scholarly journals Population genetics data help to guide the conservation of palm species with small population sizes and fragmented habitats in Madagascar

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3248 ◽  
Author(s):  
Lauren M. Gardiner ◽  
Mijoro Rakotoarinivo ◽  
Landy R. Rajaovelona ◽  
Colin Clubbe
Keyword(s):  
Genetic Diversity ◽  
Protected Area ◽  
Conservation Management ◽  
Low Cost ◽  
Large Population ◽  
Small Population ◽  
Ex Situ ◽  
Palm Species ◽  
In The Wild ◽  
Population Sizes

BackgroundThe need to incorporate genetic data into conservation management decisions is increasingly recognised. However, many published studies represent a ‘gold standard’ of sampling, techniques, and analyses. Such rigour is often not possible with limited funding and resourcing available for developing plans for the increasing number of threatened species requiring conservation management. Two endemic palm species of the Itremo Massif in central Madagascar,Dypsis ambositraeandD. decipiens, are known to be threatened with extinction and conservation management for these species is a priority for the newly created protected area in the region.MethodsThe genetic diversity of these two species was studied using the relatively low-cost and rapid AFLP technique. DNA fragments generated using three primer combinations were analysed for 20 and 50 individuals of the two species, respectively, from across their ranges.ResultsGenetic diversity was relatively low for both species. The two sites where the highly restrictedD. ambositraegrows were found to be genetically distinct (although overall heterozygosity was low). Despite having a much wider distribution and relatively large population,D. decipiensdid not show clear geographical nor genetic groupings and had similarly low genetic heterozygosity toD. ambositrae.Discussion and RecommendationsWith so few individuals remaining in the wild and two genetically distinct subpopulations, it is recommended that both sites ofD. ambositraeare conserved and that seed are collected from both forex situconservation and potential future reintroduction. It may be less important to focus resources on conserving or collectingex situmaterial from all sites whereD. decipiensis found, as the genetic diversity represented by each subpopulation is limited and increasing sampling may not protect significantly higher levels of genetic diversity. This study provides data that inform and support conservation decisions taken for both species within this region, and in the management of the newly designated Itremo Massif Protected Area, which covers most of the sites where these two species remain in the wild.

scholarly journals Genetic diversity, demographic history and neo-sex chromosomes in the Critically Endangered Raso lark

2020 ◽  
Vol 287 (1922) ◽  
pp. 20192613 ◽  
Author(s):  
Elisa G. Dierickx ◽  
Simon Yung Wa Sin ◽  
H. Pieter J. van Veelen ◽  
M. de L. Brooke ◽  
Yang Liu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Sex Chromosomes ◽  
Demographic History ◽  
Large Population ◽  
Effective Population ◽  
Island Species ◽  
Population Sizes ◽  
Approaches To Study ◽  
Genetic Signatures

Small effective population sizes could expose island species to inbreeding and loss of genetic variation. Here, we investigate factors shaping genetic diversity in the Raso lark, which has been restricted to a single islet for approximately 500 years, with a population size of a few hundred. We assembled a reference genome for the related Eurasian skylark and then assessed diversity and demographic history using RAD-seq data (75 samples from Raso larks and two related mainland species). We first identify broad tracts of suppressed recombination in females, indicating enlarged neo-sex chromosomes. We then show that genetic diversity across autosomes in the Raso lark is lower than in its mainland relatives, but inconsistent with long-term persistence at its current population size. Finally, we find that genetic signatures of the recent population contraction are overshadowed by an ancient expansion and persistence of a very large population until the human settlement of Cape Verde. Our findings show how genome-wide approaches to study endangered species can help avoid confounding effects of genome architecture on diversity estimates, and how present-day diversity can be shaped by ancient demographic events.

Weak genetic structuring suggests historically high genetic connectivity among recently fragmented urban populations of the scincid lizard, Ctenotus fallens

2015 ◽  
Vol 63 (4) ◽  
pp. 279 ◽  
Author(s):  
Josef Krawiec ◽  
Siegfried L. Krauss ◽  
Robert A. Davis ◽  
Peter B. S. Spencer
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Large Population ◽  
Geographic Distance ◽  
Genetic Erosion ◽  
Genetic Connectivity ◽  
Genetic Structuring ◽  
Low Genetic Diversity ◽  
Population Sizes

Populations in fragmented urban remnants may be at risk of genetic erosion as a result of reduced gene flow and elevated levels of inbreeding. This may have serious genetic implications for the long-term viability of remnant populations, in addition to the more immediate pressures caused by urbanisation. The population genetic structure of the generalist skink Ctenotus fallens was examined using nine microsatellite markers within and among natural vegetation remnants within a highly fragmented urban matrix in the Perth metropolitan area in Western Australia. These data were compared with samples from a large unfragmented site on the edge of the urban area. Overall, estimates of genetic diversity and inbreeding within all populations were similar and low. Weak genetic differentiation, and a significant association between geographic and genetic distance, suggests historically strong genetic connectivity that decreases with geographic distance. Due to recent fragmentation, and genetic inertia associated with low genetic diversity and large population sizes, it is not possible from these data to infer current genetic connectivity levels. However, the historically high levels of gene flow that our data suggest indicate that a reduction in contemporary connectivity due to fragmentation in C. fallens is likely to result in negative genetic consequences in the longer term.

scholarly journals Challenges to assessing connectivity between massive populations of the Australian plague locust

2011 ◽  
Vol 278 (1721) ◽  
pp. 3152-3160 ◽  
Author(s):  
Marie-Pierre Chapuis ◽  
Julie-Anne M. Popple ◽  
Karine Berthier ◽  
Stephen J. Simpson ◽  
Edward Deveson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Large Population ◽  
Movement Ecology ◽  
Effective Population ◽  
Continental Scale ◽  
Australian Continent ◽  
Population Structuring ◽  
Population Sizes ◽  
Approximate Bayesian ◽  
Australian Plague Locust

Linking demographic and genetic dispersal measures is of fundamental importance for movement ecology and evolution. However, such integration can be difficult, particularly for highly fecund species that are often the target of management decisions guided by an understanding of population movement. Here, we present an example of how the influence of large population sizes can preclude genetic approaches from assessing demographic population structuring, even at a continental scale. The Australian plague locust, Chortoicetes terminifera , is a significant pest, with populations on the eastern and western sides of Australia having been monitored and managed independently to date. We used microsatellites to assess genetic variation in 12 C. terminifera population samples separated by up to 3000 km. Traditional summary statistics indicated high levels of genetic diversity and a surprising lack of population structure across the entire range. An approximate Bayesian computation treatment indicated that levels of genetic diversity in C. terminifera corresponded to effective population sizes conservatively composed of tens of thousands to several million individuals. We used these estimates and computer simulations to estimate the minimum rate of dispersal, m , that could account for the observed range-wide genetic homogeneity. The rate of dispersal between both sides of the Australian continent could be several orders of magnitude lower than that typically considered as required for the demographic connectivity of populations.

scholarly journals Genetic diversity of seeds from four German Douglas fir (Pseudotsuga menziesii) seed orchards

2021 ◽  
Author(s):  
Birte Pakull ◽  
Pascal Eusemann ◽  
Janine Wojacki ◽  
Diana Ahnert ◽  
Heike Liesebach
Keyword(s):  
Genetic Diversity ◽  
Pseudotsuga Menziesii ◽  
Seed Orchard ◽  
Small Population ◽  
Douglas Fir ◽  
Next Generation ◽  
Seed Orchards ◽  
Population Sizes ◽  
Spatial Isolation ◽  
Offspring Generation

AbstractIn Germany, Douglas fir (Pseudotsuga menziesii Franco) is seen as a valuable species for future cultivation in times of climate change. Local seed production in seed stands and seed orchards may secure that local adaptation is transferred to the next generation, but small population sizes could lower genetic diversity and thus future adaptability. Here we analyse the transfer of genetic diversity from parent to offspring generation in four older German seed orchards. We detected low pollen contamination rates due to high levels of spatial isolation. Even with a relatively low number of 40 clones, seed orchard design with randomized and repeated planting of clones led to low selfing rates, and despite uneven parental contributions, the number of successful parents and the level of genetic intermixture were high enough to allow the transfer of an adequate part of the genetic diversity to the next generation. Larger numbers, however, might be needed to reliably conserve the entire genetic diversity over succeeding generations. Conclusions on the establishment of future seed orchards and regarding areas requiring further research are drawn at the end of the paper.

scholarly journals Classification of Genus Acanthopanax in Korea and Genetic Diversity Using Allozymes

2005 ◽  
Vol 54 (1-6) ◽  
pp. 206-210 ◽  
Author(s):  
M. K. Huh ◽  
H. W. Huh
Keyword(s):  
Genetic Diversity ◽  
Representative Sample ◽  
Genetic Relationships ◽  
Woody Species ◽  
Small Population ◽  
Geographic Ranges ◽  
Low Level ◽  
Low Genetic Diversity ◽  
Population Sizes

Abstract Genus Acanthopanax is a long-lived woody species that is primarily distributed throughout Asia. Many species of this genus are regarded as medically and ecologically important. We evaluated a representative sample of the nine taxa with allozymes to estimate genetic relationships within the genus. As some Korean populations were isolated and patchily distributed, they exhibited a low level of genetic diversity. The narrow geographic ranges, artificial distribution of habitats, and small population sizes are proposed as factors contributing to low genetic diversity. Acanthopanax seoulense was similar to A. sessiliflorus, while a cluster of the A. rufinerve population is distant from any other species. A. senticosus is closely related to A. seoulense and A. sessiliflorus, whereas other species (A. koreanum) are more distinct from the Korean populations. Korean species are clustered together and clearly differentiated from the Chinese and Russian Acanthopanax taxa, genus Acanthopanax

The effective management of threatened flora: lessons from the case of Zieria 'prostrata' ms

2000 ◽  
Vol 6 (3) ◽  
pp. 238 ◽  
Author(s):  
Patricia M. Hogbin ◽  
Rod Peakall
Keyword(s):  
Critical Evaluation ◽  
Small Population ◽  
Rare Plants ◽  
Ex Situ ◽  
North Coast ◽  
Accurate Information ◽  
Effective Management ◽  
The North ◽  
South Wales ◽  
Population Sizes

The endangered plant Zieria 'prostrata' ms is known from only four headlands along three kilometres of the north coast of New South Wales, Australia. Given its restricted range and small population sizes, Zieria 'prostrata' has been the subject of extensive management and research for almost a decade. In this paper, we review the history of management and research actions undertaken on Z. prostrata and evaluate their practical outcomes. By revisiting past management and research actions, and assessing their outcomes, we can learn much about the effective management and recovery of threatened flora. This review highlights five valuable lessons. First, effective survey is a priority for many rare plants. Second, accurate information and documentation are essential for effective conservation. Third, critical evaluation of the need for ex-situ conservation is necessary. Fourth, critical evaluation of the need for population enhancement and the most effective methods by which this can be achieved is a high priority. Fifth, adequate guidance of all those involved in recovery implementation is vital.

Genetics of reintroduced populations of the narrowly endemic thistle, Cirsium pitcheri (Asteraceae)

Botany ◽  
2013 ◽  
Vol 91 (5) ◽  
pp. 301-308 ◽  
Author(s):  
Jeremie B. Fant ◽  
Andrea Kramer ◽  
Eileen Sirkin ◽  
Kayri Havens
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Empirical Studies ◽  
Small Population ◽  
Native Plant ◽  
Effective Population ◽  
Term Survival ◽  
Inbreeding Coefficients ◽  
Native Populations ◽  
Population Sizes

The aim of any reintroduction is to provide sufficient genetic variability to buffer against changing selection pressures and ensure long-term survival. To date, few empirical studies have compared levels of genetic diversity in reintroduced and native plant populations. Using microsatellite markers, we measured the genetic diversity within reintroduced and native populations of the threatened Cirsium pitcher (Eaton) Torrey and Gray. We found that the use of local mixed source was successful in establishing populations with significantly higher genetic diversity (P < 0.005) than the native populations (allelic richness is 3.39 in reintroduced and 1.84 in native populations). However, the reintroduced populations had significantly higher inbreeding coefficients (P < 0.002) (FIS is 0.405 and 0.213 in reintroduced and in native populations, respectively), despite having multiple genetic founders, population sizes equivalent to native populations and a positive growth rate. These results may be due to inbreeding or the Wahlund effect, driven by genetic substructuring. This suggests that the small population size of these reintroduced populations may lead to genetic issues in the future, given the low number of flowering individuals each year. This highlights the importance of considering not only the number of source individuals but the effective population size of the reintroduction.

Evidence for clonality, breeding system, genetic diversity and genetic structure in large and small populations of Melaleuca deanei (Myrtaceae)

2019 ◽  
Vol 67 (1) ◽  
pp. 36 ◽  
Author(s):  
Alison Hewitt ◽  
Paul Rymer ◽  
Paul Holford ◽  
E. Charles Morris ◽  
Adrian Renshaw
Keyword(s):  
Genetic Diversity ◽  
Breeding System ◽  
Seedling Recruitment ◽  
Conservation Management ◽  
Ex Situ ◽  
Molecular Evidence ◽  
Large Populations ◽  
Root Suckering ◽  
Multiple Stems

Melaleuca deanei F.Muell. is a rare, serotinous shrub with a naturally restricted distribution centred over the sandstone ridges around Sydney. Sexual reproduction and seedling recruitment occur rarely, and plants appear to spread and persist largely by clonal root suckering. A potentially outcrossing breeding system, combined with extensive clonality, place M. deanei at a high risk of reproductive failure. Knowledge of the extent of its clonality and breeding system, and an understanding of the distribution and abundance of genetic diversity within and among its populations, will assist conservation management. The present study reports on the extent of clonality, breeding system, levels of genetic diversity, and population differentiation within small, medium and large populations of M. deanei from the northern and southern distribution regions. Multiple stems were found to comprise single genets up to ~10 m diameter on the ground and molecular evidence points to an outcrossing breeding system. Genetic diversity was positively correlated with population size and significant genetic differentiation was shown between northern and southern regions using clustering analyses. Recommendations for in situ and ex situ conservation management based on these results are provided.

RESTRICTION FRAGMENT LENGTH POLYMORPHISM IN WILD AND CULTIVATED TETRAPLOID WHEAT

1999 ◽  
Vol 47 (4) ◽  
pp. 213-224 ◽  
Author(s):  
Li Huang ◽  
Eitan Millet ◽  
Junkang Rong ◽  
Jonathan F. Wendel ◽  
Yehoshua Anikster ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Triticum Turgidum ◽  
Large Population ◽  
Tetraploid Wheat ◽  
Nuclear Genome ◽  
Wild Emmer ◽  
Long Term Study ◽  
In The Wild

RFLP diversity in the nuclear genome was estimated within and among Israeli populations of wild emmer wheat (Triticum turgidumvar.dicoccoides) from a long-term study site at Ammiad (NE Israel), and from several other geographical locations. Using 55 enzyme-probe combinations, high levels of genetic diversity were revealed in wild emmer in general and within the Ammiad site. In spite of high diversity, observed heterozygosity was low and populations consisted of a patchwork of alternate multilocus homozygotes, consistent with the reproductive biology of a predominant self-fertilizing species. Retention of genetic diversity in wild emmer may be promoted by large population sizes, microhabitat diversity, and occasional gene flow through both pollen and seed. Population genetic structure in wild emmer appears to have been influenced by historical founder events as well as selective factors. Multivariate analyses indicated that individuals tend to cluster together according to their population of origin, and that there is little geographical differentiation among populations. Sampling of 12 domesticated land-races and both primitive and modern cultivars ofT. turgidumrevealed high levels of diversity and a large number of alleles that were not detected in the wild emmer populations. This may reflect a long-term domestication process in which wild, semi-domesticated, and domesticated types grew sympatrically, continuing introgression from wild populations, and perhaps also gene flow from trans-specific sources.

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