Analysis of phylogenetic tree shape enables researchers to quantify continuous variation in speciation rates and extinction rates across evolutionary time. The distribution of branch lengths and patterns of tree balance contain information about how these rates have changed throughout the history of a clade. [@mooers_inferring_1997]
Definitions
Synthesis
Tree shape, characterized by balance statistics and branch length distributions, serves as an established quantitative signature of variation in speciation and extinction rates across clades and through evolutionary time. The mechanistic connection operates through the branching patterns that different rate dynamics produce: symmetrical or asymmetrical splits reflect how diversification is distributed across lineages, while the temporal spacing of branches encodes the pace at which speciation and extinction events occurred. This analytical framework has proven particularly effective at detecting dramatic macroevolutionary phenomena such as mass extinctions and adaptive radiations, which leave distinctive structural signatures in phylogenetic trees of extant taxa. However, the degree to which tree shape analysis can reliably associate rate variation with specific ecological or biogeographical causes remains an area of active investigation, as disentangling the relative contributions of different evolutionary processes from tree structure alone presents ongoing methodological challenges.
Related
- Tree balance and branch length distribution characterize tree shape
- Phylogenetic tree shape reflects macroevolutionary processes
- Tree shape detects mass extinctions and adaptive radiations
- Tree shape associates evolutionary rate changes with ecological causes