«Taxonomic Revision, Molecular Phylogeny and Zoogeography of the huntsman spider genus Eusparassus (Araneae: Sparassidae) Dissertation for attaining ...»
Despite being calibrated, the node age for the divergence of Salticidae-Philodromidae is pulled back considerably, possibly indicating an older age for this node (Hill and Richman, 2009), an issue contradicted and extensively discussed by Penney and Selden (2011).
Results: chapter 3.3: Molecular phylogenyFIGURE 4. Maximum clade credibility tree based on BEAST analysis of the All-outgroups-8Sparassidae dataset calibrated by four fossil records. Highest posterior density values represent the statistical range of divergence time estimates. Numbers in circles specify calibrated nodes as referred in the Methods.
In comparison to the split from the Sparianthinae, diversification within the Non-Sparianthinae was probably relatively fast, also seen in the unresolved backbone of this group. Both calibrations using outgroup (Fig. 4) and ingroup fossils (Fig. 5), generally agree with the diversification of the Non-Sparianthinae into most clades and subfamilies starting around 105 to 75 Ma., roughly corresponding with the breakup of Gondwana (Briggs, 1995; Sanmartín and Ronquist, 2004).
Results: chapter 3.3: Molecular phylogeny
It is important to mention that calibrating the initial diversification within Eusparassus (47.5 MA (95% HPD of 43–62 MA; Fig. 5)) pulled the root node of the Full-ingroup set towards a younger date (-20 Ma) in comparison to the calculations based on outgroup fossils (Fig. 4). This might indicate the fossil E. crassipes to correspond to a younger node within the genus. Its
Results: chapter 3.3: Molecular phylogenyintermarginal denticle pattern is present in several groups, none of which E. crassipes can be assigned to with certainty. The inferred divergence time within the genus thus may be slightly older as subsequently reported. However, Eusparassus likely diverged from other Sparassidae about 70 MA ago and no further diversification into subgroups is obvious for 20 million years.
Based on the distribution of Eusparassus groups an African origin is likely. Moradmand (2013) specified a Southern African origin, which is supported by the presence of the oldest lineage of Eusparassus and many old lineages within the Non-Sparianthinae (Namibia, South Africa; Fig.
5). This area shows exceptional diversity in desert dwelling organisms with high levels of very old endemism (Barnard et al., 1998; Ward, 2009). The Namib Desert in particular has been highlighted as the oldest desert on earth, with desertification probably already initiating with the Gondwanaland fracturing ca. 130–145 MA (Ward et al., 1983) and permanent aridity from at least 55 MA onwards. This stable environment probably served as a source area for many dryadapted organisms, as is assumed for Eusparassus. The high diversity of the southern African desert-dwelling Sparassidae, with the African clade members mainly distributed within and at the border of the Namib and Kalahari Deserts, and the presence of the more basal Eusparassus species (tuckeri-group) further supports this assertion. The majority of Eusparassus speciesgroups (five of six) and species (23) occur mainly in Africa and neighbouring regions, e.g., Iberia, with only the members of the doriae group (seven species) restricted to Asia.
Other deserts appeared much later, in Asia and North Africa, following a global desertification during the Tertiary, initiating around 23 Ma (Potter and Szatmari, 2009). Considering the much older age of the oldest Eusparassus fossil a potential Eurasian origination of Eusparassus is unlikely.
The extant species groups of Eusparassus generally have different areas of distribution that only exceptionally show considerable overlap. The dufouri-group is composed of eight species distributed from the Iberian Peninsula to NW Africa. We found the two Iberian species (E.
dufouri and E. levantinus) closer related to each other compared to the Moroccan E. oraniensis (Lucas, 1846). The divergence between dufouri- and walckenari+doriae- clade was estimated 41 MA (95% HPD of 32-55 MA) (Fig. 5).
The doriae-group comprises seven species distributed in the Middle East to Central Asia and parts of South Asia and is here represented by two species. The walckenaeri-group, occurs in
Results: chapter 3.3: Molecular phylogeny
Eastern Mediterranean to North-Eastern Africa and Arabian Peninsula, and is represented here by two of the three known species from various localities. The phylogeny recovered doriae- and walckenaeri-group as sister clades with highest support. Their divergence is estimated around 36 MA (95% HPD of 26-48) (Fig. 5), roughly in accordance with the closing of the Turgai Strait (30 MA) that acted as a barrier for most terrestrial biota between the eastern and western Palearctic (Sanmartín et al., 2001). We hypothesize this event to have played a role in diversification of the doriae- and walckenaeri-group, which could not be tested in the absence of most Asian representatives of the doriae-group.
This study is the first to comprehensively tackle the phylogenetic relationships within the large spider family Sparassidae, including its major subfamilies and to investigate further placement and groupings within the RTA-clade. It also provides systematic insight into one of the largest Sparassidae genus Eusparassus. For the sheer number of species and genera, our results are a starting point for future research on this conspicuous group of spiders. 1) ‘Laterigradae’ (Sparassidae, Thomisidae, Philodromidae and Selenopidae) is not recognised as a monophyletic group. Sparassidae is recovered as sister to the rest of the RTA-clade members. Our data also suggests Dionycha to be a polyphyletic ensemble.
2) The family Sparassidae and the subfamilies Sparianthinae, Heteropodinae sensu stricto, Palystinae and Deleninae are supported as monophyletic and Sparianthinae are recovered as sister to all other Sparassidae. Sparassinae appeared to be a polyphyletic group. The currently available morphological characters for the classification of Sparassidae generally seem to apply.
3) Eusparassinae is not resolved as a monophyletic group. The branch of the “African clade” consisting of Carparachne, cf. Microrchestris, Leucorchestris and Palystella comprise morphologically similar genera endemic to southern Africa. At this point, our result suffices to erect a new subfamily for this group or exclude them from Eusparassinae. Eusparassus might not be closely related to the African clade genera and if this is further supported, Eusparassinae has to be considered monotypic.
Results: chapter 3.3: Molecular phylogeny
4) Eusparassus is recovered as monophyletic with Cercetius perezi nested within the group. The monophyly of the dufouri-, doriae- and walckenaeri- group are well supported, while a tuckerigroup is not recovered. The doriae- and walckenaeri-group were found as sister groups and both likely sister to the dufouri-group.
5) Sparassidae separated from the other RTA-clade families around 186 MA, and early diverged into Sparianthinae and Non-Sparianthinae (163 MA; Fig. 4). Further divergence happened much later (106–97 MA; Figs 4-5), but surprisingly rapidly in the Non-Sparianthinae.
Financial support for this research was provided partially by the Senckenberg Research Institute and “Paul Ungerer-Stiftung”. MM received support from the SYNTHESYS Project (http://www.synthesys.info/), which is financed by the European Community Research Infrastructure Action under the FP7 "Capacities" Program to visit MRAC (Tervuren) collection.
Participation of MM in the “Phylogenetic Systematics and Molecular Dating course” at the Natural History Museum of Denmark, was financially supported by EDIT (European Distributed Institute of Taxonomy) and the Senckenberg Research Institute. MM is very thankful to all teachers of the course in particular Dr Nikolaj Scharff (University of Copenhagen). The staff of the Grunelius-Möllgaard Laboratory (Senckenberg Research Institute) are acknowledged for lab support. We are thankful to Dr Tilman Alpermann (SMF) for his kind assistance during running computational analyses. The fresh tissues of spiders and permission to extract DNA were obtained from colleagues around the world for that we are very grateful: Tharina Bird (Windhoek), Martin Forman (Prague), Charles R. Haddad (Bloemfontein), Arnaud Henrard (Tervuren), Sérgio Henriques (Lisbon), Siegfried Huber (Oberuhldingen), Vladimír Hula (Brno), Rudy Jocqué (MRAC Tervuren), František Kovařík (Prague), Kadir B. Kunt (Ankara), Dirk Kunz (Frankfurt am Main) and Vláďa Trailin (Hradec Králové). Cristina A. Rheims assisted in the identification of the New World Sparassidae. Majid Moradmand is a PhD student of the Goethe University, Frankfurt am Main. Dr Mike Rix (Western Australian Museum, Perth) is thanked for helping improve the English, as well as providing a thorough review, along with Dr Ingi Agnarsson (University of Vermont). This study is a part of MM’s PhD programme conducted at the Senckenberg Research Institute which is financially supported by the Ministry of Science, Research and Technology of Iran, which is greatly acknowledged.
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