Tag Archives: Species

Darwin online

Yesterday was the anniversary of the first publication of “On the Origin of Species”, by Charles Darwin.

You can read this book, and all Darwin’s other writings, completely free online

http://darwin-online.org.uk/

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Laura

Clade Age and Species Richness in Eukaryotic Tree of Life

No fossil record included in this study (it is discussed briefly) but interesting paper in any case.

- Laura

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Clade Age and Species Richness Are Decoupled Across the Eukaryotic Tree of
Life

Daniel L. Rabosky, Graham J. Slater, Michael E. Alfaro

Abstract  
Explaining the dramatic variation in species richness across the tree of
life remains a key challenge in evolutionary biology. At the largest
phylogenetic scales, the extreme heterogeneity in species richness observed
among different groups of organisms is almost certainly a function of many
complex and interdependent factors. However, the most fundamental
expectation in macroevolutionary studies is simply that species richness in
extant clades should be correlated with clade age: all things being equal,
older clades will have had more time for diversity to accumulate than
younger clades. Here, we test the relationship between stem clade age and
species richness across 1,397 major clades of multicellular eukaryotes that
collectively account for more than 1.2 million described species. We find no
evidence that clade age predicts species richness at this scale. We
demonstrate that this decoupling of age and richness is unlikely to result
from variation in net diversification rates among clades. At the largest
phylogenetic scales, contemporary patterns of species richness are
inconsistent with unbounded diversity increase through time. These results
imply that a fundamentally different interpretative paradigm may be needed
in the study of phylogenetic diversity patterns in many groups of organisms.

http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.pbio.1001381