scholarly journals Influence of intraspecific competition for food on the bodyweight of the adult aphidophagous ladybird, Coccinella transversalis

2021 ◽  
Vol 11 (1) ◽  
pp. 5-11
Author(s):  
Ahmad Pervez ◽  
Rupali Sharma
Keyword(s):  
Intraspecific Competition ◽  
Competition For Food ◽  
Coccinella Transversalis

The Food and the Food Supply of Sockeye Salmon (Oncorhynchus nerka Walbaum) in Cultus lake, British Columbia.

1937 ◽  
Vol 3 (5) ◽  
pp. 450-468 ◽  
Author(s):  
William E. Ricker
Keyword(s):  
Low Temperature ◽  
Intraspecific Competition ◽  
Sockeye Salmon ◽  
Abundant Species ◽  
Minor Importance ◽  
Important Food ◽  
Total Food ◽  
Competition For Food ◽  
Summer Feeding ◽  
Food Consumed

The analysis of several hundred stomachs of sockeye salmon taken from Cultus lake at all seasons shows that pelagic plankton crustaceans are practically the only food of the fingerlings, and are the most important food of the older fish. The total food consumed by fingerlings, per unit bulk, is greatest in July and August, least in winter. The entomostracan food available in the lake, as determined from plankton samples, varies seasonally in a similar manner. The percentage utilization of each of the four species of Entomostraca by a fingerling sockeye population is related directly to the plankter's abundance, and inversely to its size. Individual sockeye, however, occasionally exhibit preference for smaller or less abundant species. The summer feeding of fingerlings appears to be chiefly confined to the region between 5 and 15 metres depth, which includes the thermocline and adjacent narrow strips of the epilimnion and hypolimnion. Foraging is limited upward by scarcity of food, and downward by poor illumination or low temperature. Other fish in the lake are known to compete with sockeye for plankton, but such interspecific competition is believed to be quantitatively of minor importance, in summer at least. Intraspecific competition for food in years of large sockeye populations is sufficient to reduce their rate of growth, and is probably responsible for an unusually early decline, in those years, of the summer's supply of Entomostraca.

Habitat and Food Segregation of Dwarf and Normal Arctic Charr (Salvelinus alpinus) from Vangsvatnet Lake, Western Norway

1982 ◽  
Vol 39 (7) ◽  
pp. 1030-1045 ◽  
Author(s):  
Kjetil Hindar ◽  
Bror Jonsson
Keyword(s):  
Environmental Conditions ◽  
Intraspecific Competition ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Habitat Segregation ◽  
Growth Season ◽  
Western Norway ◽  
Lake Morphology ◽  
Food Segregation ◽  
Competition For Food

The aim of the present study was to test possible habitat and food segregation between two charr morphs in Vangsvatnet Lake. The charr population of Vangsvatnet consists of one pale phenotype with parr marks along the flanks and poorly developed spawning coloration (dwarf charr), and another phenotype with silvery flanks in nonbreeding condition and bright red spawning colors (normal charr). The habitus of the two morphs indicated that they were adapted to different niches during the growth season. The analyses of distribution and food showed that there was marked habitat and food segregation between the two morphs during summer, when dwarf charr dwelled deep-benthic and normal charr roamed in the limnetic zone. The segregation broke down in periods of food abundance, indicating that the habitat segregation was due to intraspecific competition for food. A comparison of charr morphs of Vangsvatnet with the nearby Lønavatnet Lake suggested that the number of charr morphs is adapted to local environmental conditions, among which lake morphology, food availability, and other fish species are important. We hypothesize that the number of charr morphs within a locality depends on the number of available niches during the growth season.Key words: polymorphism, camouflage, distribution, ontogeny, intra- and inter-specific competition

Primeros datos sobre la población de lagarto negro (Gallotia simonyi simonyi STEIND.) de la Isla de Hierro1

1981 ◽  
Vol 2 (4) ◽  
pp. 369-380 ◽  
Author(s):  
Juan Pablo Martinez Rica
Keyword(s):  
Canary Islands ◽  
Intraspecific Competition ◽  
Daily Activity ◽  
Plant Cover ◽  
The Sun ◽  
Protective Measures ◽  
Industrial Facilities ◽  
Vertebrate Fauna ◽  
The Status ◽  
Competition For Food

AbstractThis paper presents the first data on the ecology of the Giant Hierro Lizard (Gallotia simonyi simonyi) from Canary Islands; this animal was believed to be extinct until its recent finding, in 1975. The biotope, a very steep rocky cliff, almost inaccessible in many places, is described; the climate of the area is subdesertic and the plant cover, very sparse, is xerophytic; the vertebrate fauna is poor, but insects are abundant and diverse. The colour of this lizard is almost black, with large dull grey patches at the sides in the adults, while in the youngs the colour is earthly brown with whitish dorsal stripes. The largest specimen we measured was near 70 cm from snout to tail's end. Daily activity begins in young specimens when the sun reaches the area, while in the adult ones activity begins somewhat later, even at noon for the oldest animals. The diet consists entirely of plants, and includes lignified stems and other non-nourishing parts from several species (Kleinia neriifolia, Lavandula abrotanoides, etc.). Obviously there exists a strong intraspecific competition for food. The number of animals was very low in September 1975, about 200 specimens, half of them or more being young. This number might have been increased by now through protective measures recently adopted. Nevertheless, the status of the population is still critical and the danger of its extinction is strong. Some recent plans to modify the area, building industrial facilities nearby, may have, of course, very bad effects on this lizard.

Effects of dispersion, travel, and environmental heterogeneity on populations of the earwig Forficula auricularia L.

1975 ◽  
Vol 53 (12) ◽  
pp. 1855-1867 ◽  
Author(s):  
R. J. Lamb
Keyword(s):  
Social Interaction ◽  
Intraspecific Competition ◽  
Environmental Heterogeneity ◽  
Early Initiation ◽  
Intraspecific Aggression ◽  
Forficula Auricularia ◽  
Feeding Sites ◽  
Competition For Food

Local earwig populations were increased by the addition of artificial shelters which protected them against an inhospitable microclimate and predation by birds. The spacing of shelters and the availability of nearby food limited the use of shelters and thus the size of populations, through intraspecific competition for food. This competition was increased by the active aggregation of earwigs in shelters. Aggregation probably assists in the location of suitable shelter and provides a focus for social interaction. Enhanced growth and early initiation of foraging were observed for earwigs reared in groups.Foraging earwigs showed intraspecific aggression, especially at feeding sites. Earwigs that had not fed during the current foraging period were less likely to join aggregations early in the night. Foraging earwigs showed no ability to home to shelters or locate aggregations from a distance of more than a few centimetres, but were capable of travelling many metres in one night. These factors resulted in the exclusion of new occupants when shelter use reached a maximum.

A Model of Competition for Food. I. Frequency-Dependent Viabilities

1976 ◽  
Vol 110 (976) ◽  
pp. 1013-1027 ◽  
Author(s):  
G. De Jong
Keyword(s):  
Frequency Dependent ◽  
Competition For Food

scholarly journals Effect of Competition and Climatic Conditions on the Growth of Beech in the Mixed Pine Beech Stand: Lithuanian Case Study

2020 ◽  
Vol 3 (1) ◽  
pp. 49
Author(s):  
Edgaras Linkevičius ◽  
Gerda Junevičiūtė
Keyword(s):  
Intraspecific Competition ◽  
Tree Species ◽  
Forest Growth ◽  
Competition Effect ◽  
Diameter Increment ◽  
Cart Analysis ◽  
Crown Width ◽  
Beech Stand ◽  
Negative Effect ◽  
The Impact

Climate change and warming will potentially have profound effects on forest growth and yield, especially for pure stands in the near future. Thus, increased attention has been paid to mixed stands, e.g., pine and beech mixtures. However, the interaction of tree species growing in mixtures still remains unknown. Thus, the aim of this study was to investigate the impact of the interspecific and intraspecific competition to diameter, height, and crown width of pine and beech trees growing in mixtures, as well as to evaluate the impact of climatic indicators to the beech radial diameter increment. The data was collected in 2017 at the mixed mature pine beech double layer stand, located in the western part of Lithuania. The sample plot of 1.2 hectare was established and tree species, diameter at the breast height, tree height, height-to-crown base, height-to-crown width, and position were measured for all 836 trees. Additionally, a representative sample of radial diameter increments were estimated only for the beech trees by taking out core discs at the height of 1 m when the stand was partially cut. Competition analysis was based on the distance-dependent competition index, which was further based on crown parameters. Climatic effect was evaluated using classification and regression tree (CART) analysis. We found almost no interspecific competition effect to diameter, height, or crown width for both tree species growing in the first layer. However, it had an effect on beeches growing in the second layer. The intraspecific competition effect was important for pine and beech trees, showing a negative effect for both of them. Our results show the possible coexistence of these tree species due to niche differentiation. An analysis of climatic indicators from 1991–2005 revealed that precipitation from February–May of the current vegetation year and mean temperatures from July to September expressed radial diameter increment effects for beech trees. Low temperatures during March and April, as well as high precipitation during January, had a negative effect on beech radial increments. From 2006–2016, the highest effect on radial diameter increments was the mean temperatures from July to September, as well as the precipitation in January of the current year. From 1991–2016, the highest effect on radial diameter increments was the temperature from July to September 1991–2016 and the precipitation in June 1991–2016. Generally, cool temperatures and higher precipitation in June had a positive effect on beech radial increments. Therefore, our results show a sensitivity to high temperatures and droughts during summer amid Lithuanian’s growth conditions.

Sign in / Sign up

Export Citation Format

Share Document