Cis-elements analysis revealed that the promoter regions of GhVLNs contained various light related components and also elements responsible for phytohormones and stresses response, indicating that, when subjected to those adverse environments, cotton plants may activate the response system by targeting VLN genes to survive the crisis. Heatmaps showed that the GhVLN genes exhibited various expression patterns, some were accumulated in certain tissues, root, petal, stamen or elongating fibers, and some were obviously induced by environmental changes. Especially GhVLN3 and GhVLN10 were highly and preferentially expressed in elongating fibers and distinctly upregulated by abiotic (salt, PEG, cold and heat) and biotic (Verticillium dahliae V991) stresses. This study may provide useful information for biological function identification of GhVLN genes and gene resources for creating high-quality and various resistant cotton germplasms.