In an earlier paper we found that the proportion of the prairie deer mouse (Peromyscus maniculatu... more In an earlier paper we found that the proportion of the prairie deer mouse (Peromyscus maniculatus bairdii), among all local Peromyscus museum specimens collected in the Chicago region, had significantly declined over time. This proportion changed from about 50% before 1900 to <10% in the last 25 years. Based on this proportion a regression model predicted the local extinction of the prairie deer mouse in 2009. To evaluate that prediction, we estimated current deer mouse abundance by live trapping small mammals at 15 preserves in Cook and Lake counties, Illinois (USA) at which prairie deer mice had previously been caught or that still contained their preferred open habitat. In 1900 trap nights, 477 mammals were caught, including 251 white-footed mice (P. leucopus), but only one prairie deer mouse. The observed proportion of Peromyscus that were prairie deer mice, 0.4%, was even lower than the 4.5% predicted for 2000. Here we also introduce a simple, new community proportions model, which for any given geographic region compares the proportions of species recently caught with the proportions of species in museums. We compared proportions of seven species collected in Cook and Lake counties and examined by with proportions of these species that we caught. Ten percent of the museum community was prairie deer mice, but only 0.2% of our catch was. The current local scarcity of the prairie deer mouse is consistent with the regression-based prediction of its eminent local extinction. More conservation attention should be paid to changes in relative abundance of once-common species.
Cadmium-109 chloride (1 mg or 48 ng Cd2+/kg body wt) was administered intraperitoneally to rats a... more Cadmium-109 chloride (1 mg or 48 ng Cd2+/kg body wt) was administered intraperitoneally to rats at one of eight selected times of day. Exactly 48 hr later each animal was sacrificed, and the cadmium content of the blood, brain, heart, kidney, liver, and testes was determined. Metallothionein levels in the liver and kidney were also measured. Distribution and retention of cadmium was very different at the different dose levels. Approximately 60% of the higher dose of cadmium was retained in the six tissues examined, while only 11.5% of the lower dose could be accounted for in these six tissues. The liver retained the largest percentage of the administered cadmium at both dose levels, but the magnitude of the retention differed by a factor of 6 (57.3% of the higher dose and9.6%of the lower dose). The pattern of cadmium distribution among the other tissues was also different. At the 1-mg Cd2+/kg body wt level, the kidneys accumulated the second largest fraction of cadmium, followed by the blood, heart, testes, and brain. In the 48-ng Cd2+/kg body wt groups the order was kidney, testes, blood, heart, and brain. Only in the testes of animals receiving the low dose of cadmium was there an effect of time of day, and here the effect was marked. When cadmium was administered during the dark phase of the daily cycle, the testes contained an average of six times more cadmium than when cadmium was given during the light phase. Similarly, levels of metallothionein in the kidney were significantly higher when cadmium was administered during the dark phase. A trend toward higher metallothionein levels in the liver during the dark phase was also observed, but this trend was not statistically significant.
As an economy grows, natural capital such as timber, soil, and water is reallocated to the human ... more As an economy grows, natural capital such as timber, soil, and water is reallocated to the human economy. This conflict between economic growth and biodiversity conservation creates a conundrum for conservation biologists because traditional forms of conservation action require money. We hypothesize that conservation spending in the United States is highly correlated with income and wealth, and we tested whether selected proxies for U.S. conservation activity could be predicted by U.S. economic indicators over time scales of 7-71 years. Stock market indexes (Dow Jones Industrial Average, Standard & Poor's 500 Index), gross domestic product (GDP), and personal income (PI) explained as much as 99% of annual variation in total revenue (including contributions) to four large nongovernmental organizations (NGOs), the World Wildlife Fund, Sierra Club, Environmental Defense, The Nature Conservancy. These broad economic indicators also explained as much as 96% of the annual number of university conservation programs, 83% of membership in professional conservation organizations (Natural Areas Association, Society for Conservation Biology), 93% of national park visitation, and 99+% of national park acreage. In most analyses, the income variables GDP and PI explained more variation in conservation activity than did either of the stock-market wealth variables. After long-term growth was removed from the time series, changes in revenues to the four NGOs combined were significantly correlated with GDP but not PI over the short term. Short-term variation in park acreage was significantly correlated with GDP and PI but lagged both by 3 years. Using linear models based on GDP, we predicted increases of 2.3% in 2003 cumulative NGO revenues and 1.0% in 2006 acreage owned by the National Park Service. The conservation activity parameters we measured may exhibit positive trends even in the face of declining biodiversity, but biodiversity conservation will ultimately require the cessation of economic growth. The challenge to the conservation biology community is to retain a significant presence during and after the cessation of growth.
Bulletin of Environmental Contamination and Toxicology, 1979
The biological impact of heavy metals is a more complex problem than measurement of total concent... more The biological impact of heavy metals is a more complex problem than measurement of total concentrations of metals, for tolerance may be a complex function of internal physiological states and environmental conditions. If the magnitudes of the interactions bf the variables determining tolerance are not great, then one may be justified in concentrating study on a single variable. The toxicity of copper and zinc to a variety of ciliate protozoans has been previously studied by NYBERG (1974). Within Paramecium tetraurelia two classes of tolerance to copper were found; the resistant lines had a 24 hr TL50 of 30 ~M and the sensitive lines had a TLm of 4.0 ~M cupric ion at 27 C. The resistant phenotype was due to a single recessive gene (NYBERG 1975).
As an economy grows, natural capital such as timber, soil, and water is reallocated to the human ... more As an economy grows, natural capital such as timber, soil, and water is reallocated to the human economy. This conflict between economic growth and biodiversity conservation creates a conundrum for conservation biologists because traditional forms of conservation action require money. We hypothesize that conservation spending in the United States is highly correlated with income and wealth, and we tested whether selected proxies for U.S. conservation activity could be predicted by U.S. economic indicators over time scales of 7-71 years. Stock market indexes (Dow Jones Industrial Average, Standard & Poor's 500 Index), gross domestic product (GDP), and personal income (PI) explained as much as 99% of annual variation in total revenue (including contributions) to four large nongovernmental organizations (NGOs), the World Wildlife Fund, Sierra Club, Environmental Defense, The Nature Conservancy. These broad economic indicators also explained as much as 96% of the annual number of university conservation programs, 83% of membership in professional conservation organizations (Natural Areas Association, Society for Conservation Biology), 93% of national park visitation, and 99+% of national park acreage. In most analyses, the income variables GDP and PI explained more variation in conservation activity than did either of the stock-market wealth variables. After long-term growth was removed from the time series, changes in revenues to the four NGOs combined were significantly correlated with GDP but not PI over the short term. Short-term variation in park acreage was significantly correlated with GDP and PI but lagged both by 3 years. Using linear models based on GDP, we predicted increases of 2.3% in 2003 cumulative NGO revenues and 1.0% in 2006 acreage owned by the National Park Service. The conservation activity parameters we measured may exhibit positive trends even in the face of declining biodiversity, but biodiversity conservation will ultimately require the cessation of economic growth. The challenge to the conservation biology community is to retain a significant presence during and after the cessation of growth.
The advantage of recombination in increasing the rate of incorporation of favorable mutants is sh... more The advantage of recombination in increasing the rate of incorporation of favorable mutants is shown to disappear for large NU if substitution is occurring at only two loci. Recombination will, on the average, destroy all double favorable individuals in a haploid population until the product of the frequencies of the single favorable mutants exceeds 1/N. As NU increases there is an increasing probability of the occurrence of the double favorable my mutation alone. Recombination provides a significant advantage in the rate of incorporation of favorable mutants only if 2s/InN less than NU less than 2c when substitution is occurring at only two loci. If substitution is occurring at more than two loci the recombining population apparently has a substantial advantage for large NU.
Page 1. J. PROTOZOOL. 25(1), 107-112 (1978) Genetic Analysis of Trichocyst Discharge of theWild S... more Page 1. J. PROTOZOOL. 25(1), 107-112 (1978) Genetic Analysis of Trichocyst Discharge of theWild Stocks of Paramecium tetraurelia* ... SYNOPSIS. Aberrant discharge of trichocysts in response to picric acid occurs in 8 of the 28 wild stocks of Paramecium tetraurelia. ...
One stock, GBC, has a maximum temperature of growth about 5 degrees C lower than other recently c... more One stock, GBC, has a maximum temperature of growth about 5 degrees C lower than other recently collected stocks of Paramecium primaurelia. The resistant stocks (R) are able to grow continuously at 35 degrees C while the sensitive stock (S) cells die within 48 h. The F1s of R X S crosses exhibited a cytoplasmic pattern of inheritance and all F2-by-autogamy lines derived from the S cytoplasmic parent are sensitive. The F2-by-autogamy lines cytoplasmically descended from the R parent were predominantly (93%) R in the initial assay. Upon reinvestigation one year later, only 64% of these lines were R, 9% were S, and 27% had a new phenotype, weak (W), intermediate between R and S. Backcrosses of W lines to both R and S strongly suggest that the W lines have normal cytoplasm (i.e. R) but also have nuclear gene(s) for temperature sensitivity that are derived from the original S stock. The delayed manifestation of the W phenotype is not understood.
The trichocysts of most wild stocks of Paramecium tetraurelia discharge en masse in response to p... more The trichocysts of most wild stocks of Paramecium tetraurelia discharge en masse in response to picric acid. In most nonresponding wild stocks, the defective phenotype is simply determined by a single recessive gene difference from the standard wild type, stock 51. However, two wild stocks, 146 and 148, which are completely homozygous at all loci, express either a nondischarge, ND, or discharge, DI, phenotype. In stock 146, both ND and DI sublines generally reproduce true to type, but observed changes are highly biased. Changes from ND to DI occur more than ten times as often as changes from DI to ND. After conjugation between ND and DI cells, genomically identical exconjugant lines from the ND parent may be either ND or DI, while those from the DI parent invariably remain DI.-Interstock crosses between stocks 146 and 51 indicate that stock 146 possesses a recessive gene, nd146, which, when homozygous in stock 51 background, produces a distinct nondischarge phenotype, KO. Crosses be...
The fertility of crosses between wild stocks of Tetrahymena americanis (n = 93) and T. hegewischi... more The fertility of crosses between wild stocks of Tetrahymena americanis (n = 93) and T. hegewischi (n = 52) was not significantly related to the square root of the distance separating the parental stocks. Much of the death was probably caused by age-related damage to the micronucleus. Despite the confounding age-related death, the conclusion that neither species has detectably isolated local populations is supported.
The growth rate of 31 stocks of Euplotes, a cosmopolitan, marine, unicellular protist, on six foo... more The growth rate of 31 stocks of Euplotes, a cosmopolitan, marine, unicellular protist, on six food species representing two different food types, microalgae and bacteria, has been determined. The 31 stocks represented nine reproductively isolated groups (biological species?) based on breeding relationships. Three morphospecies, E. vannus, E. crassus, and E. minuta, each with both autogamous and cross-breeding breeding groups, were included. The mean number of fissions completed in 5 days of a breeding group growing on one of the six food species varied from zero to 17.06. There is a strong interaction between morphospecies and food type. The largest morphospecies, E. vannus, translates the nutritional content of algae into growth better than it translates that of bacteria, while the reverse is true for E. minuta, the smallest morphospecies. Autogamous breeding groups grow more rapidly on algae than on bacteria when compared to cross-breeding groups in the same morphospecies. Two breeding groups cannot grow on Escherichia coli. ANOVA of fissions completed in 5 days revealed significant main effects and interactions between many hierarchical levels of stocks and food species. These significant interactions indicate that genetically determined ecologically important information is present at all taxonomic levels-morphospecies, breeding system, breeding group, and stock. As all these levels are biologically meaningful, measuring biodiversity in the E. vannus-crassus-minuta complex solely on morphospecies will inadequately represent the ecological diversity present in the organisms and their environment.
The prairie deer mouse (Peromyscus maniculatus bairdii) was more common than the white-footed mou... more The prairie deer mouse (Peromyscus maniculatus bairdii) was more common than the white-footed mouse (P. leucopus) in museum collections from the 6 Illinois counties of the Chicago region before 1920 but constitutes only 5% of specimens deposited since 1970. Because white-footed mouse prefers woody vegetation and because prairie deer mouse is limited to prairie or large open habitats, the change in proportion is likely driven by a disproportionate loss of prairie among remaining natural habitat and increases in woody vegetation within grasslands. The decline of the prairie vole (Microtus ochrogaster) relative to the meadow vole (M. pennsylvanicus) and the lack of recent specimens of Franklin's ground squirrel (Spermophilus franklinii) corroborate the hypothesis that prairie habitats have declined much more so than wooded habitats in the Chicago region. Based on extinction models using museum records, it is probable that S. franklinii is already locally extirpated. Regression analysis suggests the white-footed mouse will be the only local Peromyscus in 0-140 years.
The life styles of ciliated protists are particularly suitable for experimental analyses of certa... more The life styles of ciliated protists are particularly suitable for experimental analyses of certain aspects of developmental and genetic biology. The progression from sexual immaturity to maturity to senescence represents one of the most intriguing aspects of developmental programs. The extent to which progeny clones, their subclones, and testers used in the assay result in different lengths of immaturity has been investigated in Euplotes crassus. Six subclones from each of 12 progeny clones from a cross between stocks EC1 and EC2 were tested for maturity with stocks EC3, EC4, and EC5 on every transfer. Analysis of variance was used to partition the total variation in fissions to maturity into parts due to clones, subclones, and testers and the interactions between these levels. The error, interaction of subclones and testers, corresponds to a standard deviation of only 4.1 fissions, while the within clone within tester means range from 15.2 to 46.7 fissions; all levels except testers contribute significantly to the total variation. Most of the variability is attributable to clones (66%), the next most to error (16%), the next most to interaction of clones by testers (13%), and the least to subclones (5%). An a posteriori analysis examined whether the differences among clones were due to the cytoplasm of the clone ancestor (exconjugant), its mat (mating-type) locus genotype, or the mated pair it came from. None of these characteristics was able to interpret simply the large variability among clones. These results provide evidence that the transition from immaturity to maturity is quantitative and complex rather than a jump from one well-defined state to another.
In an earlier paper (Pergams & Nyberg 2001) we found that the proportion of the prairie deer mous... more In an earlier paper (Pergams & Nyberg 2001) we found that the proportion of the prairie deer mouse (Peromyscus maniculatus bairdii), among all local Peromyscus museum specimens collected in the Chicago region, had significantly declined over time. This proportion changed from about 50% before 1900 to <10% in the last 25 years. Based on this proportion a regression model predicted the local extinction of the prairie deer mouse in 2009. To evaluate that prediction, we estimated current deer mouse abundance by live trapping small mammals at 15 preserves in Cook and Lake counties, Illinois (USA) at which prairie deer mice had previously been caught or that still contained their preferred open habitat. In 1900 trap nights, 477 mammals were caught, including 251 white-footed mice (P. leucopus), but only one prairie deer mouse. The observed proportion of Peromyscus that were prairie deer mice, 0.4%, was even lower than the 4.5% predicted for 2000. Here we also introduce a simple, new community proportions model, which for any given geographic region compares the proportions of species recently caught with the proportions of species in museums. We compared proportions of seven species collected in Cook and Lake counties and examined by Hoffmeister (1989) with proportions of these species that we caught. Ten percent of the museum community was prairie deer mice, but only 0.2% of our catch was. The current local scarcity of the prairie deer mouse is consistent with the regression-based prediction of its eminent local extinction. More conservation attention should be paid to changes in relative abundance of once-common species.
In an earlier paper we found that the proportion of the prairie deer mouse (Peromyscus maniculatu... more In an earlier paper we found that the proportion of the prairie deer mouse (Peromyscus maniculatus bairdii), among all local Peromyscus museum specimens collected in the Chicago region, had significantly declined over time. This proportion changed from about 50% before 1900 to <10% in the last 25 years. Based on this proportion a regression model predicted the local extinction of the prairie deer mouse in 2009. To evaluate that prediction, we estimated current deer mouse abundance by live trapping small mammals at 15 preserves in Cook and Lake counties, Illinois (USA) at which prairie deer mice had previously been caught or that still contained their preferred open habitat. In 1900 trap nights, 477 mammals were caught, including 251 white-footed mice (P. leucopus), but only one prairie deer mouse. The observed proportion of Peromyscus that were prairie deer mice, 0.4%, was even lower than the 4.5% predicted for 2000. Here we also introduce a simple, new community proportions model, which for any given geographic region compares the proportions of species recently caught with the proportions of species in museums. We compared proportions of seven species collected in Cook and Lake counties and examined by with proportions of these species that we caught. Ten percent of the museum community was prairie deer mice, but only 0.2% of our catch was. The current local scarcity of the prairie deer mouse is consistent with the regression-based prediction of its eminent local extinction. More conservation attention should be paid to changes in relative abundance of once-common species.
Cadmium-109 chloride (1 mg or 48 ng Cd2+/kg body wt) was administered intraperitoneally to rats a... more Cadmium-109 chloride (1 mg or 48 ng Cd2+/kg body wt) was administered intraperitoneally to rats at one of eight selected times of day. Exactly 48 hr later each animal was sacrificed, and the cadmium content of the blood, brain, heart, kidney, liver, and testes was determined. Metallothionein levels in the liver and kidney were also measured. Distribution and retention of cadmium was very different at the different dose levels. Approximately 60% of the higher dose of cadmium was retained in the six tissues examined, while only 11.5% of the lower dose could be accounted for in these six tissues. The liver retained the largest percentage of the administered cadmium at both dose levels, but the magnitude of the retention differed by a factor of 6 (57.3% of the higher dose and9.6%of the lower dose). The pattern of cadmium distribution among the other tissues was also different. At the 1-mg Cd2+/kg body wt level, the kidneys accumulated the second largest fraction of cadmium, followed by the blood, heart, testes, and brain. In the 48-ng Cd2+/kg body wt groups the order was kidney, testes, blood, heart, and brain. Only in the testes of animals receiving the low dose of cadmium was there an effect of time of day, and here the effect was marked. When cadmium was administered during the dark phase of the daily cycle, the testes contained an average of six times more cadmium than when cadmium was given during the light phase. Similarly, levels of metallothionein in the kidney were significantly higher when cadmium was administered during the dark phase. A trend toward higher metallothionein levels in the liver during the dark phase was also observed, but this trend was not statistically significant.
As an economy grows, natural capital such as timber, soil, and water is reallocated to the human ... more As an economy grows, natural capital such as timber, soil, and water is reallocated to the human economy. This conflict between economic growth and biodiversity conservation creates a conundrum for conservation biologists because traditional forms of conservation action require money. We hypothesize that conservation spending in the United States is highly correlated with income and wealth, and we tested whether selected proxies for U.S. conservation activity could be predicted by U.S. economic indicators over time scales of 7-71 years. Stock market indexes (Dow Jones Industrial Average, Standard & Poor's 500 Index), gross domestic product (GDP), and personal income (PI) explained as much as 99% of annual variation in total revenue (including contributions) to four large nongovernmental organizations (NGOs), the World Wildlife Fund, Sierra Club, Environmental Defense, The Nature Conservancy. These broad economic indicators also explained as much as 96% of the annual number of university conservation programs, 83% of membership in professional conservation organizations (Natural Areas Association, Society for Conservation Biology), 93% of national park visitation, and 99+% of national park acreage. In most analyses, the income variables GDP and PI explained more variation in conservation activity than did either of the stock-market wealth variables. After long-term growth was removed from the time series, changes in revenues to the four NGOs combined were significantly correlated with GDP but not PI over the short term. Short-term variation in park acreage was significantly correlated with GDP and PI but lagged both by 3 years. Using linear models based on GDP, we predicted increases of 2.3% in 2003 cumulative NGO revenues and 1.0% in 2006 acreage owned by the National Park Service. The conservation activity parameters we measured may exhibit positive trends even in the face of declining biodiversity, but biodiversity conservation will ultimately require the cessation of economic growth. The challenge to the conservation biology community is to retain a significant presence during and after the cessation of growth.
Bulletin of Environmental Contamination and Toxicology, 1979
The biological impact of heavy metals is a more complex problem than measurement of total concent... more The biological impact of heavy metals is a more complex problem than measurement of total concentrations of metals, for tolerance may be a complex function of internal physiological states and environmental conditions. If the magnitudes of the interactions bf the variables determining tolerance are not great, then one may be justified in concentrating study on a single variable. The toxicity of copper and zinc to a variety of ciliate protozoans has been previously studied by NYBERG (1974). Within Paramecium tetraurelia two classes of tolerance to copper were found; the resistant lines had a 24 hr TL50 of 30 ~M and the sensitive lines had a TLm of 4.0 ~M cupric ion at 27 C. The resistant phenotype was due to a single recessive gene (NYBERG 1975).
As an economy grows, natural capital such as timber, soil, and water is reallocated to the human ... more As an economy grows, natural capital such as timber, soil, and water is reallocated to the human economy. This conflict between economic growth and biodiversity conservation creates a conundrum for conservation biologists because traditional forms of conservation action require money. We hypothesize that conservation spending in the United States is highly correlated with income and wealth, and we tested whether selected proxies for U.S. conservation activity could be predicted by U.S. economic indicators over time scales of 7-71 years. Stock market indexes (Dow Jones Industrial Average, Standard & Poor's 500 Index), gross domestic product (GDP), and personal income (PI) explained as much as 99% of annual variation in total revenue (including contributions) to four large nongovernmental organizations (NGOs), the World Wildlife Fund, Sierra Club, Environmental Defense, The Nature Conservancy. These broad economic indicators also explained as much as 96% of the annual number of university conservation programs, 83% of membership in professional conservation organizations (Natural Areas Association, Society for Conservation Biology), 93% of national park visitation, and 99+% of national park acreage. In most analyses, the income variables GDP and PI explained more variation in conservation activity than did either of the stock-market wealth variables. After long-term growth was removed from the time series, changes in revenues to the four NGOs combined were significantly correlated with GDP but not PI over the short term. Short-term variation in park acreage was significantly correlated with GDP and PI but lagged both by 3 years. Using linear models based on GDP, we predicted increases of 2.3% in 2003 cumulative NGO revenues and 1.0% in 2006 acreage owned by the National Park Service. The conservation activity parameters we measured may exhibit positive trends even in the face of declining biodiversity, but biodiversity conservation will ultimately require the cessation of economic growth. The challenge to the conservation biology community is to retain a significant presence during and after the cessation of growth.
The advantage of recombination in increasing the rate of incorporation of favorable mutants is sh... more The advantage of recombination in increasing the rate of incorporation of favorable mutants is shown to disappear for large NU if substitution is occurring at only two loci. Recombination will, on the average, destroy all double favorable individuals in a haploid population until the product of the frequencies of the single favorable mutants exceeds 1/N. As NU increases there is an increasing probability of the occurrence of the double favorable my mutation alone. Recombination provides a significant advantage in the rate of incorporation of favorable mutants only if 2s/InN less than NU less than 2c when substitution is occurring at only two loci. If substitution is occurring at more than two loci the recombining population apparently has a substantial advantage for large NU.
Page 1. J. PROTOZOOL. 25(1), 107-112 (1978) Genetic Analysis of Trichocyst Discharge of theWild S... more Page 1. J. PROTOZOOL. 25(1), 107-112 (1978) Genetic Analysis of Trichocyst Discharge of theWild Stocks of Paramecium tetraurelia* ... SYNOPSIS. Aberrant discharge of trichocysts in response to picric acid occurs in 8 of the 28 wild stocks of Paramecium tetraurelia. ...
One stock, GBC, has a maximum temperature of growth about 5 degrees C lower than other recently c... more One stock, GBC, has a maximum temperature of growth about 5 degrees C lower than other recently collected stocks of Paramecium primaurelia. The resistant stocks (R) are able to grow continuously at 35 degrees C while the sensitive stock (S) cells die within 48 h. The F1s of R X S crosses exhibited a cytoplasmic pattern of inheritance and all F2-by-autogamy lines derived from the S cytoplasmic parent are sensitive. The F2-by-autogamy lines cytoplasmically descended from the R parent were predominantly (93%) R in the initial assay. Upon reinvestigation one year later, only 64% of these lines were R, 9% were S, and 27% had a new phenotype, weak (W), intermediate between R and S. Backcrosses of W lines to both R and S strongly suggest that the W lines have normal cytoplasm (i.e. R) but also have nuclear gene(s) for temperature sensitivity that are derived from the original S stock. The delayed manifestation of the W phenotype is not understood.
The trichocysts of most wild stocks of Paramecium tetraurelia discharge en masse in response to p... more The trichocysts of most wild stocks of Paramecium tetraurelia discharge en masse in response to picric acid. In most nonresponding wild stocks, the defective phenotype is simply determined by a single recessive gene difference from the standard wild type, stock 51. However, two wild stocks, 146 and 148, which are completely homozygous at all loci, express either a nondischarge, ND, or discharge, DI, phenotype. In stock 146, both ND and DI sublines generally reproduce true to type, but observed changes are highly biased. Changes from ND to DI occur more than ten times as often as changes from DI to ND. After conjugation between ND and DI cells, genomically identical exconjugant lines from the ND parent may be either ND or DI, while those from the DI parent invariably remain DI.-Interstock crosses between stocks 146 and 51 indicate that stock 146 possesses a recessive gene, nd146, which, when homozygous in stock 51 background, produces a distinct nondischarge phenotype, KO. Crosses be...
The fertility of crosses between wild stocks of Tetrahymena americanis (n = 93) and T. hegewischi... more The fertility of crosses between wild stocks of Tetrahymena americanis (n = 93) and T. hegewischi (n = 52) was not significantly related to the square root of the distance separating the parental stocks. Much of the death was probably caused by age-related damage to the micronucleus. Despite the confounding age-related death, the conclusion that neither species has detectably isolated local populations is supported.
The growth rate of 31 stocks of Euplotes, a cosmopolitan, marine, unicellular protist, on six foo... more The growth rate of 31 stocks of Euplotes, a cosmopolitan, marine, unicellular protist, on six food species representing two different food types, microalgae and bacteria, has been determined. The 31 stocks represented nine reproductively isolated groups (biological species?) based on breeding relationships. Three morphospecies, E. vannus, E. crassus, and E. minuta, each with both autogamous and cross-breeding breeding groups, were included. The mean number of fissions completed in 5 days of a breeding group growing on one of the six food species varied from zero to 17.06. There is a strong interaction between morphospecies and food type. The largest morphospecies, E. vannus, translates the nutritional content of algae into growth better than it translates that of bacteria, while the reverse is true for E. minuta, the smallest morphospecies. Autogamous breeding groups grow more rapidly on algae than on bacteria when compared to cross-breeding groups in the same morphospecies. Two breeding groups cannot grow on Escherichia coli. ANOVA of fissions completed in 5 days revealed significant main effects and interactions between many hierarchical levels of stocks and food species. These significant interactions indicate that genetically determined ecologically important information is present at all taxonomic levels-morphospecies, breeding system, breeding group, and stock. As all these levels are biologically meaningful, measuring biodiversity in the E. vannus-crassus-minuta complex solely on morphospecies will inadequately represent the ecological diversity present in the organisms and their environment.
The prairie deer mouse (Peromyscus maniculatus bairdii) was more common than the white-footed mou... more The prairie deer mouse (Peromyscus maniculatus bairdii) was more common than the white-footed mouse (P. leucopus) in museum collections from the 6 Illinois counties of the Chicago region before 1920 but constitutes only 5% of specimens deposited since 1970. Because white-footed mouse prefers woody vegetation and because prairie deer mouse is limited to prairie or large open habitats, the change in proportion is likely driven by a disproportionate loss of prairie among remaining natural habitat and increases in woody vegetation within grasslands. The decline of the prairie vole (Microtus ochrogaster) relative to the meadow vole (M. pennsylvanicus) and the lack of recent specimens of Franklin's ground squirrel (Spermophilus franklinii) corroborate the hypothesis that prairie habitats have declined much more so than wooded habitats in the Chicago region. Based on extinction models using museum records, it is probable that S. franklinii is already locally extirpated. Regression analysis suggests the white-footed mouse will be the only local Peromyscus in 0-140 years.
The life styles of ciliated protists are particularly suitable for experimental analyses of certa... more The life styles of ciliated protists are particularly suitable for experimental analyses of certain aspects of developmental and genetic biology. The progression from sexual immaturity to maturity to senescence represents one of the most intriguing aspects of developmental programs. The extent to which progeny clones, their subclones, and testers used in the assay result in different lengths of immaturity has been investigated in Euplotes crassus. Six subclones from each of 12 progeny clones from a cross between stocks EC1 and EC2 were tested for maturity with stocks EC3, EC4, and EC5 on every transfer. Analysis of variance was used to partition the total variation in fissions to maturity into parts due to clones, subclones, and testers and the interactions between these levels. The error, interaction of subclones and testers, corresponds to a standard deviation of only 4.1 fissions, while the within clone within tester means range from 15.2 to 46.7 fissions; all levels except testers contribute significantly to the total variation. Most of the variability is attributable to clones (66%), the next most to error (16%), the next most to interaction of clones by testers (13%), and the least to subclones (5%). An a posteriori analysis examined whether the differences among clones were due to the cytoplasm of the clone ancestor (exconjugant), its mat (mating-type) locus genotype, or the mated pair it came from. None of these characteristics was able to interpret simply the large variability among clones. These results provide evidence that the transition from immaturity to maturity is quantitative and complex rather than a jump from one well-defined state to another.
In an earlier paper (Pergams & Nyberg 2001) we found that the proportion of the prairie deer mous... more In an earlier paper (Pergams & Nyberg 2001) we found that the proportion of the prairie deer mouse (Peromyscus maniculatus bairdii), among all local Peromyscus museum specimens collected in the Chicago region, had significantly declined over time. This proportion changed from about 50% before 1900 to <10% in the last 25 years. Based on this proportion a regression model predicted the local extinction of the prairie deer mouse in 2009. To evaluate that prediction, we estimated current deer mouse abundance by live trapping small mammals at 15 preserves in Cook and Lake counties, Illinois (USA) at which prairie deer mice had previously been caught or that still contained their preferred open habitat. In 1900 trap nights, 477 mammals were caught, including 251 white-footed mice (P. leucopus), but only one prairie deer mouse. The observed proportion of Peromyscus that were prairie deer mice, 0.4%, was even lower than the 4.5% predicted for 2000. Here we also introduce a simple, new community proportions model, which for any given geographic region compares the proportions of species recently caught with the proportions of species in museums. We compared proportions of seven species collected in Cook and Lake counties and examined by Hoffmeister (1989) with proportions of these species that we caught. Ten percent of the museum community was prairie deer mice, but only 0.2% of our catch was. The current local scarcity of the prairie deer mouse is consistent with the regression-based prediction of its eminent local extinction. More conservation attention should be paid to changes in relative abundance of once-common species.
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Papers by D. Nyberg