Role of Woody Debris in Nest Site Selection by Pumpkinseed Sunfish, Lepomis gibbosus

1973 ◽  
Vol 30 (6) ◽  
pp. 853-856 ◽  
Author(s):  
Patrick Colgan ◽  
David Ealey
Keyword(s):  
Nearest Neighbor ◽  
Woody Debris ◽  
Breeding Population ◽  
Nest Site Selection ◽  
Lepomis Gibbosus ◽  
Nest Density ◽  
Spawning Activity ◽  
Pumpkinseed Sunfish ◽  
Nearest Neighbor Distances

Nesting preference for areas cleared of woody debris over areas cluttered with such debris was indicated by more nesting in cleared areas at the beginning and end of the breeding season, and more spawning activity in cleared areas. During heavy nesting, however, no preference was observed due to the density-dependent constraint of a high breeding population limiting available nesting space. This lack of difference in nesting densities at peak times indicates that breeding density cannot be enhanced in pumpkinseed sunfish by the creation of additional environmental boundaries. Nest density was influenced by the type of substrate of the site. In cluttered sections, nest diameters and distances to nearest cover were less than, and nearest neighbor distances not significantly different from, those in cleared sections.

scholarly journals THE ROLE OF MICROTUBULES IN THE MOVEMENT OF PIGMENT GRANULES IN TELEOST MELANOPHORES

1974 ◽  
Vol 61 (3) ◽  
pp. 757-779 ◽  
Author(s):  
Douglas B. Murphy ◽  
Lewis G. Tilney
Keyword(s):  
Endoplasmic Reticulum ◽  
Hydrostatic Pressure ◽  
Low Temperature ◽  
Nearest Neighbor ◽  
Cytoplasmic Matrix ◽  
Pigment Granules ◽  
Fixed Array ◽  
Nearest Neighbor Distances ◽  
Rule Out

When microtubules in teleost melanophores are disrupted with antimitotic agents, colchicine, high hydrostatic pressure, low temperature, and vinblastine, the alignment and movement of the pigment granules in these cells disappear; during recovery, the return of alignment and movement corresponds in both time and space with the repolymerization of microtubules. Furthermore, analysis of nearest neighbor distances in untreated melanophores reveals that pigment granules are closely associated with microtubules. Other structures such as microfilaments, the endoplasmic reticulum, and the cytoplasmic matrix do not appear to be involved. Thus we conclude that microtubules determine the alignment and are essential for the selective movements of the pigment granules in these cells. Investigations of the mechanism of movement show that microtubules are required for both centrifugal and centripetal migrations and that they do not change in number or location during redistribution of pigment. Our results further indicate that microtubules in melanophores behave as semistable organelles as determined by investigation with colchicine and hydrostatic pressure. These observations and others rule out a push-pull mechanism based on the polymerization and depolymerization of microtubules or one which distinguishes two operationally different sets of microtubules. We propose instead that particles move by sliding along a fixed array of microtubules.

Size- and age-related variation in the seasonal timing of nesting activity, nest characteristics, and female choice of parental male pumpkinseed sunfish (Lepomis gibbosus)

1996 ◽  
Vol 74 (10) ◽  
pp. 1834-1840 ◽  
Author(s):  
Andy J. Danylchuk ◽  
Michael G. Fox
Keyword(s):  
Body Size ◽  
Woody Debris ◽  
Selective Advantage ◽  
Spawning Season ◽  
Lepomis Gibbosus ◽  
Male Body ◽  
Pumpkinseed Sunfish ◽  
Age Related ◽  
Sand And Gravel ◽  
Nesting Activity

Parental males from a population of pumpkinseed sunfish (Lepomis gibbosus) were captured throughout the spawning season to examine age- and size-related seasonal trends in nesting activity. Females of spawning pairs were also captured to determine if male body size or nest characteristics influenced their selection of a mate. Large/old (≥ 80 mm; age 4–6 years) parental males commenced nesting earlier in the spring–summer spawning season than small/young (< 80 mm; age 2 and 3 years) parental males. As the spawning season progressed, the proportion of large/old males in the nesting population decreased until more than 70% of the males nesting late in the season were small/young individuals. Small individuals nesting late in the season were inferior in body condition to those that nested earlier in the season. These findings support the hypothesis that size-related differences in energy reserves and metabolism in centrarchids result in size-dependent variation in the timing of nesting activity. The length of females captured spawning at a nest site was not significantly correlated with the length of the parental male, water depth, or distance from shore; however, females captured spawning in firm (sand and gravel) substrates were significantly larger than those spawning in soft (silt or woody debris) substrates. Although all observed nests in the various substrates contained eggs, the positive relationship between body size and fecundity in female pumpkinseeds suggests that a selective advantage for males nesting in firm substrate may accrue through the attraction of larger females.

Application of Lattice Imaging Techniques to Amorphous Films

1975 ◽  
Vol 33 ◽  
pp. 8-9
Author(s):  
S. R. Herd ◽  
P. Chaudhari
Keyword(s):  
Nearest Neighbor ◽  
Random Network ◽  
Imaging Techniques ◽  
Network Models ◽  
Accurate Method ◽  
Direct Transmission ◽  
Lattice Imaging ◽  
Transmission Electron ◽  
Lattice Planes ◽  
Nearest Neighbor Distances

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.

Temporal Changes in Habitat Selection and Nest Spacing in a Colony of Ross' and Lesser Snow Geese

The Auk ◽  
1983 ◽  
Vol 100 (2) ◽  
pp. 335-343 ◽  
Author(s):  
M. Robert McLandress
Keyword(s):  
Nearest Neighbor ◽  
Average Distance ◽  
Habitat Preferences ◽  
Nearest Neighbors ◽  
Nest Density ◽  
Snow Goose ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Average Size ◽  
Island Habitats

Abstract I studied the nesting colony of Ross' Geese (Chen rossii) and Lesser Snow Geese (C. caerulescens caerulescens) at Karrak Lake in the central Arctic of Canada in the summer of 1976. Related studies indicated that this colony had grown from 18,000 birds in 1966-1968 to 54,500 birds in 1976. In 1976, geese nested on islands that were used in the late 1960's and on an island and mainland sites that were previously unoccupied. Average nest density in 1976 was three-fold greater than in the late 1960's. Consequently, the average distance to nearest neighbors of Ross' Geese in 1976 was half the average distance determined 10 yr earlier. The mean clutch size of Ross' Geese was greater in island habitats where nest densities were high than in less populated island or mainland habitats. The average size of Snow Goose clutches did not differ significantly among island habitats but was larger at island than at mainland sites. Large clutches were most likely attributable to older and/or earlier nesting females. Habitat preferences apparently differed between species. Small clutches presumably indicated that young geese nested in areas where nest densities were low. The establishment of mainland nesting at Karrak Lake probably began with young Snow Geese using peripheral areas of the colony. Young Ross' Geese nested in sparsely populated habitats on islands to a greater extent than did Snow Geese. Ross' Geese also nested on the mainland but in lower densities than Ross' Geese nesting in similar island habitats. Successful nests with the larger clutches had closer conspecific neighbors than did successful nests with smaller clutches. The species composition of nearest neighbors changed significantly with distance from Snow Goose nests but not Ross' Goose nests. Nesting success was not affected by the species of nearest neighbor, however. Because they have complementary antipredator adaptations, Ross' and Snow geese may benefit by nesting together.

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