Grateful for the dead: the widespread importance of dead foundation species for biodiversity, ecosystem function, and resilience.

Foundation species such as corals, trees, and bivalves enhance ecosystem function and biodiversity by creating habitat for associated organisms, ameliorating stress, and modifying energy flow. However, theory generally ignores their ecological functions after death. Here we review the traits and functions of dead foundation species relative to their living counterparts, and the processes that control their persistence. We also conduct a meta-analysis to quantify where the effect of dead foundation species on community functions is unique or redundant to their living counterparts. We focus on marine ecosystems due to the greater diversity of foundation species they support and the increasing prevalence of mass-mortality events in these systems. Our study reveals how foundation species continue to provide important functions after death and exhibit new functions that are distinct from when they are alive. We develop a framework using broad, trait-based functional differences among types of dead foundation species to predict whether they will promote stability by enhancing ecosystem resilience or promote shifts to alternate states. Our synthesis establishes how an understanding of the ecological importance of dead foundation species can assist in predicting system trajectories, enhance restoration and conservation efforts, and contribute to ecological theory on habitat heterogeneity and ecosystem function.

Spontaneous emergence of non-convertible cell states with CD24-High phenotype results in phenotypic heterogeneity that associates with poor prognosis in oral cancer

Cancer cells within individual tumors often exist in distinct phenotypic states contributing to intratumoral heterogeneity (ITH). However, studies on cell state dynamics among oral cancer cells are largely missing. Here, we have multiplexed phenotypic markers of putative oral-stem-like cancer cells (SLCCs) and characterized diversity among CD44-positive oral cancer cell subpopulations with respect to distinct expression of CD24 and aldehyde dehydrogenase (ALDH)-activity. Our in vitro experimental observations were explained by a Markov model where subpopulations followed two distinct patterns of spontaneous repopulation dynamics. Cells showed stochastic inter-conversions on ALDH-axis, harnessed by cancer cells to enrich ALDHHigh subpopulations in response to Cisplatin treatment. However, these cells followed a strict non-interconvertible transition of CD24Low to CD24High subpopulations, even in response to chemotherapy-induced stress. Using phenotype-specific RNAseq, we suggest the organization of subpopulations into hierarchical structure with possible maintenance of intermediate alternate states of stemness within the differentiating oral cancer cells. We also show that the population dynamics described here may influence tumor behaviour by increasing ITH in aggressive oral tumors. Overall, the described phenotypic subgroups not only reliably exhibited spontaneous or Cisplatin-driven cellular dynamics but also the distinct transcription states of oral cancer cells. Most importantly, our in vitro model system derived observations emphasized the prognostic power which may be translated for betterment of oral cancer patients.Graphical AbstractWe have characterized diversity among CD44-positive oral cancer cells lines with respect to distinct expression of CD24 and ALDH-activity. Cells showed stochastic inter-conversions on ALDH-axis but a strict non-interconvertible transition of CD24Low to CD24High phenotype, even in response to chemotherapy-induced stress. RNAseq study suggested the organization of subpopulations into hierarchical structure with possible maintenance of intermediate alternate states of stemness within the differentiating oral cancer cells. The described population dynamics may influence tumor behaviour by increasing intratumoral heterogeneity in aggressive oral tumors.

Characters and Character States

This chapter examines the theory and methods that allow systematists to recognize characters, character states, and the taxa they delimit. In systematics, similarity is a relative relation that exists among at least three things. For a given attribute, two things are more similar to one another than either of them is to a third thing, and when multiple attributes are assessed together, the nested degrees of similarity across the range of attributes provide evidence for hypothesizing phylogenetic relationships. Yet things can be similar in one aspect but not similar in other aspects. Once recognized and characterized in words, a theory of similarity of a feature shared among taxa may be tested in three (often interconnected) ways: (1) conjunction, (2) similarity of structure, and (3) similarity of position. Although the distinction between characters and states may be semantic, treatment of features as alternate states of the same character versus different characters is necessary for the construction of data matrices. How this is done can have important implications for character weights, and potentially the outcome of analyses.

Two alternate states: shrub, bird and mammal assemblages differ on either side of the Dingo Barrier Fence

ABSTRACT The 5500 km long dingo barrier fence (DBF) is a boundary at which the goal of dingo control programs shifts from management to elimination. Since 1980 ecologists have used the discrepancies in dingo densities across the DBF to study the ecological role of Australia’s largest terrestrial predator. We used drone imagery, ground based shrub and tree counts, and camera trap footage to test our hypothesis that there are alternate states in plant, bird and mammal assemblages on either side of the DBF. We found that shrubs and trees were twice as dense where dingoes were rare, and 28 % of shrub and tree species, 78 % of mammal species, and 14 % of bird species recorded were significantly more likely to occur on one side of the DBF than the other. We provide the first comprehensive snapshot of how flora and fauna assemblages differ across the DBF. This study adds to literature demonstrating that the removal of the dingo has led to profound shifts in the shrub, mammal and bird assemblages in arid Australia. Any expansion of dingo control in arid Australia must be considered against the far-reaching consequences for ecosystem assembly associated with the removal of a top predator.

Functional Ecology of Forest, Heath, and Shrub Savannah Alternate States in Eastern Canada

In eastern Canada, alternation of wildfire regime due to fire suppression creates alternate vegetation states converting black spruce forest to heath and shrub savannah (SS). We compared the taxonomic diversity (TD) and functional diversity (FD) of post-fire forest, heath, and SS alternate states to determine if community FD can explain their persistence. We hypothesized that (i) species diversity (TD and FD) would be the highest in forest followed by SS and heath due to decreased interspecific competition and niche differentiation, (ii) differences between TD and FD indices would be greater in communities with high TD in forest due to high trait differentiation and richness, and (iii) changes in community trait values would indicate niche limitations and resource availability. We conducted this study in Terra Nova National Park, Newfoundland, Canada. We calculated functional dispersion (alpha FD), functional pairwise dissimilarity (beta FD), Shannon’s diversity (alpha TD), and Bray–Curtis dissimilarity (beta TD) from species cover. We used five functional traits (specific root length, specific leaf area, leaf dry matter content, height, and seed mass) related to nutrient acquisition, productivity, and growth. We found lower beta diversity in forest than heath and SS; forest also had higher species diversity and greater breadth in niche space utilization. SS was functionally similar to heath but lower than forest in functional dispersion and functional divergence. It had the highest functional richness and evenness. There was no difference in functional evenness between forest and heath. Functional beta diversity was the highest in forest, and did not differ between heath and SS. Resource acquisition and availability was the greatest in forest and the lowest in heath. We suspect that this might be due to forest having the highest functional trait turnover and niche utilization. We conclude that alternate vegetation states originating from alterations to the natural fire regime negatively impact ecosystem function.

Ocean warming and acidification uncouple calcification from calcifier biomass which accelerates coral reef decline

Global climate change will drive declines in coral reefs over coming decades. Yet, the relative role of temperature versus acidification, and the ability of resultant ecosystems to retain core services such as coastal protection, are less clear. Here, we investigate changes to the net chemical balances of calcium carbonate within complex experimental coral reefs over 18 months under conditions projected for 2100 if CO2 emissions continue unmitigated. We reveal a decoupling of calcifier biomass and calcification under the synergistic impact of warming and acidification, that combined with increased night-time dissolution, leads to an accelerated loss of carbonate frameworks. Climate change induced degradation will limit the ability of coral reefs to keep-up with sea level rise, possibly for thousands of years. We conclude that instead of simply transitioning to alternate states that are capable of buffering coastlines, reefs are at risk of drowning leading to critical losses in ecosystem functions.

Broad-spectrum antibiotics alter the microbiome, increase intestinal fxr, and decrease hepatic steatosis in zebrafish short bowel syndrome

In a zebrafish model that replicates a common clinical scenario, systemic effects of the administration of broad-spectrum antibiotics in a zebrafish model of SBS identified two alternate states that led to the establishment of fat accumulation in the liver or its absence. Broad-spectrum antibiotics given to zebrafish with SBS over 2 wk altered the intestinal microbiome, decreased intestinal and hepatic inflammation, and decreased hepatic steatosis.

Shamanic Poetics

This essay examines the relationship between the biblical prophets and prophetic poetry in terms of the “shamanic complex.” First, a short characterization is given of the phenomenon of shamanism in archaic societies, shamanic techniques and alternate states of consciousness, as well as the social, cultural, and political role of shamanic figures. Second, the similarity between shamanism and biblical prophecy is considered. Third, the figure of First Isaiah as presented in the eponymous book in the Hebrew Bible is analyzed in terms of the shamanic complex and shamanic poetics as to aspects of his initiation as prophet and represented features of his actions as prophet.