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Multiple introductions from multiple sources: invasion patterns for an important Eucalyptus leaf pathogen.

Taole M, Bihon W, Wingfield BD, Wingfield MJ, Burgess TI - Ecol Evol (2015)

Bottom Line: The diversity of the invasive populations varied widely, but in general, the younger the plantation industry in a country or region, the lower the diversity of T. suttonii.Historical gene flow was from Australia, and while self-recruitment was dominant in all populations, there was evidence for contemporary gene flow, with South Africa being the most common source and Uruguay the most common sink population.This points distinctly to human activities underlying long-distance spread of this pathogen, and it highlights lessons to be learned regarding quarantine.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology National University of Lesotho P. O. 180 Roma Lesotho ; Department of Genetics Forestry and Agriculture Biotechnology Institute (FABI) University of Pretoria Pretoria 0002 South Africa.

ABSTRACT
Many population studies on invasive plant pathogens are undertaken without knowing the center of origin of the pathogen. Most leaf pathogens of Eucalyptus originate in Australia and consequently with indigenous populations available, and it is possible to study the pathways of invasion. Teratosphaeria suttonii is a commonly occurring leaf pathogen of Eucalyptus species, naturally distributed in tropical and subtropical regions of eastern Australia where it is regarded as a minor pathogen infecting older leaves; however, repeated infections, especially in exotic plantations, can result in severe defoliation and tree deaths. Nine polymorphic microsatellite markers were used to assess the genetic structure of 11 populations of T. suttonii of which four where from within its native range in eastern Australia and the remaining seven from exotic Eucalyptus plantations. Indigenous populations exhibited high allele and haplotype diversity, predominantly clonal reproduction, high population differentiation, and low gene flow. The diversity of the invasive populations varied widely, but in general, the younger the plantation industry in a country or region, the lower the diversity of T. suttonii. Historical gene flow was from Australia, and while self-recruitment was dominant in all populations, there was evidence for contemporary gene flow, with South Africa being the most common source and Uruguay the most common sink population. This points distinctly to human activities underlying long-distance spread of this pathogen, and it highlights lessons to be learned regarding quarantine.

No MeSH data available.


Related in: MedlinePlus

Assignment of and gene flow between populations of Teratosphaeria suttonii. (A) Genetic clustering (k = 7) of the 11 populations using eight microsatellite markers. Each bar represents an individual MLH divided populations and the colors code for the proportion (out of 1) of membership to each cluster. (B) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the seven clusters. (C) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the 11 populations. (D) Pie charts placed depicting the proportion of membership of each population to each cluster with lines depicting the relative intensity of gene flow between introduced populations (see Table S4) and arrows indicating the direction.
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ece31693-fig-0001: Assignment of and gene flow between populations of Teratosphaeria suttonii. (A) Genetic clustering (k = 7) of the 11 populations using eight microsatellite markers. Each bar represents an individual MLH divided populations and the colors code for the proportion (out of 1) of membership to each cluster. (B) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the seven clusters. (C) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the 11 populations. (D) Pie charts placed depicting the proportion of membership of each population to each cluster with lines depicting the relative intensity of gene flow between introduced populations (see Table S4) and arrows indicating the direction.

Mentions: Based on assessment of contemporary gene flow in BAYESASS, self‐recruitment dominated with proportions of over 0.9 for most populations (Table S4, red diagonal). In Australia, gene flow was observed from all eastern Australian populations toward Western Australia (Table S5). Within eastern Australia, there was limited evidence for gene flow between regions, with the exception of FNQ that appears to have received migrants from other eastern Australian populations (Table S5). The establishment of a new plantation industry is associated with the import of germplasm either as seeds, seedlings, or tissue culture, and it is during this phase that new pathogens can be introduced. We thus disallowed scenarios that would include migration from a younger to an older population. There was evidence of limited contemporary gene flow from native Australian populations (especially CQLD and NSW) to URY, USA, and VTN. Among exotic plantations, there appeared to be three‐way gene flow between USA, VTN, and URY populations (Table S4, Fig. 1). IDN and CHN were the source of gene flow to URY, VTN, and USA, while ZAF was a source of contemporary gene flow to all other introduced populations, in particular URY (Table S4, Fig. 1).


Multiple introductions from multiple sources: invasion patterns for an important Eucalyptus leaf pathogen.

Taole M, Bihon W, Wingfield BD, Wingfield MJ, Burgess TI - Ecol Evol (2015)

Assignment of and gene flow between populations of Teratosphaeria suttonii. (A) Genetic clustering (k = 7) of the 11 populations using eight microsatellite markers. Each bar represents an individual MLH divided populations and the colors code for the proportion (out of 1) of membership to each cluster. (B) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the seven clusters. (C) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the 11 populations. (D) Pie charts placed depicting the proportion of membership of each population to each cluster with lines depicting the relative intensity of gene flow between introduced populations (see Table S4) and arrows indicating the direction.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4588637&req=5

ece31693-fig-0001: Assignment of and gene flow between populations of Teratosphaeria suttonii. (A) Genetic clustering (k = 7) of the 11 populations using eight microsatellite markers. Each bar represents an individual MLH divided populations and the colors code for the proportion (out of 1) of membership to each cluster. (B) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the seven clusters. (C) Neighbor‐joining phenogram based on Nei's genetic distance showing the relationship between the 11 populations. (D) Pie charts placed depicting the proportion of membership of each population to each cluster with lines depicting the relative intensity of gene flow between introduced populations (see Table S4) and arrows indicating the direction.
Mentions: Based on assessment of contemporary gene flow in BAYESASS, self‐recruitment dominated with proportions of over 0.9 for most populations (Table S4, red diagonal). In Australia, gene flow was observed from all eastern Australian populations toward Western Australia (Table S5). Within eastern Australia, there was limited evidence for gene flow between regions, with the exception of FNQ that appears to have received migrants from other eastern Australian populations (Table S5). The establishment of a new plantation industry is associated with the import of germplasm either as seeds, seedlings, or tissue culture, and it is during this phase that new pathogens can be introduced. We thus disallowed scenarios that would include migration from a younger to an older population. There was evidence of limited contemporary gene flow from native Australian populations (especially CQLD and NSW) to URY, USA, and VTN. Among exotic plantations, there appeared to be three‐way gene flow between USA, VTN, and URY populations (Table S4, Fig. 1). IDN and CHN were the source of gene flow to URY, VTN, and USA, while ZAF was a source of contemporary gene flow to all other introduced populations, in particular URY (Table S4, Fig. 1).

Bottom Line: The diversity of the invasive populations varied widely, but in general, the younger the plantation industry in a country or region, the lower the diversity of T. suttonii.Historical gene flow was from Australia, and while self-recruitment was dominant in all populations, there was evidence for contemporary gene flow, with South Africa being the most common source and Uruguay the most common sink population.This points distinctly to human activities underlying long-distance spread of this pathogen, and it highlights lessons to be learned regarding quarantine.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology National University of Lesotho P. O. 180 Roma Lesotho ; Department of Genetics Forestry and Agriculture Biotechnology Institute (FABI) University of Pretoria Pretoria 0002 South Africa.

ABSTRACT
Many population studies on invasive plant pathogens are undertaken without knowing the center of origin of the pathogen. Most leaf pathogens of Eucalyptus originate in Australia and consequently with indigenous populations available, and it is possible to study the pathways of invasion. Teratosphaeria suttonii is a commonly occurring leaf pathogen of Eucalyptus species, naturally distributed in tropical and subtropical regions of eastern Australia where it is regarded as a minor pathogen infecting older leaves; however, repeated infections, especially in exotic plantations, can result in severe defoliation and tree deaths. Nine polymorphic microsatellite markers were used to assess the genetic structure of 11 populations of T. suttonii of which four where from within its native range in eastern Australia and the remaining seven from exotic Eucalyptus plantations. Indigenous populations exhibited high allele and haplotype diversity, predominantly clonal reproduction, high population differentiation, and low gene flow. The diversity of the invasive populations varied widely, but in general, the younger the plantation industry in a country or region, the lower the diversity of T. suttonii. Historical gene flow was from Australia, and while self-recruitment was dominant in all populations, there was evidence for contemporary gene flow, with South Africa being the most common source and Uruguay the most common sink population. This points distinctly to human activities underlying long-distance spread of this pathogen, and it highlights lessons to be learned regarding quarantine.

No MeSH data available.


Related in: MedlinePlus