Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Evolution of the Biodiversity Hotspot of Madagascar from the Eye of Diving Beetles: Phylogeny, colonization and speciation
Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dytiscidae, contains numerous endemic and non-endemic species on Madagascar. Their evolutionary history is largely unknown on the island. Herein, I use analyses to infer phylogenetic relationship among groups of diving beetles, with a focus on the subfamily Dytiscinae and endemic species in two other groups of Dytiscidae. Paper I represents the first phylogenetic reconstruction focusing on the tribe Aciliini based on molecular data. Several commonly used molecular markers, as well as a new marker for Hydradephagan beetles, were evaluated in this study. Our analyses suggest that six genera within Aciliini are monophyletic. The most basal clades with Neotropical and Afrotropical taxa suggest a possible Gondwanan origin. Evaluation of gene fragments indicated CAD to be the most informative marker. Paper II focuses on colonization and radiation events of large bodied endemic diving beetles of the tribes Cybistrini and Hydaticini on Madagascar. Colonization events were inferred from dated phylogenetic trees and ancestral biogeographical reconstructions. Our results suggest both multiple colonizations, and out-of-Madagascar dispersal events, mostly during the Miocene and Oligocene. In paper III, we revised the Rhantus species of Madagascar. We used both molecular and morphological data to evaluate species hypothesis and emphasized the value of Manjakatompo – one of the last remaining fragments of central highland forests. In Paper IV we reconstruct the phylogeny and use Species Distribution Modelling for the endemic genus Pachynectes in Madagascar. Our sampling has discovered that the species diversity of Pachynectes is at least three times higher than previously believed. It seems that allopatric speciation was the main driver, which led to the diversity of Pachynectes. Our results suggest that climatic gradients and the five main biomes were a better predictor than watershed systems in explaining the distribution pattern and speciation between sister species. 

Abstract [sv]

Dykarskalbaggar i familjen Dytiscidae finns över hela världen och kan hittas i såväl temporära som permanenta vattensamlingar, i rinnande såväl som i stillastående akvatiska habitat. Bland dykarskalbaggarna finns ett hundratal både endemiska och icke-endemiska arter på Madagaskar. Deras evolutionära historia på denna mytomspunna ö är dock i stort sett okänd. I den här avhandlingen använder jag molekylära data och analyser för att härleda evolutionära släktskap, s.k. fylogenier eller släktträd, för olika grupper av dykarskalbaggar med fokus på underfamiljen Dytiscinae samt endemiska arter från två andra grupper på Madagaskar. Artikel 1 är den första molekylär-fylogenetiska studien som gjort på tribuset Aciliini. Flera molekylära markörer (delar av gener) användes samt utvärderades, inklusive den nya markören CAD för Hydradephaga skalbaggar. Analysen bekräftar att tribuset Aciliini är en monofyletisk grupp (naturlig grupp som härstammar från en gemensam förfader) samt att Eretini är närmaste släktingen. Alla sex släkten med flera arter i tribuset stöddes också som monofyletiska, det sjunde släktet har bara en art. De mest basala grupperna i trädet utgjordes av Neotropiska och Afrotropiska arter vilket antyder ett ursprung på Gondwana kontinenten. Denna slutsats var dock beroende av för vilken nod i trädet (av två möjliga) som ett fossil användes som kalibreringspunkt. Utvärderingen av de olika genfragmenten ledde till slutsatsen att CAD var den mest informativa genen tätt följd av en annan nukleär proteinkodande gen, WNT. Artikel 2 fokuserar på kolonisations- och artbildningshändelser för två grupper av relativt stora dykarskalbaggar. Denna studie bygger på två tidigare publicerade dataset där vi lade till Madagaskars arter. Kolonisationshändelser härleddes genom daterade molekylära släktträd samt rekonstruktion av förfäders biogeografiska utbredningsområden. Resultaten visade både på ett flertal separata koloniseringshändelser men också "ut-ur-Madagaskar" spridning, framförallt under tidsperioden Miocen-Oligocen. Studien visade också att inga koloniseringshändelser lett till några signifikanta artradiationer på Madagaskar i dessa två grupper. I Artikel 3 reviderar vi arterna av släktet Rhantus som finns på Madagaskar, vilka alla är begränsade i sin utbredning till den centrala högplatån på Madagaskar. Vi använder både morfologi och molekylära data för att testa arthypoteser samt bestyrker det bevarandebiologiska värdet av Manjakatompo-skogen, ett av de allra sista fragmenten av skog på den centrala högplatån. I Artikel 4 härleder vi släktskapet för det endemiska rinnande-vatten släktet Pachynectes samt analyserar de ingående arternas utbredning genom modellering. Våra insamlingar runt om Madagaskar har visat att artdiversiteten i släktet är minst tre gånger så hög som man tidigare trott. Genom att integrera släktskapsanalys med utbredningsmodellering söker vi få en inblick i vad som drivit artbildningen i en endemisk artradiation. Allopatrisk artbildning verkar varit den huvudsakliga typen av artbildning inom Pachynectes. Vi testade även två huvudhypoteser som söker förklara mikroendemisk artbildning generellt på Madagaskar. Våra resultat visar att klimatgradienter och de fem huvudsakliga biomen på Madagaskar verkar ha en långt bättre förklaringsgrad än stora floder och avrinningsområden för att förklara Pachynectes arternas utbredning och släktskap.

 

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University , 2015. , 41 p.
Keyword [en]
Dytiscidae, diving beetles, Biogeography, Phylogeny, Dating, phylogenetic informativeness, colonization, speciation, microendemism, Madagascar
National Category
Zoology
Research subject
Systematic Zoology
Identifiers
URN: urn:nbn:se:su:diva-119633ISBN: 978-91-7649-223-9 (print)OAI: oai:DiVA.org:su-119633DiVA: diva2:847260
Public defence
2015-09-25, Lilla hörsalen, Swedish Museum of Natural History, Frescativägen 40, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.

Available from: 2015-09-03 Created: 2015-08-19 Last updated: 2015-09-03Bibliographically approved
List of papers
1. The utility of CAD in recovering Gondwanan vicariance events and the evolutionary history of Aciliini (Coleoptera: Dytiscidae)
Open this publication in new window or tab >>The utility of CAD in recovering Gondwanan vicariance events and the evolutionary history of Aciliini (Coleoptera: Dytiscidae)
2014 (English)In: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148, Vol. 14, 5- p.Article in journal (Refereed) Published
Abstract [en]

Background: Aciliini presently includes 69 species of medium-sized water beetles distributed on all continents except Antarctica. The pattern of distribution with several genera confined to different continents of the Southern Hemisphere raises the yet untested hypothesis of a Gondwana vicariance origin. The monophyly of Aciliini has been questioned with regard to Eretini, and there are competing hypotheses about the intergeneric relationship in the tribe. This study is the first comprehensive phylogenetic analysis focused on the tribe Aciliini and it is based on eight gene fragments. The aims of the present study are: 1) to test the monophyly of Aciliini and clarify the position of the tribe Eretini and to resolve the relationship among genera within Aciliini, 2) to calibrate the divergence times within Aciliini and test different biogeographical scenarios, and 3) to evaluate the utility of the gene CAD for phylogenetic analysis in Dytiscidae. Results: Our analyses confirm monophyly of Aciliini with Eretini as its sister group. Each of six genera which have multiple species are also supported as monophyletic. The origin of the tribe is firmly based in the Southern Hemisphere with the arrangement of Neotropical and Afrotropical taxa as the most basal clades suggesting a Gondwana vicariance origin. However, the uncertainty as to whether a fossil can be used as a stem-or crowngroup calibration point for Acilius influenced the result: as crowngroup calibration, the 95% HPD interval for the basal nodes included the geological age estimate for the Gondwana break-up, but as a stem group calibration the basal nodes were too young. Our study suggests CAD to be the most informative marker between 15 and 50 Ma. Notably, the 2000 bp CAD fragment analyzed alone fully resolved the tree with high support. Conclusions: 1) Molecular data confirmed Aciliini as a monophyletic group. 2) Bayesian optimizations of the biogeographical history are consistent with an influence of Gondwana break-up history, but were dependent on the calibration method. 3) The evaluation using a method of phylogenetic signal per base pair indicated Wnt and CAD as the most informative of our sampled genes.

Keyword
CAD, Phylogenetic informativeness, Adephaga, Biogeography, Phylogeny, Aciliini
National Category
Evolutionary Biology
Research subject
Systematic Zoology
Identifiers
urn:nbn:se:su:diva-104008 (URN)10.1186/1471-2148-14-5 (DOI)000334374000001 ()
Funder
Swedish Research Council, 621-2009-3744
Note

AuthorCount:3;

Available from: 2014-06-02 Created: 2014-05-27 Last updated: 2017-12-05Bibliographically approved
2. In or Out-of-Madagascar?-Colonization Patterns for Large-Bodied Diving Beetles (Coleoptera: Dytiscidae)
Open this publication in new window or tab >>In or Out-of-Madagascar?-Colonization Patterns for Large-Bodied Diving Beetles (Coleoptera: Dytiscidae)
2015 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 3, e0120777Article in journal (Refereed) Published
Abstract [en]

High species diversity and endemism within Madagascar is mainly the result of species radiations following colonization from nearby continents or islands. Most of the endemic taxa are thought to be descendants of a single or small number of colonizers that arrived from Africa sometime during the Cenozoic and gave rise to highly diverse groups. This pattern is largely based on vertebrates and a small number of invertebrate groups. Knowledge of the evolutionary history of aquatic beetles on Madagascar is lacking, even though this species-rich group is often a dominant part of invertebrate freshwater communities in both standing and running water. Here we focus on large bodied diving beetles of the tribes Hydaticini and Cybistrini. Our aims with this study were to answer the following questions 1) How many colonization events does the present Malagasy fauna originate from? 2) Did any colonization event lead to a species radiation? 3) Where did the colonizers come from-Africa or Asia- and has there been any out-of-Madagascar event? 4) When did these events occur and were they concentrated to any particular time interval? Our results suggest that neither in Hydaticini nor in Cybistrini was there a single case of two or more endemic species forming a monophyletic group. The biogeographical analysis indicated different colonization histories for the two tribes. Cybistrini required at least eight separate colonization events, including the non-endemic species, all comparatively recent except the only lotic (running water) living Cybister operosus with an inferred colonization at 29 Ma. In Hydaticini the Madagascan endemics were spread out across the tree, often occupying basal positions in different species groups. The biogeographical analyses therefore postulated the very bold hypothesis of a Madagascan origin at a very deep basal node within Hydaticus and multiple out-of-Madagascar dispersal events. This hypothesis needs to be tested with equally intense taxon sampling of mainland Africa as for Madagascar.

National Category
Zoology
Research subject
Systematic Zoology
Identifiers
urn:nbn:se:su:diva-116994 (URN)10.1371/journal.pone.0120777 (DOI)000352083900074 ()25794184 (PubMedID)
Note

AuthorCount:4;

Available from: 2015-05-13 Created: 2015-05-05 Last updated: 2017-12-04Bibliographically approved
3. Taxonomic revision of Madagascan Rhantus (Coleoptera, Dytiscidae, Colymbetinae) with an emphasis on Manjakatompo as a conservation priority
Open this publication in new window or tab >>Taxonomic revision of Madagascan Rhantus (Coleoptera, Dytiscidae, Colymbetinae) with an emphasis on Manjakatompo as a conservation priority
Show others...
2013 (English)In: ZooKeys, ISSN 1313-2989, E-ISSN 1313-2970, no 350, 21-45 p.Article in journal (Refereed) Published
Abstract [en]

We review the diving-beetle genus Rhantus Dejean of Madagascar (Coleoptera, Dytiscidae, Colymbetinae) based on museum collection holdings and recently collected expedition material. Both morphology and DNA is used to test species boundaries, in particular whether newly collected material from the Tsaratanana mountains in the north represent a new species or are conspecific with Rhantus manjakatompo Pederzani and Rocchi 2009, described based on a single male specimen from the central Ankaratra mountains. DNA of the holotype of R. manjakatompo was successfully extracted in a non-destructive way and sequenced. The general mixed Yule coalescent model applied to an ultrametric tree constructed from mitochondrial cytochrome c oxidase subunit I (COI) sequence data delimited three species. Morphological characters supported the same species unambiguously. We therefore recognise three species of Rhantus to occur in Madagascar: R. latus (Fairmaire, 1869), R. bouvieri Regimbart, 1900 and R. manjakatompo Pederzani and Rocchi, 2009. All three species are endemic to Madagascar and restricted to the highlands of the island. Rhantus stenonychus Regimbart, 1895, syn. n., is considered a junior synonym of R. latus. We designate lectotypes for R. bouvieri and R. goudoti Sharp, 1882, the latter a junior synonym of R. latus. We provide descriptions, a determination key, SEM-images of fine pronotal and elytral structures, distribution maps, habitus photos, and illustrations of male genitalia and pro-and mesotarsal claws. We discuss the role of the Manjakatompo forest as a refugium for Madagascan Rhantus diversity and other endemics of the montane central high plateau.

Keyword
Diving beetles, Madagascar, GMYC, species delimitation, refugium, lectotype designation, new synonymy
National Category
Zoology
Research subject
Systematic Zoology
Identifiers
urn:nbn:se:su:diva-98103 (URN)10.3897/zookeys.350.6127 (DOI)000327545800002 ()
Funder
Swedish Research Council
Note

AuthorCount:5;

Available from: 2013-12-27 Created: 2013-12-27 Last updated: 2017-12-06Bibliographically approved
4. Phylogeny, distribution and speciation in the endemic diving beetle genus Pachynectes on Madagascar
Open this publication in new window or tab >>Phylogeny, distribution and speciation in the endemic diving beetle genus Pachynectes on Madagascar
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Madagascar is well known for high levels of endemism in both the flora and fauna. More specifically most of Madagascars' endemic species have extremely restricted regional distributions, which is a characteristic of this large island’s biodiversity. Biologists are still struggling to understand the speciation processes that have produced this pattern of diversity. Several general hypotheses have been developed trying to explain the origin and microendemism of Malagasy species. Two main hypotheses focus on watersheds and climate gradients. Here, we use a phylogeny in combination with data on spatial distribution of the endemic diving beetle genus Pachynectes (Coleoptera: Dytiscidae: Bidessini) to critically evaluate the watershed versus the climatic gradient hypotheses of this river dwelling insect radiation. Based on field sampling from expeditions between 2006 and 2014, we first show that the species diversity in this genus is at least three times higher than previously believed. We reconstructed a molecular phylogeny based on five gene fragments and recovered three main clades: a western clade, an eastern clade and a "keeled" clade diagnosable based on an elytral keel. The western and keeled clades both occur mainly in the drier western parts of the country, while species in the eastern clade are typical of rivers in the eastern humid rainforest. Notably, sister species were always allopatrically distributed along either latitudinal or longitudinal-altitudinal gradients. Based on species distribution modelling (SDM) and our phylogenetic data, we conclude that the microendemic patterns of Pachynectes species are unlikely to be explained by the watershed hypothesis. In contrast, the four main bioclimatic regions are more likely to have been causally involved in the past speciation processes and might explain the current distribution pattern in this insect genus.  

National Category
Biological Sciences
Research subject
Systematic Zoology
Identifiers
urn:nbn:se:su:diva-119732 (URN)
Available from: 2015-08-24 Created: 2015-08-24 Last updated: 2016-01-29Bibliographically approved

Open Access in DiVA

fulltext(2647 kB)170 downloads
File information
File name FULLTEXT02.pdfFile size 2647 kBChecksum SHA-512
36a11c28b74c47fc01c9a97a73ac67c6c44312d8d68dd115ecddd9ce361e856b9cd6a70a9f36aae0066c36a2a63450072d1d4d9ec6eef5766de420cbb6cd5be5
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Bukontaite, Rasa
By organisation
Department of Zoology
Zoology

Search outside of DiVA

GoogleGoogle Scholar
Total: 170 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 478 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf