Anseriform Brain and Its Parts versus Taxonomic and Ecological Categories

Abstract

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.

Body condition and mercury concentration in apparently healthy goosander (Mergus merganser) wintering in the Odra estuary, Poland

“…Of the three internal organs of the goosander studied, liver weight showed the largest variability, the coefficient of variation being few to several (depending on the group) times higher than the CV of kidney and brain weights. This finding confirms observations of other authors dealing with anseriform morpho-anatomy (Drobney 1984;Kalisińska 2005;Kalisińska et al 1999). The goosander liver weight accounts, on the average, for 3.4% of the body weight and is similar to that (2.5-3.5%) of the shallow diving ducks of the genus Aythya (Austin and Fredrickson 1987;Gammonley and Heitmeyer 1990).…”

Allometric Scaling of the Tectofugal Pathway in Birds

“…Behavioral studies indicate that vision is more critical in some species than in others [Tome and Wrubleski, 1988] and there is some interspecific variation in eye movements and visual field within the order [Martin, 1986;Guilleman et al, 2002;Martin et al, 2007a]. Kalisinska [2005] reported that the optic lobes were larger in piscivorous and diving ducks than in other species and we did detect some variation in the relative size of the TeO and nRt among the species we sampled. Based on the apparent correlations among retinal morphology, tectofugal and thalamofugal brain region volumes and behavior in owls, we predict that waterfowl likely share with owls enhanced scotopic vision, but relatively poor color discrimination and visual acuity.…”

Social fishes and single mothers: brain evolution in African cichlids

“…Ecological factors appear to influence brain evolution in diverse taxa, for example diet correlates with brain size in fishes, bats, primates and birds (Hutcheon et al 2002;Kalisinska 2005;Dunbar & Shultz 2007;Yopak et al 2007). A species' habitat also poses specific cognitive challenges related to either navigation or spatial orientation (Salas et al 2003;Safi & Dechmann 2005;Pollen et al 2007;Yopak et al 2007).…”