wing geometry of anopheles darlingi root (diptera: culicidae) in five major brazilian ecoregions

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Wing geometry of Anopheles darlingi Root (Diptera: Culicidae) in five major Brazilian ecoregions Maysa Tiemi Motoki a,, Lincoln Suesdek b,c , Eduardo Sterlino Bergo d , Maria Anice Mureb Sallum a a Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, Avenida Doutor Arnaldo 715, CEP 01246-904, São Paulo, Brazil b Laboratório de Parasitologia, Instituto Butantan, Universidade de São Paulo, Avenida Vital Brazil 1500, CEP 05503-900, São Paulo, Brazil c Pós-Graduação em Biologia da Relação Patógeno-Hospedeiro, Instituto de Ciências Biomédicas, Universidade de São Paulo, CEP 05508-900, São Paulo, Brazil d Superintendência de Controle de Endemias, Secretaria de Estado da Saúde de São Paulo, Araraquara, São Paulo, Brazil article info Article history: Received 30 September 2011 Received in revised form 2 April 2012 Accepted 5 April 2012 Available online 12 April 2012 Keywords: Geometric morphometrics Wing shape Anopheles darlingi Malaria vector Ecoregions abstract We undertook geometric morphometric analysis of wing venation to assess this character’s ability to dis- tinguish Anopheles darlingi Root populations and to test the hypothesis that populations from coastal areas of the Brazilian Atlantic Forest differ from those of the interior Atlantic Forest, Cerrado, and the regions South and North of the Amazon River. Results suggest that populations from the coastal and inte- rior Atlantic Forest are more similar to each other than to any of the other regional populations. Notably, the Cerrado population was more similar to that from north of the Amazon River than to that collected of south of the River, thus showing no correlation with geographical distances. We hypothesize that envi- ronmental and ecological factors may affect wing evolution in An. darlingi. Although it is premature to associate environmental and ecological determinants with wing features and evolution of the species, investigations on this field are promising. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Anopheles (Nyssorhynchus) darlingi Root is one of the most anthropophilic anophelines in the Americas (Fleming, 1986). The species is found throughout South America from eastern Andean areas in Colombia, Venezuela, Bolivia, Peru, Ecuador, and into Brazil, the Guianas, as far south as northern Argentina (Forattini, 1962). In Central America, An. darlingi has been recorded from loca- tions in Belize, Guatemala, Honduras (Faran and Linthicum, 1981), El Salvador (Manguin et al., 1996) and Panama (Loaiza et al., 2009). In the Amazon River basin and other regions of South and Central America, this mosquito is a primary vector of the Plasmodium para- sites that cause malaria (Oliveira-Ferreira et al., 2010; Manguin et al., 1999). In the Americas, human malaria is caused by Plasmodium falciparum Welch, Plasmodium vivax Grassi and Feletti and Plasmodium malariae Laveran (Deane et al., 1948; Forattini, 2002). An. darlingi was originally described from morphological charac- teristics of adults, larvae and pupae collected in Caxiribú, near Por- to das Caxias, Itaboraí District, Rio de Janeiro State, Brazil. Galvão et al., (1937) subsequently observed morphological differences in male genitalia and eggs of individuals from Pereira Barreto munic- ipality (formerly known as Novo Oriente) in São Paulo State, Brazil. This suggested the presence of more than one species under the name An. darlingi. The Pereira Barreto population was conse- quently assigned the name An. darlingi var. paulistensis. Causey et al. (1942) would later synonymized An. darlingi var. paulistensis with An. darlingi. In addition to morphological polymorphisms in the external egg morphology of An. darlingi, other studies have shown biological variation among populations from Brazil (Lourenço-de-Oliveira et al., 1989; Forattini, 1987; Buralli and Bergo, 1988; Klein and Lima, 1990; Charlwood, 1996), Suriname (Rozendaal, 1990), French Guiana (Pajot et al., 1977), Guyana (Rambajan, 1984), Colombia (Quiñones and Suarez, 1990) and Venezuela (Rubio-Palis, 1995). Moreover, An. darlingi from northern and southern Brazil also dis- play genetic polymorphisms, including: banding patterns of fourth-instar polytene chromosomes (Kreutzer et al., 1972; Tadei et al., 1982), cuticular hydrocarbons and iso-enzyme patterns (Rosa-Freitas et al., 1992), salivary gland protein profiles (Moreira et al., 2001), and ribosomal ITS2 DNA sequences (Malafronte et al., 1999). In light of An. darlingi’s geographic and ecological breadth (Charlwood, 1996), it is intriguing that there is little evidence for the existence of a species complex (Mirabello and Conn, 2006; Conn et al., 2006; Mirabello et al., 2008). However, results from Mirabello and Conn (2006) using mitochondrial COI data indicated significant geographical differentiation between Central and South American populations, likely a consequence of ancient evolution- ary dynamics. 1567-1348/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.meegid.2012.04.002 Corresponding author. Tel./fax: +55 11 30617926. E-mail addresses: [email protected] (M.T. Motoki), [email protected] (L. Suesdek), [email protected] (E.S. Bergo), [email protected] (M.A.M. Sallum). Infection, Genetics and Evolution 12 (2012) 1246–1252 Contents lists available at SciVerse ScienceDirect Infection, Genetics and Evolution journal homepage: www.elsevier.com/locate/meegid

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Page 1: Wing geometry of Anopheles darlingi Root (Diptera: Culicidae) in five major Brazilian ecoregions

Infection, Genetics and Evolution 12 (2012) 1246–1252

Contents lists available at SciVerse ScienceDirect

Infection, Genetics and Evolution

journal homepage: www.elsevier .com/locate /meegid

Wing geometry of Anopheles darlingi Root (Diptera: Culicidae) in five major Brazilianecoregions

Maysa Tiemi Motoki a,⇑, Lincoln Suesdek b,c, Eduardo Sterlino Bergo d, Maria Anice Mureb Sallum a

a Departamento de Epidemiologia, Faculdade de Saúde Pública, Universidade de São Paulo, Avenida Doutor Arnaldo 715, CEP 01246-904, São Paulo, Brazilb Laboratório de Parasitologia, Instituto Butantan, Universidade de São Paulo, Avenida Vital Brazil 1500, CEP 05503-900, São Paulo, Brazilc Pós-Graduação em Biologia da Relação Patógeno-Hospedeiro, Instituto de Ciências Biomédicas, Universidade de São Paulo, CEP 05508-900, São Paulo, Brazild Superintendência de Controle de Endemias, Secretaria de Estado da Saúde de São Paulo, Araraquara, São Paulo, Brazil

a r t i c l e i n f o a b s t r a c t

Article history:Received 30 September 2011Received in revised form 2 April 2012Accepted 5 April 2012Available online 12 April 2012

Keywords:Geometric morphometricsWing shapeAnopheles darlingiMalaria vectorEcoregions

1567-1348/$ - see front matter � 2012 Elsevier B.V. Ahttp://dx.doi.org/10.1016/j.meegid.2012.04.002

⇑ Corresponding author. Tel./fax: +55 11 30617926E-mail addresses: [email protected] (M.T. Motok

(L. Suesdek), [email protected] (E.S. Bergo), masal

We undertook geometric morphometric analysis of wing venation to assess this character’s ability to dis-tinguish Anopheles darlingi Root populations and to test the hypothesis that populations from coastalareas of the Brazilian Atlantic Forest differ from those of the interior Atlantic Forest, Cerrado, and theregions South and North of the Amazon River. Results suggest that populations from the coastal and inte-rior Atlantic Forest are more similar to each other than to any of the other regional populations. Notably,the Cerrado population was more similar to that from north of the Amazon River than to that collected ofsouth of the River, thus showing no correlation with geographical distances. We hypothesize that envi-ronmental and ecological factors may affect wing evolution in An. darlingi. Although it is premature toassociate environmental and ecological determinants with wing features and evolution of the species,investigations on this field are promising.

� 2012 Elsevier B.V. All rights reserved.

1. Introduction

Anopheles (Nyssorhynchus) darlingi Root is one of the mostanthropophilic anophelines in the Americas (Fleming, 1986). Thespecies is found throughout South America from eastern Andeanareas in Colombia, Venezuela, Bolivia, Peru, Ecuador, and intoBrazil, the Guianas, as far south as northern Argentina (Forattini,1962). In Central America, An. darlingi has been recorded from loca-tions in Belize, Guatemala, Honduras (Faran and Linthicum, 1981),El Salvador (Manguin et al., 1996) and Panama (Loaiza et al., 2009).In the Amazon River basin and other regions of South and CentralAmerica, this mosquito is a primary vector of the Plasmodium para-sites that cause malaria (Oliveira-Ferreira et al., 2010; Manguin etal., 1999). In the Americas, human malaria is caused by Plasmodiumfalciparum Welch, Plasmodium vivax Grassi and Feletti andPlasmodium malariae Laveran (Deane et al., 1948; Forattini, 2002).

An. darlingi was originally described from morphological charac-teristics of adults, larvae and pupae collected in Caxiribú, near Por-to das Caxias, Itaboraí District, Rio de Janeiro State, Brazil. Galvãoet al., (1937) subsequently observed morphological differences inmale genitalia and eggs of individuals from Pereira Barreto munic-ipality (formerly known as Novo Oriente) in São Paulo State, Brazil.

ll rights reserved.

.i), [email protected]@usp.br (M.A.M. Sallum).

This suggested the presence of more than one species under thename An. darlingi. The Pereira Barreto population was conse-quently assigned the name An. darlingi var. paulistensis. Causeyet al. (1942) would later synonymized An. darlingi var. paulistensiswith An. darlingi.

In addition to morphological polymorphisms in the external eggmorphology of An. darlingi, other studies have shown biologicalvariation among populations from Brazil (Lourenço-de-Oliveiraet al., 1989; Forattini, 1987; Buralli and Bergo, 1988; Klein andLima, 1990; Charlwood, 1996), Suriname (Rozendaal, 1990), FrenchGuiana (Pajot et al., 1977), Guyana (Rambajan, 1984), Colombia(Quiñones and Suarez, 1990) and Venezuela (Rubio-Palis, 1995).Moreover, An. darlingi from northern and southern Brazil also dis-play genetic polymorphisms, including: banding patterns offourth-instar polytene chromosomes (Kreutzer et al., 1972; Tadeiet al., 1982), cuticular hydrocarbons and iso-enzyme patterns(Rosa-Freitas et al., 1992), salivary gland protein profiles (Moreiraet al., 2001), and ribosomal ITS2 DNA sequences (Malafronte etal., 1999).

In light of An. darlingi’s geographic and ecological breadth(Charlwood, 1996), it is intriguing that there is little evidence forthe existence of a species complex (Mirabello and Conn, 2006;Conn et al., 2006; Mirabello et al., 2008). However, results fromMirabello and Conn (2006) using mitochondrial COI data indicatedsignificant geographical differentiation between Central and SouthAmerican populations, likely a consequence of ancient evolution-ary dynamics.

Page 2: Wing geometry of Anopheles darlingi Root (Diptera: Culicidae) in five major Brazilian ecoregions

M.T. Motoki et al. / Infection, Genetics and Evolution 12 (2012) 1246–1252 1247

Within South America, Mirabello and Conn (2006) detected twoclusters coinciding with centers of endemism within the Amazonas/Solimões River basin, the Guyana shield (northern Amazon) and theEastern Amazon (Belém, Pará State), and significant evidence for aPleistocene population expansion. Recently, Pedro and Sallum(2009) showed that this expansion was not homogeneous: the pres-ence of geographic barriers (Amazonas River, the Andes and coastalmountains in eastern Brazil) contributed to the creation of at leastfour subgroups within South America. Notably, samples from theAn. darlingi type locality in Rio de Janeiro State (coastal Atlantic For-est) are markedly different from those in the interior Atlantic Forest,Central Brazil and Amazon. However, the distribution limits of thesesubgroups and the importance of landscape (as defined by Brazil’svarious ecoregions) to their variation have never been assessed.Landscape permeability may affect the genetic structuring of cer-tain species, as noted in other groups, e.g., Glossina palpalis (Bouyeret al., 2007), Triatoma infestans (Schachter-Broide et al., 2009;Hernandez et al., 2011), and songbirds (Desrochers, 2010).

Among several available approaches that assess the biologicalsignificance of species and population heterogeneity in insects,Dujardin (2008) defended the utility of wing morphometry. Wingshape has been used as a tool to both diagnose species (Dujardin,2008; Vidal et al., 2011) and to assess evolutionary aspects ofdistinct animal groups (Dujardin, 2008). It can be quantitativelydescribed by geometric morphometrics, an economical and power-ful diagnostic tool that has been employed in several studies ofdistinct organisms (Corti et al., 1998; Shipunov and Bateman,2005; Arbour et al., 2011; Clemente-Carvalho et al., 2011), includingmedically important insects (Bouyer et al., 2007; Dujardin and Slice,2007). Wing morphometric analyses revealed that the wing shapeof Aedes aegypti (Linnaeus) is quantitatively inherited, showingmicro-evolutionary variation patterns across consecutive genera-tions (Jirakanjanakit et al., 2008), among geographically distantpopulations (Henry et al., 2010), and also on small geographicalscales within a single urban area (Vidal and Suesdek, in press).Culex quinquefasciatus Say consistently exhibited wing shapevariation that was correlated to genetic diversity across distinctSouth American eco-geographic regions (Morais et al., 2010)and Anopheles funestus showed similar diversity association inCameroon (Ayala et al., 2011). However, the effect of the Brazilianeco-geographic landscape on population substructure of An. darlingihas never been assessed.

The Atlantic Forest is one of 25 biodiversity hotspots, and also themost devastated ecosystem in the world (Galindo-Leal and Câmara,2003). The Forest is subdivided into sub-regions characterized byvarious types of vegetation. The interior Atlantic Forest is comprisedof mixed seasonal semi-deciduous forest, seasonal deciduous forest,low-growing vegetation, rupestrian grassland and transition areas(Silva and Casteleti, 2003). The coastal Atlantic Forest is subdividedinto two biodiversity sub-regions: Bahia and Serra do Mar (Galindo-Leal and Câmara, 2003). The Bahia sub-region is composed of denseombrophilous forest, with patches of semi-deciduous forest, low-growing vegetation and open ombrophilous forest. The Serra doMar comprises a mountainous area extending from southern Riode Janeiro State to northern Rio Grande do Sul State (Silva andCasteleti, 2003). An. darlingi has not been reported in the Serra doMar, and this area was hypothesized to be a geographic barrier forthe species (Pedro and Sallum, 2009). The Cerrado occupies approx-imately 21% of Brazil, and it is the most diverse and most threatenedtropical savanna of the world. Cerrado has multiple vegetationphysiognomies, some areas comprise a natural mosaic of savannaand forest, for example, Atlantic Forest (Silva and Bates, 2002).The Amazon basin comprises a vast forest-river ecosystem with gra-dients of climate varying from a highly humid northwest to a wet/dry climate and long drier season in the southern and easternregions. Besides climate variation, the Amazonian ecosystem

encompass evergreen dense forest, transitional forest and areas ofcerrado (Davidson et al., 2012), with the Amazon River representinga geographic barrier to gene flow of An. darlingi (Conn et al., 2006;Pedro and Sallum, 2009). Considering the climate variation, pres-ence of distinct vegetation physiognomies and the barrier repre-sents by the Amazon River, populations from north and south ofthe Amazon River were evaluated as two separate populations.

Based partly on the results of previous studies, An. darlingiwings were analyzed using geometric morphometry methods to:(1) assess associations between ecoregions and wing differentia-tion; (2) verify if An. darlingi from the coastal Atlantic Forest differsfrom those of the interior Atlantic Forest, Cerrado, and AmazonRiver basin (North and South). Geometric properties of wings werecompared among ten An. darlingi populations from five majorBrazilian ecoregions.

2. Materials and methods

2.1. Mosquito sampling

Female An. darlingi were collected in ten localities from five Bra-zilian ecoregions (Table 1; Fig. 1) to obtain progenies that includedadult males and females associated with pupal and fourth-instarlarval exuviae.

Larvae and pupae were also sampled from adult female collec-tion localities and kept in the laboratory until adult emergence. Atleast one adult male or female was used to identify the speciesusing the identification keys of Forattini (2002). Wings weremounted on microscope slides and pupal and fourth-instar larvalexuviae of associated adults deposited in the Coleção Entomológicade Referência of Faculdade de Saúde Pública, Universidade de São Pau-lo (FSP-USP).

Individuals from the ten populations were grouped based onthe ecoregions from which they were sampled: Cerrado (CER;localities in Goiás and Tocantins states), Coastal Atlantic Forest(CAF; Espírito Santo and Rio de Janeiro states), Interior AtlanticForest (IAF; Paraná and São Paulo states), North Amazon River(NAR; Amazonas and Amapá states) and South Amazon River(SAR; Mato Grosso and Pará states). Most samples were fromthe same localities as those in Pedro and Sallum (2009), withadditional samples from Goiás and Tocantins (ecoregion CER).

2.2. Sample preparation and data collection

The left wing was removed from adult females and cured beforebeing mounted on microscope slides under a coverslip using Can-ada balsam. Curing involved soaking wings for 12 h in 10% Potas-sium Hydroxide (KOH) solution at room temperature to removewing scales. Potassium Hydroxide was removed by washing thewings in a 20% solution of acetic acid. Wings were dyed with acidfuchsin for 60 min to make wing nervures more evident and thendehydrated in an ethanol series from 80% to 98% concentration. ALeica DFC320 digital camera coupled to a Leica S6 stereomicro-scope (with plain lenses to minimize image distortion) was usedto capture wing images under 40� magnification. Coordinates of18 wing landmarks (Fig. 2) were selected and digitized. Picturesof wings dyed with acid fuchsin are deposited in CLIC morphomet-rics database (www.mpl.ird.fr/morphometrics/clic/index.html).

2.3. Morphometric analyses

Metric properties based on 18 landmarks were subjected togeneralized Procrustes analysis (Rohlf, 1996). Relative warps(RWs) of wing shape were computed, and 21 of 32 RWs were usedas input for discriminant canonical analysis. Shape metric disparity

Page 3: Wing geometry of Anopheles darlingi Root (Diptera: Culicidae) in five major Brazilian ecoregions

Table 1Specimens ID, locality and geographic coordinates of Anopheles darlingi populations.

Species ID n State, municipality Geographiccoordinates

AM61A1, AM61A2, AM61A4, AM61B1, AM61B2, AM61B3, AM61B4, AM61C1, AM61C2, AM61C3, AM61F1, AM61F2, AM61F3, AM61F4, AM61F5, AM61I1, AM61I2,AM61I3, AM61I4, AM61I5, AM61I6

21 Amazonas, Barcelos 1�5204900S62�34036.100W

AP-1, AP-2, AP-3, AP-4, AP-5, AP-6, AP-7, AP8, AP-10, AP-11, AP-12, AP-14, AP-15, AP-17, AP-18, AP-19, AP-20, AP-21, AP-22, AP-24, AP-25, AP-26, AP-27, AP-28, AP-29, AP-30, AP-32, AP33, AP-34, AP-35

30 Amapá, Macapá 0�12047.300S50�58059.800W

ES20(2)13, ES20(3)3, ES20(5)1, ES20(12)15, ES20(14)6, ES20(22)1, ES20(23)4 07 Espírito Santo,Sooretama

19�1700.4100S40�05003.800W

GO17-5, GO17-6, GO17-7, GO17-8, GO17-9, GO17-10, GO17-11, GO17-12, GO17-13, GO17-14 10 Goiás, Minaçu 13�33025.800S48�09009.500W

MT-1, MT-2, MT-3, MT-4, MT-5, MT-6, MT-7, MT-9, MT-11, MT-12, MT-13, MT-14, MT-15, MT-16, MT-17, MT-18, MT-19 17 Mato Grosso, Sinop 11�5105000S55�3001400W

PA14(1)2, PA14(2)4, PA14(3)1, PA14(4)3, PA14(5)2, PA14(6)4, PA14(7)11, PA14(9)7 08 Pará, Belterra 02�44’47.5’’S54�13’37.1’’W

PR28(2)12, PR28(4)3, PR28(6)1, PR28(7)1, PR28(9)1, PR28(10)7, PR28(25)3, PR28(26)1, PR28(27)1, PR28(29)2, PR28(32)2, PR28(45)4 12 Paraná, Guaíra 24�1601700S54�1702600W

RJ01(1)5, RJ01(2)1, RJ01(3)5, RJ01(4)7, RJ02(1)5, RJ02(2)1, RJ02(3)8, RJ02(4)2, RJ02(5)2, RJ02(6)3, RJ02(7)15, RJ02(8)2, RJ02(9)3, RJ02(10)3, RJ02(11)3, RJ02(12)1,RJ02(15)7, RJ02(17)4

18 Rio de Janeiro,Juturnaíba

22�3706000S42�1706000W

SP66(1), SP66(9) 02 São Paulo, Dourado 22�08004.900S48�23030.200W

SP69(25), SP69(26), SP69(2), SP69(3), SP69(4), SP69(5), SP73, SP73(16), SP73(17), SP73(18), SP73(19), SP73(20), SP73(21) 13 São Paulo, Dourado 22�04032.500S48�26014.500W

TO1(1), TO1(2), TO1(5), TO3(1), TO5(1), TO5(4), TO5(5), TO5(8), TO5(9), TO5(13), TO5(14), TO5(15), TO5(16), TO5(17), TO5(19), TO5(20), TO7(3), TO7(4), TO7(5),TO7(9), TO12(8), TO12(9), TO12(18)

23 Tocantins, Lagoa daConfusão

10�37018.500S49�44024.900W

1248M

.T.Motoki

etal./Infection,G

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Page 4: Wing geometry of Anopheles darlingi Root (Diptera: Culicidae) in five major Brazilian ecoregions

Fig. 1. Map describing major ecoregions of Brazil, indicating ten sampling localities of An. darlingi. Ecoregions are: north Amazon River (NAR); south Amazon River (SAR);Cerrado (CER); coastal Atlantic Forest (CAF); interior Atlantic Forest (IAF). These ecoregions are from 10 states: AM: Amazonas, AP: Amapá, ES: Espírito Santo, GO: Goiás, MT:Mato Grosso, PA: Pará, PR:Paraná, RJ: Rio de Janeiro, SP: São Paulo, TO: Tocantins.

Fig. 2. Wing of An. darlingi showing the 18 landmarks used in the present analysis.

M.T. Motoki et al. / Infection, Genetics and Evolution 12 (2012) 1246–1252 1249

between groups was evaluated using 10,000 runs of random per-mutation tests. A phenogram of Procrustes distances was also cal-culated. The global size of the wing was described by the centroidsize isometric estimator. The latter is determined by the squareroot of the summed squared distances of each landmark to a cen-troid point. Centroid sizes from samples of different populationswere compared using ANOVA. The allometric effect within eachpopulation group was examined by regression of Procrustes coor-dinates of wing centroid size and its statistical significance wasdetermined by 1000-run permutation tests.

2.4. Classification tests

To test the accuracy of cluster recognition based on wing shapeusing validated classification, each individual was reclassified

according to its wing similarity to the average shape of each group.As with premises of multivariate statistics, only 21 of 32 RWs wereused as input of discriminant analysis. Mahalanobis distances wereused to estimate this metric and statistical significance of each dis-criminant function was estimated by 1000 permutation tests.

2.5. Software

Landmark digitizing was done with tpsDig (v1.40, James Rohlf)and data analyses were performed using software packagesmorphoJ (Klingenberg, 2011), PAD and COV (J.P. Dujardin, availableat www.mpl.ird.fr/morphometrics). Graphical outputs were gener-ated using Statistica 7.0 (StatSoft Inc. 2002) and TreeView (Page,1996).

3. Results

3.1. Wing size

Centroid sizes of population representatives varied from1.43 mm to 2.00 mm. The IAF population showed the upper medianvalue of 1.74 mm and mean value of 1.76 mm, followed by CER(median and mean = 1.67 mm); whereas CAF (median = 1.61 mm;mean = 1.62 mm), NAR (median = 1.62 mm; mean = 1.61 mm) andSAR (median = 1.60 mm; mean = 1.61). ANOVA revealed significantdifferences in some comparisons (p = 0.04), which is graphicallydescribed in Fig. 3. Regression analysis of size against shape vari-ables was significant (p = 0.02), although with a slight allometric

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1250 M.T. Motoki et al. / Infection, Genetics and Evolution 12 (2012) 1246–1252

effect (1.26%). To assess the effect of allometry on shape results, asecond analysis was conducted from which the allometric residuewas removed. Results (not shown) were nearly similar to thoseyielded before removal of allometry. Quantitative phenotypic diver-gence (Qst) was 0.9100 for centroid size and 0.4476 for shape (first16 relative warps).

3.2. Wing shape

Metric disparity analyses of 18 landmarks after Procrustessuperimposition revealed a significant distinction between the fol-lowing population groups: CAF � CER (p = 0.004), IAF � NAR(p = 0.031), CAF � SAR (p = 0.011). There was marginal significancebetween CER � NAR (p = 0.064) and CAF � IAF (p = 0.057). Thephenogram indicates CAF and IAF populations as more similar be-tween themselves than to any of the remaining populations. Sim-ilarly, CER and NAR populations are more similar betweenthemselves than they are to the remaining populations. SAR isthe most dissimilar group (Fig. 4). Results of Mahalanobis distancesof discriminant analysis are shown in Table 2.

Fig. 4. Phenogram of the Procrustes distances among populations samples ofAn. darlingi.

Table 2Cross-validated reclassification of individuals from the five populational clusters ofAn. darlingi.

Clusters CER CAF IAF NAR SAR Total(100%)

ReclassificationCER 20(66%) 13(34%) – – – 33CAF 09(36%) 16(64%) – – – 25CER 29(88%) – 04(12%) – – 33IAF 08(25%) – 24(75%) – – 32CER 23(70%) – – 10(30%) – 33NAR 16(21%) – – 35(79%) – 51CER 23(70%) – – – 10(30%) 33SAR 08(32%) – – – 17(68%) 25CAF – 14(56%) 11(44%) – – 25IAF – 13(41%) 19(59%) – – 32CAF – 22(88%) – 03(12%) – 25NAR – 06(12%) – 45(88%) – 51CAF – 18(72%) – – 07(28%) 25SAR – 05(20%) – – 20(80%) 25IAF – – 28(88%) 04(12%) – 32NAR – – 09(18%) 42(82%) – 51

4. Discussion

In mosquitoes and other insects, geometric morphometricsanalysis of wing landmarks is a useful tool in studies of macro-and micro-evolution, i.e. distinguishing both species and popula-tions. For example, wing geometry was used to identify speciesof Rodnius robustus (Matias et al., 2001), and Lutzomyia longipalpis(De la Riva et al., 2001) complexes, and to differentiate sandflies(Phebotominae) species from four large ecoregion in South Amer-ica (Dujardin and Le Pont, 2004). This was similarly employed toassess population structuring associated with landscape and habi-tat isolation (Broide et al., 2004; Bouyer et al., 2007; Ayala et al.,2011), separate laboratory lines of Ae. aegypti (Jirakanjanakit andDujardin, 2005), and identifying Anopheles (Calle et al., 2008) andCulex (Vidal et al., 2011) species.

Wing size, although partly determined by quantitative heritage,may be labile and influenced by temperature (Gibert et al., 2004;Polak et al., 2004), relative humidity (Morales-Vargas et al.,2010), and food availability (Jirakanjanakit et al., 2007). Herein,we focused on the geometry of wing shape, which is usually lesssubjected to environmental influence and more evolutionary infor-mative (Dujardin, 2008; Jirakanjanakit et al., 2008).

Discriminant analyses were performed for each of ten An.darlingi geographical populations (results not shown). These

Fig. 3. Descriptive statistics of centroid sizes of samples of An. darlingi.

IAF – – 24(75%) – 08(25%) 32SAR – – 07(28%) – 18(72%) 25NAR – – – 35(69%) 16(31%) 51SAR – – – 09(36%) 16(64%) 25

indicated slight dissimilarities between all populations, althoughthe scores of Mahalanobis and Procrustes distances were notcorrelated with geographical distance. Consequently, if thereis wing micro-differentiation among An. darlingi populations,geographic distance seems to be an unimportant component.

In light of previous findings, morphometric analyses were car-ried-out to assess the influence of the five major Brazilian ecore-gions in wing shape and size. Briefly, Cerrado (CER) populationsinclude localities from Goiás and Tocantins states, Coastal AtlanticForest (CAF; Espírito Santo and Rio de Janeiro states) Interior Atlan-tic Forest (IAF; Paraná and São Paulo states), North Amazon River(NAR; Amazonas and Amapá states), and South Amazon River(SAR; Mato Grosso and Pará states).

The Procrustes distances phenogram derived from wing dataindicates that populations from the coastal Atlantic Forest (CAF)

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differ from other populations, except in comparison to the interiorAtlantic Forest (IAF); these are more similar to each other thanthey are to CER, SAR and NAR populations. According to Pedroand Sallum (2009), An. darlingi in Brazil are structured into fivemain population groups, i.e., Central Amazonia, southern Brazil,southeastern Brazil and two from the northeast Amazon basin.The Southern Brazil population includes IAF samples, whereas thatfrom southeastern Brazil is composed of CAF populations. Wingshape similarity between IAF and CAF populations does not corrob-orate results of Pedro and Sallum (2009), where the COI gene indi-cated that the Southern Brazil (IAF) population is genetically morerelated to Central Amazon than to southeastern Brazil (CAF).Although limited dispersal between the IAF and CAF due to thecoastal mountain ranges may have promoted COI divergence, itdid not influence wing shape.

The Procrustes distance phenogram also differentiated NAR andSAR populations. Similarly, Conn et al. (2006) using data from 8microsatellites from 256 An. darlingi individuals observed signifi-cant differentiation between individuals from locations north andsouth of the Amazon River, which may be caused by the geograph-ical impediment posed by Amazon River (Pedro and Sallum, 2009).The wing phenogram also showed that samples from NAR are moresimilar to those from CER than to SAR. This may be a consequenceof Amapá State containing both Cerrado and Amazon Forest, whichmay influence the dispersal of An. darlingi, however, promoting dis-persion in areas of Cerrado and Amazon Forest. In Amapá State, An.darlingi were sampled in rural areas of Macapá municipality, on theboundary between Cerrado and Amazon Forest. However, samplesfrom Barcelos, Amazon State, were collected in areas of denseAmazon Forest in rural communities along the Negro River withlow human density. In light of the mixed ecoregions of NAR sam-ples, future work should increase sample size and separate winganalyses for each ecoregion in Amapá State and compare them tosamples from Amazon Forest and CER.

The phenogram grouped CAF and IAF and differentiated thesefrom CER, NAR and SAR, a pattern that parallels recognized Brazil-ian ecoregions. Statistically significant shape disparity was ob-served for CAF vs. CER, IAF vs. NAR and CAF vs. SAR, suggestingthat both geographic distance and ecoregions may represent barri-ers that promote the heterogeneous gene flow that drives differen-tiation. Nonetheless, Qst values were high for wing size and wingshape, so that the influence of natural selection in producing thisevolutionary pattern cannot be discarded.

Ecoregions may represent barriers that limit dispersal and thusinfluence the population structuring of An. darlingi. The importanceof ecoregions in differentiating wing geometry may result fromdistinct ecological and environmental determinants among eachregion. There are differences in microclimate, environmentaldeterminants, vegetation structure and availability of larval habitatthat may impede gene flow between populations from differentecoregions. Results of the present study also confirm the useful-ness of wing geometry to diagnose macro-scale population struc-ture in An. darlingi. Finally, considering that the degree ofdifferentiation among populations of An. darlingi was lower thanthat expected for a species with a large geographical distribution,which encompasses distinct ecosystems, vegetation physiogno-mies and latitudes, results of the present study support that thismajor malaria vector represents a metapopulation. An. darlingi dis-persal may be facilitated by several river basins running throughdistinct ecoregions in Brazil.

Acknowledgements

This investigation has financial support from the Fundação deAmparo à Pesquisa do Estado de São Paulo, FAPESP (Grant 05/50903-0 to MAMS), and CNPq (BPP300300/2008-9 to MAMS).

MTM is a doctorate recipient of a FAPESP scholarship (FAPESPNo. 2007/07573-5). We are in debt to reviewers and editor forcomments and suggestions that greatly improved the previous ver-sions of the manuscript; Pedro M.C. Pedro for English editing.

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