This thesis presents the results of an investigation on the relationships between populations of closely related animals under apparent sympatric conditions. The mechanisms found have particular application toward understanding the species problem among members of the free-swimming marine copepod genus Calanus that possess a toothed inner surface on the coxopodites of the fifth pair of swirnming legs. The investigation describes the morphology, distribution, and general ecology of two forms of toothed Calanus from the far eastern North Pacific Ocean. Morphological differences were established and used to distinguish both forms on the oasis of length, shape of the anterior surface of the cephalothorax, proportionate differences in segments of the urosome and fifth swimming legs, and by the degree of asymmetry in the fifth pair of swimming legs of males. An additional feature was the length of a small spine on the fifth swimming legs of both forms. A general account of the distribution and ecology of both forms from Glacier Bay, Alaska, to the Mexican Border was derived from data gathered during several long cruises. The Large Form was found from Glacier Bay, Alaska, to Cape Mendocino, California. The Small Form was found from the Mexican Border to the vicinity of Vancouver Island, British Columbia. Along the outer coast, the Large Form appeared to be associated with Pacific Sub-Arctic water typical of the California Current, whereas the Small Form appeared to be associated with the warmer more saline water typical of Equatorial Pacific water associated with the Davidson Counter Current. A detailed analysis of the ecological relationships of both forms in a region of overlap was performed in Indian Arm, an inlet near Vancouver, British Columbia. In this inlet, the Large Form was generally associated with the cooler more saline deep water of the inlet. The Small Form occurred at shallower depths. Overlap between the populations of both forms was limited to Large Form females that rose to shallower depths during part of the year occupying nearly the same portion of the water column as the Small Form population. The yearly cycles of both forms in Indian Arm were shown to be different indicating different times of breeding for Large and Small Forms. On the basis of morphology and previous descriptions for toothed members of the genus Calanus, the Large Form appeared to be Calanus glacialis and the Small Form C. pacificus californi-cus. Based on the results of the distributional study and the ecological study, it was concluded that both forms were behaving as good species since separation of breeding populations both spatially and temporally appeared to be real, and the likelihood of interbreeding appeared to be small. In the classical sense, the two species are sympatric because their ranges overlap, and there is a strong indication that interbreeding occurs infrequently if at all. Association to different types of water and differences in yearly cycles appear to be the primary mechanisms that act to maintain the integrity of sympatric species. The vertical as well as horizontal space must be given equal consideration in planktonic studies. Under these conditions, therefore, the toothed Calanus spp. of Indian Arm are allopatric with respect to the water column. / Science, Faculty of / Zoology, Department of / Graduate

Significant differences were found to exist in the copper tolerance of the life-history stages of the marine copepod, Tiqriopus californicus, using artificial seawater as medium. The copper response of Tigriopus to copper was found to occur predominantly over the concentration range 1.0X10⁻⁶ M to 1.5X10⁻⁵ M. The N-2 was the most sensitive and the C-6 was the most tolerant life-history stage. Copper equilibrated with the food of Tiqriopus did not significantly affect adult fecundity (between 1.0x10⁻¹⁰ and 1.0X10⁻⁶ M Cu) or mortality (between 1.0x10⁻¹⁰ and 1.0X10⁻⁵ M). Copper equilibrated with SOW did not significantly alter the rate of egg survival (between 1.0X10⁻⁹ and 1.0X10⁻⁶ M) or naupliar activity (between 1.0x10⁻⁸ and 1.0X10⁻⁶ M). Exposure to widely varying but natural ecological conditions appears to have increased the tolerance of Tigriopus to unnatural stress. The copper-manganese interaction observed for some species of phytoplankton such as Thalassiosira pseudonana was not found to hold for Tiqriopus in SOW medium. No significant reduction in copper toxicity was observed upon addition of manganese (between 1.0 X 10⁻⁶ and 1.0X10⁻⁴ M) to copper 10X10⁻⁶ M) solutions. An attempt was made to quantify the proportion of copper and manganese in biologically available forms (i.e., able to react with or pass through biological membranes) using the cation resin technique of Zorkin et al., ( 1986). It is thought that this attempt failed due to the resin columns being supersaturated with metal ions. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

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A study of the digestive tract of the copepods Tigriopus californicus and Calanus plumchrus was carried out using techniques of light and electron microscopy. In Tigriopus californicus, the foregut contains a curved cuticle lined esophagus which extends from the ventral mouth to the junction of the anterior midgut and midgut caecum. The noncuticulized portion of the digestive tract consists of: 1. A single spherical midgut caecum located anteriorly, 2. An anterior midgut, 3. A posterior midgut. There are cuticulized anterior and posterior hindgut regions ending in a dorsal anus. In Calanus plumchrus, the foregut consists of a cuticle lined esophagus extending from the ventral mouth to the junction of the midgut and the midgut diverticulum. The noncuticulized portion of the digestive tract consists of: 1. A single midgut diverticulum, 2. A midgut that is divisible on the basis of epithelial cell type and function. There is a long abruptly narrowing cuticle lined hindgut ending in an anus. In Tigriopus californicus, four cell types could be distinguished and from such ultrastructural characteristics as the position in the digestive tract, abundance, position, and type of organelles, lipid content, presence and type of vesiculation, and electron density, functions for the cells were determined. Cell type '1' is an embryonic 'stem' cell. It functions as a replacement cell and differentiates when cells are worn away or lost in secretion. Cell type '2' is mainly a secretory cell and functions in the synthesis of proteins. It also plays a role in lipid absorption. Cell type '3' is absorptive, mainly for lipids. Cell type M1, found only in the anterior midgut is also an absorptive cell. The presence of electron dense vesicles suggests that lipid absorption is not its major function. From the abundance of cell type and from examination of the ultrastructure in the various regions of the digestive tract, the following conclusions were made: 1. The midgut caecum functions in the absorption of digested nutrients. 2. The anterior midgut plays a role in nutrient absorption but is important in secretion. 3. The posterior midgut cells are mainly absorptive. In Calanus plumchrus, five cell types could be distinguished. Cell type 'E' is an undifferentiated 'stem1 cell. Cell type 'R' found in the midgut diverticulum and posterior midgut regions, is absorptive. Its developed basal surfaces suggest a transport function between the cell and the haemo-coel . Cell type 'D' is found in the glandular region of the midgut and is absorptive. It has an ultrastructure similar to that observed for cell type 'R'. Cell type 'B' is a large vacuolated absorptive cell found in the glandular region of the midgut. Cell type 'F' functions in the synthesis and secretion of digestive enzymes. In Calanus plumchrus, the midgut diverticulum is specialized for the absorption of digested nutrients and transport of metabolites to the haemocoel . The anterior midgut regions are mainly absorptive. It includes a vacuolated glandular region specialized for pinocytotic absorption. In the middle section of the midgut, adjacent and posterior to the glandular region, is an area of epithelial cells specialized for secretion. The posterior midgut regions are mainly absorptive. In Tigriopus californicus biological markers can be used to determine cell type function in correlation with the observed ultrastructure. / Science, Faculty of / Zoology, Department of / Graduate

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Thesis (M.S.)--University of North Carolina Wilmington, 2008. / Vita. Title from PDF title page (viewed September 29, 2008) Includes bibliographical references (p. 31-32)

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Yen, Jeannette, Committee Member ; Weissburg, Marc, Committee Member ; Sturm, Terry, Committee Member ; Roberts, Phillip, Committee Member ; Webster, Donald R., Committee Chair.