No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The genetic structure and the conservation of the five natural populations of Pinus radiata
Canadian Journal of Forest Research
Abstract
Pinusradiata is restricted to three mainland coastal populations in California and two island populations off Baja California, Mexico. In this study each population was divided into two geographic stands based on natural disjunctions within populations. In addition to the division mentioned above, each mainland population was also divided into a number of ecological stands based on ecological and environmental criteria. Genetic variation was measured by analysing 31 allozyme loci electrophoretically using germinated seed from 272 families across all stands and populations. Moderate levels of allozyme variation were found as shown by population averages for mean number of alleles per locus (1.79), percent polymorphic loci (46.4%, 0.99 criterion), and expected heterozygosity (0.098). In fact, the overall genetic diversity in P. radiata (H T = 0.117) is low compared with that of other conifers. In comparison with populations, the levels of allozyme variation in both ecological and geographic stands were slightly lower (means across ecological stands: A = 1.56, P = 39.3%, and H e = 0.095). Of the total genetic diversity in P. radiata, 16.2% could be apportioned between populations, a high proportion for a conifer. In contrast, only 2.0 and 1.3% of the genetic diversity on average within mainland populations was between ecological and geographic stands, respectively. These results indicate a low level of genetic differentiation within populations, at least based on the ecological or geographic criteria used in this study. The implications and usefulness of these findings for the development of insitu conservation strategies are discussed.
... This area was part of an early Tertiary (65-34 Ma) refugium for pines and became an active centre for secondary radiation. The specific evolutionary history of P. radiata, interpreted for limited fossilised cones, suggests that Cedros provenance is probably the oldest and derives from an ancient mainland alliance (MORAN et al., 1988;ROGERS, 2002). Cambria and Año Nuevo are considered the youngest populations, based on their larger cone size. ...
... Seed from this collection has also been assayed for isozyme variation (MORAN et al., 1988), and microsatellites were used (KARHU et al., 2006) to study variation amongst 20 year old trees in one of the provenance bulk seedlot trials (without family identity maintained). Similar to the quantitative studies, the molecular studies have indicated large, significant differences between the provenances, particularly between the island and mainland groups. ...
... Similar to the quantitative studies, the molecular studies have indicated large, significant differences between the provenances, particularly between the island and mainland groups. The isozyme study (MORAN et al., 1988) also indicated little variability between populations within each provenance. Importantly, no relationship was found between population census size and level of genetic diversity. ...
Patterns of differentiation between populations within a species can be examined using both molecular and quantitative data, with observed differences indicative of adaptation to local conditions. Pinus radiata D. Don (radiata pine) is a species of commercial importance in many countries but also listed as conservation dependent in its native range on the Californian coast and two off shore islands. This paper presents a comparative analysis of existing molecular data with new quantitative data from a large provenance/progeny trial in southeastern Australia. Microsatellite data was reanalysed using a Bayesian model to test whether the a priori assumption of five natural occurrences was valid. With the validity of the geographic structure confirmed, two further approaches were used to examine genetic structure 1. a comparative study of Fst and Qst estimates to investigate the role of drift and selection in shaping the differentiation between the populations for breeding traits and 2. population clustering based on both quantitative and molecular data. Results strongly support the hypothesis that the island provenances of Pinus radiata are distinctly different to the mainland provenances. The molecular evidence also indicates the island provenances are different to each other. However, these differences were not apparent for the quantitative traits related to tree growth and form. The two island populations were however, strongly differentiated from each other for wood density and acoustic velocity. The patterns of phenotypic differentiation of the island provenances for these wood traits are both consistent with, and greater than, that observed for the molecular data, providing some evidence for directional selection on these traits. This study provides a background for the interpretation of molecular studies aimed at detecting molecular signatures of selection and associating genetic variation within genes with these traits.
... All provenances are located in a Mediterranean winter rainfall climate but receive additional summer moisture from ocean fog (Libby 1997). Provenances differ in soil type, elevation, temperature and total rainfall ( Table 1) (LIBBY, 1997;MORAN et al., 1988). ...
... Each of the mainland provenances was divided into 5 subpopulations and 20 trees sampled per location. This collection was subsequently planted as a provenance /progeny trial on 2 sites in New Zealand and was the subject of a major study published in 1992 (BURDON et al., 1992 a to e) 3) 1978 -a more extensive seed collection of both the mainland and island populations was jointly funded by Australian and New Zealand Governments (ELDRIDGE, 1978;JOHNSON et al., 1997;MORAN et al., 1988). This collection aimed to provide ex-situ gene conservation stands and to expand the genetic base of Pinus radiata available for future breeding. ...
... The more widespread mainland provenances were divided, on a geographic basis, into a number of populations (see Table 2) and individual tree seed collections conducted on varying numbers of parents per population. Parent trees were (from ELDRIDGE, 1978 andMORAN et al., 1988). * 220 trees along ridge top. ...
Four hundred and sixty individual families of Pinus radiata, representing all provenances and populations in a 1978 seed collection, plus a local seed orchard control, were planted together in 1980 in a large trial in southern New South Wales, Australia. Provenance means and genetic parameters for growth measured at ages 3, 8 and 26 years plus stem straightness, branch angle and nodality at age 26 years are reported. Large provenance differences were apparent for all traits. The two island provenances, Cedros and Guadalupe, were significantly inferior to the mainland provenances and, due to competition effects, very few trees survived to age 26. Within the mainland provenances, the performance of Año Nuevo and Monterey was almost identical with Cambria being less vigorous. The best performing seedlot for all traits was the local control. Differences between populations within the mainland provenances were apparent for diameter at age 26 within Año Nuevo and Cambria but not Monterey. Año Nuevo also showed population differences for stem straightness. Heritabilities for early growth were similar within Año Nuevo and Monterey but by age 26, the heritability for diameter was higher in Monterey. Within Cambria, heritabilities for growth and tree form at age 26 were close to zero. Genetic correlations between traits showed similar patterns for each of the mainland provenances, with the exception of correlations with stem straightness within Año Nuevo. Results are discussed in light of recent molecular studies of genetic architecture, levels of inbreeding in the native stands and possible effects of this inbreeding.
... The genetic diversity and differentiation of native populations vary depending on the molecular marker used. Isozyme analyses revealed that overall genetic diversity in P. radiata is lower and exhibits greater genetic differentiation between populations compared to other conifers (Moran et al., 1988;Wu et al., 1999). Similar patterns were observed using chloroplast DNA (Hong et al., 1993), with very low levels of variation and polymorphism within populations and negligible differentiation between populations. ...
... Populations that combine these conditions are often considered a genetic paradox (Estoup et al., 2016). Although P. radiata occurs in small disjunct populations in its native range, and only one population was studied in the present work, it harbors considerable amounts of adaptive genomic diversity yet those at neutral regions were similarly low as those early reported for isozymes (Karhu et al., 2006;Moran et al., 1988;Wu et al., 1999). In its introduced range in Argentina P. radiata has, on average, lower expected heterozygosity than in its native range. ...
Evolutionary forces such as genetic drift and natural selection operate during the process of biological invasion. More specifically, nonnative populations suffer genetic and demographic bottlenecks, and are exposed to new environmental, climatic and biotic filters. Thus, neutral and/or adaptive drivers may contribute to genetic differentiation of the introduced germplasm. We hypothesize that the gene pool of fire-adapted species that become invasive in fire-prone ecosystems may differ from that of originally planted and native one because of novel selective forces and founder effects. Genetic impoverishment due to genetic drift could also be buffered by demographic processes as the production of a large aerial seed bank by serotiny. We conducted genomic analyses of the world's most planted tree Pinus radiata using Single Nucleotide Polymorphisms, comparing introduced co-horts with and without fire exposure, and also with one population of the native range. Phenotypic traits of introduced cohorts were assessed for quantitative characters. In the introduced range we found lower expected heterozygosity and nucleotide diversity due to bottlenecks during introduction and commercial selection in orchards. We also detected decreased inbreeding, related to a serotinous seed bank that buffers bottlenecks. We found genomic regions under selection, both in the comparison between native and introduced range, and between introduced cohorts with and without exposure to fire. Within the introduced area, we observed possible fire-mediated diversifying selection for five quantitative traits. Our results show that both neutral and adaptive forces promote early divergence of the introduced species Pinus radiata. Also, fire acts as a rapid selection factor, prompting the incipient adaptive divergence of cohorts recruited after fires, facilitating invasion.
... With microsatellite loci the estimated level of genetic diversity in the base breeding population of radiata pine is more than eight times that from isozyme loci (MORAN and BELL, 1987). This result is despite the fact that radiata pine has been traditionally considered to have low levels of diversity (MORAN et al., 1988) compared to many other conifers such as Douglas-fir (CONKLE, 1992). Such high levels of genetic diversity enable unique genetic separation of breeding material without expending resources on assays of large numbers of loci. Figure 1 shows the probability of identity for increasing numbers of marker loci. ...
... With isozymes it was possible to narrow the origin of radiata pine in Australia to Monterey and Ano Nuevo populations in California (MORAN and BELL, 1987;MORAN et al., 1988). However finer resolution of origins within subpopulations or proportions from populations may now be possible using as a baseline the gene frequencies established in the breeding material -Lineage analysis to test the accuracy of 2 nd generation pedigrees in the Australian Pinus radiata breeding program. ...
Ten microsatellite loci were used to DNA profile 215 first and second generation breeding clones in the Australian radiata pine breeding program. The clones were essentially unique from one another and these DNA profiles were used to examine the sexual and asexual phases in the breeding program. Only 2.6% of ramets from 25 breeding clones were incorrect whereas 8.4% of progeny from 10 families were genetically incorrect. The lineages of second generation clones were checked for DNA profiles that were available for putative parents. Some parents appear to be incorrect on the basis of the DNA profiles and further sampling will be required to confirm these results across the breeding program. Microsatellite markers can now enable most questions to be resolved in breeding programs and also will allow novel breeding strategies to be used in the future.
... Thus, allele frequencies for RAPD loci were calculated from the phenotypic frequencies of null homozygotes assuming dominance and Hardy–Weinberg equilibrium. Wind-pollinated species, including the CCCP and other conifers, generally show only modest and transient departures from Hardy–Weinberg proportions (e.g., Plessas and Strauss 1986; Moran et al. 1988; Isabel et al. 1995). Genome Vol. ...
... In P. radiata, RAPD analysis indicated that the two mainland populations are more closely related to each other than to the Guadalupe Island population. This is also consistent with allozyme variation (Plessas and Strauss 1986; Moran et al. 1988), and many morphological and biochemical traits such as needle number, stem form, seed proteins, and terpenes (reviewed in Millar 1986). Based on cone morphology (Axelord 1980) and allozymes, the island populations were inferred to be most ancestorlike, consistent with our RAPD results. ...
We studied nuclear gene diversity and population differentiation using 91-98 randomly amplified polymorphic DNA (RAPD) loci in the California closed-cone pines knobcone (Pinus attenuata Lemm.), bishop (P. muricata D. Don), and Monterey (P. radiata D. Don) pines. A total of 384 trees from 13 populations were analyzed for RAPDs and another sample of 242 trees from 12 of these 13 populations were analyzed at 32-36 allozyme loci, using a published data set. Twenty-eight of 30 (93%) comigrating RAPD fragments tested were found to be homologous by Southern hybridization in all three species. Using an enriched mitochondrial DNA (mtDNA) preparation and a chloroplast DNA (cpDNA) library as probes, two fragments of cpDNA origin, and one of mtDNA origin present among RAPD profiles were excluded from analysis of nuclear gene diversity. RAPD markers revealed moderately higher intrapopulation gene diversity and substantially higher total genetic diversity and population differentiation than did allozyme markers for each species. We performed a simulation study using allozyme data, which showed that the dominant and biallelic nature of RAPD markers could explain the differences observed in differentiation parameters, but not in gene diversity; RAPD phenotypes appear to represent more underlying gene diversity than do allozyme phenotypes. Results of joint phylogenetic analyses of both the RAPD and allozyme markers strongly supported a common ancestor for P. radiata and P. attenuata pines, and south-to-north migration histories for all three species.
... Large population sizes, a predominantly outcrossing mating system, and the potential for long-distance gene flow are thought to be potential contributors to the observed pattern in the genetic structure of conifer populations (Loveless and Hamrick 1984). However, despite many studies on the genetic structure of pines, the effect of the number, size, and distributional range of populations on the distribution of genetic diversity remains poorly documented (Moran et al. 1988; Ledig 1998). There is some evidence that pine species with very disjunct distributions exhibit higher interpopulation variation (Moran et al. 1988; Gibson and Hamrick 1991). ...
... However, despite many studies on the genetic structure of pines, the effect of the number, size, and distributional range of populations on the distribution of genetic diversity remains poorly documented (Moran et al. 1988; Ledig 1998). There is some evidence that pine species with very disjunct distributions exhibit higher interpopulation variation (Moran et al. 1988; Gibson and Hamrick 1991). The few studies dealing with rare endemic pines have shown greater levels of differentiation among populations (Ledig and Conkle 1983; Delgado et al. 1999 ). ...
Mexico is a major center of diversity for the genus Pinus as it has the greatest number of species in the world. Many species are now restricted to Mexico, and some are represented by very small populations and are in danger of extinction. In this study we examined allozyme variation in three rare species of Mexican pines: Pinus pinceana Gord., Pinus lagunae M.F. Passini, and Pinus muricata D. Don, with the objective of providing conservation guidelines. The three species had relatively high levels of genetic variation with mean expected heterozygosities of 0.373, 0.386, and 0.346 for P. pinceana, P. lagunae, and P. muricata, respectively. We found marked differentiation among populations and significant inbreeding within populations of the three species. These values are larger than the range reported for most conifers and suggest that conservation strategies of these rare pines require focusing on the viability of several populations. Given that our knowledge about the demographic status of the three species is scarce, we propose a mixed strategy of conservation. For P. lagunae, we propose an in situ strategy, whereas for P. pinceana and P. muricata we propose an ex situ strategy of conservation until permanent protection can be provided for several of their populations.
... Study records indicate that a variety of Monterey pine seed lots were used, contributing an additional degree of variation in source climate. Monterey pine displays relatively high genetic diversity for a conifer (Moran et al. 1988). Field notes for this study identified scattered trees intended to be hybrids that had characteristics more consistent with pure knobcone pines, suggesting control over pollination was not always successful. ...
Given increasing forest disturbances, novel solutions are needed to rapidly recover ecosystem services such as carbon storage, while bolstering climate change adaptation. Reforestation with single-species mixed-provenance plantings is an emerging strategy that may enhance stand productivity and disturbance resistance, while assisted gene flow is a potentially powerful tool for matching seed-source with future planting-site climate. We investigated the potential of mixed-provenance plantings and assisted gene flow for maximizing early growth using a historical dataset for knobcone-Monterey pine (Pinus x attenuradiata), a fire-resilient hybrid developed for low-elevation sites in California, USA. We examined (1) 9-year individual-tree relative growth rate (RGR) in response to neighborhood seed-parent provenance diversity at two test sites and (2) 3-year RGR and survival as functions of parent seed-source climate at 4 test sites. We found 9-year RGR varied with seed provenance diversity, with 3 of 5 provenances showing a positive RGR-diversity relationship. Parent seed-source climate affected 3-year RGR but not survival. Closer climate matches in terms of precipitation as snow (PAS) showed fastest growth. Our results suggest careful selection and arrangement of genetically diverse stock may improve carbon sequestration and initial planting success in a hybrid conifer, with implications for reforestation under climate change and reburn risk.
... On the other hand, living radiata pine seedlings may in fact be resistant to P. ramorum, and cut branches (Hüberli et al., 2008) or logs (present study) may not have a completely functional defence response to P. ramorum, though there is currently no evidence to suggest this. It is more likely that the natural resistance of radiata pine explains the absence of any reported infections on this species in wildland forests, especially considering the overlap of the pathogen with the natural range of radiata pine in California (Mascheretti et al., 2008;Moran et al., 1988). ...
Radiata pine is an important plantation tree; more than 4 million ha are planted globally, and 90% of planted forests in Aotearoa New Zealand are radiata pine. It is susceptible to several root and foliar diseases caused by Phytophthora species, and is potentially susceptible to Phytophthora ramorum, the pathogen responsible for sudden oak death in the United States and Europe. A series of experiments were conducted to determine the potential risk of P. ramorum infection to radiata pine logs and seedlings in the context of forest harvest and replanting. In a natural inoculation experiment, bolts of radiata pine, Douglas‐fir and tanoak were exposed to P. ramorum inoculum produced from sporulating tanoak canopies infected with either the NA1 or EU1 lineage of P. ramorum. The experiment occurred at four sites, two NA1 and two EU1, across 2 years. Four per cent of radiata pine bolts, 8% of tanoak bolts and 0% Douglas‐fir bolts tested positive for P. ramorum. Artificial inoculations of bolts of the same species revealed a significant effect of lineage (p = .0024), species (p < .0001) and their interaction (p = .0027) on lesion length. Species was the only parameter that had a significant impact on average lesion length (p < .0001) and sporulation (p = .00144) from seedlings. No sporangia were observed on radiata pine seedlings (n = 60); few were observed on tanoak and Douglas‐fir. Although radiata pine can be colonized by P. ramorum, without a sporulating host in proximity it does not appear to be at high risk from this pathogen.
... Eucalypt plantations, both within their native range and as exotics, provide a unique model to investigate processes such as natural pathogen movement and gene flow, selection pressure, host shifts, human-mediated pathogen introductions, and globally pressing issues such as forest biosecurity. Pinus radiata has also been extensively planted as an exotic in the Southern Hemisphere; however, its original source was from only a few small populations in California (Moran et al. 1988), and it has been planted extensively as an exotic in the Southern Hemisphere in regions without related native conifers (Burgess and Wingfield 2001). Consequently, the opportunities for pathogen host shifts are much more limited. ...
Co-evolved plant pathogens play an important role in shaping natural ecosystems. However, plants used in agriculture and forestry have been distributed globally, and their associated pathogens have moved with them. Eucalypts constitute the largest component of global hardwood plantations, and they are increasingly plagued by numerous pathogens, all of which are inconsequential in the native forests. Eucalypts provide a particularly interesting model to study tree diseases because plantations have been established in countries where these trees are exotic but also in Australia adjacent to native eucalypt forests. These situations present opportunities for pathogen movement between the two systems. We present seven different scenarios considering pathogen movement, important disease epidemics, and biosecurity risks, illustrated with examples of well-known eucalypt pathogens and research largely from our laboratories. The overview shows that vigilant biosecurity is required to protect the biodiversity of native forests and the sustainability of eucalypt plantations.
... The low inbreeding depression seems to confirm our earlier suggestion that significant genetic load has been removed in radiata pine throughout the evolutionary history or through early purging in seed production, nursery culling and mortality. This lower genetic load, lower than any other conifer, can be explained by purging in natural radiata pine populations in California, due to its remnant small population (MORAN and BELL, 1987), and strong geographic isolation (ELDRIDGE, 1998). ...
A successful inbreeding and hybrid breeding strategy in tree improvement requires that 1) inbreeding (selfing) can produce superior inbred lines (effective purging of deleterious alleles), 2) there is heterosis among crosses of inbred lines, 3) early selection between lines is effective, and 4) inbreeding will not substantially reduce reproductive ability. We have previously reported that inbreeding depression on growth was lower in radiata pine relative to other conifers and segregation in the first two-generations of selfs generated superior inbred trees. In addition, we have observed that early selection among inbred trees (lines) was more effective than in out-crossed populations and there was an apparent heterosis in radiata pine. In this study, the effect of inbreeding on the reproductive ability in young and adult trees of radiata pine has been quantified from five populations of varied inbreeding levels (F = 0, 0.125, 0.25, 0.5, and 0.75). It was observed that the effects of inbreeding depression on fecundity was higher at a young age than at older age and inbreeding depression at a young age is due to two factors: 1) a delay of reproductive age (about 8.3, and 8.5% of trees delayed for F = 0.5 and F = 0.75 populations, respectively) and 2) a true reduction of flowering trees (6.7 and 13.1% more trees having no flowers for F = 0.5 and F = 0.75 populations than F = 0 population, respectively). Despite significant inbreeding depression on the percentage of female reproductive trees and the number of cones on adult trees, overall inbreeding depression on fecundity was low in radiata pine. One founder clone contributed most of the significant inbreeding depression observed for the population of eight founder clones. It was observed that fecundity varied more widely among the eight clones than among the inbreeding level (self and outcross).
... On trouvera des espèces avec des niveaux de diversité génétique élevés comme Alseis blackiana (Hamrick et Loveless, 1989), Picea glauca (Tremblay et Simon, 1989), Robinia pseudoacacia (Surles et al., 1989) et Pinus sylvestris (Kinloch et al., 1986). Les espèces qui présentent des valeurs de H très faibles sont Pinus radiata (Moran et al., 1988), Pinus pinea (Fallour et al., 1997), Thuya plicata (Copes, 1981), Acacia mangium (Moran et al., 1989), Pinus resinosa (Simon et al., 1986 ;Mosseler et al., 1991) Pinus torreyana (Ledig et Conkle, 1983) et Populus balsanea (Farmer et al., 1988 ;Hamrick et al., 1992). Les niveaux de diversité génétique moyens intra-population entre les gymnospermes et les angiospermes ne sont pas très différents (H est de 0.151 et 0.143 respectivement) malgré des caractéristiques très différentes tant biologiques qu'historiques. ...
... Pinus radiata (relatively isohydric gymnosperm) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm) are known to have contrasting stomatal regulation strategies ( McAdam et al. 2011, Brodribb andMcAdam 2013). Pinus radiata has a very restricted natural distribution, occurring in three isolated populations in California and Mexico ( Moran et al. 1988). However, it is widely planted, relatively fast growing and highly successful as a commercial timber resource around the world (>7 million ha). ...
Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive
effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects
of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in
stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal
regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and
Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response
to drought as a function of [CO2] and temperature. Both species were grown in two [CO2] (Ca (ambient, 400 μl l−1) and Ce (elevated, 640 μl l−1)) and two temperature (Ta (ambient) and Te (ambient +4 °C)) treatments in a sun-lit glasshouse under well-watered conditions. Drought plants were then exposed to a
progressive drought until mortality. Prior to mortality, extensive xylem cavitation occurred in both species, but significant
depletion of non-structural carbohydrates was not observed in either species. Te resulted in faster mortality in P. radiata, but it did not modify the time-to-mortality in C. rhomboidea. Ce did not delay the time-to-mortality in either species under drought or Te treatments. In summary, elevated temperature (+4 °C) had greater influence than elevated [CO2] (+240 μl l−1) on drought responses of the two studied gymnosperm species, while stomatal regulation strategies did not generally affect
the relative contributions of hydraulic failure and carbohydrate depletion to mortality under severe drought.
... On trouvera des espèces avec des niveaux de diversité génétique élevés comme Alseis blackiana (Hamrick et Loveless, 1989), Picea glauca (Tremblay et Simon, 1989), Robinia pseudoacacia (Surles et al., 1989) et Pinus sylvestris (Kinloch et al., 1986). Les espèces qui présentent des valeurs de H très faibles sont Pinus radiata (Moran et al., 1988), Pinus pinea (Fallour et al., 1997), Thuya plicata (Copes, 1981), Acacia mangium (Moran et al., 1989), Pinus resinosa (Simon et al., 1986 ;Mosseler et al., 1991) Pinus torreyana (Ledig et Conkle, 1983) et Populus balsanea (Farmer et al., 1988 ;Hamrick et al., 1992). Les niveaux de diversité génétique moyens intra-population entre les gymnospermes et les angiospermes ne sont pas très différents (H est de 0.151 et 0.143 respectivement) malgré des caractéristiques très différentes tant biologiques qu'historiques. ...
... However, a serious drawback with wild Guadalupe, and particularly Cedros, material is that it has significantly lower growth rates on sites ranging from high to low rainfall and at low and high altitudes (Gapare et al. 2012). It is possible that relatively high inbreeding on the Mexican islands (Moran et al. 1988) may be partially to blame for this poor performance, and further exploration of outcrossed or intraspecific hybrid material is warranted. ...
Pinus radiata (GF27- and Guadalupe-based intraspecific hybrids) and Pinus pinaster were trialled to examine the potential for commercial deployment on three lower-rainfall sites within the 500–800 mm rainfall zone of New South Wales. All three ex-pasture sites were considered to be dry for P. radiata; two lower-elevation sites to the west of Gundagai being more challenging than a high-elevation site near Bombala. Cuttings and seedlings of genetically improved P. pinaster and P. radiata and a Guadalupe × routine cross seedlot of P. radiata were planted at three stockings (625, 1250 and 1850 stems per hectare (sph)) and were assessed for survival, growth (diameter at breast height, height, volume), form (straightness, malformations, branch size, branch angle) and number of commercially acceptable trees per hectare up to age 8 years.
... In these situations, molecular markers could be used to assess what proportion of the genetic resources of key populations are captured in ex situ conservation stands. In the case of radiata pine, baseline estimates of genetic diversity in the natural populations are already available from both isozymes (Moran et al. 1988) and microsatellite markers (G. F. Moran, pers. ...
Domestication programs are currently being developed for a number of Australasian tropical tree species for plantations largely outside Australia. An assessment of the genetic resources of several species has been made on the basis of levels and patterns of genetic diversity at molecular marker loci. On the basis of growth performance and other quantitatively inherited commercial traits, populations from only limited regions of the geographic range were included in baseline selections of breeding programs for species such as Acacia mangium, A. auriculiformis, A. aulacocarpa and Eucalyptus pellita. For A. mangium, this domestication strategy resulted in a high proportion of the genetic resources of the species being included in breeding programs, but for other species such as A. aulacocarpa a significant fraction of the genetic resources were not incorporated into the baseline populations. The same molecular marker data sets enabled the formulation of conservation strategies both in situ and ex situ for these important commercial species.
Within Australia many tree species are utilised directly from native forests in the absence of domestication efforts. Preliminary results from a study on genetic impacts of silvicultural regeneration practices in native forests indicate that there is very limited loss in genetic diversity in E. sieberi, a locally abundant species, under either clearfelling with aerial resowing or the seed tree system. Questions remain concerning the impact of silvicultural regeneration practices on species that are more locally rare.
... In comparison to other provenances, the genetic base of Cedros was much narrower and possibly inferior as there was no opportunity to select seeds from the largest trees with good form during seed collection and only about 1 kg of seeds were collected from 51 trees on the Cedros Island in 1978. Furthermore, evolutionary history based on fossil record of pine cones and the genetic structure of P. radiata populations suggested that Cedros could be the most primitive line that separated from the rest of the geographical range of P. radiata several million years ago and it has been restricted in the recent evolutionary past since the separation (Axelrod 1980, Moran et al. 1988). ...
A provenance experiment involving five native provenances and an Australian landrace of Pinus radiata (D. Don) was established over three sites in the dry river valley area of Sichuan, southwest China in 2004 in order to select the most suitable provenance for environmental planting on the dry, steep and degraded slopes to reduce soil erosion. Although with much lower soil moisture supply and mean minimum temperatures in winter compared to P. radiata provenance trials established elsewhere in the world, these sites are within the working limits of the species defined by previous climate modelling and matching. Because of the difficult site conditions and severe natural disturbances after the experiment was established, mortality was high across the three sites in comparison to provenance trials in other countries. The average mortality rate among the provenance by replicate planting units over the three sites varied from 16% to 76% four years after planting, and from 40% to 88% five years after planting. The repeated measurements of tree size over time were analysed using multilevel linear mixed models to derive growth curves for the mean, median, the 75th and the 90th percentiles of the size distribution of each provenance at each site. There were significant site effects on tree growth, but no significant interactions between site and provenance was detected. Among the six provenances, Cambria was the best performer in diameter, height and stem volume growth across all sites. The better than average and the best trees of this provenance, as represented by the 75th and 90th percentiles of the nominal stem volume distribution, were significantly larger than the Australian landrace, Año Nuevo, and the two island provenances, Guadalupe and Cedros. Monterey was overall the second best performer behind Cambria. The Australian landrace, Guadalupe and Año Nuevo had similar performances in general. Cedros was significantly and consistently inferior to all other native provenances and the Australian land race. Because the genetic base of the present Australian plantations was derived largely from Año Nuevo and Monterey, the superior early growth performance of Cambria at such difficult sites brings a new promise to the search of P. radiata provenances for the vast dryland areas in New South Wales and other parts of Australia.
... Genetic diversity for elite, third-generation selections Third-generation elite selections had similar genetic diversity levels as other selected populations, regardless of generational differences. The elite selections still surpassed the range-wide levels reported for natural populations of radiata pine (Pinus radiata) (Moran et al. 1988). ...
Advanced-generation domestication programs for forest-tree species has raised some concerns about the maintenance of genetic diversity in forest-tree breeding programs. Genetic diversity in natural stands was compared with two genetic conservation options for a third-generation elite Pinus taeda breeding population. The breeding population was subdivided either on the basis of geographic origin and selection goals (multiple-population or MPBS option) or stratified according to genetic value (hierarchical or HOPE option). Most allelic diversity in the natural stands of loblolly pine is present in the domesticated breeding populations. This was true at the aggregate level for both multiple-population (MPBS) and the hierarchical (HOPE) populations. Individual subpopulations within each option had less genetic diversity but it did not decline as generations of improvement increased. Genetic differentiation within the subdivided breeding populations ranged from 1 to 5%, genetic variability is within each subpopulation rather than among subpopulations for both MPBS (>95%) and the HOPE approaches (>98%). Nei's Gst estimates for amongpopulation differentiation were biased upwards relative to estimates of θ from Weir and Cockerham (1984).
... Studies in population biology have revealed wide polymorphism in the ecogenetic population structure of many plant species, which is explained by specific differences in their centers of origin, routes and rates of migration, reproductive isolation, and habitat con ditions. Using the example of conifers in the Northern Hemisphere, it has been shown that the level of poly morphism in their insular populations is lower, while the level of genetic differentiation between them is higher in the marginal than in the central parts of their ranges (Tigerstedt, 1973;Critchfield, 1984;Gullberg et al., 1985;Moran, Bell, and Eldridge, 1988;Semer ikov and Lascoux, 2003;Sannikov et al., 2011). In general, however, specific ecogenetic features of mar ginal isolates and their role in speciation have not been studied sufficiently. ...
Analysis of geographic variation of chloroplast DNA in the eastern European and western Siberian (Tobol) groups of Calluna vulgaris populations isolated from each other for a long period of time has revealed distinct differentiation between them. It has been shown that three populations growing in the Russian Plain and Karelia share two haplotypes characteristic of central Europe, while three Tobol populations contain one haplotype F occurring in Sweden. These results confirm the hypothesis of genetic divergence between the Tobol and eastern European groups of C. vulgaris populations.
... Recently, molecular markers have been used to examine the genetic differentiation and evolution of populations of several species (Newton et al., 2002;Lise et al., 2007;Marum et al., 2009;Vercauteren et al., 2010). Endangered species confined to a small geographic range usually have, however, a lower level of genetic differentiation than some large scale forest populations (Vendramin et al., 1996), which could lead to the use of unsuitable genetic markers (Moran et al., 1988;Geburek, 1999;Peng et al., 2007). Yet, simple sequence repeats (SSRs, or microsatellites) have been used effectively under such circumstances (Menotti-Raymond and O'Brien, 1995;Taylor et al., 1994), due to the polymorphisms in highly variable regions of the genome (Powell et al., 1996), codominant of Mendelian (Fopp-Bayat and Woznicki, 2008;McGreevy et al., 2010), conservation in flanking sequence (King and Julian, 2004), reproducibility with a high individual specificity, abundant loci and heterozygosity of locus. ...
Picea mongolica is distributed exclusively in the eastern edge of the fixed sand dunes in Hunshandake Sandy Land, China. In this area, three groups of P. mongolica can be identified by their predominant fruit colours (purple, red and green). In this study, we used seven polymorphic microsatellites to investigate the level of genetic variation and differentiation among these groups. A significant level of genetic differentiation was detected in pairwise group comparisons. Pairwise FST values ranged from 0.019 to 0.028, indicating, however, a level of similarity among the groups higher than that observed in other species of the Picea genus. Cluster analysis indicated that the three groups analyzed here derived from a single gene pool. We propose that moisture differences in the sand dunes may lead to the observed differentiation in P. mongolica populations, which may be accelerated by habitat fragmentation. The observed genetic differentiation among the three groups of P. mongolica supports their classification as three different ecotypes, namely Picea mongolica f. purpurea, Picea mongolica f. rubra, and Picea mongolica f. viridis.
The shrub Hakea sericea, introduced from Australia in about 1858, has spread from limited plantings to occupy 4800km² or 14% of the area of mountain fynbos in the Cape Province of South Africa. Its range extends across about 1000km and a range of climatic regimes (winter, all-year and summer rainfall). Eleven populations, representative of the range of invaded habitats, were sampled to determine, by means of starch gel electrophoresis, the genetic structure of H. sericea in South Africa.
Comisión Nacional de Áreas Naturales Protegidas, 2005. “Estudio Previo Justificativo para el establecimiento de la Reserva de la Biosfera Islas del Pacífico de California”. México, D.F., pp. 169 + 3 anexos.
Las islas situadas en el Océano Pacífico de la Península de Baja California son reconocidas internacionalmente por su alta diversidad y abundancia de flora y fauna, y por la relativa integridad natural de sus ecosistemas. Estas islas sirven como importantes laboratorios para el estudio de los procesos naturales. El aislamiento y el hecho de ser ecosistemas relativamente simples, permiten a los ecólogos la
creación de teorías e investigar los procesos evolutivos, la extinción y colonización de especies, así como las interacciones interespecíficas. Otro interés aplicado tiene que ver con la intensa fragmentación de los hábitats continentales por efecto de las actividades humanas. El estudio de los procesos ecológicos en las islas, por analogía, aporta explicaciones útiles para la comprensión amplia y el manejo de la fragmentación
de los hábitats continentales.
No obstante que las Islas del Pacífico de Baja California aún mantienen una rica diversidad de especies nativas y endémicas, algunas de éstas están amenazadas por la depredación y la competencia de especies no nativas, introducidas o exóticas. Las condiciones evolutivas de las especies de plantas y animales de las islas las pone en desventaja sobre especies introducidas. Por ejemplo, al no haber tenido una coevolución con los herbívoros —como borregos o cabras domésticas ferales—, las plantas de las islas carecen de los mecanismos de defensa —mecánicos o químicos— contra ellos. De manera análoga, muchas especies de animales insulares no tienen temor a depredadores introducidos —como las aves marinas con relación a los gatos domésticos ferales—, o no tienen medios de escape y defensa, quedando inermes frente a depredadores introducidos. Durante la última década se han realizado numerosas acciones de conservación incluyendo la erradicación de mamíferos exóticos de estas islas, sin embargo, el trabajo no está terminado. Es necesario continuar con este esfuerzo que además incluye la prevención de reintroducción de fauna exótica. Otras amenazas específicas para las especies de vida silvestre de estas islas derivan del incremento de las actividades humanas desordenadas en las propias islas y sus alrededores, pues las poblaciones humanas costeras del noroeste de México están creciendo de manera acelerada.
Nitellopsis obtusa (starry stonewort) is a dioecious green alga native to Europe and Asia that has emerged as an aquatic invasive species in North America. Nitellopsis obtusa is rare across large portions of its native range, but has spread rapidly in northern-tier lakes in the United States, where it can interfere with recreation and may displace native species. Little is known about the invasion ecology of N. obtusa, making it difficult to forecast future expansion. Using ecological niche modeling we investigated environmental variables associated with invasion risk. We used species records, climate data, and remotely sensed environmental variables to characterize the species’ multidimensional distribution. We found that N. obtusa is exploiting novel ecological niche space in its introduced range, which may help explain its invasiveness. While the fundamental niche of N. obtusa may be stable, there appears to have been a shift in its realized niche associated with invasion in North America. Large portions of the United States are predicted to constitute highly suitable habitat for N. obtusa. Our results can inform early detection and rapid response efforts targeting N. obtusa and provide testable estimates of the physiological tolerances of this species as a baseline for future empirical research.
One of the primary materials for the study of forest landscapes of the Kanto region in the 1880fs is a set of topographic maps which were made for the first time ever in Japan to cover a wide area based on a modern survey. The other primary material is a set of records which were written as supplementary explanations of these maps. The results show that most of the forests there at that time, other than special ones such as national forests, consisted predominantly of pine trees or deciduous oak trees, and that most pine trees in the forests were less than 10 meters in height while most deciduous oak forests were less than 4 meters in height. Intensive use for fuel etc. on a rotation of 4 to 30 years was the background of such forests.
Coast redwood (Sequoia sempervirens (D. Don) Endl.) has long-lived individual trees that can reproduce both sexually and asexually. Allozyme markers indicate that, in old-growth populations in northern California, 15-34% of clones are multistemmed. Of those, they have few stems per clone, and none are very spatially pervasive. There is much variety in the clonal configurations observed, including circular, linear, and (or) disjunct arrangements. Visual assessment is a poor predictor of clonal identity and fairy ring structures more often than not contain multiple genotypes. In this first allozyme study of coast redwood, high levels of genetic variation are observed, higher than those observed for most other western conifers. These levels are perhaps related to the species' hexaploid condition, ancient phylogenetic lineage, and historically broader natural range. There are also generally high levels of genotypic diversity. Upland sites, with more frequent and intense fires, do not differ significantly in genotypic diversity from the more mesic lowland sites. Population structure in coast redwood seems to resemble the classic pattern for many open-pollinated conifers: much diversity within and little among populations. However, this is not a rangewide study. The current levels and structure of genetic and genotypic diversity in old-growth populations suggests episodic recruitment. The long-lived nature of individual stems and the capacity for asexual reproduction may allow clones to exist indefinitely, thus challenging some of the generalizations in evolutionary theory that are based on sexually reproducing species.
Genetic parameters for height (H), diameter at breast height (DBH), stem straightness (STR), and under crown clear bole height (CH) of loblolly pine (Pinus taeda L.) were estimated for 255 families (209 open pollinated (OP) and 46 controlled pollinated (CP) families) using a family model and an individual tree model at age 1, 2, 3, 5, 11, and 15 years. Heritability estimates for growth traits of individual trees at age 11 years were the highest (0.17-0.78), and those at age 15 years were the lowest (0.05-0.74). Heritability estimates for DBH, STR, and CH were lower than those for H. Genetic correlations between H and DBH were generally strongly positive, attained a maximum values at age 2 to 3, and declined slightly thereafter. The genetic correlations between CH at age 11 and both H and DBH at different ages were moderate. Age-age genetic correlations for growth traits were moderate to high (0.56-0.91) at age 5 for half-rotation age (15 years), indicating the opportunity exists for early selection. Indirect selection from the age 5 to 11 years for H and DBH could be expected to produce gains of over 50% and 35% respectively, for these two ages, relative to direct selection at age 15. Efficiencies of early selection for H and DBH indicated that growth at maturity could be improved by early selection.
Genetic variation within and among jack pine (Pinus banksiana) populations from heavy metal - Contaminated and uncontaminated areas in the Sudbury (Ontario, Canada) region was investigated using random amplified polymorphic markers (RAPDs). DNA samples from individual trees were analyzed using 15 oligonucleotides of random sequence. Eight of these primers allowed amplifications of random polymorphic (RAPD) loci. Close genetic relationships among jack pine populations from contaminated and uncontaminated sites were observed. Overall 26 % of the scored loci were polymorphic. The analysis of molecular variance revealed that the within -group (among individuals) variations accounted for 63.3 % of the total molecular variance. The difference among populations which explained 36.7% of total variation was statistically significant and higher than RAPD variations reported in P. resinosa. The jack pine trees were easily distinguished from red pine trees using RAPD markers. RAPD markers specific to P. banksiana were also identified.
In order to determine the magnitude and pattern of genetic diversity among Anatolian Black pine (Pinus nigra Arnold subspecies pallasiana) populations sampled in Bolkar Mountains and to recommend the potential populations which may be suitable for in situ conservation of genetic resources in this species, isoenzymes from 14 enzyme systems were investigated by starch gel electrophoresis. For this reason, open pollinated seed megagametophytes of half-sib families originated from the four populations (Camliyayla, Ulukisla, Cehennemdere and Gulekdere) were used. 24 loci were resolved for the 14 enzyme systems assayed. Polymorphism (P) varied between 41% in Camliyayla and 55% in Ulukisla. The mean number of alleles per locus (A) was around 1.6 and the expected heterozygosity (H(s)) was about 21%. Moreover, only Ulukisla had a unique allele (second allele of GOT2) which gave the distinctive character to the population. Genetic diversity among populations relative to the total genetic diversity (G(ST)) was averaged as 0.070, indicating that only 7% of the total genetic diversity was among populations. Furthermore, Nei's genetic distance values ranged from 0.007 to 0.032 among population, confirming that the diversity among populations was not very high. Based on the results of this study, it is recommended that Ulukisla and Gulekdere populations could be considered for in situ conservation of genetic resources of the species in the Bolkar Mountains.
Mexican temperate forests, at the southernmost end of the distribution range of this ecosystem, are the world’s centre of diversity of pine and oak, with 55 and 161 species, respectively. Such forests are threatened by land-use change, unsustainable forest management practices, and climate change; these threats reduce their diversity, alter the distribution ranges of species, modify disturbance regimes, and reduce ecosystem adaptability. This paper briefly reviews (i) the ecology of the Mexican temperate forests, (ii) the ecological basis for the unique diversity of pine and oak species, (iii) the main disturbances as well as the main drivers of global changes affecting these forests, in particular climate change, and (iv) the social, economic, and cultural factors to be considered in proposing a new forest management approach. It proposes a new conceptual framework to manage Mexican temperate forests that are in line with (i) their natural dynamics, (ii) the rapidly changing and uncertain global environmental, social, and economic conditions, and (iii) the complex adaptive system approach. This new forest management combines functional zoning, multispecies plantations, and sylvicultural interventions to increase the adaptive capacity of forests as a way to balance the increasing need for timber products with the need for other ecosystem services facing rapidly changing and uncertain future environmental, social, and economic conditions.
The genus Pinus evolved about 100 million years ago, spreading from centres in eastern North America and western Europe throughout middle latitudes of the supercontinent Laurasia. Many early subsections of Pinus are recorded from fossil remains of this period, but it is not until the early Tertiary, when the genus was fragmented by changing global climates and continental tectonics into latitudinal refugia, that secondary centres of origin appeared. From one of these areas, now Mexico and Central America, the subsection Oocarpae is thought to have arisen. This subsection includes the California closed-cone pines, P. radiata D. Don, P. muricata D. Don, and P. attenuata Lemmon, which evolved 15-25 million years ago as they migrated northward to California from Central America. Pinus radiata appears to have occupied coastal or near-coastal habitats throughout its history in the California region. A synthesis of recent evidence from microfossils in sediment cores, oxygen-isotope ratios in ice and sediment cores, and re-evaluation of available macro-fossils yields an improved characterisation of Quaternary climatic and vegetation changes in the California coast region. Over the last million years, California climates fluctuated quasi-cyclically, at long-(multi-millennial), medium-(century), and short-(decadal to annual) periodicities in patterns similar to those documented elsewhere in the world. Changing plant fossil assemblages in the California coast region reflect major and minor fluctuations, with Quercus and Compositae dominating floristic communities during warmest and driest periods, and Taxodiaceae/Cupressaceae/Taxaceae taxa dominating coldest periods. Pines, notably P. radiata, expanded in abundance and shifted locations along the coast during climates intermediate to these extremes. Such climates occurred during transitional periods of major and minor cycles, including onset and terminations of major glacial stages, extended interstadials, and shorter cool, mesic intervals within warmer climates. This evidence is used to argue against a long-standing scenario that P. radiata was broadly distributed along the coast throughout the Pleistocene (10 ka - 2 Ma), and that the Holocene climatic optimum (warm, dry period 4-8 ka) triggered contraction into the present fragmented, relictual populations. Instead, it is proposed that the species has maintained a metapopulation strategy throughout its history in the California region, growing in distinct coastal populations that were subject to repeated events of colonisation, coalescence, and local extirpation in response to fluctuating climates. Population differences are thus likely to reflect frequent founder and bottleneck effects, and complex introgression. Appropriate conservation and restoration approaches to P. radiata may be revised given this perspective. Rathern than restricting views about native populations to the five extant locations, coastal sites beyond the current distribution might also be accepted as 'neo-native'. Areas where P. radiata has naturalised along the California coast during historic climate periods similar to the present include many sites known from the Quaternary fossil record. Rather than treating P. radiata in these areas as an undesired exotic, these and other locations could be considered appropriate places in which to encourage conservation populations of P. radiata. This would mimic the natural potential of P. radiata under the generally cooler climate of the late Holocene (relative to earlier millennia) to colonise and expand in abundance, which may be inhibited currently by human development.
Gene conservation of native conifer species in British Columbia is considered necessary primarily to safeguard the future evolutionary potential of species to climate change, new biotic challenges and for commercial genetic improvement programs. The tactical options include: (i) maintaining existing protected areas, (ii) creating new reserves for in situ management, and (iii) ex situ collections of various types. A two-part strategy is presented, with emphasis on technical justifications, for the conservation of conifer tree genetic resources of 23 British Columbia species. Part I is a survey of the frequency of each species in current land reserves in BC. Part II outlines an approach that will aid in setting priorities for additional gene conservation activities for specific species. This process attempts to use information on: (i) levels of in situ protection, (ii) the status of each species in current provenance research and breeding programs, and (iii) the relative capabilities for natural regeneration for each species. Representation of the 23 native conifer species in the current network of protected areas is generally complete. For instance, western hemlock is under little threat, as extensive ex situ collections are in field tests; it is well protected in the current reserve network, and it has a great capacity for natural regeneration. At the other extreme, whitebark pine has no ex situ collections made to date, needs additional protection in some ecoregions of the province, and generally has poor natural regeneration potential. While implementation of our strategy will be an ongoing process (i.e. updating information from both new and old in situ reserves, and setting new priorities among species), several immediate issues have been noted. These include; (i) follow-up work in the area of population sampling for ex situ collections, (it) 'ground truthing' of current reserves where data are weak, and (iii) examining the merit of certain populations not located in BC (as they could be as important as those currently protected in BC). For the future, various broad management questions will need to be resolved, such as: (i) whether existing reserves will perpetuate the various gene pools, and what management will be appropriate for such areas, (ii) the impact of pollen migration from genetically improved production stands on reserve stands, and (iii) the role of commercially improved stands and the breeding populations themselves to meet gene conservation objectives.
A brief account is presented of current knowledge of the genetics of resistance of Pinus radiata to Phytophthora cinnamomi, P cryptogea, Dothistroma septospora, Cyclaneusma minus, Pineus pini, Sirex noctilio and Amylostereum areolatum. Techniques to assess field resistance to each of these pathogens or pest insects are now available. Implications of selection and breeding for resistance to pathogens and pests for clonal forestry include a reduction in genetic diversity and a possible loss of sources of potential resistance to significant exotic pathogens and pest insects. There is a need for research in the optimum number of clones for multi-clonal mixtures and the pattern in which these clones are best planted to minimise losses from disease or insect pests.
Identification of the ecosystem services provided by Mexican temperate forests is a prerequisite in ensuring their conservation and sustainable management. This study aimed (1) to describe ecosystem services provided by Mexican temperate forests (provisioning, regulating and cultural services); and (2) to identify possible trade-offs and synergies based on the types of ecosystem services available in Mexican temperate forests. We synthesized relevant literature from scientific articles, government statistics and grey literature covering the years 1985–2012. Timber extraction is the main beneficial ecosystem service of temperate forests recognized by public policy as shown by the high income from this activity; but it has trade-offs of greater magnitude with other provisioning services (water, bioenergy and non-timber forest resources), and
with other supporting, regulating and cultural ecosystem services. For example, it causes the loss of other forest resources, extinction of commercially important species and loss of the system's structural complexity. Water capture and extraction of non-timber forest resources have lesser effects on support and regulation services, and in the case of water capture, the magnitude of the effect depends on the type and reversibility of the modification of the ecosystem. The synergies between ecosystem services have mutual benefits; for example, a decision to enhance the scenic beauty in temperate forests potentially improves water cycling and provision of non-timber forest resources, and has a positive effect on cultural and regulation services. In Mexican temperate forests the recognition of ecosystem services is limited and is based largely on
grey literature. More robust scientific information is needed on the role of these forests in maintaining biodiversity and provision of ecosystem services essential to the welfare of the population. Also, monitoring of ecosystem processes of highland temperate forests in tropical regions is very limited, so it is necessary to generate research to develop a paradigm shift from forest management based strictly on logging to one based on ecosystem management.
I. TIPOLOGÍA
I.1. TAXONOMÍA, VARIEDADES Y PROCEDENCIAS
I.2. TIPOLOGÍA DE LOS PINARES DE INSIGNE
I.2.1. Masas y hábitat natural
I.2.2. Repoblaciones
II. REGENERACIÓN POR DISEMINACIÓN NATURAL Y REPOBLACIÓN FORESTAL
II.1. PRINCIPALES FACTORES QUE AFECTAN A LA REGENERACIÓN
II.1.1 Fructificación
II.1.2. Diseminación y germinación
II.1.3. Tratamientos de regeneración
II.2. TÉCNICAS DE REPOBLACIÓN
II.2.1. Calidad de la planta
II.2.2. Preparación del sitio de plantación
II.2.3. Manejo de restos de corta
III. TRATAMIENTOS PARCIALES
III.1. DESBROCES
III.2. CLAREOS
III.3. CLARAS
III.3.1. Edad de iniciación
III.3.2. Volúmenes extraídos en las claras
III.3.3. Peso y rotación de las claras
III.3.4. Selección del arbolado en las claras.
III.4. PODAS
III.5. FERTILIZACIÓN
III.6. SANITARIOS
IV. CRECIMIENTO Y PRODUCIÓN
IV.1. CALIDAD DE ESTACIÓN
IV.2. CRECIMIENTO
IV.3. TURNO
IV.4. PRODUCCIÓN
IV.5. MODELOS DE CRECIMIENTO Y PRODUCCIÓN
V. BIBLIOGRAFÍA
To counteract loss of genetic diversity crucial for current and future tree improvement, tree breeders have conserved forest genetic resources in situ in their natural ecosystems in protected areas or ex situ in plantations, seed orchards, and breeding arboreta. This article reviews the genetic consequences of these two conservation methods in terms of single-locus and multilocus population structure from electrophoretic studies of natural forests and breeding populations. Although natural forest populations have maintained high level of genetic diversity and exhibited low level of population differentiation, loss of genetic diversity would occur during the entire conservation process, from population establishment to management of breeding and production populations. Since forest trees are still at their earliest stage of domestication in Canada, loss of genetic diversity comes primarily from the initial sampling process during population establishment. We discuss the optimal sampling strategy during population establishment to conserve common and widespread alleles, common and localized alleles, rare and widespread alleles, and rare and localized alleles. We also discuss three methods for studying the multilocus structure of forest trees and show how such information would be useful for conserving co-adapted gene complexes. We conclude that being small and maintained in controlled environments, ex situ conserved populations would retain less genetic diversity than in situ conserved forest populations. While ex situ conservation is operationally convenient for the short-term gains in tree improvement, we believe in situ conservation is essential for renewing the genetic diversity to meet the changing environments of an uncertain future.
Aguirre Muñoz, A., J. Bezaury Creel, J. Carranza, E. Enkerlin Hoeflich, C. García Gutiérrez, B. Keitt, L. M. Luna Mendoza, J. A. Sánchez Pacheco y B. R. Tershy. 2003. Propuesta para el Establecimiento del Área Natural Protegida “Reserva de la Biósfera de la Isla Guadalupe”. Estudio Técnico Justificativo. Grupo de Ecología y Conservación de Islas, A.C. Ensenada, Baja California, México. 67 pp.
En este documento se propone y justifica la creación de un Área Natural
Protegida (ANP), como Reserva de la Biósfera, para isla Guadalupe y sus
islotes, frente a la costa del Pacífico abierto de la Península de Baja
California. Los argumentos se anclan en los valores duros de la conservación
y el desarrollo sustentable. Se incluye en la propuesta isla Guadalupe y los
islotes Negro, Toro, de Enmedio y Zapato, localizados al sur-suroeste de la
isla.
Por sus altos niveles de endemismo, y a pesar de severos daños
acumulativos sobre especies de su flora, esta isla mexicana tiene relevancia
a nivel global. Como ecosistema, junto con el resto de las islas del Pacífico
noroeste es única en su tipo en nuestro país.
La superficie total terrestre de la isla del ANP es de sólo 250 Km². La porción
marina, de aguas adyacentes alrededor de la isla —como área de
amortiguamiento— es de 4,519.71 Km. El total de la superficie propuesta,
sumadas las aguas y la isla, representa sólo cerca de dos milésimas partes
de la Zona Económica Exclusiva en el Pacífico mexicano. Es una minúscula
superficie que tendrá destacadísimos efectos en la conservación de la
biodiversidad y de los recursos naturales de la región.
La riqueza biológica de esta isla del Pacífico de Baja California está bastante
bien documentada. En ella existe un total de 216 especies de flora vascular
conocidas. Alrededor de 30 de ellas están probablemente extintas en la isla.
45 especies, principalmente europeas, son relativamente recientes. 171 son
consideradas como posiblemente nativas; de éstas, 34 especies y
subespecies (21.8%) son endémicas incluyendo 5 extintas. 114 especies
(73%) crecen también en la alta California y sólo 5% en Baja California. 101
especies (65%) crecen en las islas de California, 19 de estas (12.2%) son
endémicas insulares, y 6 de ellas tienen un parentesco cercano con las islas
del sur de California. Asimismo tiene bosques de especies o variedades
endémicas de pino, cedro y ciprés en la parte más alta de la isla en su
porción norte, devastada por cabras (Moran Reid 1996), pero con un muy
relevante y probado potencial de restauración.
Considerando su alta viabilidad técnica, administrativa, económica y social, y
a la luz de su riqueza biológica, es difícil imaginar una oportunidad mayor en
México para la conservación. Su protección es indispensable, pues es un
ecosistema que, por su mismo aislamiento histórico y evolutivo, resulta muy
vulnerable a las actividades humanas y efectos derivados, como son los
graves daños causados por las especies introducidas, especialmente cabras y
gatos, y que no generan ningún beneficio socioeconómico.
La propuesta ha sido elaborada por el Grupo de Ecología y Conservación de
Islas, A.C. —asociación civil ganadora del Premio Nacional de Conservación
del 2002—, en coordinación con la Comisión Nacional de Áreas Naturales
6
Protegidas. Cuenta con el apoyo formal de la cooperativa pesquera que opera
en forma en la isla, “Abuloneros y Langosteros de Isla Guadalupe”, de
participación estatal, dedicada básicamente a la captura de abulón y
langosta. Igualmente, la propuesta es respaldada por organizaciones no
gubernamentales especializadas en la conservación ambiental.
Insights into the relative contributions of locus specific and genome-wide effects on population genetic diversity can be gained through separation of their resulting genetic signals. Here we explore patterns of adaptive and neutral genetic diversity in the disjunct natural populations of Pinus radiata (D. Don) from mainland California. A first-generation common garden of 447 individuals revealed significant differentiation of wood phenotypes among populations (P
ST), possibly reflecting local adaptation in response to environment. We subsequently screened all trees for genetic diversity at 149 candidate gene single nucleotide polymorphism (SNP) loci for signatures of adaptation. Ten loci were identified as being possible targets of diversifying selection following F
ST outlier tests. Multivariate canonical correlation performed on a data set of 444 individuals identified significant covariance between environment, adaptive phenotypes and outlier SNP diversity, lending support to the case for local adaptation suggested from F
ST and P
ST tests. Covariation among discrete sets of outlier SNPs and adaptive phenotypes (inferred from multivariate loadings) with environment are supported by existing studies of candidate gene function and genotype–phenotype association. Canonical analyses failed to detect significant correlations between environment and 139 non-outlier SNP loci, which were applied to estimate neutral patterns of genetic differentiation among populations (F
ST 4.3 %). Using this data set, significant hierarchical structure was detected, indicating three populations on the mainland. The hierarchical relationships based on neutral SNP markers (and SSR) were in contrast with those inferred from putatively adaptive loci, potentially highlighting the independent action of selection and demography in shaping genetic structure in this species.
The genetic differentiation [Formula: see text] within a subdivided population can be partitioned into two proportions, one due to differentiation within sub-populations and the other due to differentiation among subpopulations. A simple mathematical derivation of this procedure, known as Nei's G ST -statistics, is presented. The significance of considering the differing relative sizes of subpopulations is stressed. Possible fields of applications for breeders and conservationists who are concerned with the establishment of genetically diverse populations are mentioned.
A genetic linkage map for radiata pine (Pinus radiata D. Don) has been constructed using segregation data from a three-generation outbred pedigree. A total of 208 loci were analyzed including 165 restriction fragment length polymorphism (RFLP), 41 random amplified polymorphic DNA (RAPD) and 2 microsatellite markers. The markers were assembled into 22 linkage groups of 2 or more loci and covered a total distance of 1382 cM. Thirteen loci were unlinked to any other marker. Of the RFLP loci that were mapped, 93 were detected by loblolly pine (P. taeda L.) cDNA probes that had been previously mapped or evaluated in that species. The remaining 72 RFLP loci were detected by radiata pine probes from a PstI genomic DNA library. Two hundred and eighty RAPD primers were evaluated, and 41 loci which were segregating in a 1∶1 ratio were mapped. Two microsatellite markers were also placed on the map. This map and the markers derived from it will have wide applicability to genetic studies in P. radiata and other pine species.
The relationship between inbreeding depression and inbreeding coefficient (F) for several important traits was investigated in an 11-year trial of maritime pine (Pinus pinaster). Five levels of inbreeding (F=0; 0.125; 0.25; 0.5; 0.75) were obtained in a mating design involving ten plus-trees, or their progenies, as parents (total of 51 families). For F=0.75, the mean inbreeding depressions were 27% for height, 37% for circumference at breast height (63% for bole volume), 23% for basal straightness (better straightness of the inbred trees), and 89% for female fertility (number of cones). Large differences were observed among inbred families for the same level of inbreeding. The evolution of depression with F was more or less linear, depending on the traits. Significant differences among F-levels appeared very early for height (from 5-years of age). Inbreeding depression was much more expressed during unfavorable years than during favorable years for yearly height growth. When compared with other Pinus species, maritime pine appears to be less affected by inbreeding, especially for the percentage of filled seeds and general vigor. A reduced genetic load in maritime pine may result from the evolutionary history of the species and its scattered distribution.
DNA sequence analysis of chloroplast genomes has revealed many short nucleotide repeats analogous to nuclear microsatellites, or simple sequence repeats (SSRs). We designed PCR primers flanking five of these regions identified in the chloroplast sequence from Pinus thunbergii and tested them for amplification in Pinus radiata, P. elliotii, P. taeda, P. strobus, Pseudotsuga menziesii, Cupressus macrocarpa, four New Zealand native conifer species (Podocarpus totara, Podocarpus hallii, Podocarpus nivalis, Agathis australis), and four angiosperms (Vitex lucens, Nestegis cunninghamii, Actinidia chinensis, and Arabidopsis thaliana). A PCR product in the expected size range was amplified from all species and interspecific polymorphism was detected at all five loci. Intraspecific polymorphism was detected in P. radiata with four of the five primer pairs. One of these polymorphic chloroplast SSR (cpSSR) was then used to determine the inheritance of chloroplasts in 206 progeny from four control-pollinated, full-sibling P. radiata families. Approximately 99% of the progeny had the cpSSR variant of the pollen parent indicating that in Pinus radiata, like most other conifers, chloroplasts are typically inherited from the paternal parent. These results suggest that polymorphic chloroplast SSRs will be a valuable tool for studying chloroplast diversity, cyto-nuclear disequilibrium, and plastid inheritance in a range of species, and for the analysis of gene flow via pollen and paternity in species with paternal transmission of chloroplasts.
We presented a novel orthogonally linearly polarized Nd:YVO4 laser. Two pieces of alpha-cut grown-together composite YVO4/Nd:YVO4 crystals were placed in the resonant cavity with the c-axis of the two crystals orthogonally. The polarization and power performance of the orthogonally polarized laser were investigated. A 26.2-W orthogonally linearly polarized laser was obtained. The power ratio between the two orthogonally polarized lasers was varied with the pump power caused by the polarized mode coupling. The longitudinal modes competition and the corresponding variable optical beats were also observed from the orthogonally polarized laser. We also adjusted the crystals with their c-axis parallele to each other, and a 40.7-W linearly polarized TEM00 laser was obtained, and the beam quality factors were Mx2 = 1.37 and My2 = 1.25.
Seed from 126 trees from populations representing 15 geographic locations covering much of the natural range of shortleaf pine (Pinus echinata Mill,) were analyzed using 23 enzyme systems covering 39 loci to determine patterns of genetic variation and structure. populations were polymorphic (p) at 87.2% of the loci, had 2.18 alleles (A) per locus, and had 2.35 alleles per polymorphic locus (A(p)) Mean expected heterozygosity (H-e) was 0.194 and mean observed heterozygosity (H-o) was 0.174. Western populations had a higher p, higher A, similar A(p), and a higher H-o and H-c than eastern populations, in part because of six private alleles (alleles seen only in one population) in the west but only one in the east. Genetic structure analysis revealed interpopulation genetic variation at 9%, meaning 91% of the genetic variation; in shortleaf pine resides within populations. Interpopulation gene flow was 2.56, indicating two or three allele migrations per generation, which is relatively high and explains the low interpopulation genetic variation in the species. There was no apparent relationship between geographic distance among populations and their genetic distance. Shortleaf pine populations exist in naturally outcrossing random-mating populations and have a relatively large amount of natural variability, Western populations are more diverse than their eastern counterparts.
Twelve natural populations of four cedar pine species,Pinus sibirica, P. cembra, P. pumila, andP. koraiensis, occurring in the Soviet Union were investigated by starch-gel electrophoresis. Frequencies of 55 alleles at 19 loci were determined. Interpopulation genetic diversity inP. sibirica andP. pumila was only 2–4 per cent of the total genetic diversity. Nei's distance coefficient (Dn) was used to estimate the level of genetic differentiation among conspecific populations and among species. Dn values among populations ranged from 0.006 to 0.038. A dendrogram constructed using Dn values divided cedar pines species into 2 clusters:sibirica-cembra (Dn = 0.030) andpumila-koraiensis (Dn = 0.143). Nei's distance between these clusters was 0.232. On the basis of the data obtained it was possible to draw the following conclusion:P. sibirica, P. pumila, andP. koraiensis are distinct species, whileP. cembra should apparently be regarded as geographicalP. sibirica race.
Wood and foliage mono- and sesquiterpenes of 45 Pinus radiata trees from the three native mainland populations in California were analysed using conventional and chiral gas chromatography. The wood was found to contain no detectable sesquiterpenes. Wood monoterpenes mainly consisted of β-pinene [98.5% (−), 1.5% (+)] and variable ratios of (−) and (+)α-pinene, the (−) enantiomer predominating in the southernmost population; twenty other monoterpenes were detected. The main foliage monoterpenes were (−)α- and (−)β-pinene, (−)limonene and (−)β-phellandrene. (−)α-Pinene increased from north to south, while (−)β-phellandrene and especially (−)limonene decreased. The predominant foliage sesquiterpenes were caryophyllene, germacrene D, bicyclogermacrene and 4α-hydroxygermacra-1(10),5-diene (4αHGD); twenty-four other sesquiterpenes were detected. The central (Monterey) population was distinguished by higher amounts of germacrene D and decreased levels of caryophyllene, bicyclogermacrene and 4αHGD.Canonical discriminant analysis of each data set (foliage monoterpenes, sesquiterpenes and wood monoterpenes) for all trees showed good separation among the populations with about 95% of the trees correctly grouped. When the three data sets were combined, the populations were completely separated and all trees were correctly grouped. The Mahalanobis distance between the southern pair (Monterey/Cambria) was less than between the northern pair (Año Nuevo/Monterey).
Seven Pinus species (P. canariensis, P. halepensis, P. pinaster, P. pinea, P. nigra, P. uncinata, P. sylvestris) present on the Iberian Peninsula and the Canary Islands were characterized using polyacrylamide gel electrophoresis (PAGE). Acid phosphatases (ACP), esterases (EST), glutamate oxalacetate transaminase (GOT) and superoxide dismutase (SOD) isoenzyme systems showed a clear expression and were used for the study. Pinus canariensis, Pinus halepensis, Pinus pinaster, Pinus pinea and the group formed by Pinus nigra, Pinus uncinata and Pinus sylvestris were clearly distinguished by means of ACP or both GOT and SOD. On the other hand Pinus nigra, Pinus uncinata and Pinus sylvestris were distinguished using the EST system. Consequently the technique allows for the characterization of the studied taxa. Further work is being carried out in order to analyze the possibility of discriminating different populations of a given species.
Seeds from 28 stands representing most of the range of Pinus monticola were analyzed for electrophoretically demonstrable variation on 10 proteins encoded by 12 genetic loci. On average, 65% of the loci per stand were polymorphic, and expected heterozygosity of offspring was 18%. Populations could be assigned to 2 geographic groups, a broad northern one and a rather restricted southern one. The southern group consisted of populations from the Sierra Nevada and southern Cascade mountains in northern California and from the Warner Mountains in south-central Oregon. Across the northern part of the species' distribution (British Columbia, Washington, northern Oregon, Idaho, and Montana) differences among stands were minor and essentially random. Collections from stands in the central and southern Oregon Cascades and the Siskiyou Mountains of northwestern California were more nearly like the northern stands but exhibited some characteristics indicative of a transition area between the Sierra and northern types.-from Authors Sierra Nevada ascade Mountains iskiyou Mountains alifornia arner Mountains regon ritish Columbia ashington daho ontana.
Two northern California bishop pine populations differing in stomatal form, monoterpene composition, flowering time, and allozyme frequency are separated by a cline of less than 3 km width. Allelic frequencies at a marker allozyme locus in standing trees changed from an average of 0.97 north of the cline to 0.23 south of the cline. Differences in allelic frequencies between mature trees and embryos are attributed to long distance pollen flow across the cline. Data on wind direction and flowering phenology support this hypothesis. Genetic, ecological, and paleontological evidence suggests that the cline resulted from recent contact of formerly isolated populations.
Unbiased estimators of genotype and allele frequencies and their respective variances are obtained for loci identified by mendelian segregation in haploid female gametophytes from individual trees. By a minimum sampling variance criterion, the allocation of experimental effort between the number of female gametophytes analysed per tree and the number of trees sampled per population is examined for a fixed total amount of experimental effort. For estimating heterozygosity, the optimum sampling design for many (generally most) cases is three female gametophytes per tree, but may be more than three depending upon the true genotype frequencies in the population. For estimating allele frequencies, the optimum sampling design is one female gametophyte per tree except in cases where a strong negative correlation exists between alleles within genotpyes. Guidelines are discussed for determining a suitable number of female gametophytes to be analysed per tree in order to estimate heterozygosity.
Female gametophytes of knobcone pine were used to study genetic variation at 58 loci in 26 enzyme systems. Mendelian segregation and linkage were tested at 21 loci. Got1, Pgi2, Mnr3, Adh2, and Lap2 were linearly arrayed in a single linkage group. Est and Acp3, and Flest and Lap1, formed two independent linkage groups. Although Mendelian segregation was the rule, several cases of segregation distortion were observed. Pooled over trees, Lap1 and Aap1 showed significant distortion. Of 11 cases of distortion observed for individual trees, 10 showed an excess of common alleles. Pooled over both loci and trees, giving a total sample of 17,183 gametes, the common alleles were significantly overrepresented by 1.1%, and heterogeneity was highly significant. Our results, and others in the literature, suggest that segregation distortion may affect the genetic structure of conifer populations.
Despite the fact that forest trees are in early stages of domestication there has been little direct evaluation of either the origin of, or genetic diversity within the breeding material in tree improvement programs. Allozyme variation was used to compare the total genetic diversity in the breeding programs of P. radiata within Australia and the five wild populations in North America. The current breeding populations were very similar genetically and were essentially homogenous with only 1.8% of the variation among programs. The total genetic diversity in the species was 0.12, which is a low estimate compared to most conifers. Overall in the Australian material the genetic diversity was somewhat less. The comparison of allelic frequencies in the five native populations with the Australian material indicates that the Monterey and Año Nuevo populations were probably the major source of the original introductions and that a substantial portion of the genetic diversity in the two populations has been captured in current breeding programs. The three southern populations do not appear to be currently represented in the breeding programs. The implications for future breeding strategies are discussed.
Four- to six-year-old trees were sampled from 9 to 10 stands in each of three natural populations of Monterey pine (Pinusradiata D. Don) and studied for genetic diversity at 37 allozyme loci. Among loci, Nei's gene diversity ranged from 73 to 100% within stands, 0 to 10% between stands within populations, and 0 to 27% between populations; average values were 94.9, 1.6, and 3.5%, respectively. F-statistic analyses (B. S. Weir and C. C. Cockerham. 1984. Evolution (Lawrence, Kans.), 38: 1358–1370) indicated higher levels of stand and population differentiation than did Nei's diversity statistics: 2.6 ± 0.7 and 6.2 ± 2.6%, respectively. Homozygotes were significantly in excess relative to expectations under random mating (F IS = 0.065). Most loci showed highly significant variation of allele frequencies among populations; Nei's genetic distance averaged 0.014. Genetic and geographic distances among stands were correlated only at Año Nuevo. Introgression of genes from knobcone pine (Pinusattenuata Lemm.) was evident in the one stand where the species were sympatric. Contrary to inferences from growth and morphological characters, allozyme frequencies and other biochemical characters suggest that the Año Nuevo population diverged prior to Cambria and Monterey. Differentiation among three cohorts was studied at 10 loci. Allele frequencies varied nonsignificantly between cohorts; mean fixation indices, however, decreased monotonically with cohort age, from 0.081 in embryos to 0.038 in 5-year-old trees to −0.119 in 14- to 17-year-old trees. Selection for the more outbred progeny was the outcome of stand development.
Early investigations suggested that genetic variability might be associated with longevity, and that tree species were the most heterozygous of organisms. However, these ideas may be modified as species representing a wider range of population structure are investigated. Torrey pine, a California endemic, occurs in only two populations, one on the coast at San Diego and one 280 km northwest on Santa Rosa Island. Populations number only ca. 7,000 and 2,000 individuals, respectively. Each population is composed of identical homozygous genotypes at 59 isozyme loci. The island population is fixed for alternate alleles to those in the coastal population at two of the 59 loci. These results agree with other lines of evidence that suggest Torrey pine is characterized by minor differences between relatively uniform populations. Drift is the most likely explanation for lack of variability in Torrey pine. It probably experienced one or more reductions in population size, most recently during the Xerothermic period 8,500 to 3,000 B.P. The founder effect may have operated during colonization of Santa Rosa Island ca. 18,000 B.P. Apparently, the Northern Channel Islands to which Santa Rosa belongs were not connected to the adjacent mainland in recent geologic history, and colonization would require transport across at least a 6- to 7-km channel. Red pine and western redcedar, conifers with greater ranges than Torrey pine, are only slightly more variable. Thus, despite the presence of mechanisms to maintain high levels of outbreeding, it appears the conifer breeding system can survive inbreeding with its consequence of genetic depauperization.
Discusses a variety of ecological characteristics, summarising their predicted effects on genetic structure within and between populations, then analyses data describing genetic differentiation in plants to determine which ecological variables are consistent predictors of genetic organization. A major section of the review examines ecological and life history traits affecting genetic structure, including such ecological variables as breeding systems, floral morphology, mode of reproduction, pollination mechanisms, seed dispersal, seed dormancy, phenology, life cycle, timing of reproduction, successional stage, geographical range, population size, density, and population spatial structure. -P.J.Jarvis
A method is presented by which the gene diversity (heterozygosity) of a subdivided population can be analyzed into its components, i.e., the gene diversities within and between subpopulations. This method is applicable to any population without regard to the number of alleles per locus, the pattern of evolutionary forces such as mutation, selection, and migration, and the reproductive method of the organism used. Measures of the absolute and relative magnitudes of gene differentiation among subpopulations are also proposed.
The decomposition of the total gene diversity in a substructured population into its components is presented when the sizes on the subpopulations are not necessarily equal. The effect of unequal subpopulation sizes on the coefficient of gene diversity is also discussed. The sampling variance of this index of subdivision, derived here, can be used to measure the extent of the effect of subdivision more objectively.