scholarly journals Repeatability of Foraging Tactics in Young Brook Trout, Salvelinus fontinalis

2008 ◽  
Vol 122 (1) ◽  
pp. 40 ◽  
Author(s):  
Peter A. Biro ◽  
Mark S. Ridgway
Keyword(s):  
Brook Trout ◽  
Foraging Activity ◽  
Highly Active ◽  
Foraging Tactics ◽  
Selection For ◽  
Foraging Movement ◽  
Morphological Differences ◽  
Movement Parameters ◽  
Field Setting ◽  
Bimodal Variation

In this study, we repeatedly observed individually marked Brook Trout in a field setting to determine if the bimodal variation in foraging tactics previously observed in young salmonid populations (without distinct morphological differences) is generated by individuals specializing at different foraging tactics. We found significant but low repeatability in several foraging movement parameters. This indicated that while individuals did have tendencies to be sedentary versus highly active, there was considerable variation in foraging activity within individuals. These results suggest that relatively consistent differences among individuals may facilitate selection for specialized morphology and that there may be a heritable component to activity. Erratum included.

scholarly journals Understanding sex differences in the cost of terrestrial locomotion

2011 ◽  
Vol 279 (1729) ◽  
pp. 826-832 ◽  
Author(s):  
John J. Lees ◽  
Robert L. Nudds ◽  
Lars P. Folkow ◽  
Karl-Arne Stokkan ◽  
Jonathan R. Codd
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Male And Female ◽  
Locomotor System ◽  
Terrestrial Locomotion ◽  
Female Data ◽  
Selection For ◽  
Morphological Differences ◽  
Lagopus Muta ◽  
The Cost

Little is known regarding the physiological consequences of the behavioural and morphological differences that result from sexual selection in birds. Male and female Svalbard rock ptarmigans ( Lagopus muta hyperborea ) exhibit distinctive behavioural differences during the breeding season. In particular, males continuously compete for and defend territories in order to breed successfully, placing large demands on their locomotor system. Here, we demonstrate that male birds have improved locomotor performance compared with females, showing both a lower cost of locomotion (CoL) and a higher top speed. We propose that the observed sex differences in locomotor capability may be due to sexual selection for improved male performance. While the mechanisms underlying these energetic differences are unclear, future studies should be wary when pooling male and female data.

Genetic control of immune responses to parasites: selection for responsiveness and non-responsiveness to Trichuris muris in random-bred mice

Parasitology ◽  
1975 ◽  
Vol 71 (3) ◽  
pp. 377-384 ◽  
Author(s):  
D. Wakelin
Keyword(s):  
Immune Responses ◽  
Genetic Control ◽  
Trichuris Muris ◽  
Immunological Mechanisms ◽  
Worm Expulsion ◽  
Selection For ◽  
Dominant Characteristic ◽  
Almost All ◽  
Genetically Determined ◽  
Bimodal Variation

Populations of Schofield strain, random-bred mice were shown to have a bimodal variation in ability to bring about immune expulsion of the nematode Trichuris muris. This variation was genetically determined and independent of the size of infection experienced. The proportion of mice unable to achieve worm expulsion (non-responders) was relatively constant in various populations of the strain but was increased by selective breeding from mice of known status. Crosses made between non-responder and responder mice produced progeny that were almost all (92%) of responder phenotype, showing that the ability to achieve worm expulsion was inherited as a dominant characteristic. It is suggested that the genetic control involves a small number of genes; the possible immunological mechanisms by which control is mediated are briefly discussed.

Selection by Brook Trout (Salvelinus fontinalis) and Juvenile Atlantic Salmon (Salmo salar) of Shade Related to Water Depth

1975 ◽  
Vol 32 (9) ◽  
pp. 1652-1656 ◽  
Author(s):  
R. John Gibson ◽  
G. Power
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Water Depth ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
The Other ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon ◽  
Selection For ◽  
Salmon Parr

Salmon parr and small brook trout were observed in two stream tanks providing choices of cover. One tank was shallow (24–29 cm) and the other deep (43–50 cm). In the shallow tank brook trout occurred most frequently in shade. When salmon were the sole species, they were most frequently in shade, but were mostly away from shade in the presence of trout. This selection for shade was not evident by either species in the deep tank.

Evidence of a heritable component to body shape in the northern redbelly dace (Phoxinus eos)

1997 ◽  
Vol 75 (8) ◽  
pp. 1247-1253 ◽  
Author(s):  
C. Anna Toline ◽  
Allan J. Baker
Keyword(s):  
Body Shape ◽  
Natural Populations ◽  
The Body ◽  
Foraging Ability ◽  
Environmental Induction ◽  
Foraging Tactics ◽  
Selection For ◽  
Shape Changes ◽  
Common Laboratory

Hypotheses about the role of selection on body-shape evolution assume a heritable component to this phenotypic character. To examine the influence of environmental induction on body shape, offspring form two morphologically differentiated populations of northern redbelly dace (Phoxinus eos) were reared in a common laboratory environment. Additionally, shape changes were monitored over 3 consecutive years in six populations. Offspring reared in a common environment retained the body shape of individuals from their natal pond, and shape changes among fish in different ponds were maintained in natural populations over years. These results strongly suggest a heritable component to body shape in P. eos. These results complement earlier work examining foraging tactics as a potential selection pressure on body shape and support the conclusion that body-shape differences among fish in different ponds are being maintained by selection for foraging ability.

Unusual carotenoid use by the Western Tanager (Piranga ludoviciana) and its evolutionary implications

1991 ◽  
Vol 69 (9) ◽  
pp. 2311-2320 ◽  
Author(s):  
Jocelyn Hudon
Keyword(s):  
The Other ◽  
Coniferous Forests ◽  
Close Relative ◽  
Minimal Effect ◽  
Red Pigment ◽  
Western North America ◽  
Reflectance Spectrophotometry ◽  
Endogenous Production ◽  
Selection For ◽  
Morphological Differences

I used spectrophotometric, chromatographic, and chemical means to establish that rhodoxanthin, a 3-keto-retrodehydro carotenoid, was the only red pigment in the head feathers of the Western Tanager (Piranga ludoviciana). In contrast, the red head and body feathers of a close relative, the Scarlet Tanager (P. olivacea), exhibited several 4-keto-carotenoids. Other tanagers and emberizids also displayed 4-keto-carotenoids. The deposition of presumed canary xanthophylls and phaeomelanins differed quantitatively between the Western Tanager and other tanagers belonging to the genus Piranga. Uniquely among the Piranga spp. examined, the head feathers of the Western Tanager had flattened bards without barbules. Partly because the head colors of the Western and Scarlet tanagers were indistinguishable either in the hand or when examined by reflectance spectrophotometry, I excluded selection for a variant color as the basis for the observed chemical and morphological differences. Biochemical costs, including putative costs associated with the endogenous production of 4-keto-carotenoids, could have led to the conversion in the Western Tanager to an available dietary pigment. This tanager, unlike the other species studied, has access to an abundant source of rhodoxanthin in the coniferous forests of western North America. The pigment changes in the Western Tanager could have taken place with minimal effect on head color.

scholarly journals Rapid bursts and slow declines: on the possible evolutionary trajectories of enzymes

2015 ◽  
Vol 12 (107) ◽  
pp. 20150036 ◽  
Author(s):  
Matilda S. Newton ◽  
Vickery L. Arcus ◽  
Wayne M. Patrick
Keyword(s):  
Experimental Data ◽  
Energy Efficiency ◽  
Catalytic Efficiency ◽  
Neutral Drift ◽  
Cellular Energy ◽  
Highly Active ◽  
The Earth ◽  
Evolutionary Trajectories ◽  
Selection For ◽  
Catalytic Power

The evolution of enzymes is often viewed as following a smooth and steady trajectory, from barely functional primordial catalysts to the highly active and specific enzymes that we observe today. In this review, we summarize experimental data that suggest a different reality. Modern examples, such as the emergence of enzymes that hydrolyse human-made pesticides, demonstrate that evolution can be extraordinarily rapid. Experiments to infer and resurrect ancient sequences suggest that some of the first organisms present on the Earth are likely to have possessed highly active enzymes. Reconciling these observations, we argue that rapid bursts of strong selection for increased catalytic efficiency are interspersed with much longer periods in which the catalytic power of an enzyme erodes, through neutral drift and selection for other properties such as cellular energy efficiency or regulation. Thus, many enzymes may have already passed their catalytic peaks.

Occurrence and behaviour of transient killer whales: seasonal and pod-specific variability, foraging behaviour, and prey handling

1995 ◽  
Vol 73 (7) ◽  
pp. 1300-1311 ◽  
Author(s):  
Robin W. Baird ◽  
Lawrence M. Dill
Keyword(s):  
Foraging Behaviour ◽  
Open Water ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Foraging Tactics ◽  
Morphological Differences ◽  
Prey Handling ◽  
Mixed Groups

We studied the occurrence and behaviour of so-called transient killer whales (Orcinus orca) around southern Vancouver Island from 1986 to 1993. Occurrence and behaviour varied seasonally and among pods; some pods foraged almost entirely in open water and were recorded in the study area throughout the year, while others spent much of their time foraging around pinniped haulouts and other nearshore sites, and used the study area primarily during the harbour seal (Phoca vitulina) weaning–postweaning period. Overall use of the area was greatest during that period, and energy intake at that time was significantly greater than at other times of the year, probably because of the high encounter rates and ease of capture of harbour seal pups. Multipod groups of transients were frequently observed, as has been reported for "residents," but associations were biased towards those between pods that exhibited similar foraging tactics. Despite the occurrence of transients and residents within several kilometres of each other on nine occasions, mixed groups were never observed and transients appeared to avoid residents. Combined with previous studies on behavioural, ecological, and morphological differences, such avoidance behaviour supports the supposition that these populations are reproductively isolated.

A scanning electron microscopic study of the eggs of Culicoides variipennis (Diptera: Ceratopogonidae)

1987 ◽  
Vol 45 ◽  
pp. 884-885 ◽  
Author(s):  
R. A. Nunamaker ◽  
C. E. Nunamaker ◽  
B. C. Wick
Keyword(s):  
Distinct Species ◽  
Hemorrhagic Disease ◽  
Insect Vector ◽  
Electron Microscopic ◽  
Important Species ◽  
Scanning Electron Microscopic Study ◽  
Laboratory Colony ◽  
Culicoides Variipennis ◽  
Morphological Differences ◽  
Scanning Electron

Culicoides variipennis (Coquillett) is probably the most economically important species of biting midge in the U.S. due to its involvement in the transmission of bluetongue (BT) disease of sheep, cattle and ruminant wildlife, and epizootic hemorrhagic disease (EHD) of deer. Proposals have been made to recognize the eastern and western populations of this insect vector as distinct species. Others recommend use of the term “variipennis complex” until such time that the necessary biosystematic studies have been made to determine the genetic nature and/or minute morphological differences within the population structure over the entire geographic range of the species. Increasingly, students of ootaxonomy are relying on scanning electron microscopy (SEM) to assess chorionic features. This study was undertaken to provide comparative chorionic data for the C. variipennis complex.Culicoides variipennis eggs were collected from a laboratory colony maintained in Laramie, Wyoming.

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