No abstract

Understanding and predicting how species' distributions will shift as climate changes are central questions in ecology today. The late Quaternary of North America represents a natural experiment in which we can evaluate how species responded during the expansion and contraction of the glaciers. Here, we ask whether species' range shifts differ because of taxonomic affinity, life-history traits, body size or topographic heterogeneity and whether the species survived the megafaunal extinction. There was no difference in range shifts between victims and survivors of the megafaunal extinction. In general, the change in the size of a species' range is not well correlated with any of the ecological or life-history traits evaluated. However, there are significant relationships between some variables and the movements of the centroids of ranges. Differences in the distances shifted exist among orders, although this is probably a result of body size differences as larger bodied species show larger shifts. Although there are a few exceptions, the distance that species shifted their range was weakly correlated with life-history traits. Finally, species in more topographically heterogeneous areas show smaller shifts than species in less-diverse areas. Overall, these results indicate that when trying to predict species range shifts in the future, body size, lifespan and the topographic relief of the landscape should be taken into account.

To study how changes in gene regulation shape phenotypic variations in rice, we performed a comparative analysis of genome expression in the heading-stage panicle from six lineages of cultivated and wild rice, including Oryza sativa subsp. indica, japonica and javanica, O. nivara , O. rufipogon and O. glaberrima. While nearly three-quarters of the genes are expressed at a constant level in all six lineages, a large portion of the genome, ranging from 1767 to 4489 genes, exhibited differential expression between Asian domesticated and wild rice with repression or down-regulation of genome expression in Asian cultivated rice as the dominant trend. Importantly, we found this repression was achieved to a large extent by the differential expression of a single member of paralogous gene families. Functional analysis of the differentially expressed genes revealed that genes related to catabolism are repressed while genes related to anabolism up-regulated. Finally, we observed that distinct evolutionary forces may have acted on gene expression and the coding sequences in the examined rice lineages.