scholarly journals A clue to invasion success: genetic diversity quickly rebounds after introduction bottlenecks

2020 ◽  
Author(s):  
Peter Kaňuch ◽  
Åsa Berggren ◽  
Anna Cassel-Lundhagen
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Large Scale ◽  
Invasion Biology ◽  
Invasion Success ◽  
Founder Population ◽  
Establishment Success ◽  
Propagule Size ◽  
Introduced Populations ◽  
Species Invasiveness

AbstractOne of the fundamental questions in invasion biology is to understand the genetic mechanisms behind success or failure during the establishment of a species. However, major limitations to understanding are usually a lack of spatiotemporal population data and information on the populations’ colonisation history. In a large-scale, detailed study on the bush-cricket Metrioptera roeselii 70 groups of founders were introduced in areas outside the species’ distribution range. We examined how (1) the number of founders (2–32 individuals), (2) the time since establishment (7 or 15 years after introduction) and (3) possible gene flow affected establishment success and temporal genetic changes of the introduced populations. We found higher establishment success in introductions with larger propagule sizes but genetic diversity indices were only partly correlated to propagule size. As expected, introduced populations were more similar to their founder population the larger the propagule size was. However, even if apparent at first, most of the differentiation in the small propagule introductions disappeared over time. Surprisingly, genetic variability was regained to a level comparable to the large and outbreeding founder population only 15 generations after severe demographic bottlenecks. We suggest that the establishment of these populations could be a result of several mechanisms acting in synergy. Here, rapid increase in genetic diversity of few introductions could potentially be attributed to limited gene flow from adjacent populations, behavioural adaptations and/or even increased mutation rate. We present unique insights into genetic processes that point towards traits that are important for understanding species’ invasiveness.

scholarly journals Microbial’s Effects on Invasive Grass’ Response to Water and Nutrient Stress

2020 ◽  
Author(s):  
Bo Zhang ◽  
Yingdan Yuan ◽  
Karolina M. Pajerowska-Mukhtar ◽  
Michelle Afkhami ◽  
Alan Hastings ◽  
...  
Keyword(s):  
Large Scale ◽  
Interactive Effect ◽  
Invasion Biology ◽  
Imperata Cylindrica ◽  
Invasion Success ◽  
Nutrient Concentrations ◽  
Sequencing Analysis ◽  
Drought Treatment ◽  
Plant Microbe Interaction ◽  
Invasion Mechanisms

Abstract Background Soil microbiomes play important roles in invasion biology, yet it is often treated as a ‘black box’ in modeling or large-scale field studies. Hence, investigating the change of association between invasive vegetation and soil microbes under changing environmental conditions, and exploring the genetic functions of associated microbiomes will provide a deeper understanding of invasion mechanisms. We performed a microcosm experiment with cogongrass (Imperata cylindrica (L.) P. Beauv.), which is one of the 100 worst invasive plants in the world. We combined rigorous sequencing analysis, including 16S rRNA, ITS, and shotgun metagenome sequencing, for the first time, to investigate the interactive effect of change in soil water and nutrient concentrations on microbiomes diversity, composition and genetic functions under invasion. Results We found that experimental drought has a stronger effect on the bacterial community than the fungal community. We discovered an enrichment of microbial groups, including Proteobacteria, Actinobacteria, Bacteroidetes and Chloroflexi under drought treatment, could likely contribute to invasion success. Further, we showed a striking trend of induction of cell wall, membrane and desiccation-related genes in drought treatment and a marked downregulation in regular treatment, which could create a more hydrated microenvironment, facilitating biofilm formation and better protection from desiccation.Conclusions Our work contributes to highlighting the associated microbial communities may have a potential long-term impact on increasing cogongrass drought resistance, ultimately, future invasion might be severe due to the plant-microbe interaction. These findings are important because current modeling practice, lacking comprehensive consideration of the plant-microbe interaction, could lead to a significant underestimate of predictions of future invasion patterns.

scholarly journals Timing between successive introduction events determines establishment success in bacteria with an Allee effect

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190598 ◽  
Author(s):  
Michael D. Dressler ◽  
Josue Conde ◽  
Omar Tonsi Eldakar ◽  
Robert P. Smith
Keyword(s):  
Infectious Disease ◽  
Allee Effect ◽  
Propagule Pressure ◽  
Temporal Distribution ◽  
Invasion Biology ◽  
Theoretical Studies ◽  
Establishment Success ◽  
Propagule Size ◽  
Population Establishment ◽  
Principal Parts

Propagule pressure is a leading determinant of population establishment. Yet, an experimental understanding of how propagule size and number (two principal parts of propagule pressure) determine establishment success remains incomplete. Theoretical studies suggest that the timing between introduction events, a component of propagule number, can influence establishment success. However, this dynamic has rarely been explored experimentally. Using Escherichia coli engineered with an Allee effect, we investigated how the timing of two introduction events influences establishment. For populations introduced below the Allee threshold, establishment occurred if the time between two introduction events was sufficiently short, with the length of time between events further reduced by reducing growth rate. Interestingly, we observed that as the density of bacteria introduced in one introduction event increased, the time between introduction events that allowed for establishment increased. Using a mathematical model, we provide support that the mechanism behind these trends is the ability of the first population to modify the environment, which can pave the way for establishment of the second population. Our results provide experimental evidence that the temporal distribution of introduction events regulates establishment, furthering our understanding of propagule pressure and may have implications in invasion biology and infectious disease.

scholarly journals High-Level Gene Flow Restricts Genetic Differentiation in Dairy Cattle Populations in Thailand: Insights from Large-Scale Mt D-Loop Sequencing

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1680
Author(s):  
Nattakan Ariyaraphong ◽  
Nararat Laopichienpong ◽  
Worapong Singchat ◽  
Thitipong Panthum ◽  
Syed Farhan Ahmad ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Genetic Differentiation ◽  
Dairy Cattle ◽  
Large Scale ◽  
Genetic Relationships ◽  
Extensive Study ◽  
Distribution Analysis ◽  
Cattle Breeds ◽  
D Loop

Domestication and artificial selection lead to the development of genetically divergent cattle breeds or hybrids that exhibit specific patterns of genetic diversity and population structure. Recently developed mitochondrial markers have allowed investigation of cattle diversity worldwide; however, an extensive study on the population-level genetic diversity and demography of dairy cattle in Thailand is still needed. Mitochondrial D-loop sequences were obtained from 179 individuals (hybrids of Bos taurus and B. indicus) sampled from nine different provinces. Fifty-one haplotypes, of which most were classified in haplogroup “I”, were found across all nine populations. All sampled populations showed severely reduced degrees of genetic differentiation, and low nucleotide diversity was observed in populations from central Thailand. Populations that originated from adjacent geographical areas tended to show high gene flow, as revealed by patterns of weak network structuring. Mismatch distribution analysis was suggestive of a stable population, with the recent occurrence of a slight expansion event. The results provide insights into the origins and the genetic relationships among local Thai cattle breeds and will be useful for guiding management of cattle breeding in Thailand.

scholarly journals Characterising the methylome of Legionella longbeachae serogroup 1 clinical isolates and assessing geo-temporal genetic diversity

2020 ◽  
Author(s):  
S Slow ◽  
T Anderson ◽  
DR Murdoch ◽  
S Bloomfield ◽  
D Winter ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
New Zealand ◽  
Complete Genome ◽  
Large Scale ◽  
Common Ancestor ◽  
Sequence Motifs ◽  
Plasmid Recombination ◽  
Legionnaires Disease ◽  
Temporal Genetic Diversity

AbstractLegionella longbeachae is an environmental bacterium that is commonly found in soil and composted plant material. In New Zealand (NZ) it is the most clinically significant Legionella species causing around two-thirds of all notified cases of Legionnaires’ disease. Here we report the sequencing and analysis of the geo-temporal genetic diversity of 54 L. longbeachae serogroup 1 (sg1) clinical isolates that were derived from cases from around NZ over a 22-year period, including one complete genome and its associated methylome.Our complete genome consisted of a 4.1 Mb chromosome and a 108 kb plasmid. The genome was highly methylated with two known epigenetic modifications, m4C and m6A, occurring in particular sequence motifs within the genome. Phylogenetic analysis demonstrated the 54 sg1 isolates belonged to two main clades that last shared a common ancestor between 108 BCE and 1608 CE. These isolates also showed diversity at the genome-structural level, with large-scale arrangements occurring in some regions of the chromosome and evidence of extensive chromosomal and plasmid recombination. This includes the presence of plasmids derived from recombination and horizontal gene transfer between various Legionella species, indicating there has been both intra-species and inter-species gene flow. However, because similar plasmids were found among isolates within each clade, plasmid recombination events may pre-empt the emergence of new L. longbeachae strains.Our high-quality reference genome and extensive genetic diversity data will serve as a platform for future work linking genetic, epigenetic and functional diversity in this globally important emerging environmental pathogen.Author SummaryLegionnaires’ disease is a serious, sometimes fatal pneumonia caused by bacteria of the genus Legionella. In New Zealand, the species that causes the majority of disease is Legionella longbeachae. Although the analyses of pathogenic bacterial genomes is an important tool for unravelling evolutionary relationships and identifying genes and pathways that are associated with their disease-causing ability, until recently genomic data for L. longbeachae has been sparse. Here, we conducted a large-scale genomic analysis of 54 L. longbeachae isolates that had been obtained from people hospitalised with Legionnaires’ disease between 1993 and 2015 from 8 regions around New Zealand. Based on our genome analysis the isolates could be divided into two main groups that persisted over time and last shared a common ancestor up to 1700 years ago. Analysis of the bacterial chromosome revealed areas of high modification through the addition of methyl groups and these were associated with particular DNA sequence motifs. We also found there have been large-scale rearrangements in some regions of the chromosome, producing variability between the different L. longbeacahe strains, as well as evidence of gene-flow between the various Legionella species via the exchange of plasmid DNA.

Invasion success and genetic diversity of introduced populations of guppies Poecilia reticulata in Australia

2005 ◽  
Vol 14 (12) ◽  
pp. 3671-3682 ◽  
Author(s):  
ANNA K. LINDHOLM ◽  
FELIX BREDEN ◽  
HEATHER J. ALEXANDER ◽  
WOON-KHIONG CHAN ◽  
SUMITA G. THAKURTA ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Poecilia Reticulata ◽  
Invasion Success ◽  
Introduced Populations

scholarly journals Global wind patterns shape genetic differentiation, asymmetric gene flow, and genetic diversity in trees

2021 ◽  
Vol 118 (17) ◽  
pp. e2017317118
Author(s):  
Matthew M. Kling ◽  
David D. Ackerly
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Large Scale ◽  
Landscape Connectivity ◽  
Genetic Data ◽  
Plant Ecology ◽  
Wind Pollination ◽  
Genetic Patterns ◽  
Partial Correlations ◽  
Wind Currents

Wind disperses the pollen and seeds of many plants, but little is known about whether and how it shapes large-scale landscape genetic patterns. We address this question by a synthesis and reanalysis of genetic data from more than 1,900 populations of 97 tree and shrub species around the world, using a newly developed framework for modeling long-term landscape connectivity by wind currents. We show that wind shapes three independent aspects of landscape genetics in plants with wind pollination or seed dispersal: populations linked by stronger winds are more genetically similar, populations linked by directionally imbalanced winds exhibit asymmetric gene flow ratios, and downwind populations have higher genetic diversity. For each of these distinct hypotheses, partial correlations between the respective wind and genetic metrics (controlling for distance and climate) are positive for a significant majority of wind-dispersed or wind-pollinated genetic data sets and increase significantly across functional groups expected to be increasingly influenced by wind. Together, these results indicate that the geography of both wind strength and wind direction play important roles in shaping large-scale genetic patterns across the world’s forests. These findings have implications for various aspects of basic plant ecology and evolution, as well as the response of biodiversity to future global change.

Genetic rescue by augmenting gene flow

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Inbreeding Coefficient ◽  
Outbreeding Depression ◽  
Genetic Rescue ◽  
Evolutionary Potential ◽  
Beneficial Effects ◽  
The Difference ◽  
Inbred Populations ◽  
Harmful Effects

Inbreeding is reduced and genetic diversity enhanced when a small isolated inbred population is crossed to another unrelated population. Crossing can have beneficial or harmful effects on fitness, but beneficial effects predominate, and the risks of harmful ones (outbreeding depression) can be predicted and avoided. For crosses with a low risk of outbreeding depression, there are large and consistent benefits on fitness that persist across generations in outbreeding species. Benefits are greater in species that naturally outbreed than those that inbreed, and increase with the difference in inbreeding coefficient between crossed and inbred populations in mothers and zygotes. However, benefits are similar across invertebrates, vertebrates and plants. There are also important benefits for evolutionary potential of crossing between populations.

scholarly journals Mitogenomics of the endangered Mediterranean monk seal (Monachus monachus) reveals dramatic loss of diversity and supports historical gene-flow between Atlantic and eastern Mediterranean populations

2020 ◽  
Author(s):  
Alba Rey-Iglesia ◽  
Philippe Gaubert ◽  
Gonçalo Espregueira Themudo ◽  
Rosa Pires ◽  
Constanza De La Fuente ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
North Atlantic ◽  
Marine Mammals ◽  
Eastern Mediterranean ◽  
The Black Sea ◽  
Mediterranean Populations ◽  
Geographic Ranges ◽  
Western Sahara ◽  
The Mediterranean

Abstract The Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals, with only 600–700 individuals restricted to three populations off the coast of Western Sahara and Madeira (North Atlantic) and between Greece and Turkey (eastern Mediterranean). Its original range was from the Black Sea (eastern Mediterranean) to Gambia (western African coast), but was drastically reduced by commercial hunting and human persecution since the early stages of marine exploitation. We here analyse 42 mitogenomes of Mediterranean monk seals, from across their present and historical geographic ranges to assess the species population dynamics over time. Our data show a decrease in genetic diversity in the last 200 years. Extant individuals presented an almost four-fold reduction in genetic diversity when compared to historical specimens. We also detect, for the first time, a clear segregation between the two North Atlantic populations, Madeira and Cabo Blanco, regardless of their geographical proximity. Moreover, we show the presence of historical gene-flow between the two water basins, the Atlantic Ocean and the Mediterranean Sea, and the presence of at least one extinct maternal lineage in the Mediterranean. Our work demonstrates the advantages of using full mitogenomes in phylogeographic and conservation genomic studies of threatened species.

scholarly journals Hierarchical Analysis of Genetic Structure in Native Fire Ant Populations: Results From Three Classes of Molecular Markers

Genetics ◽  
1997 ◽  
Vol 147 (2) ◽  
pp. 643-655 ◽  
Author(s):  
Kenneth G Ross ◽  
Michael J B Krieger ◽  
D DeWayne Shoemaker ◽  
Edward L Vargo ◽  
Laurent Keller
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Solenopsis Invicta ◽  
Large Scale ◽  
Fire Ant ◽  
Nuclear Markers ◽  
Social Forms ◽  
Native Populations ◽  
Nest Level ◽  
Nuclear Differentiation

We describe genetic structure at various scales in native populations of the fire ant Solenopsis invicta using two classes of nuclear markers, allozymes and microsatellites, and markers of the mitochondrial genome. Strong structure was found at the nest level in both the monogyne (single queen) and polygyne (multiple queen) social forms using allozymes. Weak but significant microgeographic structure was detected above the nest level in polygyne populations but not in monogyne populations using both classes of nuclear markers. Pronounced mitochondrial DNA (mtDNA) differentiation was evident also at this level in the polygyne form only. These microgeographic patterns are expected because polygyny in ants is associated with restricted local gene flow due mainly to limited vagility of queens. Weak but significant nuclear differentiation was detected between sympatric social forms, and strong mtDNA differentiation also was found at this level. Thus, queens of each form seem unable to establish themselves in nests of the alternate type, and some degree of assortative mating by form may exist as well. Strong differentiation was found between the two study regions usinga all three sets of markers. Phylogeographic analyses of the mtDNA suggest that recent limitations on gene flow rather than longstanding barriers to dispersal are responsible for this large-scale structure.

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