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Altitudinal Barrier to the Spread of an Invasive Species: Could the Pyrenean Chain Slow the Natural Spread of the Pinewood Nematode?

Haran J, Roques A, Bernard A, Robinet C, Roux G - PLoS ONE (2015)

Bottom Line: Conversely, strong admixture was detected between populations located on both sides of low elevation hills, and especially at the east and west extremities of the mountain range.Simulations also showed that temperature rise due to climate change may significantly reduce the extent of the barrier formed by highest elevations.Our results support the hypothesis that the Pyrenean chain represents a partial barrier to the natural spread of nematode-infested beetles.

View Article: PubMed Central - PubMed

Affiliation: INRA, UR633 Zoologie Forestière, F-45075 Orléans, France; Université d'Orléans, Orléans, France.

ABSTRACT
Mountain ranges may delimit the distribution of native species as well as constitute potential barriers to the spread of invasive species. The invasive pinewood nematode, Bursaphelenchus xylophilus, is a severe forest pest inducing pine wilt disease. It is vectored in Europe by a native long-horned beetle, Monochamus galloprovincialis. This study explored the potential of the Pyrenean chain to slow or prevent the natural spread of nematode-infested beetles from the Iberian Peninsula, where the nematode is established and is expanding its range, towards France and the rest of Europe. An analysis of the genetic structure and migration patterns of the beetle populations throughout the Pyrenean mountain range was combined with a spread model simulating the potential movements of nematode-infested beetles across it. The central part of the Pyrenees, which corresponds to the highest elevation zone, was shown to prevent gene flow between the French and Spanish populations of M. galloprovincialis on each side of the mountains. Conversely, strong admixture was detected between populations located on both sides of low elevation hills, and especially at the east and west extremities of the mountain range. Simulations of the spread of nematode-infested beetles under various thresholds of beetle survival and pine wilt disease expression gave results consistent with the variation in genetic make-up, suggesting that western and eastern hillsides may represent corridors favoring natural spread of the nematode from the Iberian Peninsula to France. Simulations also showed that temperature rise due to climate change may significantly reduce the extent of the barrier formed by highest elevations. Our results support the hypothesis that the Pyrenean chain represents a partial barrier to the natural spread of nematode-infested beetles. These results, which have to be considered together with potential human-assisted long-distance spread of the nematode, highlight priority zones for future pest monitoring and management programs. More generally, such an integrated approach could be used to assess the role of mountain chains in the potential spread of other invasive pests.

No MeSH data available.


Related in: MedlinePlus

Temperatures, pine cover and resident populations in the Pyrenees.A) Mean of minimum temperature (°C) in winter (December, January and February; called TN) over 1950–2000. B) Mean temperatures (°C) in July over 1950–2000. C) Pine cover (%). D) Projection of the distribution and density of resident populations of M. galloprovincialis over the Pyrenean chain. Maximal elevation threshold for the beetle survival set to 1590 m for this representation. Scale refers to the population density (number of individuals per km2).
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pone.0134126.g004: Temperatures, pine cover and resident populations in the Pyrenees.A) Mean of minimum temperature (°C) in winter (December, January and February; called TN) over 1950–2000. B) Mean temperatures (°C) in July over 1950–2000. C) Pine cover (%). D) Projection of the distribution and density of resident populations of M. galloprovincialis over the Pyrenean chain. Maximal elevation threshold for the beetle survival set to 1590 m for this representation. Scale refers to the population density (number of individuals per km2).

Mentions: Based on the carrying capacity (K0) estimated across the study area, we found that M. galloprovincialis is expected to be widely distributed over the Pyrenees (Fig 4D). The highest K0 was found along the Mediterranean and the Atlantic coasts, and on the Spanish side of the Pyrenees. Conversely, low K0 was observed in an area located away from the coast on the French Pyrenean side. Based on trapping, we found an average carrying capacity of K0 = 0.027 insect / tree (S2 Table) and a ratio between Ki and K0 of Ki≈4 K0 (See S3 Table for details). Results of simulations are represented by areas colonized by intervals of 10 successive generations (Figs 5 and 6). When considering no thresholds of temperature and elevation, model simulations of the spread of infested populations of M. galloprovincialis showed a wave of colonization which expanded over all suitable habitats in Spain and France.


Altitudinal Barrier to the Spread of an Invasive Species: Could the Pyrenean Chain Slow the Natural Spread of the Pinewood Nematode?

Haran J, Roques A, Bernard A, Robinet C, Roux G - PLoS ONE (2015)

Temperatures, pine cover and resident populations in the Pyrenees.A) Mean of minimum temperature (°C) in winter (December, January and February; called TN) over 1950–2000. B) Mean temperatures (°C) in July over 1950–2000. C) Pine cover (%). D) Projection of the distribution and density of resident populations of M. galloprovincialis over the Pyrenean chain. Maximal elevation threshold for the beetle survival set to 1590 m for this representation. Scale refers to the population density (number of individuals per km2).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519352&req=5

pone.0134126.g004: Temperatures, pine cover and resident populations in the Pyrenees.A) Mean of minimum temperature (°C) in winter (December, January and February; called TN) over 1950–2000. B) Mean temperatures (°C) in July over 1950–2000. C) Pine cover (%). D) Projection of the distribution and density of resident populations of M. galloprovincialis over the Pyrenean chain. Maximal elevation threshold for the beetle survival set to 1590 m for this representation. Scale refers to the population density (number of individuals per km2).
Mentions: Based on the carrying capacity (K0) estimated across the study area, we found that M. galloprovincialis is expected to be widely distributed over the Pyrenees (Fig 4D). The highest K0 was found along the Mediterranean and the Atlantic coasts, and on the Spanish side of the Pyrenees. Conversely, low K0 was observed in an area located away from the coast on the French Pyrenean side. Based on trapping, we found an average carrying capacity of K0 = 0.027 insect / tree (S2 Table) and a ratio between Ki and K0 of Ki≈4 K0 (See S3 Table for details). Results of simulations are represented by areas colonized by intervals of 10 successive generations (Figs 5 and 6). When considering no thresholds of temperature and elevation, model simulations of the spread of infested populations of M. galloprovincialis showed a wave of colonization which expanded over all suitable habitats in Spain and France.

Bottom Line: Conversely, strong admixture was detected between populations located on both sides of low elevation hills, and especially at the east and west extremities of the mountain range.Simulations also showed that temperature rise due to climate change may significantly reduce the extent of the barrier formed by highest elevations.Our results support the hypothesis that the Pyrenean chain represents a partial barrier to the natural spread of nematode-infested beetles.

View Article: PubMed Central - PubMed

Affiliation: INRA, UR633 Zoologie Forestière, F-45075 Orléans, France; Université d'Orléans, Orléans, France.

ABSTRACT
Mountain ranges may delimit the distribution of native species as well as constitute potential barriers to the spread of invasive species. The invasive pinewood nematode, Bursaphelenchus xylophilus, is a severe forest pest inducing pine wilt disease. It is vectored in Europe by a native long-horned beetle, Monochamus galloprovincialis. This study explored the potential of the Pyrenean chain to slow or prevent the natural spread of nematode-infested beetles from the Iberian Peninsula, where the nematode is established and is expanding its range, towards France and the rest of Europe. An analysis of the genetic structure and migration patterns of the beetle populations throughout the Pyrenean mountain range was combined with a spread model simulating the potential movements of nematode-infested beetles across it. The central part of the Pyrenees, which corresponds to the highest elevation zone, was shown to prevent gene flow between the French and Spanish populations of M. galloprovincialis on each side of the mountains. Conversely, strong admixture was detected between populations located on both sides of low elevation hills, and especially at the east and west extremities of the mountain range. Simulations of the spread of nematode-infested beetles under various thresholds of beetle survival and pine wilt disease expression gave results consistent with the variation in genetic make-up, suggesting that western and eastern hillsides may represent corridors favoring natural spread of the nematode from the Iberian Peninsula to France. Simulations also showed that temperature rise due to climate change may significantly reduce the extent of the barrier formed by highest elevations. Our results support the hypothesis that the Pyrenean chain represents a partial barrier to the natural spread of nematode-infested beetles. These results, which have to be considered together with potential human-assisted long-distance spread of the nematode, highlight priority zones for future pest monitoring and management programs. More generally, such an integrated approach could be used to assess the role of mountain chains in the potential spread of other invasive pests.

No MeSH data available.


Related in: MedlinePlus