Genetic diversity is the amount of variation observed between DNA sequences from distinct individuals of a given species. This pivotal concept of population genetics has implications for species health, domestication, management and conservation. Levels of genetic diversity seem to vary greatly in natural populations and species, but the determinants of this variation, and particularly the relative influences of species biology and ecology versus population history, are still largely mysterious. Here we show that the diversity of a species is predictable, and is determined in the first place by its ecological strategy. We investigated the genome-wide diversity of 76 non-model animal species by sequencing the transcriptome of two to ten individuals in each species. The distribution of genetic diversity between species revealed no detectable influence of geographic range or invasive status but was accurately predicted by key species traits related to parental investment: long-lived or low-fecundity species with brooding ability were genetically less diverse than short-lived or highly fecund ones. Our analysis demonstrates the influence of long-term life-history strategies on species response to short-term environmental perturbations, a result with immediate implications for conservation policies.

Summary Tissue regeneration is a multi-step process mediated by diverse cellular hierarchies and states that are also implicated in tissue dysfunction and pathogenesis. Here we leveraged single-cell RNA sequencing in combination with in vivo lineage tracing and organoid models to finely map the trajectories of alveolar-lineage cells during injury repair and lung regeneration. We identified a distinct AT2-lineage population, damage-associated transient progenitors (DATPs), that arises during alveolar regeneration. We found that interstitial macrophage-derived IL-1β primes a subset of AT2 cells expressing Il1r1 for conversion into DATPs via a HIF1α -mediated glycolysis pathway, which is required for mature AT1 cell differentiation. Importantly, chronic inflammation mediated by IL-1β prevents AT1 differentiation, leading to aberrant accumulation of DATPs and impaired alveolar regeneration. Together, this stepwise mapping to cell fate transitions shows how an inflammatory niche controls alveolar regeneration by controlling stem cell fate and behavior.

The N6-methyladenosine (m 6 A) is an abundant internal RNA modification 1,2 catalysed predominantly by the METTL3-METTL14 methyltransferase complex 3,4 . The m 6 A writer METTL3 has been linked to the initiation and maintenance of acute myeloid leukaemia (AML), but its true therapeutic importance is still unknown [5][6][7] . Here we present the identification and characterisation of a highly potent and selective first-in-class catalytic inhibitor of METTL3 (STM2457) and its co-crystal structure bound to METTL3/METTL14. Treatment with (Extended Data Fig. 2f). These data demonstrate that STM2457 is a highly potent, specific and bioavailable inhibitor of METTL3, suitable for in vivo investigations. Cellular and molecular effects of STM2457To study the anti-leukaemic potential of STM2457 we examined the proliferation of a panel of human AML cell lines post-treatment and detected significant growth reduction in a concentration-dependent manner (Fig. 2a) while we found that STM2457 did not affect the colony-forming ability of normal human cord blood CD34 + cells (Extended Data Fig. 3a). We also observed no impact on the proliferation of MOLM-13 cells treated with the control small molecule STM2120, unlike our observations with STM2457 (Extended Data Fig. 3b). Additionally, treatment with STM2457 significantly reduced the clonogenic potential of primary murine AML cells (Fig. 2b and Extended Data Fig. 3c), while having no effect on normal haematopoietic stem and progenitor cells (HSPCs) (Fig. 2c). Pharmacological inhibition of METTL3 also caused significant myeloid differentiation 6,11 and cell cycle arrest in MOLM-13 and primary murine AML cells (Fig. 2d, e). In contrast, the same effects were not identified using the non-leukaemic haemopoietic cell line HPC7 (Fig. 3e and Extended Data Fig. 3d). Moreover, treatment with STM2457 induced apoptosis in human and mouse AML models but not in normal non-leukaemic haemopoietic cells (Fig. 2f and Extended Data Fig. 3e). To assess the impact of pharmacological inhibition of METTL3 on two known METTL3 biomarkers associated with AML, SP1 6,12 and BRD4 13,14 , we treated MOLM-13 cells with STM2457 and observed a dose-dependent reduction of SP1 and BRD4 protein levels (Fig. 2g). Notably, ectopic expression of SP1 significantly reduced the sensitivity of MOLM-13 cells to STM2457 (Extended Data Fig. 3f, g). These data establish that the catalytic function of METTL3 is important for leukaemia growth, in line with previous findings 6,7,15 . We next sought to investigate the molecular mechanism by which STM2457 affects AML. RNAseq analysis of MOLM-13 cells treated with STM2457 revealed 1,338 up-regulated and 489 down-regulated genes (Extended Data Fig. 4a and Supplementary Table 1). Gene ontology (GO) analysis of the differentially expressed genes showed enrichment in pathways related to myeloid differentiation, cell cycle and leukaemia progression (Extended Data Fig. 4b, c) in close agreement with our phenotypic observations (Supplementary Table 2). To examine the impact of the pharmac...