| Popis: |
A morphospace has been developed that connects the ancestral pecking design to filter feeding in birds. The morphospace represents a pattern of transformations in which first surface tension transport of drops along a slightly lengthened and slenderized beak was thought to occur. Then lingual retraction was introduced to transfer the system step by step into an improved suction-based filter system. Different lingual protractions lead then to a bifurcation in the pattern: 1) a flamingo-like back-and-forth pump; and 2) a duck-like through pump. Geese-like filtering is considered as a very early offshoot, derived from grazing/grasping. The earlier deduced morphospace that connects the ancestral pecking system to probing, as is found in waders (ZWEERS & GERRITSEN, 1997), has been combined with the present morphospace. That overall morphospace is considered an evolutionary phenogram: it shows 6 major bifurcations and predicts 9 possible trophic radiations. Scenarios were developed in this morphospace for evolutionary pathways of trophic radiation. These phyletic radiation patterns were then compared to phylogenies based on other data, including molecular systematics, cladistic analysis, and paleontology. The outcome is that within waterfowl large compatibility was found. Within the wader-complex, including the Charadriiformes, however, there is both compatibility, as well as differences. These differences were due to the hierarchical organization of the trophic design transfer that results from the deductive method. Further, transfering phyletic evolution to ordinal phylogeny would require that for some cases the level of independent evolutionary status must be taken at family level. It was shown that a Burhinimorph trophic ecomorph could quite well have been the ancestor system of the wader-waterfowl complex; and that a Presbyornithimorph trophic system does not connect the two major taxa under consideration, but rather represents an early Anatinimorph offshoot. |
