mean crowding

mean crowding

A term used in parasitology for the intensity of parasite infestation relative to each other. It is only of use for density-dependent studies.
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For example, if we observed three groups of animals in the wild, and their group sizes were 1, 3, and 5, respectively (for a total of 9 individuals), then the crowding values would be 1, 3, 3, 3, 5, 5, 5, 5, 5, and the mean crowding value would be (1 + 3 + 3 + 3 + 5 + 5 + 5 + 5 + 5)/9 = 3.89.
The estimated mean crowding value for mixed-sex groups (30.45 [+ or -] 1.15) were significantly larger than for both female groups (13.80 [+ or -] 0.52; t = 26.29, p < 0.01) and male groups (12.45 [+ or -] 0.48; t = 26.13, p < 0.01) throughout the year.
Mean crowding values of female groups varied significantly among months ([F.sub.11,38069] = 9.813, p < 0.001), and further analysis found this index was largest in June (26.43 [+ or -] 3.36) and smallest in December (6.51 [+ or -] 0.80) (Fig.
For male groups, mean crowding values also varied significantly across months ([F.sub.11,38069] = 12.733, p < 0.001), and further analysis found the largest values in August and September (August: 22.87 [+ or -] 3.05; September: 23.94 [+ or -] 3.21), and smallest in December (5.14 [+ or -] 0.68) (Fig.
This problem usually resolves by a combination of a slight increase in the inter-canine width, labial positioning of the permanent incisors relative to the primary incisors, and slight backward movement of the canines into the primate space.1 It is estimated that the mean crowding of the lower incisors reduces approximately 0.9mm from the initial eruption of the lower permanent incisors to the initial eruption of the permanent canines.2 When crowding is of a greater magnitude, correction by normal development may not occur and early intervention might be required.
Mean crowding values revealed differences in small-scale distribution of scallops that were undetectable with density estimates.
Distributions of juvenile and adult scallops were plotted across Georges Bank and tile Mid-Atlantic Bight, and mean density and mean crowding were calculated for juveniles and adults in both areas and years.
Crowding is the number of organisms found within a given proximity of an individual of interest, and mean crowding is the average of crowding values for all individuals in the study area.
In a previous study carried out in Florencio Varela city (34[degrees] 46' 30" S, 58[degrees] 16' 04" W), Buenos Aires province, Argentina, Macia (2006) estimated a crowding of about 90 larvae per liter in automobile tires and 300 larvae per liter in ovitraps using Lloyd's (1967) index of mean crowding. During the course of that study, I found densities ranging from 74 to 460 larvae/l, and an average of 193 larvae/l.
"Local mean crowding index" is the number of neighbors an average recovered fruit segment had within a sampling area (1250 [cm.sup.2]) plus one (itself), corrected for sampling (Lloyd 1967).
"Wide-scale mean crowding index" is the number of neighbors an average fruit segment has within a sampling area (1250 [cm.sup.2]) plus one (itself), corrected for sampling, and assuming that the fruit segments that were dispersed beyond the census area occur singly, or at a density of one per sampling area.
The wide-scale mean crowding index is based on the approximation that the fruit segments that were dispersed out of the census area occur at low densities.
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