Anseriform brain and its parts versus taxonomic and ecological categories.
The size of the brain and its macro-anatomical parts in 206 birds representing 19 anseriform species and 4 tribes (Anserini, Anatini, Aythyini and Mergini) was the subject of a comparative analysis. The comparisons involved two aspects: taxonomic (differences among species within tribes and differences among tribes) and ecological (diet composition: vegetation, invertebrates, or fish and the foraging mode: browsing, dabbling, shallow diving, and deep diving). The relative size of the encephalon (E) and its parts (optic tectum, OT; cerebellum, C; brain stem, BS; hemispheres, H) were described using appropriate indices. Five of them, called the cerebral-body indices (E/BW, OT/BW, C/BW, BS/BW, H/BW), involved a ratio between the weight of E or its parts and that of the body (BW). Four intracerebral indices (OT/E, C/E, BS/E, H/E) and allometric equations were used as well. Almost all the indices showed a high intraspecific variability within the Anserini and Mergini; on the other hand, the intracerebral indices did not differ between the species of the Anatini and Aythyini (except for OT/E in the Aythyini). Between-tribe differences were reflected in all 9 indices. The birds feeding on different diets were found to differ in their OT/E and H/E. The herbivorous anserifom OT/E was clearly lower than that of those birds feeding on invertebrates and fish. The highest OT/E was that of the piscivorous birds. In terms of foraging mode, significant differences were revealed in 7 out of the 9 indices used (differences in OT/BW and C/BW proved non-significant). OT/E of the browsing birds was clearly lower than that of the deep diving ducks; BS/E of the browsers was much lower than that of the dabbling and shallow diving ducks. Geese and swans (browsers) showed much higher H/E compared to the deep diving sea ducks. The latter revealed the highest C/E, but significant differences were detected only in comparison with C/E of the shallow diving ducks. The taxonomic (among tribes) and ecological comparisons showed more differences in the intracerebral indices than in the cerebral-body indices.
Kalisińska
Elzbieta
E
Department of Zoology, Agricultural University in Szczecin, Doktora Judyma 20, 71-466 Szczecin, Poland. Kalisinska@biot.ar.szczecin.pl
D000818:Animals; D046090:Anseriformes / Q000033:anatomy & histology* / Q000145:classification* / Q000502:physiology; D001824:Body Constitution; D049628:Body Size; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology; D001933:Brain Stem / Q000033:anatomy & histology / Q000502:physiology; D002531:Cerebellum / Q000033:anatomy & histology / Q000502:physiology; D002540:Cerebral Cortex / Q000033:anatomy & histology / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology*; D008959:Models, Neurological; D009929:Organ Size; D010802:Phylogeny; D013045:Species Specificity; D013477:Superior Colliculi / Q000033:anatomy & histology / Q000502:physiology