Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “conservation genetics”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2006

Estimation of breed contributions to present and future genetic diversity of 44 North Eurasian cattle breeds using core set diversity measures.

Extinction of breeds threatens genetic diversity of livestock species. The need to conserve genetic diversity is widely accepted but involves in general two questions: (i) is the expected loss of diversity in a set of breeds within a defined future time horizon large enough to establish a conservation plan, and if so (ii) which breeds should be prioritised for such a conservation plan? The present study uses a marker assisted methodology to address these questions. The methodology combines core set diversity measures with a stochastic method for the estimation of expected future diversity and breed marginal diversities. The latter is defined as the change in the total diversity of all breeds caused by a one unit decrease in extinction probability of a particular breed. The stochastic method was validated by means of simulations. A large field data set consisting of 44 North Eurasian cattle breeds was analysed using simplified determined extinction probabilities. The results show that the expected loss of diversity in this set within the next 20 to 50 years is between 1 and 3% of the actual diversity, provided that the extinction probabilities which were used are approximately valid. If this loss is to be reduced, it is sufficient to include those three to five breeds with the highest marginal diversity in a conservation scheme.

Animals↗
PubMed2003

Applying molecular genetic tools to the conservation and action plan for the critically endangered Far Eastern leopard (Panthera pardus orientalis).

A role for molecular genetic approaches in conservation of endangered taxa is now commonly recognized. Because conservation genetic analyses provide essential insights on taxonomic status, recent evolutionary history and current health of endangered taxa, they are considered in nearly all conservation programs. Genetic analyses of the critically endangered Far Eastern, or Amur leopard, Panthera pardus orientalis, have been done recently to address all of these questions and develop strategies for survival of the leopard in the wild. The genetic status and implication for conservation management of the Far Eastern leopard subspecies are discussed.

Animals↗
PubMed1983

Isozyme assessment of plant genetic resources.

The genetic resources of cultivated plants consist of the genetic diversity present among developed cultivars, in the land races or primitive stocks, and in wild populations of their evolutionary relatives. Genetic evaluation of these resources through isozyme studies provides an important aid in efficient collection, storage, and use. Recent isozyme studies with barley exemplify these points. The allelic isozyme diversity present in 12 land race samples from Iran has been compared with that found in cultivars on the one hand, and natural populations of wild barley (H spontaneum) on the other. The primitive materials were on average more variable than the cultivars but less variable than the wild populations, supporting the view that the land races are or crucial importance in genetic conservation. Some roles for isozyme data in the manipulation of genetic resources have been outlined.

Agriculture↗
PubMed2000

Evolution of the mitochondrial genetic system: an overview.

Mitochondria, semi-autonomous organelles possessing their own genetic system, are commonly accepted to descend from free-living eubacteria, namely hydrogen-producing alpha-proteobacteria. The progressive loss of genes from the primitive eubacterium to the nucleus of the eukaryotic cell is strongly justified by the Muller rachet principle, which postulates that asexual genomes, like mitochondrial ones, accumulate deleterious and sublethal mutations faster than sexual genomes, like the nucleus. According to this principle, the mitochondrial genome would be doomed to death; instead, we observe that the mitochondrial genome has a variable size and structure in the different organisms, though it contains more or less the same set of genes. This is an example of genetic conservation versus structural diversity. From an evolutionary point of view the genetic system of organelles is clearly under strong selective pressure and for its survival it needs to utilize strategies to slow down or halt the ratchet. Anyway, the mitochondrial genome changes with time, and the rate of evolution is different for both diverse regions of the mtDNA and between lineages, as demonstrated in the case of mammalian mt genomes. We report here our data on the evolution of the mitochondrial DNA in mammals which demonstrate the suitability of mtDNA as a molecular tool for evolutionary analyses.

Animals↗
PubMed1995

[Studies on theory and models of systemic conservation of animal and poultry genetic resources. I. Theory analysis of systemic conservation of animal and poultry genetic resources].

The concept and fundamentals of Systemic Conservation of Animal and Poultry Genetics Resources (SCAPGR) and mathematical models of genetic structure with conservation population were proposed. The SCAPGR regarded all genes of a given species in definite time and space as conservation object and live animal preservation combining with modern biotechnology as basic method. The SCAPGR might systematically conserve genes controlling the characters of a given species as well as regional varieties. In a no overlapping generation population with selection, mutation migration and random drift under consideration, two mathematical models presented in this paper might describe change of frequencies of multiple alleles at a locus and population mean of metrical characters resp.

Animals↗
PubMed1999

Preserving genes, species, or ecosystems? Healing the fractured foundations of conservation policy.

The scientific foundations of conservation policy are the subject of a recent tripolar debate, with systematists arguing for the primacy of phylogenetic rankings, ecologists arguing for protection at the level of populations or ecosystems, and evolutionary biologists urging more attention for the factors that enhance adaptation and biodiversity. In the field of conservation genetics, this controversy is manifested in the diverse viewpoints of molecular systematists, population biologists, and evolutionary (and quantitative) geneticists. A resolution of these viewpoints is proposed here, based on the premise that preserving particular objects (genes, species, or ecosystems) is not the ultimate goal of conservation. In order to be successful, conservation efforts must preserve the processes of life. This task requires the identification and protection of diverse branches in the tree of life (phylogenetics), the maintenance of life-support systems for organisms (ecology), and the continued adaptation of organisms to changing environments (evolution). None of these objectives alone is sufficient to preserve the threads of life across time. Under this temporal perspective, molecular genetic technologies have applications in all three conservation agendas; DNA sequence comparisons serve the phylogenetic goals, population genetic markers serve the ecological goals, quantitative genetics and genome explorations serve the evolutionary goals.

Animals↗
PubMed2005

Strong spatial genetic structure in peripheral but not core populations of Sitka spruce [Picea sitchensis (Bong.) Carr.].

We examined spatial genetic structure within eight populations of Sitka spruce classified as core or peripheral based on ecological niche, and continuous or disjunct based on species distribution. In each population, 200 trees were spatially mapped and genotyped for eight cDNA-based sequence tagged site (STS) codominant markers. Spatial autocorrelation was assessed by estimating p(ij), the average co-ancestry coefficient, between individuals within distance intervals. The distribution of alleles and genotypes within core populations was almost random, with nonsignificant co-ancestry values among trees as close as 50 m in core populations. In contrast, the distribution of alleles and genotypes within peripheral populations revealed an aggregation of similar multilocus genotypes, with co-ancestry values greater than 0.20 among trees up to 50 m apart and significant, positive values between trees up to 500 m. The relatively high density of reproductive adults in core populations may lead to highly overlapping seed shadows that limit development of spatial genetic structure. However, in peripheral populations with a lower density of adults, the distribution of alleles and genotypes was highly structured, likely due to offspring establishment near maternal trees and subsequent biparental inbreeding, as well as more recent population establishment at the leading edge of post-Pleistocene range expansion. Conserving genetic diversity in peripheral populations may require larger reserves for in situ conservation than required in core populations. These data on spatial genetic structure can be used to provide guidance for sampling strategies for both ex situ conservation and research collections.

British Columbia↗
PubMed2002

Population structure of the tsetse fly Glossina pallidipes estimated by allozyme, microsatellite and mitochondrial gene diversities.

Diversities at nuclear and mitochondrial loci were examined in eleven natural populations of Glossina pallidipes from east and southern Africa. Alleles in each class of loci are assumed to be selectively neutral. Allozyme gene diversities (heterozygosities) averaged over eight loci were 0.146 among seven Kenya populations and 0.201 among four southern African populations. Microsatellite diversity averaged over three loci was 0.250 in Kenya and only 0.218 in southern Africa. Mitochondrial diversities averaged 0.504 in Kenya and only 0.156 in southern Africa. Mitochondrial and microsatellite diversities in the populations were strongly correlated with each other, but uncorrelated with allozyme diversities. In contrast to the allozyme diversities, mitochondrial and microsatellite variation indicated a severe and prolonged reduction in population size in southern Africa. Genetic distances among populations increased with the geographical distances between them. Allozyme diversities in southern populations were conserved. Genetic differentiation at allozyme loci among populations was greatly damped when compared with the other markers. The foregoing can be explained if allozyme diversities were maintained by balancing selection. Three main points emerged: genetic data confirm the historical evidence that southern G. pallidipes populations experienced a severe and prolonged bottleneck; allozyme variation was conserved in the bottlenecked populations; and gene flow among populations is surprisingly restricted.

Alleles↗
PubMed2005

Comparative genomic hybridizations reveal genetic regions within the Mycobacterium avium complex that are divergent from Mycobacterium avium subsp. paratuberculosis isolates.

Mycobacterium avium subsp. paratuberculosis is genetically similar to other members of the Mycobacterium avium complex (MAC), some of which are nonpathogenic and widespread in the environment. We have utilized an M. avium subsp. paratuberculosis whole-genome microarray representing over 95% of the predicted coding sequences to examine the genetic conservation among 10 M. avium subsp. paratuberculosis isolates, two isolates each of Mycobacterium avium subsp. silvaticum and Mycobacterium avium subsp. avium, and a single isolate each of both Mycobacterium intracellulare and Mycobacterium smegmatis. Genomic DNA from each isolate was competitively hybridized with DNA from M. avium subsp. paratuberculosis K10, and open reading frames (ORFs) were classified as present, divergent, or intermediate. None of the M. avium subsp. paratuberculosis isolates had ORFs classified as divergent. The two M. avium subsp. avium isolates had 210 and 135 divergent ORFs, while the two M. avium subsp. silvaticum isolates examined had 77 and 103 divergent ORFs. Similarly, 130 divergent ORFs were identified in M. intracellulare. A set of 97 ORFs were classified as divergent or intermediate in all of the nonparatuberculosis MAC isolates tested. Many of these ORFs are clustered together on the genome in regions with relatively low average GC content compared with the entire genome and contain mobile genetic elements. One of these regions of sequence divergence contained genes homologous to a mammalian cell entry (mce) operon. Our results indicate that closely related MAC mycobacteria can be distinguished from M. avium subsp. paratuberculosis by multiple clusters of divergent ORFs.

Conserved Sequence↗
PubMed2006

Population structure of brush-tailed rock-wallaby (Petrogale penicillata) colonies inferred from analysis of faecal DNA.

Genetic data obtained using faecal DNA were used to elucidate the population structure of four brush-tailed rock-wallaby (Petrogale penicillata) colonies located in Wollemi National Park, New South Wales. The results suggested that the four sampled colonies are genetically differentiated and do not form a panmictic unit. Based on assignment tests, approximately 5% of sampled individuals were inferred to be dispersers and both male and female migrants were detected. Multilocus spatial autocorrelation analyses provided evidence for increased philopatry among females compared to males within the largest colony in the valley. Females in close spatial proximity were more genetically similar than expected under a random distribution of females, and females separated by more than 400 m were less genetically similar than expected. In contrast, there was no evidence of a significant clustering of related males. This suggests that within-colony dispersal is male biased. We also investigated the best strategies for conserving genetic diversity in this population. All of the four sampled colonies were found to contain distinct components of the genetic diversity of the Wolgan Valley P. penicillata population and loss of any colony is likely to result in the loss of unique alleles. Conservation and management plans should take into account that these colonies represent genetically differentiated discrete subpopulations. This approach is also the best strategy for maintaining the genetic diversity of the populations in this valley.

Analysis of Variance↗
PubMed2000

Interrelations between effective population size and other pedigree tools for the management of conserved populations.

Genetic parameters widely used to monitor genetic variation in conservation programmes, such as effective number of founders, founder genome equivalents and effective population size, are interrelated in terms of coancestries and variances of contributions from ancestors to descendants. A new parameter, the effective number of non-founders, is introduced to describe the relation between effective number of founders and founder genome equivalents. Practical recommendations for the maintenance of genetic variation in small captive populations are discussed. To maintain genetic diversity, minimum coancestry among individuals should be sought. This minimizes the variances of contributions from ancestors to descendants in all previous generations. The method of choice of parents and the system of mating should be independent of each other because a clear-cut recommendation cannot be given on the latter.

Breeding↗
PubMed1994

The use of museum specimens to reconstruct the genetic variability and relationships of extinct populations.

In this review, we discuss the use of DNA from museum specimens to address conservation genetic questions. We provide four examples from our previous studies of the northern hairy-nosed wombat, African wild dog, Ethiopian wolf and red wolf. These species were genetically surveyed using two molecular approaches: first, analysis of short sequences in the mitochondrial genome using species-specific primers, and second, analysis of hypervariable microsatellite loci. The studies demonstrate that museum-derived DNA adds an important dimension to the genetic study of extant populations. Inaccessible populations can be studied, and both the loss of genetic variation and its distribution over space and time can be better understood. Finally, analysis of additional museum material provides definitive evidence for a hybrid origin of the red wolf.

Animals↗
PubMed1996

Hypothesis on a casual link between EMF and an evolutionary class of cancer and spontaneous abortion.

A biophysical theory is presented that supports a causal link between EMF exposures and the different biological endpoints of cancer and spontaneous abortion. The model for time-dependent instability of DNA specificity [Biochem. Genet. 32, 383 (1994)] is assumed to have been operational since DNA became selected as the molecular structure for the genome. Species were consequently required to adapt mechanisms to protect haploid gene pools from the continuous time-dependent accumulation of evolutionary base substitutions. To this end, conserved genetic domains containing mutation-intolerance thresholds are a result of natural selection operating on time-dependent base substitutions. "P53-type" genes are examples of such conserved domains with point mutation thresholds. When the oocyte is fertilized, conserved domains express wild type keto-amino genetic information. During subsequent development and growth, time-dependent evolution events populate G-C sites with enol-imine stationary states that can be transcribed and/or replicated to express transversion and transition mutations. As the level of evolution events would approach the intolerance threshold in the haploid genome, point mutation sensitive genes from conserved diploid domains, e.g. "p53-type" genes, would generate amino acid substituted proteins that have been evolutionarily selected to participate in species preservation by removing from the gene pool those haploid genomes containing advanced levels of mutation which, if propagated, would be inconsistent with survival. Consistent with the evolutionary origin of cancer hypothesis [Cancer Biochem. Biophys: 13, 147 (1993)], perturbations that would enhance rates of populating G-C sites with enol-imine states could accelerate point mutation "activation" of "p53-type" genes that could be manifested as premature cancer in living populations or expressed as spontaneous abortion in unborn populations. The evolution event "rate constant" is (gamma/h)2 where gamma is the quantum mechanical energy shift between G-C states. This expression implies that "additional" magnetic fields could increase rates of populating enol-imine states due to Lorentz force momentum transfer to metastable proton oscillators where induced electric fields and local currents would subject elevated energy proton oscillators to collisional de-exciatations which would increase the energy density of chemical bonds that support hydrogen bonds in DNA, thereby introducing larger energy shift values in (gamma/h)2. This hypothesis is explored for "additional" magnetic fields in the range of 0.15 to 0.01 gauss where the influence of magnetic enhancement energies on rates of populating enol-imine stationary states is evaluated, using Gurney and Condon tunneling time calculations for unperturbed and magnetically enhanced protons to escape metastable keto-amino energy wells. Model calculations are qualitative and are consistent with the experimentally testable hypothesis that "additional" magnetic fields could cause increased rates of accumulating evolutionary base substitutions, thereby increasing probabilities of activating "p53-type" genes which could cause increased incidence of spontaneous abortion in unborn populations and increased incidence of cancer in living populations.

Abortion, Spontaneous↗
PubMed2005

Low genetic diversity in a marine nature reserve: re-evaluating diversity criteria in reserve design.

Little consideration has been given to the genetic composition of populations associated with marine reserves, as reserve designation is generally to protect specific species, communities or habitats. Nevertheless, it is important to conserve genetic diversity since it provides the raw material for the maintenance of species diversity over longer, evolutionary time-scales and may also confer the basis for adaptation to environmental change. Many current marine reserves are small in size and isolated to some degree (e.g. sea loughs and offshore islands). While such features enable easier management, they may have important implications for the genetic structure of protected populations, the ability of populations to recover from local catastrophes and the potential for marine reserves to act as sources of propagules for surrounding areas. Here, we present a case study demonstrating genetic differentiation, isolation, inbreeding and reduced genetic diversity in populations of the dogwhelk Nucella lapillus in Lough Hyne Marine Nature Reserve (an isolated sea lough in southern Ireland), compared with populations on the local adjacent open coast and populations in England, Wales and France. Our study demonstrates that this sea lough is isolated from open coast populations, and highlights that there may be long-term genetic consequences of selecting reserves on the basis of isolation and ease of protection.

Analysis of Variance↗
PubMed2004

Contributions of Portuguese cattle breeds to genetic diversity using marker-estimated kinships.

The quantitative assessment of genetic diversity within and between populations is important for decision-making in genetic conservation plans. In our study, we applied the livestock core set method to define the contribution of 15 cattle breeds, 11 of which are Portuguese indigenous cattle breeds, to genetic diversity. In livestock core set theory genetic diversity is defined as the maximum genetic variance that can be obtained in a random-mating population that is bred from the populations present in that core set. Two methods to estimate marker-estimated kinships to obtain the contributions to the core set were used in this study: the weighted log-linear model (WLM) and the weighted log-linear mixed model (WLMM). The breeds that contributed most to diversity in the core set were Holstein-Friesian followed by the Portuguese Mertolenga and Cachena for both WLM and WLMM methods. The ranking of relative contributions of cattle breeds was maintained when we considered only the Portuguese cattle breeds. Furthermore, we were able to identify the marginal contributions and respective losses of diversity for each of the 11 Portuguese cattle breeds when we considered a subset of populations that are not threatened of being lost (the Safe set composed of the four exotic breeds present in this study). When WLM was used losses in genetic diversity ranged from 2.68 to 0.65% while the loss in founder genome equivalents ranged from 37.37 to 8.43% for Mertolenga and Brava de Lide breeds respectively. When WLMM was used losses in genetic diversity and founder genome equivalents were less extreme than for the WLM method, ranging from 1.27 to 0.69 and 26.8 to 12.99 respectively.

Animals↗
PubMed1995

[Studies on theory and models of systemic conservation of animal and poultry genetic resources. II. Simulation experiment of systemic conservation of animal and poultry genetic resources].

Tribolium castaneum simulation and computer simulation proved the feasibility and rationality of Systemic Conservation of Animal and Poultry Genetic Resources (SCAPGR) theory and the biological meaning of the SCAPGR mathematical models. It also demonstrated that the right effective population size should be maintained and gene flow among populations should be controlled and adequate selecting method and mating system should determined according to population genetic characters of gene conserved in the SCAPGR population.

Animals↗
PubMed1992

Natural genetic engineering in evolution.

The results of molecular genetics have frequently been difficult to explain by conventional evolutionary theory. New findings about the genetic conservation of protein structure and function across very broad taxonomic boundaries, the mosaic structure of genomes and genetic loci, and the molecular mechanisms of genetic change all point to a view of evolution as involving the rearrangement of basic genetic motifs. A more detailed examination of how living cells restructure their genomes reveals a wide variety of sophisticated biochemical systems responsive to elaborate regulatory networks. In some cases, we know that cells are able to accomplish extensive genome reorganization within one or a few cell generations. The emergence of bacterial antibiotic resistance is a contemporary example of evolutionary change; molecular analysis of this phenomenon has shown that it occurs by the addition rearrangement of resistance determinants and genetic mobility systems rather than by gradual modification of pre-existing cellular genomes. In addition, bacteria and other organisms have intricate repair systems to prevent genetic change by sporadic physicochemical damage or errors of the replication machinery. In their ensemble, these results show that living cells have (and use) the biochemical apparatus to evolve by a genetic engineering process. Future research will reveal how well the regulatory systems integrate genomic change into basic life processes during evolution.

Animals↗
PubMed2004

Genetic variation increases during biological invasion by a Cuban lizard.

A genetic paradox exists in invasion biology: how do introduced populations, whose genetic variation has probably been depleted by population bottlenecks, persist and adapt to new conditions? Lessons from conservation genetics show that reduced genetic variation due to genetic drift and founder effects limits the ability of a population to adapt, and small population size increases the risk of extinction. Nonetheless, many introduced species experiencing these same conditions during initial introductions persist, expand their ranges, evolve rapidly and become invasive. To address this issue, we studied the brown anole, a worldwide invasive lizard. Genetic analyses indicate that at least eight introductions have occurred in Florida from across this lizard's native range, blending genetic variation from different geographic source populations and producing populations that contain substantially more, not less, genetic variation than native populations. Moreover, recently introduced brown anole populations around the world originate from Florida, and some have maintained these elevated levels of genetic variation. Here we show that one key to invasion success may be the occurrence of multiple introductions that transform among-population variation in native ranges to within-population variation in introduced areas. Furthermore, these genetically variable populations may be particularly potent sources for introductions elsewhere. The growing problem of invasive species introductions brings considerable economic and biological costs. If these costs are to be mitigated, a greater understanding of the causes, progression and consequences of biological invasions is needed.

Animal Migration↗