Birder's Guide

OCT 2014

Birder's Guide is the American Birding Association's newest publication. Each issue focuses on a key subject, providing tips from experienced birders on a wide variety of topics like Travel, Listing & Taxonomy, Gear, and Conservation & Community.

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Page 26 of 57

25 October 2014 | Birder's Guide to Listing and Taxonomy arate them from other populations, but which have not yet acquired reproduc- tive isolation. (The plural of subspecies is subspecies.) Sympatric Speciation. Speciation of geo- graphically overlapping populations, usually driven by ecological adaptation. Taxa. Plural of taxon. A taxon is a biologi- cal group or classifcation of organisms. Classes, orders, families, genera, spe- cies, and subspecies are all various lev- els of taxon. Taxonomy. The study of the classifca- tion of organisms (taxa), based on their shared characteristics and relatedness, and the subsequent nomenclature (i.e., naming) of those classifcations. Taxonomic describes things related to this pursuit. Taxonomy also refers to a specifc classifcation scheme, or "list". For example, the AOU and the British Ornithologists' Union utilize different taxonomies. Typological Species Concept (TSC). Species concept which says that a spe- cies is a group of organisms for which the presence of discrete morphological features (e.g., plumage pattern, bill size) differentiates it from other species. Zygote. A fertilized egg. which is a set of physical characteristics. Phylogenetic Species Concept (PSC). Species concept which says that species are the smallest distinguishable cluster of populations within a phylogeny and that members of species share a com- mon evolutionary history. Phylogeny. A reconstruction, based on analysis of shared traits, of the evolution- ary history of a group of organisms. It is usually depicted in a tree-like diagram. Reproductive Isolation. A state whereby a species can not produce offspring with another species, through differences in behavior and anatomy. Speciation. The evolutionary process by which two or more populations of one species diverge to become separate species. Species Concept. A set of criteria used to defne what species means. Split. When scientists decide that a taxon (often, a species) is really two or more taxa, the resulting action is called a split. Also used as a verb (e.g., Rufous-sided Towhee was split into Eastern Towhee and Spotted Towhee). Subspecies. A geologically discrete popu- lation of organisms which share features (e.g., plumage, bill shape, size) that sep- try, with subsequent divergence in ecol- ogy, behavior, appearance, and/or other characteristics. Allopatry. Segregation of populations by geography. Biological Species Concept (BSC). Species concept which says that species are populations of interbreeding or po- tentially interbreeding individuals and that members of a species cannot pro- duce viable offspring with other species. Clinal Variation. Variation that occurs on a gradient (i.e., gradually changes from one population to another), without a distinct "break" between populations. Often associated with changes in climate. Diagnosability. The quality of having traits that allow a group of organisms to be distinguished from other groups. Lump. When scientists decide that two or more species are better treated as one species, the resulting action is a lump. Also used as a verb (e.g., Yellow-shafted and Red-shafted fickers are currently lumped together as Northern Flicker). Monophyly. The quality or state of being monophyletic. Monophyletic describes a group of organisms (in a phylogeny) that all share a common ancestor. Morphological. Pertaining to morphology, Many birds still have a contentious taxonomy. For instance, it's still uncertain if "Myrtle" (left) and "Audubon's" (right) Yellow-rumped warblers should be treated as separate species. There is evidence that suggests "Audubon's" may in fact have originated as a hybrid swarm between more northerly "Myrtle" Warblers and Mexican "Black-fronted" Warblers (not shown). Photos © Robert Royse

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