Access

You are not currently logged in.

Access JSTOR through your library or other institution:

login

Log in through your institution.

Journal Article

Continuous Track Analysis: A New Phylogenetic and Biogeographic Method

John Alroy
Systematic Biology
Vol. 44, No. 2 (Jun., 1995), pp. 152-178
DOI: 10.2307/2413704
Stable URL: http://www.jstor.org/stable/2413704
Page Count: 27
Were these topics helpful?
See something inaccurate? Let us know!

Select the topics that are inaccurate.

Cancel
  • Download ($42.00)
  • Add to My Lists
  • Cite this Item
Continuous Track Analysis: A New Phylogenetic and Biogeographic Method
Preview not available

Abstract

Continuous track analysis (CTA) can depict reticulate evolutionary patterns in phylogenetics and biogeography. A reticulate connection implies convergence, hybridization, or introgression in an evolutionary graph of taxa and implies dispersal in an evolutionary graph of biogeographic areas. CTA finds graphs that (1) have a minimal number of connections and (2) imply that most character states or taxa have distributions or tracks across taxa or areas (objects) that are continuous, i.e., can be traced across the connections among the objects including that state without traveling through any other objects. Continuous tracks imply either that character states in phylogenies have unique evolutionary origins or that taxa in biogeographic analyses are monophyletic. Relatively simple graphs usually cannot imply completely continuous tracks. Therefore, CTA graphs seek to minimize the number of track fragments, which are locally continuous parts of a track; tracks with more than one fragment are discontinuous. Minimizing fragments is the same as minimizing character-state transitions only if there are no reticulations. Because hypothetical ancestors do little to reduce the number of fragments, CTA tends to place known taxa or areas at internal nodes. A heuristic algorithm analogous to tree bisection-reconnection is used to find highly parsimonious CTA graphs. In phylogenetic analyses, CTA employs a special complementary binary coding convention that serendipitously solves the missing characters/missing data problem. Although the problem of ancestors "inheriting" states from hybrid descendants is irrelevant if reticulations merely represent convergence patterns, CTA includes an optional algorithm that avoids such instances by explicitly identifying ancestors and descendants. CTA was compared with standard parsimony analysis using a data set of 17 Neogene species of North American fossil hipparionine horses. CTA separates the three major clades and illustrates their convergent features with reticulations, whereas standard parsimony analysis groups the three in an unresolved polytomy. CTA also minimizes the number of hypothetical, unsampled ancestors and lineages.

Page Thumbnails

  • Thumbnail: Page 
152
    152
  • Thumbnail: Page 
153
    153
  • Thumbnail: Page 
154
    154
  • Thumbnail: Page 
155
    155
  • Thumbnail: Page 
156
    156
  • Thumbnail: Page 
157
    157
  • Thumbnail: Page 
158
    158
  • Thumbnail: Page 
159
    159
  • Thumbnail: Page 
160
    160
  • Thumbnail: Page 
161
    161
  • Thumbnail: Page 
162
    162
  • Thumbnail: Page 
163
    163
  • Thumbnail: Page 
164
    164
  • Thumbnail: Page 
165
    165
  • Thumbnail: Page 
166
    166
  • Thumbnail: Page 
167
    167
  • Thumbnail: Page 
168
    168
  • Thumbnail: Page 
169
    169
  • Thumbnail: Page 
170
    170
  • Thumbnail: Page 
171
    171
  • Thumbnail: Page 
172
    172
  • Thumbnail: Page 
173
    173
  • Thumbnail: Page 
174
    174
  • Thumbnail: Page 
175
    175
  • Thumbnail: Page 
176
    176
  • Thumbnail: Page 
177
    177
  • Thumbnail: Page 
178
    178