scholarly journals Effects of habitat fragmentation and human disturbance on the population dynamics of the Yunnan snub-nosed monkey from 1994 to 2016

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6633 ◽  
Author(s):  
Xumao Zhao ◽  
Baoping Ren ◽  
Dayong Li ◽  
Zuofu Xiang ◽  
Paul A. Garber ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Dynamics ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Linear Models ◽  
Conservation Strategies ◽  
Source Population ◽  
Forest Patches ◽  
Current Conservation ◽  
Conservation Policies

In this study, we integrate data from field investigations, spatial analysis, genetic analysis, and Generalized Linear Models (GLMs) to evaluate the effects of habitat fragmentation on the population dynamics, genetic diversity, and range shifts in the endangered Yunnan snub-nosed monkey (Rhinopithecus bieti). The results indicate that from 1994 to 2016, R. bieti population size increased from less than 2,000 to approximately 3,000 individuals. A primary factor promoting population recovery was the establishment of protected nature reserves. We also found that subpopulation growth rates were uneven, with the groups in some areas, and the formation of new groups. Both the fragmentation index, defined as the ratio of the number of forest patches to the total area of forest patches (e.g., increased fragmentation), and increasing human population size had a negative effect on population growth in R. bieti. We recommend that government conservation plans prioritize the protection of particular R. bieti populations, such as the Baimei and Jisichang populations, which have uncommon haplotypes. In addition, effective conservation strategies need to include an expansion of migration corridors to enable individuals from larger populations such as Guyoulong (Guilong) to serve as a source population to increase the genetic diversity of smaller R. bieti subpopulations. We argue that policies designed to protect endangered primates should not focus solely on total population size but also need to determine the amount of genetic diversity present across different subpopulations and use this information as a measure of the effectiveness of current conservation policies and the basis for new conservation policies.

scholarly journals Genetic diversity and structure of Saussurea polylepis (Asteraceae) on continental islands of Korea: Implications for conservation strategies and management

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0249752
Author(s):  
Seon A. Yun ◽  
Seung-Chul Kim
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Population Size ◽  
Anthropogenic Activities ◽  
Large Population ◽  
Conservation Strategies ◽  
Source Population ◽  
Genetic Diversity And Structure ◽  
Continental Islands

Saussurea polylepis Nakai is an herbaceous perennial endemic to Korea and is highly restricted to several continental islands in the southwestern part of the Korean Peninsula. Given its very narrow geographical distribution, it is more vulnerable to anthropogenic activities and global climate changes than more widely distributed species. Despite the need for comprehensive genetic information for conservation and management, no such population genetic studies of S. polylepis have been conducted. In this study, genetic diversity and population structure were evaluated for 97 individuals from 5 populations (Gwanmaedo, Gageodo, Hongdo, Heusando, and Uido) using 19 polymorphic microsatellites. The populations were separated by a distance of 20–90 km. We found moderate levels of genetic diversity in S. polylepis (Ho = 0.42, He = 0.43). This may be due to long lifespans, outcrossing, and gene flow, despite its narrow range. High levels of gene flow (Nm = 1.76, mean Fst = 0.09), especially from wind-dispersed seeds, would contribute to low levels of genetic differentiation among populations. However, the small population size and reduced number of individuals in the reproductive phase of S. polylepis can be a major threat leading to inbreeding depression and genetic diversity loss. Bayesian cluster analysis revealed three significant structures at K = 3, consistent with DAPC and UPGMA. It is thought that sea level rise after the last glacial maximum may have acted as a geographical barrier, limiting the gene flow that would lead to distinct population structures. We proposed the Heuksando population, which is the largest island inhabited by S. polylepis, as a source population because of its large population size and high genetic diversity. Four management units (Gwanmaedo, Gageodo, Hongdo-Heuksando, and Uido) were suggested for conservation considering population size, genetic diversity, population structure, unique alleles, and geographical location (e.g., proximity).

scholarly journals Low genetic diversity in the endangered Taxus yunnanensis following a population bottleneck, a low effective population size and increased inbreeding

2016 ◽  
Vol 65 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Y. C. Miao ◽  
Z. J. Zhang ◽  
J. R. Su
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Effective Population Size ◽  
Spatial Genetic Structure ◽  
Population Bottleneck ◽  
Effective Population ◽  
Taxus Yunnanensis ◽  
Low Genetic Diversity ◽  
Two Populations

Abstract Taxus yunnanensis, which is an endangered tree that is considered valuable because it contains the effective natural anticancer metabolite taxol and heteropolysaccharides, has long suffered from severe habitat fragmentation. In this study, the levels of genetic diversity in two populations of 136 individuals were analyzed based on eleven polymorphic microsatellite loci. Our results suggested that these two populations were characterized by low genetic diversity (NE = 2.303/2.557; HO = 0.168/0.142; HE = 0.453/0.517), a population bottleneck, a low effective population size (Ne = 7/9), a high level of inbreeding (FIS = 0.596/0.702), and a weak, but significant spatial genetic structure (Sp = 0.001, b = −0.001*). Habitat fragmentation, seed shadow overlap and limited seed and pollen dispersal and potential selfing may have contributed to the observed gene tic structure. The results of the present study will enable development of practical conservation measures to effectively conserve the valuable genetic resources of this endangered plant.

scholarly journals Low Neutral Genetic Diversity in an Isolated Greater Sage Grouse (Centrocercus Urophasianus) Population in Northwest Wyoming

2012 ◽  
Vol 35 ◽  
pp. 119-133
Author(s):  
Sarah Schulwitz ◽  
Jeff Johnson ◽  
Bryan Bedrosian
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Centrocercus Urophasianus ◽  
Small Population ◽  
Suitable Habitat ◽  
Sage Grouse ◽  
Asymmetric Dispersal ◽  
Anthropogenic Habitat ◽  
Neutral Genetic Diversity

Habitat loss is well recognized as an immediate threat to biodiversity. Depending on the dispersal capabilities of the species, increased habitat fragmentation often results in reduced functional connectivity and gene flow followed by population decline and a higher likelihood of eventual extinction. Knowledge of the degree of connectivity between populations is therefore crucial for better management of small populations in a changing landscape. A small population of greater sage-grouse (Centrocercus urophasianus) exists in northwest Wyoming within the Jackson Hole valley, including Grand Teton National Park and the National Elk Refuge. To what degree the Jackson population is isolated is not known as natural dispersal barriers in the form of mountains and anthropogenic habitat fragmentation may limit the population’s connectivity to adjacent populations. Using 16 microsatellite loci and 300 greater sage-grouse samples collected throughout Wyoming and southeast Montana, significant population differentiation was found to exist among populations. Results indicated that the Jackson population was isolated relative to the other sampled populations, including Pinedale, its closest neighboring large population to the south. The one exception was a small population immediately to the east of Jackson, in which asymmetric dispersal from Jackson into Gros Ventre was detected. Both Jackson and Gros Ventre populations exhibited significantly reduced levels of neutral genetic diversity relative to other sampled populations. More work is warranted to determine the timing at which Jackson and Gros Ventre populations had become isolated and whether it was primarily due to recent habitat fragmentation or more historic processes. Due to its small population size, continual monitoring of the population is recommended with the goal of at least maintaining current population size and, if possible, increasing suitable habitat and population size to levels recorded in the past.

scholarly journals Genetic consequences of subtropical rainforest fragmentation on Macadamia tetraphylla (Proteaceae)

2011 ◽  
Vol 60 (1-6) ◽  
pp. 241-249 ◽  
Author(s):  
C. S. Spain ◽  
A. J. Lowe
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Population Size ◽  
Population Differentiation ◽  
Adult Population ◽  
Population Divergence ◽  
Population Bottlenecks ◽  
Significant Difference ◽  
Adult Tree ◽  
Eventual Loss

Abstract Habitat fragmentation can bring about a variety of gene-flow alterations in plant populations, potentially threatening adaptive potential and local persistence. It is expected that following habitat fragmentation an increased level of inbreeding will be evident. In addition, a reduction in genetic diversity and increased genetic differentiation is expected following severe or long term population bottlenecks. We examined population genetic parameters for the subtropical rainforest tree Macadamia tetraphylla (Proteaceae) at six field sites throughout its recently fragmented range, using four microsatellite loci. Genetic diversity (HE) of the juvenile cohort was significantly correlated with estimated population size. No significant difference was observed for genetic diversity between adult and juvenile cohorts, but juveniles, and not adults, exhibited significant population differentiation (θ =0.061; P<0.0001 and θ =0.016; P=0.23, respectively). A second, standardised measure of differentiation, ×′, yielded similarly large differences between the two cohorts, though higher estimates of differentiation overall (adults – θ′=0.034, juveniles – θ′=0.116). The coefficient of population inbreeding (f) was significant and positive in all juvenile, and four out of six adult, populations, and was significantly positively correlated with adult tree density, but not adult population size. Since fragmentation is relatively recent for this species, the population bottleneck must have been quite severe to have produced the observed patterns of population differentiation and genetic diversity. Fragmentation of forest across the study area over the last 100+ years has led to the genetic isolation of M. tetraphylla populations resulting in increased population divergence and likely eventual loss of genetic variation in future generations.

scholarly journals Population genetic structure of the Natterjack toad (Epidalea calamita) in Ireland: implications for conservation management

2021 ◽  
Author(s):  
Marina Reyne ◽  
Kara Dicks ◽  
Claire McFarlane ◽  
Aurélie Aubry ◽  
Mark Emmerson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Population Genetic ◽  
Species Conservation ◽  
Conservation Strategies ◽  
Population Declines ◽  
Effective Population ◽  
Genetic Structuring ◽  
Genetic Diversity And Structure ◽  
Epidalea Calamita

AbstractMolecular methods can play a crucial role in species management and conservation. Despite the usefulness of genetic approaches, they are often not explicitly included as part of species recovery plans and conservation practises. The Natterjack toad (Epidalea calamita) is regionally Red-Listed as Endangered in Ireland. The species is declining and is now present at just seven sites within a highly restricted range. This study used 13 highly polymorphic microsatellite markers to analyse the population genetic diversity and structure. Genetic diversity was high with expected heterozygosity between 0.55 and 0.61 and allelic richness between 4.77 and 5.92. Effective population sizes were small (Ne < 100 individuals), but not abnormal for pond breeding amphibians. However, there was no evidence of historical or contemporary genetic bottlenecks or high levels of inbreeding. We identified a positive relationship between Ne and breeding pond surface area, suggesting that environmental factors are a key determinant of population size. Significant genetic structuring was detected throughout the species’ range, and we identified four genetic entities that should be considered in the species’ conservation strategies. Management should focus on preventing further population declines and future loss of genetic diversity overall and within genetic entities while maintaining adequate local effective population size through site-specific protection, human-mediated translocations and head-start programs. The apparent high levels of genetic variation give hope for the conservation of Ireland’s rarest amphibian if appropriately protected and managed.

scholarly journals Conservation biology of threatened Mediterranean chasmophytes: The case of Asperula naufraga endemic to Zakynthos island (Ionian islands, Greece)

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246706 ◽  
Author(s):  
Anna-Thalassini Valli ◽  
Vassiliki Lila Koumandou ◽  
Gregoris Iatrou ◽  
Marios Andreou ◽  
Vasileios Papasotiropoulos ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Extinction Risk ◽  
Conservation Status ◽  
Small Population ◽  
Ex Situ ◽  
Current Conservation ◽  
Ionian Islands ◽  
Small Population Size ◽  
Area Of Occupancy

Asperula naufraga is a rare and threatened obligate chasmophyte, endemic to Zakynthos island (Ionian islands, Greece). In this study, we provide a combined approach (including monitoring of demographic and reproductive parameters and study of genetic diversity) to assess the current conservation status of the species and to estimate its future extinction risk. The five subpopulations of A. naufraga were monitored for five years (2014–2018). Population size markedly fluctuated between 68–130 mature individuals during the monitoring period. The extent of occurrence (EOO) was estimated at 28.7 km2 and the area of occupancy (AOO) was 8 km2. Stage-structure recordings were similar for all subpopulations, characterized by high proportions of adult and senescent individuals, following a common pattern, which has been observed in other cliff-dwelling plants. Preliminary genetic analysis with SSRs markers revealed low heterozygosity within subpopulations and significant departure from H-W equilibrium, which combined with small population size suggest increased threat of genetic diversity loss. Our results indicate that the species should be placed in the Critically Endangered (CR) IUCN threat category, while according to Population Viability Analysis results its extinction risk increases to 47.8% in the next 50 years. The small population size combined with large fluctuations in its size, low recruitment and low genetic diversity, indicate the need of undertaking effective in situ and ex situ conservation measures.

scholarly journals Does the Genetic Diversity of Macuilillo, Oreopanax xalapensis (Araliaceae), Change Along Successional Gradients of the Montane Cloud Forest?

2019 ◽  
Vol 12 ◽  
pp. 194008291987292
Author(s):  
Farah Z. Vera-Maloof ◽  
Lorena Ruiz-Montoya ◽  
Neptalí Ramírez-Marcial
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Forest Succession ◽  
Cloud Forest ◽  
Conservation Strategies ◽  
Age Classes ◽  
Successional Stage ◽  
Montane Cloud Forest ◽  
Successional Species ◽  
Successional Stages

Forest regeneration after human-induced or natural disturbances results in a sequential replacement of species, starting with colonizing of pioneer species that modifies the physical conditions of the environment, which later allows the establishment of mid- and late-successional species. Whether the forest succession implies a reduction of population size of tree species might be expected a less genetic diversity in populations inhabiting oldest succession stages. We aimed to study whether genetic diversity of Macuilillo, Oreopanax xalapensis (a understory tree), decreases in advanced age-classes and in late successional of montane cloud forest at Huitepec Ecological Reserve (Chiapas, Mexico). We counted individuals from three age classes: seedlings, saplings, and young reproductive individuals in nine plots along three successional stages (early-, middle-, and late-successional forests). Seven enzyme systems (SOD, AP, FUM, G6PDH, GOT, GPI, and G3PDH) were used to obtain common genetic diversity; Φ-statistics and a Bayesian model were used to infer population structure. At the early-successional stage, O. xalapensis had a bigger population size and significantly high numbers of seedlings. In general, among the successional stages, the genetic diversity of O. xalapensis was moderate to high ( He = 0.25–0.46); the saplings presented the highest expected genetic diversity ( He). Populations were genetically structured by age-classes but not by successional stages. The successional stages affected the demographic dynamics with a mild impact on the genetic structure across age-classes of O. xalapensis. The scenic and recreational conservation strategies implemented in this forest have effectively allowed for population development of O. xalapensis and provide some explanation of genetic diversity at early-succession stage.

scholarly journals Population structure and genetic diversity of Magnolia cubensis subsp. acunae (Magnoliaceae): effects of habitat fragmentation and implications for conservation

Oryx ◽  
2020 ◽  
Vol 54 (4) ◽  
pp. 451-459
Author(s):  
Majela Hernández ◽  
Alejandro Palmarola ◽  
Emily Veltjen ◽  
Pieter Asselman ◽  
Ernesto Testé ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Habitat Fragmentation ◽  
Extinction Risk ◽  
Leaf Tissue ◽  
Genetic Data ◽  
Conservation Strategies ◽  
Mountain Range ◽  
Natural Landscape ◽  
Irregular Shapes ◽  
Landsat Satellite

AbstractGenetic data on threatened plant populations can facilitate the development of adequate conservation strategies to reduce extinction risk. Such data are particularly important for species affected by habitat fragmentation such as Magnolia cubensis subsp. acunae, a Critically Endangered magnolia subspecies endemic to Cuba. Using genetic data from 67 individuals, we aimed to evaluate the effect of habitat fragmentation on two subpopulations in the Guamuhaya mountain range, in Topes de Collantes Protected Natural Landscape and Lomas de Banao Ecological Reserve. We characterize the structure and genetic diversity of these subpopulations, with the objective of managing their conservation more effectively. We used Landsat satellite images to determine land-cover types at the two locations and calculated indices of habitat fragmentation. For genetic analyses, we extracted DNA from the leaf tissue of individuals from the two subpopulations and used 11 microsatellite markers to genotype them. We calculated heterozygosity, allelic richness and the F-statistics, to evaluate genetic variability. The montane rainforest in Topes de Collantes was most affected by habitat fragmentation, with smaller patches of more irregular shapes, compared to submontane forest at this location and both montane and submontane forests in Lomas de Banao. Genetic diversity was higher in Topes de Collantes, but we found no genetic differentiation between subpopulations. Our findings suggest the two subpopulations can be considered a single evolutionary unit and conservation entity. We propose to use individuals from both subpopulations for reinforcement to increase the overall genetic diversity of the subspecies.

scholarly journals Genetic diversity and outcrossing rate of Dipterocarpus dyeri in Ma Da lowland tropical forest (Dong Nai)

2018 ◽  
Vol 16 (3) ◽  
pp. 431-437
Author(s):  
Nguyen Minh Duc ◽  
Nguyen Minh Tam ◽  
Vu Dinh Duy ◽  
Bui Thi Tuyet Xuan ◽  
Dang Phan Hien ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Tropical Forests ◽  
Habitat Destruction ◽  
Conservation Strategy ◽  
Ex Situ ◽  
Conservation Strategies ◽  
Mixed Mating ◽  
Forest Patches ◽  
Lowland Tropical Forest ◽  
Mating Rate

Human activities often lead to the disturbed and fragmented habitat and consequently threated species. Dipterocarpus dyeri (Dipterocarpaceae) is widely distributed in lowland rainforests in southeast Vietnam. Due to over- exploitation and habitat destruction in the 1980s and 1990s, the species is listed as threatened. Understanding the genetic variation and mating rate within D. dyeri population that occurs in forest patches is necessary to establish effectively conservation strategies for this species. To conserve the species in tropical forests, genetic diversity and mating rate were investigated on the basis of eight microsatellites (single sequence repeat, SSR). All of the eight loci were polymorphic. A total of 33 different alleles were observed across the screened loci. The SSR data indicated high genetic diversities (NA = 4.1; HO = 0.461 and HE = 0.543) and the inbreeding value was high (0.185). The mating system parameters were determined using the mixed mating model and indicated high outcrossing rates (tm = 0.884 and ts = 0.645). The differences of significant tm - ts value indicated that inbreeding contributed to selfing rate for this species in lowland tropical forests of Ma Da. This study also indicated the importance of conserving the genetic resources of Dipterocarpus dyeri species in Ma Da rainforests. Genetic conservation should derive from correlated outcrossing. The conservation strategy should be established an ex-situ conservation site with new big population for this species from all genetic groups, which might improve its fitness under different environmental stresses.

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