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Articles 931 - 933 of 933

Full-Text Articles in Zoology

Growth And The Expression Of Alternative Life Cycles In The Salamander Ambystoma Talpoideum (Caudata: Ambystomatidae), Travis J. Ryan, Raymond D. Semlitsch Jan 2003

Growth And The Expression Of Alternative Life Cycles In The Salamander Ambystoma Talpoideum (Caudata: Ambystomatidae), Travis J. Ryan, Raymond D. Semlitsch

Scholarship and Professional Work - LAS

Complex life cycles (CLCs) contain larval and adult phases that are morphologically and ecologically distinct. Simple life cycles (SLCs) have evolved from CLCs repeatedly in a wide variety of lineages but the processes that may underlie the transition have rarely been identified or investigated experimentally. We examined the influence of larval growth rate on the facultative expression of alternative life cycles (metamorphosis or maturation as gill-bearing adults [= paedomorphosis]) in the salamander Ambystoma talpoideum. We manipulated growth rates by altering the amount of food individuals received throughout larval development. The expression of alternative life cycles in A. talpoideum is influenced …

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Historical Biogeography And Modes Of Speciation Across High-Latitude Seas Of The Holarctic: Concepts For Host-Parasite Coevolution Among The Phocini (Phocidae) And Tetrabothriidae (Eucestoda), Eric P. Hoberg Jan 1995

Historical Biogeography And Modes Of Speciation Across High-Latitude Seas Of The Holarctic: Concepts For Host-Parasite Coevolution Among The Phocini (Phocidae) And Tetrabothriidae (Eucestoda), Eric P. Hoberg

Harold W. Manter Laboratory of Parasitology: Faculty Publications

Species of Anophryocephalus are host-specific parasites of pinnipeds in the Holarctic. Phylogenetic analysis of 7 species postulates A. anophrys as the basal taxon and A. inuitorum as basal to A. skrjabini; A. arcticensis is basal to A. nunivakensis and A. eumetopii + A. ochotensis (single tree; consistency index = 74.4%; homoplasy slope ratio = 36.45%). Evaluation of host and geographic distributions postulates ringed seals of the Atlantic-Arctic as ancestral hosts, and the Arctic basin as a paraphyletic area with respect to the North Pacific. Cospeciation within this assemblage was dependent on intense isolation of small effective populations of definitive hosts …

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Evaporative Water Loss In Two Northwest Snakes: Pituophis Catenifer And Crotalus Viridis, Donald R. Woolery Jun 1971

Evaporative Water Loss In Two Northwest Snakes: Pituophis Catenifer And Crotalus Viridis, Donald R. Woolery

All Master's Theses

A study by Gans, Krakauer and Paganelli (1968) dealt with twenty-six species of snakes representing five families. They found that the "rate of water loss was proportional to surface area" and that water loss correlates with the aridity of the selected habitat. No comparative information resulting from the direct separation of the pulmonary and cutaneous avenues of water loss is currently available. Also, no direct comparisons of this separation in sympatric species are available. These comparisons are the basis for this study.

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