Breeding Systems and Resistance to Environmental Stress in Ciliates

Nyberg, Dennis

doi:10.2307/2407158

Cited by 32 publications

(27 citation statements)

References 9 publications

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“…Nyberg (1974) studying different species of freshwater ciliates, belonging to Paramecium aurelia, P, multimicronucleatum, and Tetrahymena pyriformis complexes, noted a n impressive consistency of the relationship of greater tolerance to various stressing agents in outbreeders. Nyberg's and the present results both point to a greater ability of outbreeding forms of ciliates to cope directly with changing conditions.…”

Section: Discussionmentioning

confidence: 99%

“…The procedure employed by Nyberg (1974Nyberg ( , 1975 for heavy metal tolerance tests in freshwater ciliates was followed with several modifications. An appropriate amount of 10-3 M HgC12 was diluted with seawater to produce the test solution of the highest concentration used (1.26 W ) .…”

Section: Bioassay Proceduresmentioning

confidence: 99%

“…Once these observations become established, the investigation of the mechanisms responsible for the differential susceptibility of the organisms, and the factors affecting their ability to withstand varied toxicant concentrations in the environment, become the major tasks for the biologist. The system of breeding (the degree of inbreeding or outbreeding) followed by a n organism may be an impor--This work was partially accomphshed at the Ramsay Wright Zoological Laboratories, University of Toronto, Canada, with the support of a NATO Fellowship awarded to F. Dini through the Italian National Research Council (CNR) " Present address: Instituto di Zoologia, Universita di Pisa, Via A. Volta4, 56100 Pisa, Italy tant factor determining the degree of resistance to environmental stress (Nyberg, 1974).…”

Section: Introductionmentioning

confidence: 99%

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Relationship Between Breeding Systems and Resistance to Mercury In Euplotes crassus (Ciliophora Hypotrichida)

Dini¹

1981

Mar. Ecol. Prog. Ser.

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A toxicity bioassay was used to measure the median tolerance limit to mercuric ion of different stocks of the marine hypotrichous ciliate Euplotes crassus. The stocks were representatives of local populations diversified in their breeding systems (inbreeding or outbreeding). The results show a greater tolerance to mercury in outbreeders Genetic analysis of interstock tolerance-differences indicates no simple genetic basis. An interpretation is presented which suggests that the different degrees of mercury tolerance revealed by the representatives of inbreeding and outbreedlng populations could depend on their peculiar genetic organizations. Such peculiar genetic organizations might be the product of the distinct ecogenetic strategies followed by the populations to which the stocks belong.

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Section: Discussionmentioning

confidence: 99%

Section: Bioassay Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Relationship Between Breeding Systems and Resistance to Mercury In Euplotes crassus (Ciliophora Hypotrichida)

Dini¹

1981

Mar. Ecol. Prog. Ser.

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“…That this is not the case argues that deterministic forces are acting either on the allozyme genes scored in this study or on closely linked genes. The high rate of self-fertilization in H. jubatum may also be an im-portant factor in this pattern, since one of its consequences is believed to be a potential for close, rapid adaptation to local environments (Allard et al, 1968;Clegg and Allard, 1972;Hamrick and Allard, 1972;Nyberg, 1974). Of additional interest is the observation that one of the loci which shows strong differentiation between the two habitats and hence indicates the action of natural selection (CPX-6, see Table 2) also shows strong clinal differentiation among populations sampled throughout the United States with allele "33" in high frequency in northern populations and at high elevations (Babbel, unpubl.…”

Section: Discussionmentioning

confidence: 99%

PATTERNS OF ALLOZYMIC SIMILARITY IN ECOLOGICALLY CENTRAL AND MARGINAL POPULATIONS OF HORDEUM JUBATUM IN UTAH

Shumaker

Babble

1980

Evolution

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“…Species with short immaturity intervals typically have a group of characters which allow inbreeding, while those with long immaturity intervals have characters which encourage outbreeding [6]. Whether a species is predominantly inbreeding or outbreeding has a variety of evolutionary consequences, and in particular affects the species response to environmental stress [7]. Whether a species is predominantly inbreeding or outbreeding also is related to the timing of senescence [6].…”

Section: Introductionmentioning

confidence: 99%

The immaturity interval in Tetrahymena: Genetic and environmental sources of variation

Nyberg¹,

Bishop²

1981

Dev. Genet.

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The development of sexual maturity has been studied in Tetrahymena hegewischi. Progeny lines d o not typically change from immaturity to mating with all different mating types during a single test interval, but about 30% d o mature abruptly. Some testers are more likely than others to participate in the earliest mating reactions of progeny lines which d o not mature abruptly. Subcaryonidal vegetative pedigrees of 10 pairs from 4 crosses revealed considerable intrapair variation in the time, measured in fissions, of maturity. The average intrapair coefficient of variation was 20%. A nested ANOVA revealed significant genomic effects on the immaturity interval, but no significant cytoplasmic or caryonidal effects; 56% of the total variation was non-genomic. Growth in different environments had highly significant effects on the immaturity interval. Subclones grown at 27°C with alternate day transfers took on the average 2 to 3 times as many fissions to mature as sister subclones grown at 27°C with daily transfers. Subclones grown at 18°C or 34°C and transferred on alternate days had intermediate maturation times. The greatest range in the immaturity interval among lines of the same genotype was from 34 to 143 fissions. The development of maturity in this species involves genetic control of timing, but the genetic differences are obscured by a large amount of intraclonal variation and sensitivity to the environment.

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Breeding Systems and Resistance to Environmental Stress in Ciliates

Cited by 32 publications

References 9 publications

Relationship Between Breeding Systems and Resistance to Mercury In Euplotes crassus (Ciliophora Hypotrichida)

Relationship Between Breeding Systems and Resistance to Mercury In Euplotes crassus (Ciliophora Hypotrichida)

PATTERNS OF ALLOZYMIC SIMILARITY IN ECOLOGICALLY CENTRAL AND MARGINAL POPULATIONS OF HORDEUM JUBATUM IN UTAH

The immaturity interval in Tetrahymena: Genetic and environmental sources of variation

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