CHOROL und STATCHO, zwei neue Computerprogramme zur Darstellung und vergleichenden Analyse von chorologischen Daten für die Neotropen1)

Summary Two new computer programs for comparative chorology are presented. They employ the Flora Neotropica base maps (from 30° N to 30° S) with an one degree grid system, and run on IBM compatible Personal Computers with two disk drives or one harddisk. Both programs can be used successfully also with minor computer experience, easy handling and drawing of distribution data for e.g. taxonomical revisions is provided. With “CHOROL” a database of the geographical distribution patterns of an unlimited number of different neotropical taxa may be constructed (per taxon you need in average of about 2000 bytes). Every geographical data of a species file can be annotated and edited. The geographical distribution patterns of one to five taxa can be shown simultaneously (i) on the screen, (ii) with a matrix printer (Fig. 7), or (iii) can be plotted onto a Flora Neotropica map (Figs. 2—3). The latter are ready for publication. For plotting, 15 different symbols are available (Fig. 1), the legend can be easily moved around the map and its size can be varied. Furthermore, CHOROL is able to fuse data from different files, can print a list of the taxa stored in the databank or a list of the data of each file and can put the taxa into an alphabetical order. “STATCHO” is compatible with “CHOROL” and uses its data. It can fuse the single dots of a distribution map to continuous distribution areas depending on different resolution factors from one to twenty degrees (i.e. a resolution factor of 5° fuses all dots that have a distance of 5° or less from each other: see Fig. 4). The total sizes of the defined areas are calculated automatically and shown as the number of grids (Figs. 4, 5). One to several selected taxa can be compared with each other or with the whole database in respect to their geographical distribution, i.e. the percentage of their overlapping areas is calculated and arranged in a list (Fig. 6). Thus, it allows to select typical distribution patterns for the neotropical flora. Furthermore, the number of dots per species or geographical maximum values for selected species can be listed on the screen or on the printer. Based on a database of 230 taxa from the Neotropics (original data and data from the literature), the significance of the comparative analysis carried out by “STATCHO” has been tested. E.g. the distribution of Guarea kunthiana has been compared with that of all the other taxa. Using different resolution factors (Fig. 6) it could be shown that (i) the program selected mostly species with the same distribution patterns (Figs. 4, 5) and that (ii) there was only a minor variation in species selection using resolution factors between 3° and 10°. Even resolution factors of 1°—2° showed reasonable results. Some additional characteristic distribution patterns of the neotropical flora, revealed by our programs, are shown and discussed: e.g. general Amazonian distribution and C. Brazilian distribution (Fig.2), W. Amazonian distribution, SE. Brazilian distribution and West Indies distribution (Fig. 3), Amazonian — Guyana — SE. Brazilian disjunction (Figs.4, 5). An English version and manual of CHOROL is also available and can be ordered from the senior author. It is planned to adapt the programs to other geographical areas (e.g. to Africa) and to extend their functions.