Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Povzetek: Madagascar is a biodiversity hotspot with high endemism and ancient phylogenetic diversity. We here report the discovery of Osmooka aphana gen. nov., sp. nov. from Marojejy National Park. Phylogenomic analyses place Osmooka as sister to the Australian Paraplectanoides Keyserling, 1886, and this doublet is sister to Nephilidae Simon, 1894. When proposed, Paraplectanoididae Kuntner, Coddington, Agnarsson & Bond, 2023 was exclusively Australian and monogeneric, but was predicted to contain additional, undescribed taxa. The discovery of Osmooka and its phylogenetic placement in Paraplectanoididae supports this prediction. We present a taxonomic treatment of Osmooka and Paraplectanoides, and a reappraisal of Orbipurae morphological homologies. With this new discovery, we revalidate Paraplectanoididae, Nephilidae, and Phonognathidae Simon, 1894, ranks resurrected as exclusive, monophyletic, and well-diagnosed families, whereas Araneidae Clerck, 1757 requires further redefinition. Finally, we test the hypothesis of East Gondwanan vicariant origin of Osmooka and Paraplectanoides. This scenario would predict an ancient age of their ancestor, predating the 130 Ma breakup of Gondwana. Divergence dating refutes this hypothesis by estimating their common ancestor at 57 Ma. Rather than through vicariance, the disjunct distribution of Osmooka and Paraplectanoides is best explained through Cenozoic intercontinental dispersal and/or extinctions. Potential discovery of additional paraplectanoidid diversity might better elucidate the timing, modes, and trajectories of historic dispersal and extinction events.
Ključne besede: Madagascar, biodiversity, Osmooka aphana gen. nov., sp. nov., Paraplectanoididae, spiders
Objavljeno v DiRROS: 23.03.2026; Ogledov: 279; Prenosov: 347
Raziskovalni podatki (7,31 MB)
Gradivo ima več datotek! Več...

Povzetek: Madagascar is a biodiversity hotspot with high endemism and ancient phylogenetic diversity. We here report the discovery of Osmooka aphana gen. nov., sp. nov. from Marojejy National Park. Phylogenomic analyses place Osmooka as sister to the Australian Paraplectanoides Keyserling, 1886 and this doublet is sister to Nephilidae Simon, 1894. When proposed, Paraplectanoididae Kuntner, Coddington, Agnarsson & Bond, 2023 was exclusively Australian and monogeneric, but was predicted to contain additional, undescribed taxa. The discovery of Osmooka and its phylogenetic placement in Paraplectanoididae support this prediction. We present a taxonomic treatment of Osmooka and Paraplectanoides, and a reappraisal of Orbipurae morphological homologies. With this new discovery, we revalidate Paraplectanoididae, Nephilidae, and Phonognathidae Simon, 1894 ranks resurrected as exclusive, monophyletic, and well-diagnosed families, whereas Araneidae Clerck, 1757 requires further redefinition. Finally, we test the hypothesis of East Gondwanan vicariant origin of Osmooka and Paraplectanoides. This scenario would predict an ancient age of their ancestor, predating the 130 Ma breakup of Gondwana. Divergence dating refutes this hypothesis by estimating their common ancestor at 57 Ma. Rather than through vicariance, the disjunct distribution of Osmooka and Paraplectanoides is best explained through Cenozoic intercontinental dispersal and/or extinctions. Potential discovery of additional paraplectanoidid diversity might better elucidate the timing, modes, and trajectories of historic dispersal and extinction events.
Ključne besede: phylogenomics, classification, palpal homology, arachnology, zoology
Objavljeno v DiRROS: 22.01.2026; Ogledov: 545; Prenosov: 487
Celotno besedilo (3,94 MB)
Gradivo ima več datotek! Več...
Gradivo je zbirka in zajema 1 gradivo!

Povzetek: Among terrestrial animals, spiders exhibit the most striking examples of sexual size dimorphism (SSD) but better understanding of its evolution requires improved taxonomy and phylogeny. Many sexually dimorphic spiders lack adequate description, phylogenetic placement, and natural history observations. In South Africa, we documented the natural history of a poorly known spider, Megaraneus gabonensis (Lucas, 1858), with extreme, female-biased SSD (eSSD, female:male approximately 4:1). Here, we redescribe M. gabonensis, place Megaraneus Lawrence, 1968 phylogenetically for the first time, assess whether the observed eSSD represents an independent evolutionary origin, and test whether the macroevolutionary pattern is better explained by male dwarfism or female gigantism. The recovered phylogenetic placement of Megaraneus in the araneid ‘backobourkiines’, a clade previously considered as restricted to East Asia and Australasia, extends the range of this clade to the Afrotropics. We find that eSSD was present in the common ancestor of the ‘backobourkiines’, with further increases in female body length occurring independently in Megaraneus, Backobourkia Framenau, Dupérré, Blackledge & Vink, 2010, and the currently misplaced Parawixia dehaani (Doleschall, 1859). We conclude that the evolution of eSSD reflects a complex pattern of sex-specific size changes across spider phylogeny, but that in Megaraneus it results from female gigantism.
Ključne besede: sexual size dimorphism, backobourkiines, trait evolution, South Africa
Objavljeno v DiRROS: 30.09.2025; Ogledov: 753; Prenosov: 384
Celotno besedilo (3,58 MB)
Gradivo ima več datotek! Več...

Povzetek: Island systems provide excellent arenas to test evolutionary hypotheses pertaining to gene flow and diversification of dispersal-limited organisms. Here we focus on an orbweaver spider genus Cyrtognatha (Tetragnathidae) from the Caribbean, with the aims to reconstruct its evolutionary history, examine its biogeographic history in the archipelago, and to estimate the timing and route of Caribbean colonization. Specifically, we test if Cyrtognatha biogeographic history is consistent with an ancient vicariant scenario (the GAARlandia landbridge hypothesis) or overwater dispersal. We reconstructed a species level phylogeny based on one mitochondrial (COI) and one nuclear (28S) marker. We then used this topology to constrain a time-calibrated mtDNA phylogeny, for subsequent biogeographical analyses in BioGeoBEARS of over 100 originally sampled Cyrtognatha individuals, using models with and without a founder event parameter. Our results suggest a radiation of Caribbean Cyrtognatha, containing 11 to 14 species that are exclusively single island endemics. Although biogeographic reconstructions cannot refute a vicariant origin of the Caribbean clade, possibly an artifact of sparse outgroup availability, they indicate timing of colonization that is much too recent for GAARlandia to have played a role. Instead, an overwater colonization to the Caribbean in mid-Miocene better explains the data. From Hispaniola, Cyrtognatha subsequently dispersed to, and diversified on, the other islands of the Greater, and Lesser Antilles. Within the constraints of our island system and data, a model that omits the founder event parameter from biogeographic analysis is less suitable than the equivalent model with a founder event.
Ključne besede: biogeography, spiders
Objavljeno v DiRROS: 23.07.2024; Ogledov: 1338; Prenosov: 797
Celotno besedilo (1,62 MB)
Gradivo ima več datotek! Več...

Povzetek: Aim A wholistic biogeographical reconstruction should combine a phylogeny with specifics of organismal biology, plate tectonics and consequent probabilities of historic dispersal events. Here, we demonstrate this approach by reconstructing the geographical origin and sequence of intercontinental colonization of the golden orbweaving spiders, a global clade. We test two alternative hypotheses about their ancestral range. Due to the highest contemporary species diversity in Africa, the ‘Out of Africa’ hypothesis predicts the Afrotropics as their most likely ancestral area. The alternative, ‘Out of West Burma’ hypothesis aims to explain a Burmese amber fossil as stem nephilid. Because the West Burma block probably detached from Australia, then rafted towards Laurasia, either on its own or with India, this hypothesis predicts either Australasia or Indomalaya (or both) as the ancestral area. Location Worldwide. Taxon Golden orbweaving spiders, family Nephilidae. Methods We construct an expanded phylogeny of nephilid spiders and apply RASP (Reconstruct Ancestral State in Phylogenies) to infer their global biogeographical history. We fit the data to six integrated biogeographical models: DEC, DIVALIKE, BAYAREALIKE and their +j variants. We fine-tune the analysis by evaluating varying probabilities of dispersal between geographical areas throughout the clade's evolutionary history. We use the physical distance between the areas as a proxy for dispersal probabilities, thus accounting for plate tectonics. Results The best supported model reconstructs both Australasia and Indomalaya as ancestral area. In several parts of the phylogeny, these areas persist for the estimated 130-million-year evolutionary history. However, numerous intercontinental shifts in nephilid biogeographical history are also inferred. Since nephilid origins are clearly Gondwanan, our study supports the interpretations that Burmese amber contains Gondwanan biota. Main conclusions These results are consistent with the Out of West Burma hypothesis but reject the Out of Africa hypothesis. That certain clades persist in their ancestral ranges while others may shift continents aligns well with the known nephilid biology. Our methodological approach that assesses organismal specific dispersal probabilities through concrete distances measured though time slices of the Earth's history can be applied to biogeographical reconstruction of any lineage.
Ključne besede: spiders, golden orbweavers, Nephilidae, reconstruction of lineage, biogeography
Objavljeno v DiRROS: 22.07.2024; Ogledov: 1732; Prenosov: 1022
Celotno besedilo (1,90 MB)
Gradivo ima več datotek! Več...