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<jats:p>Hülsmann and Hartig suggest that ecological mechanisms other than specialized natural enemies or intraspecific competition contribute to our estimates of conspecific negative density dependence (CNDD). To address their concern, we show that our results are not the result of a methodological artifact and present a null-model analysis that demonstrates that our original findings—(i) stronger CNDD at tropical relative to temperate latitudes and (ii) a latitudinal shift in the relationship between CNDD and species abundance—persist even after controlling for other processes that might influence spatial relationships between adults and recruits.</jats:p>

<jats:p> LaManna <jats:italic>et al</jats:italic> . (Reports, 30 June 2017, p. 1389) found higher conspecific negative density dependence in tree communities at lower latitudes, yielding a possible mechanistic explanation for the latitudinal diversity gradient. We show that their results are artifacts of a selective data transformation and a forced zero intercept in their fitted model. A corrected analysis shows no latitudinal trend. </jats:p>

<jats:title>Mapping the planarian transcriptome</jats:title> <jats:p> A cell type's transcriptome defines the active genes that control its biology. Two groups used single-cell RNA sequencing to define the transcriptomes for essentially all cell types of a complete animal, the regenerative planarian <jats:italic>Schmidtea mediterranea.</jats:italic> Because pluripotent stem cells constantly differentiate to rejuvenate any part of the body of this species, all developmental lineages are active in adult animals. Fincher <jats:italic>et al.</jats:italic> determined the transcriptomes for most, if not all, planarian cell types, including some that were previously unknown. They also identified transition states and genes governing positional information. Plass <jats:italic>et al.</jats:italic> used single-cell transcriptomics and computational algorithms to reconstruct a lineage tree capturing the developmental progressions from stem to differentiated cells. They could then predict gene programs that are specifically turned on and off along the tree, and they used this approach to study how the cell types behaved during regeneration. These whole-animal transcriptome “atlases” are a powerful way to study metazoan biology. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.aaq1736">eaaq1736</jats:related-article> , p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.aaq1723">eaaq1723</jats:related-article> </jats:p>

<jats:title>Bile acids and liver cancer</jats:title> <jats:p> Liver cancer is a leading cause of cancer-related deaths in the United States. The composition of the gut microbiome influences many human diseases, including liver inflammatory disorders. Ma <jats:italic>et al.</jats:italic> found that commensal gut bacteria can recruit the immune system to control the growth of liver tumors in mice (see the Perspective by Hartmann and Kronenberg). <jats:italic>Clostridium</jats:italic> species modified bile acids to signal liver sinusoidal endothelial cells to produce the chemokine CXCL16. This recruited natural killer T (NKT) immune cells to perform antitumor surveillance of the liver. Growth of both primary and metastatic cancer was reduced by NKT cell–driven killing. </jats:p> <jats:p> <jats:italic>Science</jats:italic> , this issue p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" related-article-type="in-this-issue" xlink:href="10.1126/science.aan5931">eaan5931</jats:related-article> ; see also p. <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" issue="6391" page="858" related-article-type="in-this-issue" vol="360" xlink:href="10.1126/science.aat8289">858</jats:related-article> </jats:p>