Graduation date: 1983

Advocates of the theory of r-K selection claim that high levels of density-independent mortality select for a high intrinsic rate of natural increase (r- strategist), while density-dependent mortality selects for greater competitive ability and a higher carrying capacity (K- strategist). Furthermore, environmental stability is thought to affect the amount of density-independent or density-dependent mortality that a species encounters with unpredictable and highly variable environments leading primarily to density-independent mortality, and more predictable, less variable environments leading primarily to density-dependent mortality. Species can be positioned on an r-K continuum on the basis of several life history characteristics which are correlated to the intrinsic rate of natural increase. Thus it is suggested that selection should favour rapid development, single reproduction, early maturity, smaller body size, and higher birth rate for r- strategists, and slower development, repeated reproduction, later maturity, larger body size and lower birth rates for K-strategists. I compared two species of isopods from the upper and lower intertidal zone for the reproductive parameters correlated with high intrinsic rate of increase. I considered the upper intertidal environment to be more variable and unpredictable because of the increased time of exposure to air, and the resulting changes in temperature and humidity, compared to the more stable conditions which exist when submerged. Thus the species from the upper intertidal, Idotea wosnesenskii, was expected to have life history characteristics which were r- selected with respect to those of Idotea montereyensis, from the lower intertidal. I found the differences in two of the correlates to be in the direction predicted by r- and K- selection, two other correlates to be in the opposite direction, and a fifth not to differ between the two species. By ranking these parameters with respect to their influence on the intrinsic rate of population increase, I found the two most important parameters, age of first reproduction and birth rate, to support the predictions of r-K theory, and I concluded that I. wosnesenskii was an r- strategist relative to I. montereyensis. Reproductive effort, the proportion of food energy resources allocated to reproduction, was also used as a measure of a species' position on the r-K continuum. Three different measures of reproductive effort supported the prediction of r-K theory, and showed that I. wosnesenskii had a higher reproductive effort that did I. montereyensis. / Science, Faculty of / Zoology, Department of / Graduate

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Thesis (Ph. D.)--University of Chicago, 1912. / "Reprinted from the Journal of experimental zoology, vol. 13, no. 2, August 1912." Bibliography: p. 343-344.

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Thesis (M.S.)--University of New Orleans, 2004. / Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in the Department of Biological Sciences."--Thesis t.p. Vita. Includes bibliographical references.

Academical dissertation--Uppsala. / "The following work deals with the bulk of the very abundant material of marine antarctic and subantarctic Isopoda preserved in the Swedish state museum (Riksmuseum) at Stockholm."--Pref. "Reprint from Further zoological results of the Swedish antarctic expedition 1901-1903. vol. III, no. 1. Stockholm 1933." Bibliography: p. 279-284.

Made available in DSpace on 2014-06-12T22:59:13Z (GMT). No. of bitstreams: 2 arquivo2640_1.pdf: 8693100 bytes, checksum: 53b036ae6aea9f5d45e4d21d58ff776b (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Faculdade de Amparo à Ciência e Tecnologia do Estado de Pernambuco / O presente trabalho abordou a taxonomia, a distribuição geográfica e batimétrica da superfamília Anthuroidea no Brasil. Todo o material utilizado é proveniente de diversos projetos oceanográficos realizados entre 1960 e 2008 na costa brasileira. A área de estudo abrangeu as regiões Norte e Nordeste do país, desde o estado do Amapá até o estado do Espírito Santo. Os Anthuroidea foram amostrados desde a zona entre-marés até 800 m de profundidade. No entanto, quase todo o material é oriundo da plataforma continental (10-100 m de profundidade). Foram analisados 239 exemplares de 14 espécies e três famílias. A família Hyssuridae é registrada pela primeira vez no litoral nordeste do Brasil. Anthuridae foi a família mais representativa, com nove espécies registradas. Isto significou 69,67% dos espécimes analisados. Quatro novas espécies são descritas: Amakusanthura n. sp.; Mesanthura n. sp.; Kupellonura n. sp. e Accalathura n.sp. Mesanthura brasiliensis foi redescrita e discutida, esclarecendo erros de identificação. As espécies Amakusanthura significa, A. magnifica, Mesanthura paucidens, Accalathura setosa e Leptanthura glacialis tiveram sua distribuição geográfica ampliada. O estudo da distribuição batimétrica das espécies mostrou padrões muito semelhantes aos descritos em trabalhos sobre Anthuroidea

This study is of five species of isopods common to the Dillon Beach area, each of which represents a different level in the transition toward land life. Cirolana harfordi was used as a completely marine form. Idothea (Pentidotea) wosnesenskii represents a step toward land life as it inhabits an area uncovered by most low tides. Ligia occidentalis is found in the splash zone, receiving spray from the action of the surf. This illustrates another, higher, level in the transition. Alloniscus perconvexus was the fourth species studied. It is commonly found burrowed in the sand in the area of the berm, which is the nearly level portion of the beach formed by high tidal wave action. Finally, the terrestrial form, Porcellio (Porcellion) scaber, was used to illustrate those isopods best adapted to land life. The physiological data presented in this paper includes salinity tolerances and humidity tolerances. Some information on acclimating one species to lowered salinities is also presented. The results of these experiments are used to illustrate the degrees of adaptation to land life shown by the isopods in different areas of the transition. A discussion of the adaptive morphology and behavioral characteristics is also related to the environmental situations in which each animal is found.

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