Judy Loo - Academia.edu (original) (raw)

Papers by Judy Loo

This paper is one of several requested by the Commission on Genetic Resources for Food and Agricu... more This paper is one of several requested by the Commission on Genetic Resources for Food and Agriculture that seek to review and examine the impacts of climate change on genetic resources of organisms that are important for human well-being, and the potential role of these resources in mitigating and adapting to change. This paper, which focuses on forest genetic resources (FGR), does so in the context of trees in natural forests, plantations and agroforestry systems. The paper is structured to match those being prepared by the other sectors and consists of a review of the current state of knowledge, followed by the identification of gaps and priorities for action. A glossary is included to clarify terms.

The Forestry Chronicle, 1992

Most global climate models predict a rapid increase in temperature over the next few decades as a... more Most global climate models predict a rapid increase in temperature over the next few decades as a result of elevated levels of carbon dioxide and other greenhouse gases. Although the resolution of the existing models is not sufficient to predict specific weather patterns for the Maritimes region, the predicted rate of change is such that forest tree populations will be unable to adapt fully to future conditions. If conventional rotation lengths are planned, presently adapted seedlings will be poorly adapted to the new conditions by the time of harvest. A three-pronged approach is proposed to mitigate the impact of climate change in the Maritimes: development of short rotation clonal forestry, testing and breeding for stability of genotypes over a range of climatic conditions, and collection, storage, and testing of native and non-native materials of potential value.

The Forestry Chronicle, 2007

Guidelines were developed by the New Brunswick Forest Gene Conservation Working Group for conserv... more Guidelines were developed by the New Brunswick Forest Gene Conservation Working Group for conserving genetic resources of four native tree species in New Brunswick. Gene conservation guidelines for three of these species aim to maintain sufficient gene pools of known or putatively resistant stock to retain or develop the potential for restoration. Natural populations of American beech (Fagus grandifolia) are known to have genotypes resistant to the beech scale at low frequencies. Gene conservation approaches include in situ and ex situ measures, including resistance breeding. White elm (Ulmus americana) demonstrates a degree of resistance to Dutch elm disease (DED), and will benefit from a mixture of in situ and ex situ conservation measures. Resistance to butternut canker has not yet been demonstrated in populations of butternut (Juglans cinerea), but ex situ conservation of putatively resistant genotypes will be of increasing importance as the frequency of butternut canker escalat...

Canadian Journal of Forest Research, 1991

The relative density profile from pith to bark was examined in young Douglas-fir (Pseudotsugamenz... more The relative density profile from pith to bark was examined in young Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stems at 1.3, 0.7, and 0.4 m above the ground. The trees represented 22 half-sib families growing at two progeny test locations. The objective was to evaluate the reliability of wood samples taken from below breast height (1.3 m) for selection for relative density in young coastal Douglas-fir progeny tests. The relative density profile appeared to be different for the first 6 or 7 years from the pith at the different sampling heights, but the difference decreased with cambial age. Genetic correlation estimates were sufficiently high to indicate identical genetic control at the three sampling heights, but heritability estimates were higher at 1.3 and 0.7 m than at 0.4 m. Sampling at 0.7 m is as effective as at 1.3 m. This allows reliable selection 1 to 2 years earlier than by sampling at 1.3 m.

Pollen and seed dispersal are key processes affecting the demographic and evolutionary dynamics o... more Pollen and seed dispersal are key processes affecting the demographic and evolutionary dynamics of plant species and are also important considerations for the sustainable management of timber trees. Through direct and indirect genetic analyses, we studied the mating system and the extent of pollen and seed dispersal in an economically important timber species, Entandrophragma cylindricum (Meliaceae). We genotyped adult trees, seeds and saplings from a 400-ha study plot in a natural forest from East Cameroon using eight nuclear microsatellite markers. The species is mainly outcrossed (t = 0.92), but seeds from the same fruit are often pollinated by the same father (correlated paternity, rp = 0.77). An average of 4.76 effective pollen donors (Nep) per seed tree contributes to the pollination. Seed dispersal was as extensive as pollen dispersal, with a mean dispersal distance in the study plot approaching 600 m, and immigration rates from outside the plot to the central part of the plot reaching 40% for both pollen and seeds. Extensive pollen- and seed-mediated gene flow is further supported by the weak, fine-scale spatial genetic structure (Sp statistic = 0.0058), corresponding to historical gene dispersal distances (σg) reaching approximately 1,500 m. Using an original approach, we showed that the relatedness between mating individuals (Fij = 0.06) was higher than expected by chance, given the extent of pollen dispersal distances (expected Fij = 0.02 according to simulations). This remarkable pattern of assortative mating could be a phenomenon of potentially consequential evolutionary and management significance that deserves to be studied in other plant populations

he forests of North America are diverse, covering the spectrum of forested landscapes from the no... more he forests of North America are diverse, covering the spectrum of forested landscapes from the northern taiga of Canada and Alaska to the tropical humid forests of Mexico. The Commission for Envi-

Biotropica, 2018

Molecular genetics research can benefit efforts to conserve the genetic diversity of tropical pla... more Molecular genetics research can benefit efforts to conserve the genetic diversity of tropical plant species. Clear and efficient procedures are needed to access DNA samples, while respecting tropical countries' and local communities' rights on genetic resource usage. The Nagoya Protocol on Access and Benefit-Sharing, which took effect in 2014, provides an opportunity to establish such procedures. However, scientists are concerned that its emphasis on monetary gains restricts research focused on scientific, societal, and environmental benefits. Despite much political and scientific debate, few concrete cases have demonstrated the practical functioning of the Nagoya Protocol. This paper describes the first application of the Protocol in Guatemala, where it was used to grant permission to a non-commercial study on gene flow in mahogany (Swietenia macrophylla King) populations in the Maya Biosphere Reserve of Pet en. On the basis of this study, we discuss five strategies to enhance the application of molecular genetics to conservation biology under the Nagoya Protocol: (1) generate short and standardized procedures; (2) enable science communication; (3) cultivate a common understanding between users, providers, and potential beneficiaries; (4) involve local research and practitioner organizations; and (5) integrate participatory research. Positive societal views on the application of molecular genetics to conservation biology generate further support for work in this discipline and promote adoption of research results for the conservation of genetic diversity of tropical plant species.

Conservation Genetics, 2019

The genus Khaya includes some of the highest-value timber species in natural forests in Africa, w... more The genus Khaya includes some of the highest-value timber species in natural forests in Africa, which are under heavy exploitation pressure. Genetic identification of Khaya species is important to confirm the taxonomic classification for biodiversity conservation purposes and as a forensic tool aiding law enforcement in the fight against illegal logging. We collected samples from a total of 2222 trees belonging to five or six (depending on classification) different Khaya species (K. ivorensis, K. anthotheca/K. nyasica, K. grandifoliola, K. senegalensis, K. madagascariensis). Representative sampling was conducted over the natural ranges of all sampled Khaya species, in humid tropical forest and savanna zones. We genotyped individuals based on 101 molecular markers (67 nuclear, 11 chloroplast and 22 mitochondrial SNPs, 1 chloroplast indel). Bayesian clustering produced three main genetic groups assigning all K. ivorensis and all K. senegalensis trees, respectively, in two different clusters and all remaining individuals in a third cluster. Genetic self-assignment tests with all 101 SNPs had success rates of 97-100% for all species except for K. nyasica and K. madagascariensis, which could not be clearly distinguished from each other. A success rate for species identification nearly as high was observed using a subset of 15 highly differentiated SNPs. There was only very little evidence for hybridization among species and the vast majority (> 97%) of individuals were assigned to the same species group as identified based on morphological characters.

Molecular Ecology, 2017

Article type : Original Article Extensive seed and pollen dispersal and assortative mating in the... more Article type : Original Article Extensive seed and pollen dispersal and assortative mating in the rain forest tree Entandrophragma cylindricum (Meliaceae) inferred from indirect and direct analyses

Leaves, flowers and pods of African locust bean Common name African locust bean (English) Néré, n... more Leaves, flowers and pods of African locust bean Common name African locust bean (English) Néré, nété, mimosa pourpre, arbre à farine (French) Scientific name Parkia biglobosa (Jacq.) R.Br. ex G.Don Synonyms Parkia africana R. Br.; Parkia clappertoniana Keay; Parkia filicoidea var. glauca Baker; Parkia intermedia Oliver; Mimosa biglobosa Jacq.; Inga biglobosa (Jacq.) Willd; Inga faeculifera Desv.

This leaflet highlights the nutritional and socioeconomic potential of African baobab and provide... more This leaflet highlights the nutritional and socioeconomic potential of African baobab and provides information to assist those working with the species. The focus is on conserving genetic diversity and promoting sustainable use of African baobab. The leaflet presents a synthesis of current knowledge about the species. The recommendations provided should be regarded as a starting point, to be further developed according to local or regional conditions. These guidelines will be updated as new information becomes available. An old baobab tree in Semeré Centre (North Benin) © P. NUÑEZ Common name African baobab, baobab, monkey bread tree, Ethiopian sour gourd, cream of tartar tree, upside down tree (English) Baobab, arbre aux calebasses, arbre de mille ans, calebassier du Sénégal (French) Scientific name Adansonia digitata L. Synonyms Adansonia baobab Gaertn., Adansonia digitata var. congolensis A.

Wood and fiber science: journal of the Society of Wood Science and Technology

Genetic variation in wood specific gravity is reported for Japanese larch from twenty seed source... more Genetic variation in wood specific gravity is reported for Japanese larch from twenty seed sources at age 17 years from planting in central New Brunswick, Canada. Information on native tamarack and European larch is also presented. Differences in mean specific gravity among provenances of Japanese larch (range 0.385 to 0.417) are highly significant. Specific gravity is not correlated with 12year height, specific gravity of trees of the same provenances growing in Michigan, or with latitude, or elevation of the provenances. There is a weak but significant negative correlation between specific gravity and tree diameter at 1.3 m. Provenance x environment interaction in respect to specific gravity is high. making it difficult to identify provenances that will be superior over a wide area.

Journal of Biogeography, 2015

ABSTRACT Aim Our goal was to test the hypothesis that ancient humans substantially contributed to... more ABSTRACT Aim Our goal was to test the hypothesis that ancient humans substantially contributed to shaping the current distribution of Brazil nut (Bertholletia excelsa), an Amazonian tree species that has been important for human livelihoods since pre-Columbian times. We scrutinized the putative association between Brazil nut and Amazonian Dark Earth soils (ADE) and geometric earthworks called geoglyphs, and examined the existence of continental patterns in human footprints on Brazil nut stands. Location Amazon Basin. Methods We carried out a spatially explicit meta-analysis of the variation of Brazil nut stand metrics across the Amazon Basin based on 87,617 density estimates, and 488 average stand diameter assessments, and related these to previously published datasets and suitability maps of Brazil nut, ADE and geoglyphs. Results We found consistently higher Brazil nut suitability scores, stand densities and average stand diameters in the vicinities of ADE than at larger distances, regardless of their position along a gradient from south-western to north-eastern Amazonia. For geoglyph sites such a pattern was only found for Brazil nut habitat suitability scores. The available data further revealed an accumulation of Brazil nut stands with increasing densities and average diameters from south-western to central and eastern Amazonia. Main conclusions Our findings suggest that the chance of encountering Brazil nut stands bearing the marks of past human influences increases from south-western to central and eastern Amazonia. In south-western Amazonia, the regeneration of Brazil nut seems to have been controlled predominantly by natural processes, whereas in central and eastern Amazonia, anthropogenic disturbance has been more important since pre-Columbian times. However, it remains challenging to disentangle human influences on the distribution and abundance of Brazil nut from existing environmental gradients across the Amazon Basin. In general, the results of this meta-analysis bode well for the future coexistence of Brazil nut with different forms of contemporary human land use. Keywords: Amazonian Dark Earth soils, Brazil nut, disturbance, genetic diversity, geoglyphs, historical ecology, megafauna, palaeodistribution, seed dispersal anachronism, terra preta.