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C Gliddon

Publications and source records attributed to C Gliddon.

5 recordsLinked to original sources
PubMed2003

A global assessment using PCR techniques of mycorrhizal fungal populations colonising Tithonia diversifolia.

Tithonia diversifolia (Mexican sunflower) is a shrub commonly used as a green manure crop in Central and South America, Asia and Africa as it accumulates high levels of phosphorus and other nutrients, even in depleted soils. In root samples collected from the global distribution of Tithonia, we examined the degree of mycorrhizal colonisation and estimated the families of associated arbuscular mycorrhizal (AM) fungi. No colonisation by ectomycorrhizas was found. The degree of colonisation by AM fungi was on average 40%, but ranged between 0 and 80%. No mycorrhizal colonisation was found in the samples collected from the Philippines or in one each of the Rwandan and Venezuelan samples. Throughout its global distribution (Costa Rica, Nicaragua, Indonesia, Honduras, Mexico, Kenya and Rwanda), Tithonia forms mainly associations with Glomaceae. Only in one location in Nicaragua were associations with another family ( Acaulosporaceae) found.

Asteraceae↗
PubMed1999

A comparison of two indirect methods for estimating average levels of gene flow using microsatellite data.

We compare the performance of Nm estimates based on FST and RST obtained from microsatellite data using simulations of the stepwise mutation model with range constraints in allele size classes. The results of the simulations suggest that the use of microsatellite loci can lead to serious overestimations of Nm, particularly when population sizes are large (N > 5000) and range constraints are high (K < 20). The simulations also indicate that, when population sizes are small (N </= 500) and migration rates are moderate (Nm approximately 2), violations to the assumption used to derive the Nm estimators lead to biased results. Under ideal conditions, i.e. large sample sizes (ns >/= 50) and many loci (nl >/= 20), RST performs better than FST for most of the parameter space. However, FST-based estimates are always better than RST when sample sizes are moderate or small (ns </= 10) and the number of loci scored is low (nl < 20). These are the conditions under which many real investigations are carried out and therefore we conclude that in many cases the most conservative approach is to use FST.

Alleles↗
PubMed1998

Risk and benefit.

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Biotechnology↗
PubMed1994

The genetic structure of metapopulations and conservation biology.

A range of models describing metapopulations is surveyed and their implications for conservation biology are described. An overview of the use of both population genetic elements and demographic theory in metapopulation models is given. It would appear that most of the current models suffer from either the use of over-simplified demography or the avoidance of selectively important genetic factors. The scale for which predictions are made by the various models is often obscure. A conceptual framework for describing metapopulations by utilising the concept of fitness of local populations is provided and some examples are given. The expectation that any general theory, such as that of metapopulations, can make useful predictions for particular problems of conservation is examined and compared with the prevailing 'state of the art' recommendations.

Animals↗