![]() Separate, nationwide dichotomous keys to given families and/or genera are also being produced, which will be eventually integrated into a complete national key they are available online at. A first comprehensive key, including all species known from Northern Italy (2.239 infrageneric taxa) has been already published online for testing (Nimis 2019). This first step can be followed by either a field-guide-like page, illustrating the remaining taxa, or (as in the case of our keys) by a dynamically generated single-access key to those taxa only.Īfter the completion of a new checklist of the lichens of Italy (Nimis 2016), and its incorporation into ITALIC, the online information system on the lichens of Italy (Nimis and Martellos 2002 Martellos 2012), work has started on the preparation of a computer-aided lichen flora of the country, containing keys and descriptions. While in a free-access key users must select a single character state at each step of the identification process, multi-entry keys permit to use several characters at the same time, via a multi-character query-form. Well-known free-access key for lichens are those provided by LIAS (Rambold et al. 2000 onwards), NaviKey (Neubacher and Rambold 2005 onwards), and Xper3 (Vignes Lebbe et al. Examples are DELTA-IntKey (Dallwitz et al. Although printable free-access keys do exist, they are most suitable for computer-aided identification tools, and have a long development history. Thus, a free-access key is the set of all possible single-access keys that arise by permutating the order of characters. Whereas in a single-access key the sequence of choices (decisions) is fixed by the author (providing a single path to each result), in a free-access key it is up to users, which, at every step, can select from a list one character state at a time. Free-access keys (also known as matrix keys) are alternative to single-access keys. The advent of computers has allowed the generation of other types of keys, such as free-access and multi-entry keys (Hagedorn et al. The equivalent term in computer science is “decision tree” (Hagedorn et al. The generalizing term “single-access key” is used here to include both dichotomous and polytomous keys. Dichotomous keys are a special case of polytomous keys, and a key may be also a mixture of simple polytomous and complex dichotomous choices. All leads that need to be evaluated for a single decision form a “couplet”. The structure of such keys typically consists of a series of alternative statements, called “leads”. This characteristic can allow you to identify them more precisely (e.g., as a gull and a duck).Traditionally, most identification tools for lichens were paper-published as dichotomous, or more rarely polytomous keys. In this case, you notice that one of the swimming birds is ocean-going, and one is not.The single land bird will be identified as such, but you will have to further differentiate the swimming birds. Two of the birds swim, but one of them does not. ![]() You will break them down into these groups, then sub-divide the birds. For instance, you might find yourself looking at some birds, and some reptiles. Some specimens will be differentiated before the end, as you work through your contrasting characteristics.Eventually, you will reach the point until you have questions that only ask you to differentiate two specimens, and your key will be complete. Come up with characteristics that can break your specimens down as needed into groups E/F, G/H, etc. ![]() Keep formulating more questions or statements of ever-increasing specificity based on the physical characteristics you identified.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |