Diabrotica v. virgifera wing shape variation reveals multiple populations across the European expansion front

Darija Lemic1, Katarina M Mikac2, Hugo A Benitez 3,

Renata Bažok1, Marina Buketa 1

1University of Zagreb, Department for Agricultural Zoology, Croatia2Institute for Conservation Biology & Law, University of Wollongong, Australia

3 Faculty of Life Sciences, University of Manchester, United Kingdom

International Conference on the German Diabrotica Research Program: Berlin 14 - 16 November 2012

• To enhance management & control understanding the temporal & spatial genetic structure (FST), number of genetic clusters (K) & pattern of gene flow (Nm) is required

• Despite multiple genetic studies revealed no genetic structure among population in the US or Europe

• A preliminary study of the genetic structure of 6 populations in Croatia also showed no genetic structureusing ‘core set’ msat markers

• A need for alternative markers that detect inter-population variation are required

WCR in Europe & Croatia

Kim & Sappington (2005) Molecular Ecology Resources; Ciosi et al. (2008) Molecular Ecology; Kim et al. (2008) Environmental Entomology

• GM techniques provide information on [wing] shape through the relative position of homologous landmarks

• Wing size & shape has been used to estimate the population structure of insect vectors of Trypanosomiasis

Geometric morphometrics (GM)

Camara et al. (2006) Journal of Medical Entomology; Bouyer et al. (2007) Journal of Medical Entomology; Dumonteil et al. (2007) American Journal of Tropical Medicine & Hygiene; Gurgel-Gonçalves et al. (2008) Acta Tropica

GM vs Msats

• GM estimates of population structure supported msats estimates for Triatoma dimidiata

& Glossina palpalis gambiensis

• Surprisingly, wing shape analysis of G. p. gambiensis found population structure at a greater resolution than the msats

Camara et al. (2006); Dumonteil et al. (2007) American Journal of Tropical Medicine & Hygiene

1. Use the ‘core set’ msats to estimate the historical & contemporary (1996 & 2009) population genetic structure of WCR inCroatia

2. Explore the use of wing shape (geometric morphometrics (GM)) to estimate the population structure of WCR in Croatia

Aim

Materials & Methods

Study location/sites

LOCATIONn

1996 2009 2011

1. BOŠNJACI 30 30 30

2. MIKANOVCI 30 30 30

3. VRBANJA 30 30 30

4. OTOK 30 30 30

5. NUŠTAR 30 30 30

GeneticAnalyses

GM Analyses

Genetic MethodsDNA extraction

Kim & Sappington (2005) Molecular Ecology Notes; Kim et al. (2008) Environmental Entomology; Miller et al. (2007) Journal of Applied Entomology; Raymond & Rousset (1995a,b) Evolution, Journal of Heredity; Rosenberg (2004) Molecular Ecology Notes; Weir & Cockerham (1984) Evolution; Pritchard et al. (2000) Genetics

Populations• 1996• 2009Total 201

individuals

Msats (core set)

Multiplex PCR

DVV-D2

DVV-T2

Dba 05

Multiplex PCR

DVV-D4

DVV-D8

Dba 07

Genotyped using ABI 3130XL

Genetic Analyser

Statistical analysis

HWEGenetic Clusters/

Genetic StructureNumber of Alleles

Identification

of source

GM Methods

LOCATIONn

2011

1. BOŠNJACI 30R, 30L

2. MIKANOVCI 30R, 30L

3. VRBANJA 30R, 30L

4. OTOK 30R, 30L

5. NUŠTAR 30R, 30L

Total: 150 Left & 150 Right wings

Materials & Methods

Statistics

• Landmark digitizing – tpsDIG v2.16 (Rohlf, 2008)

• MorphoJ v1.04a (Klingenberg, 2011) Asymmetry and sexual dimorphism analyses GM data analyses Principal component analyses Canonical variate analyses Mahalanobis distances Isolation by distance

Bošnjaci 1996

Mikanovci1996

Vrbanja 1996

Otok1996

Nuštar1996

Bošnjaci 2009

Mikanovci2009

Vrbanja 2009

Otok 2009

Nuštar 2009

K96=1 K09=1Microsatellites showed little genetic

differentiation across populations & time

(1996 & 2009)

FST:96=0.027 FST:09=0.009

Results & DiscussionGenetic Analyses

Results & DiscussionGM Wing Shape

Bošnjaci

Mikanovci

Vrbanja

Otok

Nuštar

Results & DiscussionGM– Mahalanobis distances

Bošnjaci Mikanovci Vrbanja Otok Nuštar

Bošnjaci 42 21 17 38

Mikanovci 2, 61 79 42 31

Vrbanja 2, 68 2, 34 25 61

Otok 4, 10 4, 49 3, 96 29

Nuštar 2, 06 2, 26 2, 40 4, 36

4.228

2.862

2.770

2.925

2.845

Bošnjaci

Mikanovci

Vrbanja

Otok

Nuštar

IBD (r = 0.4, P<0.05)

Significant pairwise differences in 2011 were

noted between all sampled sites

Conclusion

Perhaps microsatellites aren’t able to detect fine scale variation associated with rapidly mobile invasive species,

therefore the use of others genetic markers or phenotypic markers must be explored

This study found that a significant amount of variation in wing morphology (shape & size) exists in WCR across their

invaded range in Croatia

Use of wing morphology can provide valuableaddition information on population structurewhen used with msats especially acrosssuspected genetically homogenous geographiclandscapes

Implications

Acknowledgements

• Dr Mark Schutze, QUT, Australia

• Ms Stephanie Ivkosic, UOW, Australia

• Mr Joshua Douglas, UOW, Australia