Experimentelle Untersuchungen über den Generationswechsel der Rädertiere

Buchner, Hans

doi:10.1007/bf01850141

Cited by 10 publications

(6 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…An association between population density and mixis has been found in field observations of several species (e.g. Wesenberg‐Lund, 1930; Buchner, 1941; Ito & Iawi, 1958; Bogoslavsky, 1963; King & Snell, 1980), as well as in both laboratory and field experiments (e.g. Ito, 1960; Hino & Hirano, 1976; Miracle & Guiset, 1977; Pozuelo, 1977; Lubzens et al ., 1985; Snell & Boyer, 1988; Carmona et al ., 1993).…”

Section: Introductionmentioning

confidence: 73%

Optimal rates of bisexual reproduction in cyclical parthenogens with density-dependent growth

Serra

1999

Journal of Evolutionary Biology

View full text Add to dashboard Cite

This work explores theoretical patterns of reproduction that maximize the production of resting eggs and the long‐term fitness of genotypes in cyclical parthenogens. Our focus is on density‐dependent reproduction as it influences the consequences of a trade‐off between producing amictic daughters – which reproduce parthenogenetically and subitaneously – and producing mictic daughters – which undergo meiosis and bisexual reproduction. Amictic females increase competitive ability and allow the population to achieve a larger size; mictic females directly contribute to population survival through harsh periods by producing resting eggs. Although morphologically indistinguishable, the two types of females differ greatly in their ecological and reproductive roles. What factors underlie the differential allocation of resources to produce amictic and mictic females? Using a demographic model based on readily accessible parameters we demonstrate the existence of a frequency of mictic females that will maximize the population's long‐term fitness. This frequency, termed the optimal mictic ratio, mo, is 1 − (q/b)1/2, where q is the mortality rate and b is the maximum birth rate. Using computer simulation we compared the fitness of a population with this constant mictic ratio with populations having multiple switches from complete parthenogenetic growth to complete allocation in mixis (mictic ratio either 0 or 1). Two important conclusions for optimal mixis in density‐dependent growth conditions are: (1) intermediate mictic ratios are optimal, and (2) optimal mictic ratios are higher when habitat conditions are better. Physiological cues responding to differences in birth and death rates are common so that it is possible that populations may adjust their relative rates of mictic and amictic female production in response to environmentally induced changes to the optimum mictic ratio. Our analysis demonstrates that different patterns of mixis are expected in different type of habitats. Since the optimal mictic ratio is sensitive to the effects of a variety of environmental challenges, our model makes possible a new means to evaluate life history evolution in cyclical parthenogens.

show abstract

Section: Introductionmentioning

confidence: 73%

Optimal rates of bisexual reproduction in cyclical parthenogens with density-dependent growth

Serra

1999

Journal of Evolutionary Biology

View full text Add to dashboard Cite

show abstract

“…There are few studies about the occurrence of sexual reproduction in natural populations of the genus Brachionus (Wesenberg-Lund, 1930 ;Buchner, 1941 ;Ito & Iwai, 1958 ;Bogoslavsky, 1963 ;Pourriot, 1965 ;Halbach & Halbach-Keup, 1972 ;Miracle & Guiset, 1977), and only two of them have provided data on B. plicatilis . Ito & Iwai (1958) noted that mixis in this species was associated with high levels of population density .…”

Section: Discussionmentioning

confidence: 99%

Mictic patterns of the rotifer Brachionus plicatilis M�ller in small ponds

1995

View full text Add to dashboard Cite

Populations of the rotifer Brachionus plicatilis were monitored in three small ponds in a marsh on the Mediterranean coast . Samples were taken approximately every three weeks from July 1992 to November 1993 . Salinity, temperature, conductivity, pH and oxygen concentration were measured in the field . Population density was determined from preserved quantitative samples . Individuals were classified as mictic females, amictic females, non-ovigerous females, and males, differentiating between two morphotypes ('S' and`L'). From these counts, a level of mixis was calculated . We also determined the proportion of mictic females in natural populations by culturing females isolated from fresh samples . From these data, mictic patterns over time and correlation between levels of mixis and environmental and population parameters were analyzed . From a previous study `S' and `L' morphotypes were known to correspond to genetically different clonal groups . Our data showed that reproduction was predominantly parthenogenetic in these clonal groups, but mictic females were found in most samples, the proportion of mictic females ranging from 0 to 29% . The clonal groups showed different patterns of mixis . L clonal group presented a continuous sexual reproductive pattern . In contrast, S clones showed a rather punctuated mictic pattern . A positive correlation between levels of sexual reproduction and population density was found for S and L groups . However, they differed in their density threshold for mictic reproduction . The adaptive meaning of these patterns and their implications in maintaining genetic diversity within and between populations are discussed .

show abstract

“…Species of K emtella other than cochlearis, and related genera, have been cultm·t>d for prolongt>d periods with Chiarella and. various other small algae as food (Lunz 1926, Buchner 1936, de Beauchamp 1938and Pourriot 1957. Pom·riot (1957) studied the effectiveness of 12 algae as food for 3 different taxa of Brachionus, members of the same family as K eratella and K ellicottia, but somewhr.t larger.…”

Section: Food Organisms Included In Thementioning

confidence: 99%