Multiple, independent colonizations of the Hawaiian Archipelago by the family Dolichopodidae

21 Pages·2016·0.73 MB·English

Multiple, independent colonizations of
the Hawaiian Archipelago by the family
Dolichopodidae (Diptera)
KariRoeschGoodman1, NealEvenhuis2, PavlaBartošová-Sojková3 and Patrick
MichaelO’Grady1
1DepartmentofEnvironmentalScience,PolicyandManagement,UniversityofCalifornia,
Berkeley,CA,UnitedStates
2DepartmentofNaturalSciences,BerniceP.BishopMuseum,Honolulu,HI,UnitedStates
3InstituteofParasitology,BiologyCentreoftheCzechAcademyofSciences,
ČeskéBudějovice,CzechRepublic
ABSTRACT
The family Dolichopodidae forms two of the four largest evolutionary radiations in
the Hawaiian Islands across all flies: Campsicnemus (183 spp) and theEurynogaster
complex(66spp).TheyalsoincludeasmallradiationofConchopus(6spp).Ahandful
of other dolichopodid species are native to the islands in singleton lineages or small
radiations.Thisstudyprovidesaphylogeneticperspectiveonthecolonizationhistory
ofthedolichopodidfaunaintheislands.Wegeneratedamulti-genedatasetincluding
representativesfrom11ofthe14endemicHawaiiandolichopodidgeneratoexamine
thehistoryofcolonizationtotheislands,andanalyzeditusingBayesianandmaximum
likelihoodphylogeneticmethods.WeusedasubsetofthedatathatincludedConchopus
and the eight genera comprising the Eurynogaster complex to estimate the first
phylogenetichypothesisfortheseendemicgroups,thenusedBeasttoestimatetheirage
ofarrivaltothearchipelago.TheEurynogaster complex,CampsicnemusandConchopus
are clearly the result of independent colonizations. The results strongly support the
Eurynogaster complex as a monophyletic group, and also supports the monophyly
of 4 of the 8 described genera within the complex (Adachia,Arciellia,Uropachys and
Eurynogaster).MembersofthefamilyDolichopodidaehavebeendispersingovervast
Submitted15July2016
Accepted 19October2016 distancestocolonizetheHawaiianArchipelagoformillionsofyears,leadingtomultiple
Published17November2016 independentevolutionarydiversificationevents.TheEurynogaster complexarrivedin
Correspondingauthor theHawaiianArchipelago11.8Ma,wellbeforethearrivalofCampsicnemus(4.5Ma),
PatrickMichaelO’Grady, andtheevenmorerecentConchopus(1.8Ma).Datapresentedheredemonstratethat
[email protected]
the Hawaiian Dolichopodidae both disperse and diversify easily, a rare combination
Academiceditor that lays the groundwork for field studies on the reproductive isolating mechanisms
DezeneHuber
andecologicalpartitioningofthisgroup.
AdditionalInformationand
Declarationscanbefoundon
page15
SubjectsEntomology,EvolutionaryStudies
DOI10.7717/peerj.2704 Keywords Colonizationhistory,Diptera,Divergencedating,Dolichopodidae,Evolutionary
radiation,Longdistancedispersal,Hawaiianislands
Copyright
2016Goodmanetal.
INTRODUCTION
Distributedunder
CreativeCommonsCC-BY4.0
Long distance dispersal from continental populations is critical to the formation of
OPENACCESS the Hawaiian flora and fauna (Carson&Kaneshiro,1976; O’Grady,Magnacca&Lapoint,
HowtocitethisarticleGoodmanetal.(2016),Multiple,independentcolonizationsoftheHawaiianArchipelagobythefamily
Dolichopodidae(Diptera).PeerJ4:e2704;DOI10.7717/peerj.2704
2009),butisconsideredrare.Thisinfrequentarrivalandestablishmenthasledtoafloraand
faunathatisdisharmonicrelativetothoseonthecontinentsthatservedassources(Gillespie
&Roderick,2002).Recently,severalstudies(reviewedinHeaney,2007;Bellemain&Ricklefs,
2008) have shown that reverse colonization from Hawaii to continental landmasses is
observedinbirds(Filardi&Moyle,2005),plants(Harbaugh&Baldwin,2007)andinsects
(O’Grady&DeSalle,2008;Lapoint,Magnacca&O’Grady,2014),suggestingthatdispersal
playsalargerrolethanpreviouslythoughtandevidenceisaccumulatingtoindicatethat
movementtoandfromislandsystemsismorecommon,especiallyatgeologicaltimescales
(Heaney,2007; Ciboisetal.,2011; Hembryetal.,2013; Casquetetal.,2015). If a lineage is
vagileenoughtorepeatedlycolonizeanarea,thereisareducedchancethatitwillgenerate
thereproductiveisolationnecessarytospeciateandthenradiate.Furthermore,ifradiation
doesoccurinalineageandthereissubsequentcolonizationoftheareabycloserelatives,
ecological theory would predict that the existing niches would be pre-empted (Hardin,
1960), rendering a second radiation unsuccessful. Thus, clear examples where a lineage
colonizesandradiatesrepeatedlyandsubstantiallyarerare.
The Hawaiian-Emperor Archipelago has a long and dynamic geological history, well
isolated in the central Pacific Ocean far from any continental mass. It has been forming
by the motion of the Pacific plate over a stationary hotspot (Wilson,1963), generating
an island chain that is at least 80 million years old (Clague&Dalrymple,1987; Duncan
&Keller,2004;Sharp&Clague,2006).Islandformationduringthislonghistoryhasbeen
episodic, with some periods characterized by only few, low elevation atolls and reduced
speciesdiversityandothertimeswithmultiplehighislandscapableofsupportingadiverse
floraandfauna(Price&Clague,2002).Manyoftheolderislandsthatarenowsubmerged
or heavily eroded to small land masses once provided the kind of high island habitat we
arefamiliarwithinthecontemporaryhighislands(Niihau,Kauai,Oahu,Molokai,Lanai,
Maui, Kahoolawe and Hawaii), which have been forming very recently—only over the
pastfivemillionyears(Clague&Dalrymple,1987;Clague,1996:Fig.1).Thecurrenthigh
islandsprovidearicharrayofhabitats,rangingfromlowtohighelevationandverydryto
verywetvegetationtypes.
Allofthefloraandfaunaarrivedtothisdynamicarchipelagovialongdistancedispersal
in an unlikely sequence of events in which taxa both managed to land on the islands
and persist once there (Zimmerman,2001; Gillespieetal.,2012). Recent phylogenetic
studies of Hawaiian insects (Jordan,Simon&Polhemus,2003; Mendelson&Shaw,2005;
Shapiro,Strazanac&Roderick,2006; Medeirosetal.,2009; Lapoint,Gidaya&O’Grady,
2011; Medeiros&Gillespie,2011; O’Gradyetal.,2011; Haines&Rubinoff,2012; Bennett
&O’Grady,2013; Bess,Catanach&Johnson,2013; Goodman&O’Grady,2013; Lapoint,
O’Grady&Whiteman,2013; Goodmanetal.,2014; Haines,Schmitz&Rubinoff,2014;
Lapoint,Magnacca&O’Grady,2014), have begun to reveal the history of colonization
to and diversification within the Hawaiian Archipelago, and it appears that history is
somewhat idiosyncratic. Some large groups, such as Hawaiian Drosophilidae with an
estimated 1,000 species, colonized the Hawaiian Islands tens of millions of years ago.
Other diverse groups, such as Nesophrosyne leafhoppers, with 72 described and over
100 undescribed species (Bennett&O’Grady,2011), andCampsicnemus flies with about
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 2/21
Figure1 MaximumcladecredibilitytreesummarizingBEASTanalysisoftheEurynogastercomplexwithgeologichistoryofthearchipelago.
Nodebarsarethe95%highestposteriordensityintervalsofthedivergencetimeestimate.Thecolorofeachbarindicatesthelevelofmaximumlike-
lihoodbootstrapsupportforeachclade(darkblue,>95%;lightblue,75–95%;white,<75%).Timelineofshieldformation(black),maximumel-
evation>3,000m(darkgreen)andmaximumelevation>1,000m(lightgreen)isshownforthepast30millionyears.Islandareaestimates,re-
drawnfromPrice&Clague(2002),areshownforthepresentdayand10,15and25millionyearsbeforepresent.Islandcolorinthepresentdaycor-
respondstoislandoccurrenceforeachsampledtaxon(red,Hawaii;blue,Maui;orange,Molokai;purple,Oahu;green,Kauai).
200species(Goodmanetal.,2014)areyoung,datingtoonlyafewmillionyears.Onething
isclear,however—veryfewendemicHawaiianplantoranimalfamilieshavesuccessfully
colonizedtheislandsmultipletimes(e.g.,Araliaceae;Plunkett,Soltis&Soltis,1997;Costello
&Motley,2001) and in no case have any of these generated two radiations of with more
than50specieseach.
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 3/21
Table1 CompositionandstatusofDolichopodidaefaunaofHawaii. Generawithendemicspeciesareboldface.
Genus Totalspp.inHawaii Numberofendemicspp. Numberofnon-endemic Numberofdescribedspp,included
spp. inthisstudy(undescribedspp.)
[includedfromoutsideHawaii]
Achradocera 2 0 2 0
Amblypsilopus 1 0 1 0
Asyndetus 1 1 0 0
Austrosciapus 1 0 1 0
Campsicnemus 183 183 0 70[14]
Chrysosoma 2 0 2 0
Chrysotus 1 0 1 1(1)[1]
Conchopus 6 6 0 3
Condylostylus 1 0 1 1
Dactylomyia 1 0 1 0
Diaphorus 1 0 1 0
Dolichopus 1 0 1 1
Eurynogastercomplex
Adachia 6 6 0 2(1)
Arciellia 3 3 0 2
Elmoia 8 8 0 2
Eurynogaster 23 23 0 6(7)
Major 1 1 0 1
Sigmatineurum 11 11 0 1
Sweziella 7 7 0 1
Uropachys 7 7 0 3
Hydrophorus 2 2 0 0
Krakatauia 1 0 1 0
Medetera 1 0 1 0
Paraliancalus 2 2 0 0
Pelastoneurus 1 0 1 0
Sympycnus 1 0 1 1[5]
Syntormon 1 0 1 1[5]
Tachytrechus 1 0 1 1
Thinophilus 1 1 0 1
Flies in the family Dolichopodidae are remarkable in that they have colonized the
Hawaiian Islands multiple times and still have managed to generate two of the largest
evolutionary radiations within the Hawaiian Diptera: Campsicnemus Haliday, 183
spp. (Goodmanetal.,2014), and the Eurynogaster complex, 66 spp. in eight genera
(Evenhuis,2005). In addition, they also generated a small radiation of 6 spp., Conchopus
Takagi. In addition to these three radiations, four other dolichopodid genera contain
endemic species: Asyndetus (1), Hydrophorus (2), Paraliancalus (2), and Thinophilus (1)
(Table 1). Thus, the family Dolichopodidae offers a unique opportunity to examine the
timingandfrequencyoflongdistancecolonizationeventsinthefoundingoftheendemic
Hawaiian fauna. While recent molecular phylogenies of Dolichopodidae (e.g., Limet
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 4/21
al.,2010; Bernasconi,Pollet&Ward,2007) have sampled some of these genera (e.g.,
Campsicnemus,Hydrophorus,Thinophilus), uneven sampling between studies and the
lack of Hawaiian exemplars makes it difficult to infer the colonization history in detail.
Furthermore,whilethebiogeographyofCampsicnemushasbeenstudied(Goodmanetal.,
2014),theevolutionaryrelationshipsamongthethreeradiationsandthemonophylyand
biogeographyofthelargeEurynogaster complexhaveneverbeenexamined.
The primary goal of this paper is to address the colonization history of the endemic
Hawaiian Dolichopodidae and assess how many colonization events have generated the
present-day diversity within this lineage. We sampled 11 of the 14 genera with endemic
Hawaiian species and included samples from across the family Dolichopodidae. We
sequencedacombinationoffivemitochondrialandtwonucleargenesandusedthesedata
toestimatecolonizationtimesusingtheBayesianalgorithmimplementedinBeasttoinfer
thecolonizationhistoryofthisfamilyinHawaii.Withoursamplingwealsoprovidethe
first molecular phylogenetic analysis of the Eurynogaster complex, with which we assess
themonophylyofthislineagesanditsconstituentgenera.
MATERIALS & METHODS
Taxonomic sampling
Specimenswerecollectedfrom2004to2012fromsitesacrosstheHawaiianIslands.The
bulkofHawaiianDolichopodidaespeciesareendemictohighelevation(900–1,700m.)rain
foresthabitats,andthuscollectingeffortswereconcentratedintheseareas.Otherhabitats
(e.g.,coastalstrand,dryandmesicforests,alpinezone)werealsosampled,includingrocky
beaches,theonlyknownhabitatofConchopus,Thinophilus,AsyndetusandHydrophorus.
We succeeded in collecting specimens from 11 of the 14 Hawaiian dolichopodid genera
with endemic species known from the islands (Campsicnemus,Conchopus,Thinophilus
andeightgenerafromthe Eurynogaster complex,TableS1AinAppendixS1).Datafrom
the Hawaiian Campsicnemus are included here from a previous study from our group,
and are described in Appendix A from Goodmanetal.(2014). Material was collected
by general sweeping of vegetation and leaf litter, pan and Malaise trapping, and hand
collecting. Toevaluate monophyly ofand diversity withintheEurynogaster complex, we
included representatives from each of its eight constituent genera (Table 1; Evenhuis,
2005). No Eurynogaster complex lineages were omitted from our sampling. All material
waspreservedin95%ethanol.
All material was identified using the most recent key to species in Tenorio(1969)
and Evenhuis(2005). Descriptions of new species from within the Eurynogaster complex
discoveredasaresultofthisprojectareinpreparation.Unpublishednewspeciesincluded
in the study were given letters (e.g., Eurynogaster n. sp. A, B, C, etc.). In addition to the
extracted specimens, whenever possible, a series of conspecifics from the same site were
alsopreservedin95%ethanol.VouchermaterialhasbeendepositedintheBernicePauahi
Bishop Museum (Honolulu). In addition, new sequences were generated for outgroup
specimens from the non-endemic Dolichopodidae: five specimens of Dolichopusexsul,
two specimens of Chrysotuslongipalpis, and one specimen each of Condylostylussp. and
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 5/21
Table2 Primernamesandreferences.MitochondrialprimernumberscorrespondtothelocationintheDrosophilayakubamitochondrialgenome
(Clary&Wolstenholme,1985).Sequenceswithnoreferenceweredesignedasapartofthisstudy.
Primername Length Genome ReferenceorSequence
CytochromeOxidaseI(COI):2183or 829 mitochondrial Bonacumetal.(2001)
2640and3041
CytochromeOxidaseII(COII):3037and 681 mitochondrial Bonacumetal.(2001)
3771
NADHDehydrogenase2(ND2):192and 527 mitochondrial Bonacumetal.(2001)
732
16S 530 mitochondrial DeSalle(1992)
12S 559 mitochondrial F14233,R14922(Simonetal.,1994)12S_exF:5(cid:48)-TCCAGTACA
TCTACTATGTTACG-3(cid:48)12S_inF:5(cid:48)-ATGTGTRCATATTTT
AGAGC-3(cid:48)12S_inR:5(cid:48)-TATTRGCTAAATTTGTGCCAGC-3(cid:48)
rudimentary(CAD),nestedreaction:320F 896 nuclear Moulton&Weigmann(2004)
and843R,338Fand680R
EF1αA 1,036 nuclear EF4andEF5(Collins&Wiegmann,2002)EFF:5(cid:48)-CNCCTGGCC
ATCGTGATTTC-3(cid:48)EFR:5(cid:48)-CAGCATCTCCYGATTTGA
TGGC-3(cid:48)
EF1αB 858 nuclear EFF_B:5(cid:48)-GATTACTGGTACATCTCAAGC-3(cid:48)EFR_B:5(cid:48)-
TAGCAGCATCYCCYGATT-3(cid:48)
Tachytrechusangustipennis. Finally, sequences from Hercostomusindonesianus were also
downloaded from GenBank to include in the outgroup (see Table S1A in Appendix S1).
AccessandcollectionpermitsweregrantedbytheStateofHawaiiDepartmentofLandand
NaturalResources,theNationalParkService(HawaiiVolcanoesandHaleakalaNational
Parks), Maui Land and Pineapple, East Maui Irrigation, Parker Ranch, and The Nature
ConservancyofHawaii(AppendixS4).
Phylogenetic analysis
Relationships within Dolichopodidae and colonization of the Hawaiian
Islands
To address the question of whether the endemic dolichopodid fauna, including the
three major radiations (Campsicnemus, the Eurynogaster complex and Conchopus) is
the result of a single or multiple colonizations, new sequences were generated for the
samples described above (and in Table S1A in Appendix S1) and were combined with
the entire data matrix generated from the Goodmanetal.(2014) Campsicnemus study.
GenomicDNAwasextractedfromindividualsusingaQiagenDNeasy(QiagenInc.)DNA
extractionkit,followingthemanufacturer’sprotocol.LociusedaredescribedinTable2.
Thermal cycling involved a simple protocol for EF1a, a touchdown protocol for the
mitochondrialgenesandanestedreactionforCAD(describedinMoulton&Weigmann,
2004).Thesimpleprotocolbeganwithaninitialdenaturingstepat95Cfor4min,30cycles
of90Cfor30s,54–58Cfor30s,72Cfor60sandafinalextensionfor5–10min72C.The
touchdownprotocolbeganwithaninitialactivationcycleat96Cfor2.5minfollowedby25
cyclesof30sdenaturingat96C,30sannealingthroughatouchdownseriesstartingfrom
55Candsteppingdown0.4Cpercycle,with45sextensionat72C.Thiswasfollowedby15
cyclesof30sdenaturingat96C,30sannealingat45Cand45sextensionat72C.Afinal
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 6/21
extension for 7 min at 72C ended the touchdown protocol. PCR products were purified
usingExo-SAP-IT(USBCorporation,Cleveland,OH,USA)followingstandardprotocols,
andtheproductsweresenttotheUCBerkeleyDNASequencingCenterforsequencingin
bothdirectionsonanABI3,730capillarysequencer.Elevenofthe14dolichopodidgenera
with endemic species are represented. This yielded an alignment, referred to as dataset
A,containing183individualsandsevenlocicontaining4,763basepairsthatwasusedto
assessdeeptemporalandbiogeographicpatternswithinHawaiianDolichopodidae.
Phylogenetic relationships within the Eurynogaster complex
To assess the monophyly of the Eurynogaster complex and its component genera,
seventeen described, four new, and five possible new species (labeled as ‘‘sp. nr’’.) were
included in the phylogenetic analysis (Table 1). This matrix was designated as dataset
B. Phylogenetic analyses were performed on a data set consisting of 57 individuals
(see Table S1 in Appendix S1) and seven loci containing 5,908 base pairs. The more
restrictedtaxonsamplingindatasetBwastomaximizethecompletenessofthesevenloci
sampled,manyofwhichweren’tsampledinthelargerdatasetA.Resultsbetweenthetwo
studies are largely congruent. Analyses were conducted on each gene individually using
maximumlikelihood(ML,seebelow).DatasetBwasusedtoassessbiogeographicpatterns
withintheEurynogaster complexofgenera.
DatasetsAandBwerebothanalysedusingMLandBayesianinference(BI)optimality
criteria.ForeachoftheMLandtheBIanalyses,theoptimumpartitioningschemeswere
calculated in PartitionFinder (Lanfearetal.,2012). The optimal partitioning scheme for
the combined analysis of Hawaiian Dolichopodidae (dataset A), was calculated from 18
originaldatapartitions(16S,12Sand1st,2nd,and3rdcodonpositionsforCOI,COII,ND2,
CAD,EF1α andoneCADintronregion).PartitioningwascalculatedfortheEurynogaster
complexdataset(datasetB)from20originaldatapartitions(16S,12Sand1st,2nd,and3rd
codonpositionsforCOI,COII,ND2,CAD,EF1αAandEF1αB,intronregionsforCAD,
EF1αA,EF1αBandND2)andselectedusingBayesianInformationCriterion(TableS2Bin
Appendix2).Forbothdatasets,intheBIanalyses,thebest-fitmodelofsequenceevolution
for each data partition was also selected using PartitionFinder (Table S2B in Appendix
S2:Lanfearetal.,2012).Selectionofmodelsandpartitionsproceededasdescribedabove
and these are reported in Table S1B in Appendix S1. The ML analyses were performed
onindividualgenesandontheconcatenateddatasetsinRAxML3.7.2(Stamatakis,2006)
onCIPRES(Miller,Pfeiffer&Schwartz,2010)undertheGTRGAMMAmodelwith1,000
bootstrapreplicatesandafinalsearchforthebesttree.TheBIanalyseswereperformedon
theconcatenateddatasetsusingMrBayes3.1.2(Huelsenbeck&Ronquist,2001)onCIPRES
(Miller,Pfeiffer&Schwartz,2010),witheachanalysesrunfor30milliongenerationswith
2independentrunseach.
MCMCconvergencediagnostics: For the BI analyses, stationarity was assessed within
and convergence among each of the runs using several complimentary approaches: (1)
convergence metrics provided by MrBayes 3.1.2 were checked (Huelsenbeck&Ronquist,
2001)toensurethatthemaximumstandarddeviationofsplitfrequenciesofanyoftheruns
wasunder0.05andthatthepotentialscalereductionfactorforallparametersapproached
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 7/21
1.0,and(2)thelog-likelihoodvaluesforeachrunwereplotted,theEffectiveSampleSizes
(ESS)werecheckedtoensuretherewereanadequatenumberofindependentsamples,and
theposteriordistributionsofallparameterswereexaminedusingTracerv.1.72(Rambaut&
Drummond,2012).Tracerv.1.72wasalsousedtodeterminetheburn-inphasebyassessing
each run’s plot of log-likelihood values over generations—stationarity was assumed to
havebeenreachedwhentheloglikelihoodvaluesreachedastableplateau.Finally,a50%
majorityruleconsensustreeswascreatedfromtheresultingpostburn-intrees.
Divergence time estimation in the Eurynogaster complex
To estimate the age of the Eurynogaster complex lineage, divergence time estimation
was performed on dataset B using a Bayesian relaxed-clock method implemented in
BEAST 1.7.5 (Drummondetal.,2012) on CIPRES (http://www.phylo.org: Miller,Pfeiffer
&Schwartz,2010).TheageoftheEurynogaster complexisunknownasrepresentativesof
the genus are not known outside of Hawaii and biota in the Hawaiian Islands does not
fossilize well. There is a fossil available for one genus that has an endemic species in the
HawaiianIslands(ThinophilusWahlberg:subfamilyHydrophorinae),butthewiderange
inagesofthefossils(Balticamber—Eocene/Oligocene;ca.35–60mya)comparedwiththe
very young ages of the islands make them unsuitable for use in this analysis. Instead, we
usedthreebiogeographiccalibrationsbasedontheislandagesofKauai,MauiandHawaii
(see Table S2A and Fig. S2A). We then evaluated the impact of the Kauai calibration by
runningananalysiswithonlytheMauiandHawaiicalibrations,andalsorantwoalternate
analysesforcomparisonbasedonevolutionaryrates,describedinAppendixS2.
We selected two well-supported nodes for calibration from within a lineage of the
genus Eurynogaster that exhibit a clear progression from older to younger islands
(Oahu to Maui to Hawaii). We also performed a maximum likelihood ancestral state
reconstruction in Mesquite v.2.7.2 (Maddison&Maddison,2009) to assign ancestral
areas to all nodes in the phylogeny. We then selected a third well-supported node for
calibration with a clear ancestral range reconstruction to the oldest island of Kauai. All
three nodes were calibrated with island dates from Carson&Clague(1995) (Table S2A
and Fig. S2A). While island calibrations have been widely used for the estimation of
divergencetimesinHawaiianlineages(e.g.,Rubinoff&Schmitz,2010;Lerneretal.,2011),
itisplausiblethatdivergenceamongpopulationsoccurredpriortoislandemergenceand
was thus unrelated, or that it occurred well after the emergence of the younger island
(Heads,2005).Standarddeviationswerechosentoaccommodatesomeofthisuncertainty,
including a biologically relevant timeframe during which habitat was likely available on
theislands,andthefactthattheinsectsmayhavecolonizedtheislandswellbeforeorafter
theyreachedtheirpeakheights(TableS2A).
Divergence time estimation was performed on dataset B described above. The same
seven gene concatenated data set (COI, COII, ND2, 12S, 16S, EF1α and CAD) was
analysedineachoftheanalysesdescribedhereandinAppendixS2.Partitionsandthebest
fit models of evolution for each partition were selected using BIC in PartitionFinder
(Lanfearetal.,2012). Initial analyses indicated that these models overparameterized the
data in that the ESS values were extremely low for some parameters, despite being run
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 8/21
withverylongchains(beast-usersGooglegroupdiscussions).Forthefinalruns,allGTR
modelswerechangedtoHKY(TableS1B)andESSincreasedsignificantlywhiledivergence
times and tree topology did not change. Base frequencies were estimated from the data.
The partitioning scheme in the divergence rate analyses differed only slightly from the
island calibration analyses in that COI was assigned its own partition (Table S1B). Site
and clock models were unlinked and all partitions were analysed using an uncorrelated
lognormalrelaxedclockexceptforthepartitioncomprisedofCAD(positions1&2)and
theEF1α intron,forwhichastrictclockcouldnotberejectedandwasthusapplied.The
tree-shapepriorwaslinkedacrosspartitionsandthetree-shapepriorwasspecifiedasaYule
Process.Thexmlfilewashandeditedtoincludeastartingtree,generatedusingmaximum
likelihood in RAxML 3.7.2 (Stamatakis,2006). Two independent MCMC searches were
conducted,eachrunningfor50milliongenerationsandsampledevery1000generations.
ThenumberofgenerationswasselectedtogenerateESSvaluesgreaterthan200foreachof
theparameters(Drummondetal.,2012).ConvergencewasassessedusingTracerv.1.7.5
and trees were summarized to one Maximum Clade Credibility (MCC) tree using Tree
Annotatorv.1.7.5afterremovingaburn-inphase.
RESULTS & DISCUSSION
Phylogenetic relationships within the endemic Hawaiian
Dolichopodidae
The family Dolichopodidae includes more than 6,800 described species (Yangetal.,
2006)in232generaworldwide(Pape&Thompson,2013).Atotalof29generaarefound
in the Hawaiian Islands. Of these, fifteen have been introduced in the past 150 years,
most likely through human activity, while the remaining fourteen genera present in the
archipelago are known to contain endemic Hawaiian taxa (Table 1). The relationships
between Campsicnemus and the Eurynogaster complex and the colonization history of
these genera have remained an open question, largely due to the difficulty of placing
both in a subfamilial context. While Campsicnemus is clearly placed in the subfamily
Sympycninae, the placement of the Eurynogaster complex has been more difficult to
ascertain(seeAppendixS3).Individualtaxahavepreviouslybeendescribedasmembersof
thesubfamiliesSympycninae,Hydrophorinae,andThinophilinae.Hardy&Kohn(1964)
considered Eurynogaster and associated genera as part of the Sympycninae (see Fig. S3A
inAppendix3).Later,Evenhuis(2005)transferredtheentireEurynogaster complextothe
Hydrophorinae.Ifthecurrenttaxonomyplacingtheselineagesintwoseparatesubfamiliesis
correct,CampsicnemusandtheEurynogaster complexrepresentindependentcolonizations
totheHawaiianIslands.
Molecular evidence demonstrates that the endemic Hawaiian dolichopodid fauna is
clearly the result of multiple colonizations to the archipelago (Fig. 2, Figs. S1A & S1B in
AppendixS1).Severalkeynodesarewellsupportedandallowustoinferthehistoryofthe
HawaiianDolichopodidae.Conchopus(posteriorprobability(PP)=1,bootstrap(BS)=
100: node A, Fig. 2), the Eurynogaster complex (PP = 1, BS = 100: node B, Fig. 2), and
Campsicnemus (PP = 1, BS = 98: node C, Fig. 2) are each supported as monophyletic
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 9/21
Figure2 MajorityruleconsensustreesummarizingBayesiananalysisoftheendemicDolichopodi-
dae,withthelargeradiations,EurynogastercomplexandCampsicnemuscollapsed. Bayesianposterior
probabilities(Mr.Bayes)andbootstrapsupportsfromthemaximumlikelihoodanalysis(RAxML)aredis-
playedasovals.
with respect to other dolichopodid genera. Another key node that is supported in both
analyses(PP=1,BS=99:nodeD,Fig.2)isthelargecladethatincludesCampsicnemus
and a number of non-Hawaiian genera in the subfamily Sympycninae (e.g., Sympycnus,
Teuchophorus) and does not include the Eurynogaster complex. This demonstrates that
therewereatleastthreecolonizationstoHawaiibythefamilyDolichopodidae,oneeach
bythethreeradiations:Campsicnemus,theEurynogaster complex,andConchopus.
ThereislittlesupportfortheplacementofThinophilus,soitshistoryofarrivaltoHawaii
remainsenigmatic(Fig.2,Figs.S1A&S1BinAppendixS1).Thisgenusisknownprimarily
from the Indo-Pacific, with one species each known from the Galapagos Islands and the
HawaiianIslands.Previouslyithasonlybeencollectedfromrocky,wetsandonthesouth
shoresofOahu(Carlton&Eldredge,2009).Thespecimenincludedinthisstudyrepresents
Goodmanetal. (2016),PeerJ,DOI10.7717/peerj.2704 10/21