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  • 1
    Electronic Resource
    Electronic Resource
    Habitat heterogeneity as a determinant of mammal species richness in high-energy regions (1997)
    [s.l.] : Nature Publishing Group
    Nature 385 (1997), S. 252-254 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Climatic factors, environmental stability, land area, habitat heterogeneity, historical influences (such as Pleistocene glaciations) and energy availability are the factors most often discussed as determinants of regional variability in species richness8"13. Energy explains most of the ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/385252a0
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  • 2
    Electronic Resource
    Electronic Resource
    Unexpected patterns of parentage and relatedness in a primitively eusocial bee (1995)
    [s.l.] : Nature Publishing Group
    Nature 373 (1995), S. 239-241 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The social behaviour of Halictus ligatus varies geographically9 13. At our study site in southern Ontario, Canada, each overwintered foundress rears a brood consisting mainly of workers, with a few males. The workers then rear a second brood of males and gynes12'13. Dissections showed that many ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/373239a0
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  • 3
    Electronic Resource
    Electronic Resource
    A Test of the Mating Limitation Hypothesis for Caste Determination in Evylaeus albipes (Hymenoptera: Halictidae), a Primitively Eusocial Halictine Bee (1998)
    Springer
    Journal of insect behavior 11 (1998), S. 119-128 
    Details
    ISSN: 1572-8889
    Keywords: social evolution ; caste determination ; mating ; halictine bee
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Yanega's (1997) mating limitation hypothesis (MLH) states that “if a female mates promptly after emerging, she then becomes a member of the maximally reproductive behavioral caste” (i.e., in most cases an overwintering gyne). Females that do not mate early become workers. We tested the MLH in laboratory colonies of a eusocial population of Evylaeus albipes. Of 24 worker brood females (13 from queenright and 11 from orphaned nests), 13 mated on the first day of flight activity and all mated within the first 5 days; there were no significant differences between mating rates of females from the two colony types. All 24 commenced foraging as workers after an average of between 3 and 4 days postmating. We conclude that the MLH does not apply to this species despite the fact that the only known halictine for which this hypothesis has been experimentally tested is the fairly closely related E. marginatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020874702045
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  • 4
    Electronic Resource
    Electronic Resource
    The Impact of Climate Change on Mammal Diversity in Canada (1998)
    Springer
    Environmental monitoring and assessment 49 (1998), S. 263-270 
    Details
    ISSN: 1573-2959
    Keywords: biodiversity ; climate change ; latitudinal gradients ; mammal species richness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Current large-scale mammalian diversity patterns in Canada can be accurately explained using various measurements of heat energy. Unfortunately, climatic change is predicted to alter the fundamental climatic basis for contemporary diversity gradients, with the expected consequence that much of the Canadian biota will need to migrate in order to remain within climatically suitable regions. We make predictions regarding future mammal diversity patterns in Canada, and therefore provide a preliminary indication of where management intervention should be directed in order to conserve mammal diversity as climate changes. We also examine the current distributions of individual mammal species in Canada in order to determine which taxa cannot migrate farther north because of the Arctic Ocean barrier. Of the 25 species that fall into this category, we examine the predicted loss of habitat in one keystone species – Dicrostonyx groenlandicus, the collared lemming – and find that this taxon is likely to lose approximately 60% of its habitat with unpredictable but likely detrimental consequences for the arctic biota. We discuss the implications of our findings briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005846910199
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  • 5
    Electronic Resource
    Electronic Resource
    A comparison of genetic variation in two sibling species pairs of haplodiploid insects (1993)
    Springer
    Biochemical genetics 31 (1993), S. 185-200 
    Details
    ISSN: 1573-4927
    Keywords: bees ; sawflies ; sibling species ; genetic distance ; heterozygosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Sibling species pairs of sweat bees (Halictus confusus andH. tumulorum) and pine sawflies (Neodiprion pratti andN. maurus) were surveyed for genetic variability using enzyme electrophoresis. Levels of heterozygosity were found to be within the ranges earlier recorded for Hymenoptera. Expected heterozygosities were not significantly higher in the sawflies than in the sweat bees. Estimates of genetic identity between the sibling species were not lower than those generally found for diplodiploid insect species: no evidence was found for an increased rate of evolution in these haplodiploids. Genetic identity data among populations ofH. confusus and betweenHalictus species were within the range expected for conspecific populations and sibling species, respectively. InNeodiprion all genetic distances were low but the two populations ofN. pratti had similar genetic distances as each did toN. maurus, indicating the necessity for further systematic studies of the genus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00553855
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  • 6
    Electronic Resource
    Electronic Resource
    Allozyme variation in bumble bees (Hymenoptera: Apidae) (1992)
    Springer
    Biochemical genetics 30 (1992), S. 443-453 
    Details
    ISSN: 1573-4927
    Keywords: heterozygosity ; allozymes ; Hymenoptera ; Bombus ; Psithyrus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Allozyme variation at an average of 37.3 loci was assessed in queens of 16Bombus and 2Psithyrus bumble bee species from North America. The mean expected heterozygosity $$(\bar H)$$ for theBombus species was 0.008±0.006 (95% confidence limits) and that for thePsithyrus was 0.007±0.007. These levels are significantly lower than found in other Hymenoptera but are comparable to those found in previous studies of bumble bees based on far fewer loci. Neutral mutation and random genetic drift can account for the observed variation, but this implies a very small effective population size for species of bumble bees.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01037585
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  • 7
    Electronic Resource
    Electronic Resource
    A comparison of genetic variation in two sibling species pairs of haplodiploid insects (1993)
    Springer
    Biochemical genetics 31 (1993), S. 185-200 
    Details
    ISSN: 1573-4927
    Keywords: bees ; sawflies ; sibling species ; genetic distance ; heterozygosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Sibling species pairs of sweat bees (Halictus confusus andH. tumulorum) and pine sawflies (Neodiprion pratti andN. maurus) were surveyed for genetic variability using enzyme electrophoresis. Levels of heterozygosity were found to be within the ranges earlier recorded for Hymenoptera. Expected heterozygosities were not significantly higher in the sawflies than in the sweat bees. Estimates of genetic identity between the sibling species were not lower than those generally found for diplodiploid insect species: no evidence was found for an increased rate of evolution in these haplodiploids. Genetic identity data among populations ofH. confusus and betweenHalictus species were within the range expected for conspecific populations and sibling species, respectively. InNeodiprion all genetic distances were low but the two populations ofN. pratti had similar genetic distances as each did toN. maurus, indicating the necessity for further systematic studies of the genus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399925
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic differentiation between two host “races” and two species of cleptoparasitic bees and between their two hosts (1995)
    Springer
    Biochemical genetics 33 (1995), S. 97-109 
    Details
    ISSN: 1573-4927
    Keywords: bees ; host races ; genetic differentiation ; heterozygosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In this paper we test the following two hypotheses: (1) that apparently conspecific samples of the cleptoparasitic beeCoelioxys funeraria, differing markedly in size and reared from different host species, do indeed represent one panmictic population; (2) that bees that nest in holes in wood or twigs have higher levels of genetic variation than those nesting in the ground. Based upon 41 loci, the genetic differences between the two samples ofC. funeraria could be explained entirely in terms of sampling error. In contrast, the sympatricC. moesta showed 16 fixed allelic differences from theC. funeraria samples. Similarly, the two hosts ofC. funeraria, Megachile relativa andM. inermis, had 21 fixed allelic differences between them out of 42 presumptive gene loci. Heterozygosities among the wood-nesting bees were not particularly high for Hymenoptera, ranging from 0.045 to 0.054. Comparisons of heterozygosity estimates among bees remain ambiguous as to whether soil nesting confers sufficient environmental buffering effects to reduce possible advantages of heterosis in ground-nesting species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00557948
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  • 9
    Electronic Resource
    Electronic Resource
    The environmental basis of North American species richness patterns among Epicauta (Coleoptera: Meloidae) (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 617-628 
    Details
    ISSN: 1572-9710
    Keywords: Epicauta ; latitudinal gradients ; macroecology ; potential evapotranspiration ; species richness-energy hypothesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Understanding regional variability in species richness is necessary for conservation efforts to succeed in the face of large-scale environmental deterioration. Several analyses of North American vertebrates have shown that climatic energy provides the best explanation of contemporary species richness patterns. The paucity of analyses of insect diversity patterns, however, remains a serious obstacle to a general hypothesis of spatial variation in diversity. We collected species distribution data on a North American beetle genus, Epicauta (Coleoptera: Meloidae) and tested several major diversity hypotheses. These beetles are generally grasshopper egg predators as larvae, and angiosperm herbivores as adults. Epicauta richness is highest in the hot, dry American southwest, and decreases north and east, consistent with the species richness-energy hypothesis. Potential evapotranspiration, which is also the best predictor of richness patterns among North American vertebrates, explains 80.2% of the variability in Epicauta species richness. Net primary productivity and variables measuring climatic heat energy only (such as PET) are not generally comparable, though they are sometimes treated as if they were equivalent. We conclude that the species richness-energy hypothesis currently provides a better overall explanation for Epicauta species richness patterns in North America than other major diversity hypotheses. The observed relationship between climatic energy and regional species richness may provide significant insight into the response of ecological communities to climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008846131749
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  • 10
    Electronic Resource
    Electronic Resource
    Social evolution and its correlates in bees of the subgenus Evylaeus (Hymenoptera; Halictidae) (1985)
    Springer
    Behavioral ecology and sociobiology 17 (1985), S. 143-149 
    Details
    ISSN: 1432-0762
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eleven behavioural characteristics of eight species of the subgenus Evylaeus were analysed using principal components analysis. The first component axis represents social level and explains over forty percent of the total variation in the data. The following characteristics are highly correlated with social level — (i) a reduction in the proportion of males in the first brood, (ii) a reduction in the proportion of workers that mate, (iii) a reduction in the proportion of workers that have developed ovaries, (iv) an increase in the mean number of workers, (v) increased contact between adults and developing brood and (vi) an increase in the size difference between queens and workers. Because these factors appear, in general, to be under the control of the queen it is argued that parental manipulation has been an important component of social evolution in these bees. The number of worker broods and the mechanism of male production are also related to social level but are less important. Nest architecture, nest defense and polygyny seem to be unrelated to social level. Variation in nest architecture may be in response to edaphic features of the substrate. The lack of any relationship between polygyny and social level implies that the semisocial route to eusociality was not the one taken. It is likely that polygyny can only occur where the substrate is suitable for the winter hibernation of sisters in their natal nest. Multivariate methods are useful in determining the relative social level of closely related halictine species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00299246
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