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  • 1
    Electronic Resource
    Electronic Resource
    Temporal mechanisms influencing gender expression and pollen flow within a self-incompatible perennial, Amianthium muscaetoxicum (Liliaceae) (1989)
    Springer
    Oecologia 78 (1989), S. 231-236 
    Details
    ISSN: 1432-1939
    Keywords: Dichogamy ; Gender expression ; Pollen interference ; Pollen longevity ; Stigma receptivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Temporal mechanisms that influence the synchrony of gender expression and the patterns of withinplant pollen flow were examined in Amianthium muscatoxicum. In this species self-incompatible pollinations can clog stigmas, interfere with the growth of outcrossed pollen tubes, and reduce fecundity. The majority of flowers have partial dichogamy: a two-day period of pollen dehiscence and a four-day period of pollen viability are nested in a six-day period of pistil viability. An indeterminate flowering sequence among flowers on the same plant and partial dichogamy within flowers help reduce pollen flow within the whole plant. The combined effects at both of these levels should reduce pollen wastage and lower the incidence of stigma clogging by incompatible self pollen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377160
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  • 2
    Electronic Resource
    Electronic Resource
    The effects of pollination distance on seed production in three populations of Amianthium muscaetoxicum (Liliaceae) (1989)
    Springer
    Oecologia 79 (1989), S. 260-264 
    Details
    ISSN: 1432-1939
    Keywords: Breeding system ; Fecundity ; Outcrossing distance ; Pollination ecology ; Population structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We examined the effects of varying pollination distances on seed production and its components in three populations of the perennial lily Amianthium muscaetoxicum. We performed hand pollinations using pollen from near neighbors and from plants separated by 5, 15, and 60 meters. Pollination by near neighbors reduced fruit set and the numbers of seeds per fruit in comparison to other treatments in two of the three populations; variation in pollination distance beyond near-neighbor pollination produced no effect. In the third population, in which nearneighbor pollination did not affect seed production, nearneighbor pollination reduced seed weight by 11%, compared to other pollination distances. Seed weights from the 5-, 15-, and 60-m pollination treatments did not differ, and pollination distance did not affect seed weight in the other two populations. The effects of pollination-distance treatments explained a very small proportion of the variance in seed production and seed weight. Heterogeneity among individual plants, despite full hand pollination of every plant, accounted for much more variance (by one to two orders of magnitude) than variation in pollination distance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388486
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  • 3
    Electronic Resource
    Electronic Resource
    How can the functional response best be determined? (1989)
    Springer
    Oecologia 78 (1989), S. 571-571 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378751
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  • 4
    Electronic Resource
    Electronic Resource
    How can the functional reponse best be determined? (1988)
    Springer
    Oecologia 76 (1988), S. 206-214 
    Details
    ISSN: 1432-1939
    Keywords: Curve fitting ; Density dependence ; Functional response ; Logit ; Predation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We evaluated three methods for the analysis of functional response data by asking whether a given method could discriminate among functional responses and whether it could accurately identify regions of positive density-dependent predation. We evaluated comparative curve fitting with foraging models, linear least-squares analysis using the angular transformation, and logit analysis. Using data from nature and simulations, we found that the analyses of predation rates with the angular transformation and logit analysis were best at consistently determining the “true” functional response, i.e. the model used to generate simulated data. These methods also produced the most accurate estimates of the “true” regions of density dependence. Of these two methods, functional response data best fulfill the assumptions of logit analysis. Angularly transformed predation rates only approximate the assumptions of linear leastsquares analysis for predation rates between 0.1 and 0.9. Lack-of-fit statistics can reveal inadequate fit of a model to a data set where simple regression statistics might erroneously suggest a good match.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379954
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  • 5
    Electronic Resource
    Electronic Resource
    Seasonal pollen flow and progeny diversity in Amianthium muscaetoxicum: ecological potential for multiple mating in a self-incompatible, hermaphroditic perennial (1988)
    Springer
    Oecologia 77 (1988), S. 19-24 
    Details
    ISSN: 1432-1939
    Keywords: Amianthium muscaetoxicum ; Inflorescence size ; Pollen flow ; Progeny diversity ; Seasonal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ecological potential for multiple mating is high in Amianthium muscaetoxicum. The percentage of long-distance pollinations (20–100 m) is greater than reported for most insect-pollinated systems. Estimations of neighborhood area are at least an order of magnitude larger than any previously reported for plant species. Seasonal effects on fluorescent dust dispersal indicate that neighborhood areas change during the flowering season. The number of flowers marked with fluorescent dust on an inflorescence increases with increasing inflorescence size, and the proportions of available inflorescences that are marked decrease with distance from the source. Allozyme analysis indicates that heterozygosity levels are typical of outcrossing plants. The diversity of seed genotypes is increased by increasing the size of the floral display. The present investigation is the first to consider the effects of floral display on seed diversity and adds to existing data indicating that inflorescence size is important to fecundity and/or pollen donation in some systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380919
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  • 6
    Electronic Resource
    Electronic Resource
    Interactions among factors affecting growth, development and survival in experimental populations of Bufo terrestris (Anura: Bufonidae) (1986)
    Springer
    Oecologia 69 (1986), S. 110-116 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We designed a series of field experiments to investigate the importance of interactions between biotic and abiotic factors on the survival and development of larval cohorts of Bufo terrestris. Five “blocks” in a large pond represented environments of varying physical harshness. In the more severe blocks, increased density inhibited growth rates, yet in the more benign blocks, increased density enhanced growth rate. Although different blocks produced very different levels of survival to metamorphosis and size at metamorphosis, there were no interactions with density. Increased density produced lengthened development times in the harsher blocks, but had no effect in the less stressful blocks. Hatchlings that were in the lowest of 3 initial size classes never caught up with their larger contemporaries and survived poorly. Hatchlings in the middle and largest size classes performed equivalently in all parameters of growth and development, but hatchlings from the middle size class were less likely to survive than their larger contemporaries. The effects of initial size did not interact with block. The inhibitory patterns displayed by density in conjunction with varying physical environments are similar to those found in comparable experiments with plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00399045
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  • 7
    Electronic Resource
    Electronic Resource
    Interaction of pH, density, and priority effects on the survivorship and growth of two species of hylid tadpoles (1991)
    Springer
    Oecologia 88 (1991), S. 331-339 
    Details
    ISSN: 1432-1939
    Keywords: Low pH ; Density dependence ; Abiotic factors ; Amphibian communities ; Mesocosms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We examined the interactions of an abiotic factor (pH) and a biotic factor (density) on the survival and growth of two species of anuran larvae (Hyla gratiosa and Hyla femoralis) in outdoor tanks. Three levels of pH (4.3, 4.6, or 6.0) and three levels of density (0, 30 or 60 embryos) were arranged in a blocked design and replicated three times for Hyla gratiosa. At the end of this experiment the effects of pH (4.3, 4.6, or 6.0), density of H. femoralis (30 or 60), and prior use by H. gratiosa (at 0, 30, or 60 larvae per tank) on the survival and growth of H. femoralis, were examined. Higher density increased larval period and decreased size at metamorphosis of H. gratiosa. Lower pH decreased survival rate and also decreased size at metamorphosis. Body sodium concentrations were lowest at the low pH values. Lower pH increased the susceptibility of H. gratiosa tadpoles to the adverse effects of higher densities. For H. femoralis higher density decreased survival, increased larval period and decreased size at metamorphosis. Hyla femoralis also had lower survivorship at low pH and exhibited decreased size at metamorphosis. However, unlike the results with Hyla gratiosa, there were no interactive effects between pH and density for any of the life-history traits studied. The effect of previous colonization by H. gratiosa on H. femoralis survival was facilitative. Body sodium concentrations of H. femoralis were lowest at the highest pH value. Metamorphs of the same size had much lower levels of sodium in H. femoralis than H. gratiosa. In general, H. femoralis was less affected by pH variation than H. gratiosa. These results demonstrate that abiotic factors can interact strongly with biotic effects such as density and they suggest that interspecific interactions can be strongly modulated by the background abiotic environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317575
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  • 8
    Electronic Resource
    Electronic Resource
    Environmental effects on adult growth patterns in the male sailfin molly, Poecilia latipinna (Poeciliidae) (1989)
    Springer
    Environmental biology of fishes 26 (1989), S. 119-127 
    Details
    ISSN: 1573-5133
    Keywords: Juvenile experience ; Phenotypic plasticity ; Fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Widespread male body size variation in P. latipinna appears to be attributable to genetic variation in the size at maturation. The contribution of adult growth needs to be assessed because adult growth rates may vary with size at maturation and local environment. In our laboratory study we examined adult growth patterns as a function of size at maturation and juvenile experience (favorable or unfavorable conditions). In our field study we assessed adult growth as a function of initial size and environmental condition (using males in enclosures in contrasting habitats). Adult growth rates in the laboratory were an order of magnitude higher than rates observed in field enclosures. Growth rates varied with male size, increasing with increasing male size in the laboratory study but decreasing with increasing male size in the field study. The laboratory results alone would have cast considerable doubt on the ability to interpret size distributions of field-collected males, but the field results indicate that adult growth is sufficiently low that it can be ignored as a source of body size variation within and among populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00001028
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  • 9
    Electronic Resource
    Electronic Resource
    Phenology of recruitment and infection patterns of Ascocotyle pachycystis, a digenean parasite in the sheepshead minnow, Cyprinodon variegatus (1998)
    Springer
    Environmental biology of fishes 51 (1998), S. 87-96 
    Details
    ISSN: 1573-5133
    Keywords: host fitness ; host-parasite population dynamics ; dispersion patterns ; trematode ; killifish ; estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In northwest Florida, Cyprinodon variegatus are parasitized by Ascocotyle pachycystis, a digenean parasite that forms metacercarial cysts in the lumen of the bulbus arteriosus. Field experiments revealed that fish accumulated parasites at an uneven rate within the highly seasonal trematode recruitment period. Older (= larger) fish had higher rates of parasite recruitment and higher parasite prevalences and densities (numbers of metacercariae per individual fish) than did younger (= smaller) fish. Nearly all adults were parasitized (prevalence range 70-100%), and parasite densities ranged from zero to 6800 per fish. Parasite distributions were clumped (= aggregated) in fish of all age classes but were less heterogeneous in early juveniles and adults than they were in late juveniles. Parasites affected the population dynamics of sheepshead minnows by causing reduced winter survivorship, as evidenced by an increase in the average size of fish and a decrease in the average infection intensity over the winter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007341322937
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  • 10
    Electronic Resource
    Electronic Resource
    The effect of ontogenetic experience on variation in growth, maturation, and sexual behavior in the sailfin molly,Poecilia latipinna (Pisces: Poeciliidae) (1989)
    Springer
    Environmental biology of fishes 26 (1989), S. 39-48 
    Details
    ISSN: 1573-5133
    Keywords: Biotic effects ; Growth ; Ontogenetic influences ; Sexual behavior ; Size hierarchy ; Social environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis We investigated the potential effect of social interactions between juveniles on the adult body size and male sexual behavior of the live-bearing teleostPoecilia latipinna, the sailfin molly. Contrary to expectation, juveniles exhibited very low levels of aggression. Juvenile growth rates did not differ between fish raised alone and fish raised in pairs (although males reared alone were slightly larger at one point in time), and the variance between members of a pair did not exceed the variance displayed among isolated individuals. Similar results were found for age and size at sexual maturation in males. Females reared in isolation were slightly but significantly larger at maturity than females raised in pairs. There was some evidence that females raised in pairs displayed coordinated development. Male sexual behavior patterns displayed relationships with body size that matched previous descriptions: there was no effect of the rearing condition once body size effects were accounted for. These results differ dramatically from those described for other poeciliids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002474
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