scholarly journals Understanding the genetic diversity of the guayabillo (Psidium galapageium), an endemic plant of the Galapagos Islands

2020 ◽  
Author(s):  
Diego Urquia ◽  
Gabriela Pozo ◽  
Bernardo Gutierrez ◽  
Jennifer K. Rowntree ◽  
Maria de Lourdes Torres
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Galapagos Islands ◽  
Conservation Strategies ◽  
Galápagos Islands ◽  
Santa Cruz ◽  
Endemic Plant ◽  
Important Indicator ◽  
Genetic Diversity And Structure ◽  
History Of

ABSTRACTOceanic archipelagos are known to host a variety of endemic plant species. The genetic diversity and structure of these species is an important indicator of their evolutionary history and can inform appropriate conservation strategies that mitigate the risks to which they’re exposed, including invasive species and environmental disturbances. A comprehensive consideration of the role of their natural history, as well as the landscape features and the geological history of the islands themselves is required to adequately understand any emerging patterns. Such is the case for the guayabillo (Psidium galapageium), an understudied endemic plant from the Galapagos Islands with important ecological and economic roles. In this study we designed and evaluated 13 informative SSR markers and used them to investigate the genetic diversity, population structure and connectivity of the guayabillo populations from San Cristobal, Isabela and Santa Cruz islands. A total of 208 guayabillo individuals were analyzed, revealing a strong population structure between islands and two distinct genetic lineages for the Santa Cruz population. Overall, the guayabillo genetic diversity is relatively high, an unusual pattern for an insular endemic species which is possibly explained by its polyploidy and the geographical features of the islands. These include their broad altitudinal ranges and habitat heterogeneity. For populations displaying a lower genetic diversity such as San Cristobal, the history of human disturbance could be an important factor explaining these observations. Some similarities between individuals in Santa Cruz and the San Cristobal population could be explained by population differentiation or distinct natural histories of separate lineages. Our findings highlight the complex population dynamics that shape the genetic diversity of species like the guayabillo and emphasize the need to explore the currently unresolved questions about this Galapagos endemic plant.

scholarly journals Origin and dispersion pathways of guava in the Galapagos Islands inferred through genetics and historical records

2021 ◽  
Author(s):  
Diego Urquia ◽  
Bernardo Gutierrez ◽  
Gabriela Pozo ◽  
Maria Pozo ◽  
Maria Torres
Keyword(s):  
Genetic Diversity ◽  
Psidium Guajava ◽  
Galapagos Islands ◽  
Genetic Distances ◽  
Galápagos Islands ◽  
Santa Cruz ◽  
Historical Sources ◽  
Introduction History ◽  
Galapagos Archipelago ◽  
History Of

Guava (Psidium guajava) is one of the most aggressive invasive plants in the Galapagos Islands. Determining its provenance and genetic diversity could provide valuable information for its control. With this purpose, we analyzed 11 SSR markers in guava individuals collected from Isabela, Santa Cruz, San Cristobal and Floreana islands in the Galapagos, as well as from mainland Ecuador. The mainland guava population appeared genetically differentiated from the Galapagos populations, with higher genetic diversity levels found in the former. By using different approaches for data analysis, we consistently found that the Central Highlands region of mainland Ecuador is one of the most likely origins of the Galapagos populations. Moreover, the guavas from Isabela and Floreana show a potential genetic input from southern mainland Ecuador, while the population from San Cristobal would be linked to the coastal mainland regions. Interestingly, the proposed origins for the Galapagos guava coincide with the first human settlings of the archipelago. By employing Approximate Bayesian Computation, we propose a model where San Cristobal was the first island to be colonized by guava from the mainland, from which it would have spread to Floreana and finally to Santa Cruz; Isabela would have been seeded from Floreana. An independent trajectory could also have contributed in the invasion of Floreana and Isabela. The pathway shown in our model agrees with the human colonization history of the different islands in the Galapagos. Our model, in conjunction with the clustering patterns of the guava individuals (based on genetic distances), suggests that guava introduction history in the Galapagos archipelago was driven predominantly by a single event (or events in rapid succession) instead of several independent introductions. We thus show that genetic analyses supported by historical sources can be used to answer questions on the variability and history of guava in the Galapagos Islands.

scholarly journals Psidium guajava in the Galapagos Islands: population genetics and history of an invasive species

2018 ◽  
Author(s):  
Diego Urquía ◽  
Bernardo Gutiérrez ◽  
Gabriela Pozo ◽  
María José Pozo ◽  
Analía Espín ◽  
...  
Keyword(s):  
Population Genetics ◽  
Invasive Plant ◽  
Psidium Guajava ◽  
Galapagos Islands ◽  
Historical Record ◽  
Galápagos Islands ◽  
Santa Cruz ◽  
Island Populations ◽  
Galapagos Archipelago ◽  
History Of

AbstractThe threat of invasive plant species in island populations prompts the need to better understand their population genetics and dynamics. In the Galapagos islands, this is exemplified by the introduced guava (Psidium guajava), considered one of the greatest threats to the local biodiversity due to its effective spread in the archipelago and its ability to outcompete endemic species. To better understand its history and genetics, we analyzed individuals from three inhabited islands in the Galapagos archipelago with 11 SSR markers. Our results reveal similar genetic diversity between islands, suggestive of gene flow between them. Populations appear to be distinct between the islands of San Cristobal and Isabela, with the population of Santa Cruz being composed as a mixture from both. Additional evidence for genetic bottlenecks and the inference of introduction events suggests an original introduction of the species in San Cristobal, from where it was later introduced to Isabela, and finally into Santa Cruz. Alternatively, an independent introduction event for Isabela is also possible. These results are contrasted with the historical record, providing a first overview of the history of P. guajava in the Galapagos islands and its current population dynamics.

scholarly journals Genetic Diversity and Population Structure of Two Tomato Species from the Galapagos Islands

2017 ◽  
Vol 8 ◽  
Author(s):  
Yveline Pailles ◽  
Shwen Ho ◽  
Inês S. Pires ◽  
Mark Tester ◽  
Sónia Negrão ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Galapagos Islands ◽  
Galápagos Islands ◽  
Tomato Species

scholarly journals Understanding the genetic diversity of the guayabillo (Psidium galapageium), an endemic plant of the Galapagos Islands

2020 ◽  
Vol 24 ◽  
pp. e01350
Author(s):  
Diego Urquía ◽  
Gabriela Pozo ◽  
Bernardo Gutierrez ◽  
Jennifer K. Rowntree ◽  
Maria de Lourdes Torres
Keyword(s):  
Genetic Diversity ◽  
Galapagos Islands ◽  
Galápagos Islands ◽  
Endemic Plant

scholarly journals Evolutionary History of the Galápagos Rail Revealed by Ancient Mitogenomes and Modern Samples

Diversity ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 425
Author(s):  
Jaime A. Chaves ◽  
Pedro J. Martinez-Torres ◽  
Emiliano A. Depino ◽  
Sebastian Espinoza-Ulloa ◽  
Jefferson García-Loor ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
De Novo ◽  
Galapagos Islands ◽  
Separate Analysis ◽  
Population Bottlenecks ◽  
Galápagos Islands ◽  
Low Genetic Diversity ◽  
Lack Of Information ◽  
History Of ◽  
Black Rail

The biotas of the Galápagos Islands are one of the best studied island systems and have provided a broad model for insular species’ origins and evolution. Nevertheless, some locally endemic taxa, such as the Galápagos Rail Laterallus spilonota, remain poorly characterized. Owing to its elusive behavior, cryptic plumage, and restricted distribution, the Galápagos Rail is one of the least studied endemic vertebrates of the Galapagos Islands. To date, there is no genetic data for this species, leaving its origins, relationships to other taxa, and levels of genetic diversity uncharacterized. This lack of information is critical given the adverse fate of island rail species around the world in the recent past. Here, we examine the genetics of Galápagos Rails using a combination of mitogenome de novo assembly with multilocus nuclear and mitochondrial sequencing from both modern and historical samples. We show that the Galápagos Rail is part of the “American black rail clade”, sister to the Black Rail L. jamaicensis, with a colonization of Galápagos dated to 1.2 million years ago. A separate analysis of one nuclear and two mitochondrial markers in the larger population samples demonstrates a shallow population structure across the islands, possibly due to elevated island connectivity. Additionally, birds from the island Pinta possessed the lowest levels of genetic diversity, possibly reflecting past population bottlenecks associated with overgrazing of their habitat by invasive goats. The modern and historical data presented here highlight the low genetic diversity in this endemic rail species and provide useful information to guide conservation efforts.

scholarly journals Rediscovery of rodents (Genus Nesoryzomys) considered extinct in the Galápagos Islands

Oryx ◽  
2000 ◽  
Vol 34 (2) ◽  
pp. 109-117 ◽  
Author(s):  
Robert C. Dowler ◽  
Darin S. Carroll ◽  
Cody W. Edwards
Keyword(s):  
Charles Darwin ◽  
Rattus Rattus ◽  
Galapagos Islands ◽  
Santa Fe ◽  
Galápagos Islands ◽  
Santa Cruz ◽  
Emergency Plans ◽  
Extant Species ◽  
History Of ◽  
Rodent Populations

AbstractThe history of the endemic rodents of the Galápagos Islands began with the discovery of the first Galápagos rice rat species by Charles Darwin in 1835 and the last species was described as recently as 1980. Unfortunately, of the seven described species known to occur in the islands during the past 150 years, only two were known to be extant to 1995. Since then, two expeditions to the Galápagos Islands have been conducted to survey endemic rodent populations. The first confirmed the existence of a small endemic rice rat, Nesoryzomys fernandinae, on Fernandina, known previously only from owl pellet remains found in 1979. In 1997, an expedition to Santiago revealed a population of the larger rice rat N. swarthi, a species collected alive only once in 1906 and considered extinct in all recent literature on the Galápagos Islands. Survey efforts on Santa Cruz resulted only in the collection of introduced rodent species (Rattus rattus, R. norvegicus and Mus musculus). The extant species of native rodents in the Galápagos Islands now number four: N. narboroughi and N. fernandinae on Fernandina; N. swarthi on Santiago; and Oryzomys bauri on Santa Fe. Three species are found on islands where no introduced rodents or cats occur, whereas only one (N. swarthi) co-exists with R. rattusand M. musculus. Nesoryzomys darwini and N. indefessus on Santa Cruz and O. galapagoensis on San Cristóbal are still considered extinct. Strategies for conservation should include monitoring islands for introduced rodents and cats, development of emergency plans in the event of introductions, and captive management.

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 Blue whale (Balaenoptera musculus musculus) genome: population structure and history in the North Atlantic

2021 ◽  
Author(s):  
Sushma Jossey ◽  
Oliver Haddrath ◽  
Livia Loureiro ◽  
Burton Lim ◽  
Jacqueline Miller ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
North Atlantic ◽  
Conservation Strategies ◽  
Balaenoptera Musculus ◽  
Blue Whale ◽  
Genetic Diversity And Structure ◽  
Population Structuring ◽  
The Impact ◽  
Blue Whales

Knowledge of genetic diversity and structure is essential for developing conservation strategies for endangered species. The advances in museum genomics can assist in better understanding the effects of over-hunting on the genome by comparing historical to present-day samples. Blue whales were hunted to the point of near extinction in the mid-twentieth century. Herein, we use whole genome sequencing to elucidate the poorly understood population structure of North Atlantic (NA) blue whales (Balaenoptera musculus musculus). We generated a de novo genome assembly of 2.49 Mbp for a NA blue whale (N50 of 1.46 Mb) to analyze 19 whole genomic sequences and 28 complete mitochondrial genomes. We included present-day and historical samples (earliest from 1900) from the Atlantic and Antarctica to understand the impact of whaling on the genetic diversity. We found low population structuring, but high genetic diversity, suggesting a single, panmictic population in the NA. We identified gene flow from fin whale to blue whales, accounting for ~3.5% of the genome. Introgression between blue and fin whales was observed in all the present-day samples but were lacking in some whales sampled early in the 20th century, which suggests increasing disruption in mate choice concomitant with decline in blue whale population. We also assembled and analyzed the transcriptome and revealed positive selection of oncogenes, which may be involved in reduced cancer rates in this largest of mammals ever known. Our sequencing and population structuring studies provide a genomic framework to guide ongoing conservation strategies for this iconic species.

scholarly journals Genetic diversity and population structure of Plasmodium falciparum in Nigeria: insights from microsatellite loci analysis

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Fehintola V. Ajogbasile ◽  
Adeyemi T. Kayode ◽  
Paul E. Oluniyi ◽  
Kazeem O. Akano ◽  
Jessica N. Uwanibe ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Plasmodium Falciparum ◽  
Population Structure ◽  
Microsatellite Loci ◽  
Control Strategies ◽  
Population Diversity ◽  
Parasite Population ◽  
Nested Polymerase Chain Reaction ◽  
Public Health Burden ◽  
Genetic Diversity And Structure

Abstract Background Malaria remains a public health burden especially in Nigeria. To develop new malaria control and elimination strategies or refine existing ones, understanding parasite population diversity and transmission patterns is crucial. Methods In this study, characterization of the parasite diversity and structure of Plasmodium falciparum isolates from 633 dried blood spot samples in Nigeria was carried out using 12 microsatellite loci of P. falciparum. These microsatellite loci were amplified via semi-nested polymerase chain reaction (PCR) and fragments were analysed using population genetic tools. Results Estimates of parasite genetic diversity, such as mean number of different alleles (13.52), effective alleles (7.13), allelic richness (11.15) and expected heterozygosity (0.804), were high. Overall linkage disequilibrium was weak (0.006, P < 0.001). Parasite population structure was low (Fst: 0.008–0.105, AMOVA: 0.039). Conclusion The high level of parasite genetic diversity and low population structuring in this study suggests that parasite populations circulating in Nigeria are homogenous. However, higher resolution methods, such as the 24 SNP barcode and whole genome sequencing, may capture more specific parasite genetic signatures circulating in the country. The results obtained can be used as a baseline for parasite genetic diversity and structure, aiding in the formulation of appropriate therapeutic and control strategies in Nigeria.

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