Food Specialization By Individual Trout

Bryan, James E.; Larkin, Peter

doi:10.1139/f72-248

Cited by 136 publications

(98 citation statements)

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“…The large standard errors associated with the mean gut fullness indices suggest that there was considerable heterogeneity in feeding behaviour among the fish. Individual feeding differences have been reported in several other studies (Egglishaw 1967;Elliott 1967;Bryan & Larkin 1972), suggesting that juvenile trout do not all feed at the same time. It is, however, unknown whether this is because the fish can adjust to their individual food requirements or because competition in a dominance hierarchy (Fausch 1984) favours the dominant fish.…”

Section: Diel Variationsmentioning

confidence: 51%

Aspects of juvenile rainbow trout (Oncorhynchus mykiss) diet in relation to food supply during summer in the lower Tongariro River, New Zealand

Dedual¹,

Collier²

1995

New Zealand Journal of Marine and Freshwater Research

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Section: Diel Variationsmentioning

confidence: 51%

Aspects of juvenile rainbow trout (Oncorhynchus mykiss) diet in relation to food supply during summer in the lower Tongariro River, New Zealand

Dedual¹,

Collier²

1995

New Zealand Journal of Marine and Freshwater Research

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“…Several studies of other animal species (33)(34)(35)(36)(37)(38) report individual feeding specializations that do not appear to be constrained by the animals' age, sex, or morphology. "Majoring" and "minoring" of bumblebees, which often involve complex behaviors that must be learned initially and practiced to attain proficiency (34), appear to be analogous to the specializations we observed in the Cocos Finch.…”

Section: Discussionmentioning

confidence: 99%

Behavioral feeding specialization in Pinaroloxias inornata , the “Darwin's Finch” of Cocos Island, Costa Rica

Werner

Sherry

1987

Proc. Natl. Acad. Sci. U.S.A.

156

120

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As a population, Cocos Finches exhibit a broad range of feeding behaviors spanning those of several families of birds on the mainland, while individuals feed as specialists year-round. Although this extreme intraspecific variability occurs as predicted in a tropical oceanic island environment, these specializations challenge contemporary ecological theory in that they are not attributable to individual differences in age, sex, gross morphology, or opportunistic exploitation of patchy resources. Instead, they appear to originate and be maintained behaviorally, possibly via observational learning. This phenomenon adds another direction to the evolutionary radiation of the Darwin's Finches and underscores the necessity for detailed behavioral and ecological studies at the individual level for understanding animal feeding systems and the causation of phenotypic variation.Animals within a population that uses a broad array of food types can feed in diverse ways. In extreme cases, individuals can either use all available foods, as generalists, or specialize relative to other individuals. Biologists predict that generalist populations of feeding specialists will occur under conditions of (i) high food predictability (little or no seasonality), (ii) high food availability and variety, (iii) high population density, (iv) low competition between species, and (v) low territoriality (1-5). Additionally, feeding specializations among individuals within a population often correspond with morphological differences among individuals (1, 3, 6-11).The Darwin's Finches (Geospizinae), a textbook example of adaptive radiation in which striking beak differences among species correspond with ecological differences among species (11-16), provide strong support as well for the correspondence between ecological and morphological differences among individuals within a population (9-11): Within the Medium Ground Finch (Geospizafortis) population on Isla Daphne Major, for example, larger-billed finches are able to crack and eat harder and larger seeds than smaller-billed finches. Darwin's Finch populations with the strongest correspondence between diet and morphology tend also to have the greatest morphological variability, due partly to genetic introgression from other populations (10, 11). The Cocos Finch, the only geospizine found outside of the Galapagos Archipelago, has no known opportunity for genetic introgression from another population, and it has correspondingly low morphological variation (11). This low morphological variability is surprising, nonetheless (17), because the foraging behaviors and resources used by this species span those typical of many different families of birds in adjacent mainland habitats, a circumstance generally believed to promote morphological variability (3,11,18,19 (23,25). The almost invariant finch diets year-round (see below; Fig. 1), the high endemism and low turnover rate of the Cocos avifauna (26), and dietary specialization by the Cocos Flycatcher (20) provide additional evidence for a ...

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“…Such a strategy could permit efficient, flexible predation behaviour. Many fish species are opportunistic feeders, showing marked individual differences in patterns of prey consumption (Bryan & Larkin 1972, Bres 1989 and an ability to respond to changes in food availability (e.g. Robertson 1987, Brewer & Warburton 1988).…”

Section: * B I I I I T S I T Ementioning

confidence: 99%

Patterns of recruitment and resource use in a shallow-water fish assemblage in Moreton Bay, Queensland

Warburton¹,

Blaber²

1992

Mar. Ecol. Prog. Ser.

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Seven shallow-water sites in the western part of Moreton Bay, Queensland, Australia, were sampled by beam trawl on 7 occasions durlng 1987 and 1988. The sites differed significantly in their macrophyte and loose shell cover. The most abundant f~s h species was cardinal fish Apogon fasciatus, followed by fan-bellied leatherjacket Monacanthus chinensis, leatherlacket Paramonacanthus otisensis, trumpeter Pelates quadnlineatus and pony fish Leiognathus moretoniensls. Other species were comparatively rare. Small juveniles of the 5 specles recruited to the area, with all except L. moretoniensis being most abundant at the most vegetated site. Mean catch rates differed s~gn~flcantly between s~t e s , and patterns of habitat use, seasonality and d~e l behaviour varied between specles. There was evidenceof ontogenetic m~gration into deeper water in all specles, although this was weakest for A. fasciatus. Diets of the 5 species were distlngulshed by gravimetric, numerical and occurrence techniques. P quadrilineatus and L. moretoniensis took large amounts of polychaetes and copepods, M. chinensis and P otisensis consumed more amph~pods, molluscs and vegetation, and A. fasciatus exploited a wide slze range of prey, Including crabs, f~s h and small crustaceans. Interspecific diet overlap was greater in larger fish, but was less than intraspecif~c overlap between slze classes. Daytime feeders dominated the assemblage, but catch rates were higher at night. Overall patterns of resource use suggested species partitioning, but strong evidence of niche separat~on was obtalned only for L moretoniensis, which was distinct on all 3 major resource axes (food, habitat and time) Therefore, scope e x~s t e d for interspecific competition between members of the assemblage.

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Food Specialization By Individual Trout

Cited by 136 publications

References 0 publications

Aspects of juvenile rainbow trout (Oncorhynchus mykiss) diet in relation to food supply during summer in the lower Tongariro River, New Zealand

Aspects of juvenile rainbow trout (Oncorhynchus mykiss) diet in relation to food supply during summer in the lower Tongariro River, New Zealand

Behavioral feeding specialization in Pinaroloxias inornata , the “Darwin's Finch” of Cocos Island, Costa Rica

Patterns of recruitment and resource use in a shallow-water fish assemblage in Moreton Bay, Queensland

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