Feeding ecology and diet overlap in riverine cichlids from western Uganda
Feeding ecology and diet overlap in riverine cichlids from western Uganda
复制标题
乌干达西部河流慈鲷的摄食生态和饮食重叠
DOI：
--
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
L. Chapman
中科院分区：
文献类型：
--
作者：
S. Binning;L. Chapman
Cichlid fishes ofthe Great Lakes in East Africa represent some of the most diverse and well-studied vertebrate fish faunas in the world (McKAYE & MARSH 1983) and are ofparticular interest to ecologists and evolutionary biologists exploring adaptive radiation, trophic diversity, and niche specialization (LIEM 1991, YAMAOKA 1991). Specialization in feeding morphology and diets o f these fishes has been used to explain both the coexistence of such a large number of closely related fishes and the multitude of endemic species in any given lake (FRYER & ILES 1972, BARLOW 2000). Many of the Great Lakes in East Africa have their own unique cichlid flocks with up to 99% endemicity (RIBBINK 1991). In addition, a small number of eurytopic cichlids inhabit a broad range of habitats throughout the region. These widespread species show high levels o f p1asticity in traits, such as diet preference (HuYSSEUNE 1995) and other morpho-physiological traits, and this phenotypic flexibility may facilitate their broad habitat range. However, relatively 1ittle is known about the ecology ofthe riverine cichlid faunas; in fact, most widespread species have been intensively studied in the lakes where they tend to have a more restricted diet (GREENwooo 1964, FRYER & ILES 1972). In particular, the widespread cichlid, Astatoreochromis alluaudi, is ubiquitous in the Great Lakes region of East Africa and is associated with a range of different habitats and feeding behaviours (WITTE 1981). This species shows 2 distinct morphs characterized by the degree of hypertrophy observed in the pharyngeal jaw structures (SMITS et al. 1996). Hypertrophied morphs have been associated with a molluscivorous diet, whereas reducedjaw morphs are believed to feed on items such as insects and plant materials (SMITS et al. 1996). In Lake Victoria, where the diet of A. alluaudi was initially described, the species was found to feed predominantly on the snail species Melanoides tuberculata (GREENwooo 1964). However, it has been proposed that in the absence of interspecific competition from other insectivorous cichlids, A. alluaudi will preferentially consume softer food items (SLOOTWEG et al. 1994). In fact, SLOOTWEG et al. (1994) attributed the failure of introduced A. alluaudi to control snail densities (intermediate hosts for the causal agents of schistosomiasis) to the laek of an intact cichlid fauna that could outcompete the molluscivore for more profitable insect prey. Interestingly, populations of A. alluaudi persist in river systems in western Uganda where mollusks are rare, but where the density ofhaplochromine generalist insectivores is high. In this situation, both the abundance and distribution of A. alluaudi may be limited in terms of an alternative prey base. Little is known, however, about the feeding ecology of riverine cichlids in this region. The objectives of this study were (l) to quantify the diet of A. alluaudi in a habitat characterized by a high biomass of other haplochromine cichlids and low snail abundance and (2) to determine whether other species of cichlids have similar diets to A. alluaudi, and therefore have the potential to act as competitors for scarce resources. W e hypothesized that A. alluaudi living in rivers where mollusk prey are rare feed omnivorously when closely related cichlids compete with A. alluaudi for its preferred insect prey.
