Skip to main content Accessibility help
×
Home

Cladistics and the rate of homoplastic morphological evolution

  • Mark Wilkinson (a1) and Michael J. Benton (a1)

Abstract

Estimates of evolutionary rates require measurement of amounts of change and the period of time over which such change has occurred. Many methods of estimating amount of morphological change are available (including phenetic and morphometric measures) but in cladistics the unit of change is the step or transformation.

For a given cladistic data set the length (total number of steps) of the most parsimonious cladogram gives a lower bound estimate of the amount of evolution that has occurred within the clade. This measure is correlated with numbers of characters and taxa (and other internal parameters) in the data sets and so cannot be used to compare amounts of evolution in different clades where data set sizes vary. Further, the number of characters incorporated into cladistic studies varies widely and is likely to be a poor basis for an estimate of overall amounts of change.

One approach to the measurement of amounts of change which avoids some of these problems is to focus upon comparative levels of homoplasy rather than total amounts of morphological evolution. Most parsimonious cladograms provide lower bound estimates of the amount of homoplasy measured as extra steps.

Maximally homoplastic data provides the theoretical upper limit to the amount of homoplasy that can be estimated for a particular data set. Combining this with estimates of group duration derived from the fossil record or from molecular clocks provides an estimate of maximum rates of homoplastic evolution that can be measured using cladistic parsimony and discrete data.

Randomly permuted data provides a measure of the amount of homoplastic evolution that would be reconstructed by parsimony analysis for character data that is independent of phylogeny. Combining this with estimates of group duration provides estimates of rate of homoplastic evolution that would be sufficient to render the application of parsimony to the problems of phylogeny reconstruction inappropriate.

Comparative estimates of the rates of homoplastic evolution in different clades can be used to test macroevolutionary theories.

    • Send article to Kindle

      To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

      Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

      Find out more about the Kindle Personal Document Service.

      Cladistics and the rate of homoplastic morphological evolution
      Available formats
      ×

      Send article to Dropbox

      To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

      Cladistics and the rate of homoplastic morphological evolution
      Available formats
      ×

      Send article to Google Drive

      To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

      Cladistics and the rate of homoplastic morphological evolution
      Available formats
      ×

Copyright

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed