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Cretaceous (top) and Eocene (bottom) reconstructions of Earth topography and bathymetry. Although these reconstructions provide a good view of the separation of Africa, Madagascar, and India from the rest of Gondwanaland, they do not depict the land connections beween Antarctica and either South America, or Australia, respectively, that are thought to have persisted well into the Eocene (Yanbin 1998, Lawver et al. 1999, Sanmartín 2002, Francis et al. 2008, and others). © by Ron Blakely, NAU Geology. Noncommercial use with attribution permitted.
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... Edwin Hill At the breakup of Gondwanaland (~130―110 Ma), Africa, India, and Madagascar moved away from South America and Antarctica, with Australia still firmly conjoined to the latter (Figure 1). This movement left South America connected to Antarctica―Australia by a long isthmus ( Ithmus of Scotia ) of the southern Andes, at least from the Late Cretaceous (Campanian) through the Eocene (Yanbin 1998, Lawver et al. 1999, Sanmartín 2002). This Antarctic land bridge remained in place from the late Cretaceous through the Paleocene (65.5 ± 0.3 Ma to 55.8 ± 0.2 Ma) and Eocene (55.8 ± 0.2 to 33.9 ± 0.1 Ma) epochs. At times it may have included short island arcs at either the Australian (Tasmanian) or South American ends. This land bridge, associated with a tropical to temperate Antarctic climate (Francis et al. 2008), was thus available to support the dispersal of plant and animal species for about 75 to 95 million years after the separation of Africa, a very long time. One very interesting aspect about this interval is that it also brackets the mass extinction event at the end of the Cretaceous. According to Penney et al. (2003), however, that event did nothing to reduce the diversity of spiders as a ...
Citations
... These circumstances have given rise to intricate scenarios that could explain the hyper diversity of the Neotropical region [71]. Additionally, this diversity could have been boosted by geological events through time, including: (i) continental drift [72,73]; (ii) the intermittent connection through bridges, such as the Antarctic bridge that connected the southern cone of South America with the Australian Region [74,75], and the Berigian bridge with a northern connection to the Palearctic Region [76]; and (iii) the complex geological dynamics in the northern Neotropical such as, for example, formation of the Isthmus of Tehuantepec and Panama [77][78][79]. ...
... Mya (95% HPD: 43-31.6 Mya), an age that matches with the end of the Antarctic bridge connection of the southern hemisphere, in the Late Eocene, at about 35 Mya [74,75]. The origin age of the diversification of the genus has been estimated at 74-60 Mya by Seabolt [23], which is close to the start of continental connections of the southern hemisphere at 65 Mya [74,75]. ...
... Mya), an age that matches with the end of the Antarctic bridge connection of the southern hemisphere, in the Late Eocene, at about 35 Mya [74,75]. The origin age of the diversification of the genus has been estimated at 74-60 Mya by Seabolt [23], which is close to the start of continental connections of the southern hemisphere at 65 Mya [74,75]. Both scenarios do not rule out a Southern Hemisphere fauna connection. ...
Background: Amblyomma is the third most diversified genus of Ixodidae that is distributed across the Indomalayan, Afrotropical, Australasian (IAA), Nearctic, and Neotropical biogeographic ecoregions, reaching the Neotropic its highest diversity. There have been hints in previously published phylogenetic trees from mitochondrial genome, nuclear rRNA, from combinations of both and morphology that the Australasian Amblyomma or the Australasian Amblyomma plus the Amblyomma species from the southern cone of South America, might be sister group to the Amblyomma of the rest of the world. However, a stable phylogenetic framework of Amblyomma for a better understanding of the biogeographic patterns underpinning its diversification is lacking.
Methods: We used genomic techniques to sequence complete and nearly complete mitochondrial genomes –ca. 15 kbp– as well as the nuclear ribosomal cluster –ca. 8 kbp– for 17 Amblyomma ticks in order to study the phylogeny and biogeographic pattern of the genus Amblyomma, with particular emphasis on the Neotropical region. The new genomic information generated here together with genomic information available on 43 ticks (22 other Amblyomma species and 21 other hard ticks–as outgroup–) were used to perform probabilistic methods of phylogenetic and biogeographic inferences and time‐tree estimation using biogeographic dates.
Results: In the present paper, we present the strongest evidence yet that Australasian Amblyomma may indeed be the sister group to the Amblyomma of the rest of the world (species that occur mainly in the Neotropical and Afrotropical zoogeographic regions). Our results showed that all Amblyomma subgenera (Cernyomma, Anastosiella, Xiphiastor, Adenopleura, Aponomma, and Dermiomma) are not monophyletic, except for Walkeriana and Ambly- omma. Likewise, our best biogeographic scenario supports the origin of Amblyomma and its posterior diversification in the southern hemisphere at 47.8 and 36.8 Mya, respectively. This diversification could be associated with the end of the connection of Australasia and Neotropical ecoregions by the Antarctic land bridge. Also, the biogeographic analyses let us see the colonization patterns of some neotropical Amblyomma species to the Nearctic.
Conclusions: We found strong evidence that the main theater of diversification of Amblyomma was the southern hemisphere, potentially driven by the Antarctic Bridge’s intermittent connection in the late Eocene. In addition,
the subgeneric classification of Amblyomma lacks evolutionary support. Future studies using denser taxonomic sampling may lead to new findings on the phylogenetic relationships and biogeographic history of Amblyomma genus.
... America with the Australian Region [75][76] and Berigian bridge with a northern connection to with Palearctic Region [77], iii. and the complex geological dynamics in the northern Neotropical, e.g., formation of the Isthmus of Tehuantepec and Panama [78-80]. ...
... According LnL and AICc values, the DEC + J model was the best selected model (Table S5) and therefore, we focus on reporting the results under this model. Our best biogeographic scenario supports the origin of the diversi cation of Amblyomma in the southern hemisphere at the end of the Eocene (Fig. 3), potentially associated with the faunistic ow in the nal Antarctic Bridge connection [75][76]. This agrees with the South America and Australia lineages (here well represented) as the early divergent event in Amblyomma (Fig. 1) reached with high statistical support. ...
... Further work is needed to evaluate the time divergences of Amblyomma using solid topologies, perhaps including nuclear information and calibrations of endemic species of Islands (e.g., Galapagos, Hispaniola).The origin of diversi cation of Amblyomma was estimated to have occurred 36.8 Mya (95% HPD, 43-31,6), an age that match with the end of the Antarctic bridge connection of the southern hemisphere, in the Late Eocene, at about 35 Mya[75][76]. The origin age of the diversi cation of the genus has been estimated at 74-60 Mya by Seabolt,[23], close ages to the starting connection of the southern hemisphere at 65 Mya[75][76]. ...
Background
Amblyomma is the second most diversified genus of Ixodidae that is distributed across the Indomalayan, Afrotropical, Australasian (IAA), Nearctic, and Neotropical biogeographic ecoregions, reaching in the Neotropic its higher diversity. There have been hints in previously published phylogenetic trees from mitochondrial (mt) genome, nuclear rRNA, from combinations of both and morphology that the Australasian Amblyomma or the Australasian Amblyomma plus the Amblyomma species from the southern cone of South America, might be the sister-group to the Amblyomma of the rest of the world. However, a stable phylogenetic framework of Amblyommafor a better understanding of the biogeographic patterns underpinning its diversification is lacking.
Methods
We used genomic techniques to sequence complete and nearly complete mt genomes –ca. 15 kbp– as well as the ribosomal operons –ca. 8 kbp– for 17 Amblyomma ticks in order to study the phylogeny and biogeographic pattern of the genus Amblyomma, with particular emphasis on the Neotropical region. The new genomic information generated here together with genomic information available of 43 ticks (22 other Amblyommaspecies and 21 other hard ticks –as outgroup–) were used to perform probabilistic methods of phylogenetic and biogeographic inferences and time-tree estimation using biogeographic dates.
Results
In the present paper, we present the strongest evidence yet that Australasian Amblyomma may indeed be the sister group to the Amblyomma of the rest of the world (species that occur mainly in the Neotropical and Afrotropical zoogeographic regions). Our results showed that all Amblyomma subgenera included, but Walkeriana and Amblyomma, are not monophyletic, as in the cases of Cernyomma, Anastosiella, Xiphiastor, Adenopleura, Aponomma, and Dermiomma. Likewise, our best biogeographic scenario supports the origin of Amblyomma and its posterior diversification in the southern hemisphere at 47.8 and 36.8 Mya, respectively. This diversification could be associated with the end of the connection of Australasia and Neotropical ecoregions by the Antarctic land bridge. Also, the biogeographic analyses let us see the colonization patterns of some neotropical Amblyomma species to the Nearctic.
Conclusions
We found strong evidence that the main theatre of diversification of Amblyomma was the southern hemisphere, potentially driven by the Antarctic Bridge's intermittent connection in the late Eocene. In addition, the subgeneric classification of Amblyomma lacks evolutionary support. Future studies using denser taxonomic sampling may take us to new findings on the phylogenetic relationships and biogeographic history of Amblyommagenus.
... The subfamily Asterophryinae is the most speciose group within Microhylidae, currently consisting of 327 species inhabiting the tropical forests of northern Australia, New Guinea, and adjacent Australasian islands westwards to Sulawesi, southern Philippines, and crossing the Wallace line in Bali (Frost, 2018). The original biogeographic hypothesis for this subfamily suggested that the common ancestor of Asterophryinae dispersed to Australia via an Antarctic land bridge (Hill, 2009;Savage, 1973), where it diversified and subsequently dispersed to New Guinea and adjacent Australasian islands. However, based on multilocus phylogenetic analyses, Kurabayashi et al. (2011) demonstrated that the enigmatic genus Gastrophrynoides from Sundaland (Borneo and Malay Peninsula) belongs to the subfamily Asterophryinae as a sister-lineage with respect to all Australasian taxa, suggesting that the basal split of the subfamily may not have occurred in Gondwana, but instead on the Eurasian mainland. ...
We report on the discovery of a new genus of microhylid subfamily Asterophryinae from northern and eastern Indochina, containing three new species. Vietnamophryne Gen. nov. are secretive miniaturized frogs (SVL<21 mm) with a mostly semi-fossorial lifestyle. To assess phylogenetic relationships, we studied 12S rRNA-16S rRNA mtDNA fragments with a final alignment of 2?591 bp for 53 microhylid species. External morphology characters and osteological characteristics analyzed using micro-CT scanning were used for describing the new genus. Results of phylogenetic analyses assigned the new genus into the mainly Australasian subfamily Asterophryinae as a sister taxon to the genus Siamophryne from southern Indochina. The three specimens collected from Gia Lai Province in central Vietnam, Cao Bang Province in northern Vietnam, and Chiang Rai Province in northern Thailand proved to be separate species, different both in morphology and genetics (genetic divergence 3.1%≤P≤5.1%). Our work provides further evidence for the "out of Indo-Eurasia" scenario for Asterophryinae, indicating that the initial cladogenesis and differentiation of this group of frogs occurred in the Indochina Peninsula. To date, each of the three new species of Vietnamophryne Gen. nov. is known only from a single specimen; thus, their distribution, life history, and conservation status require further study.
... Most previous works, though varying on taxon sampling and molecular data, suggested that Microhylidae are of Gondwanan origin and gave evidence supporting the "Antarctic route scenario" for the Australasian subfamily Asterophryinae, as suggested for several other vertebrate taxa that are distributed in Australia (Van Bocxlaer et al., 2006;Van der Meijden et al., 2007). According to this scenario, the basal split of Microhylidae took place in Gondwana and the ancestor of Asterophryinae dispersed to Australia via Antarctic land bridge (Hill, 2009), where the subfamily diversified (it comprises 323 recognized species to date, Frost, 2017) and subsequently dispersed to New Guinea and adjacent Australasian islands, but was unable to cross the Wallace line with exception of the genus Oreophryne Boettger, which is also known from the island of Bali (west from the Wallace line, see Fig. 1). ...
We report on a discovery of Siamophryne troglodytesGen. et sp. nov., a new troglophilous genus and species of microhylid frog from a limestone cave in the tropical forests of western Thailand. To assess its phylogenetic relationships we studied the 12S rRNA–16S rRNA mtDNA fragment with final alignment comprising up to 2,591 bp for 56 microhylid species. Morphological characterization of the new genus is based on examination of external morphology and analysis of osteological characteristics using microCT-scanning. Phylogenetic analyses place the new genus into the mainly Australasian subfamily Asterophryinae as a sister taxon to the genus Gastrophrynoides , the only member of the subfamily known from Sundaland. The new genus markedly differs from all other Asterophryinae members by a number of diagnostic morphological characters and demonstrates significant mtDNA sequence divergence. We provide a preliminary description of a tadpole of the new genus. Thus, it represents the only asterophryine taxon with documented free-living larval stage and troglophilous life style. Our work demonstrates that S. troglodytesGen. et sp. nov. represents an old lineage of the initial radiation of Asterophryinae which took place in the mainland Southeast Asia. Our results strongly support the “out of Indo-Eurasia” biogeographic scenario for this group of frogs. To date, the new frog is only known from a single limestone cave system in Sai Yok District of Kanchanaburi Province of Thailand; its habitat is affected by illegal bat guano mining and other human activities. As such, S. troglodytesGen. et sp. nov. is likely to be at high risk of habitat loss. Considering high ecological specialization and a small known range of the new taxon, we propose a IUCN Red List status of endangered for it.
... (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) than those with Africa (Hill, 2009), a greater similarity exists between the floras of the aforementioned continents (Axelrod and Raven, 1978). Numerous components of the Gondwanan flora have vanished from Africa, but still survive in the modern floras of Australia, New Zealand and Patagonia (Kooyman et al., 2014;Macphail, 1999;Macphail et al., 1993Macphail et al., , 1995. ...
A multi-proxy study of an offshore core in Saldanha Bay (South Africa) provides new insights into fluvial deposition,
ecosystems, phytogeography and sea-level history during the late Paleogene-early Neogene. Offshore seismic data
reveal bedrock topography, and provide evidence of relative sea levels as low as -100 m during the Oligocene. 3D
landscape reconstruction reveals hills, plains and an anastomosing river system. A Chattian or early Miocene age for
the sediments is inferred from dinoflagellate taxa Distatodinium craterum, Chiropteridium lobospinosum, Homotryblium
plectilum and Impagidinium paradoxum. The subtropical forest revealed by palynology includes lianas and vines,
evergreen trees, palms and ferns, implying higher water availability than today, probably reduced seasonal drought
and stronger summer rainfall. From topography, sedimentology and palynology we reconstruct Podocarpaceaedominated
forests, Proto-Fynbos, and swamp/riparian forests with palms and other angiosperms. Rhizophoraceae
present the first South African evidence of Palaeogene/Neogene mangroves. Subtropical woodland-thicket with
Combretaceae and Brachystegia (Peregrinipollis nigericus) probably developed on coastal plains. Some of the last
remaining Gondwana elements on the sub-continent, e.g., Araucariaceae, are recorded. Charred particles signal fires
prior to the onset of summer dry climate at the Cape. Marine and terrestrial palynomorphs, together with organic and
inorganic geochemical proxy data, suggest a gradual glacio-eustatic transgression. The data shed light on Southern
Hemisphere biogeography and regional climatic conditions at the Palaeogene-Neogene transition. The proliferation of
the vegetation is partly ascribed to changes in South Atlantic oceanographic circulation, linked to the closure of the
Central American Seaway and the onset of the Benguela Current ~14 Ma.
... The initial Drake Passage would have been an extremely narrow, deep seaway at c. 30 Ma (Eagles and Jokat, 2014). It was also likely that a chain of islands persisted between South America and Antarctica during the opening of the Drake Passage and this may have facilitated biotic dispersal from Antarctica well into the Oligocene (Hill, 2009;Eagles and Jokat, 2014) (Fig. 2). So, the Antarctic land bridge may have at first existed as a terrestrial connection during the Jurassic and Cretaceous, but evolved into islands separated by narrow, shallow water bodies (first lakes, later seas) through the Eocene and perhaps until the Oligocene. ...
Amphi-Pacific disjunct distributions between South America and Australasia are correlated with the breakup and changing palaeo-climate of Gondwana. For a long period, with a temperate climate, Antarctica formed a land bridge between Australia and South America, allowing species to disperse/vicariate between both continents. Dated phylogenies in the literature, showing sister-clades with a distribution disjunction between South America and Australia, were used for the correlation. The initiation of the Antarctic Circumpolar Current, and a change to a colder Antarctic climate is associated with the opening of the Drake Passage between South America and Antarctica at c. 30 Ma, and the final separation of Australia and Antarctica along the South Tasman Rise at c. 45 Ma. The distribution data highlighted the existence of a “southern disjunct distribution” pattern, which may be the result of continental vicariance/dispersal. This is strongly indicative of a connection between Antarctica, South America and Australia; which later provided a dispersal pathway and facilitated vicariance after break up. The taxa that likely dispersed/vicariated via Antarctica included all species with a more (sub)tropical climate preference. Twelve distributions, younger than 30 Ma, are interpreted as the result of long distance dispersal between South America and Australia; these taxa are suited to a temperate climate. The climatic signal shown by all taxa is possibly a consequence of the Australian plate's asynchronous rifting over tens of millions of years in combination with climate changes. These events may have provided opportunities for tropical and sub-tropical species to disperse and speciate earlier than what we observe for the more temperate taxa.
... Some prominent deviations to the typical salticid body plan can be found in different clades (e.g. dorso-ventrally flattened Holoplatys Simon and ant-mimicking Myrmarachne MacLeay in Astioida; dorso-ventrally flattened Platycryptus Hill and ant-mimicking Peckhamia Simon in Marpissoida) (Maddison et al. 2008;Hill 2009), suggesting that these modifications have occurred more than once in the evolutionary history of Salticidae. In order to understand the ecological and evolutionary forces that constrain some species to a typical form and drive others so far away from it, we need to understand the ecological consequences of breaking out of conventional patterns. ...
... As noted previously in other studies (Maddison et al. 2008;Hill 2009), it appears that several 'body plans' have evolved repeatedly in separate clades of the Salticidae, including large-bodied morphs, flattened morphs and ant-mimicking genera. It is curious to note that, despite the availability of other habitats around the world that are similar to the escarpments of the Kimberley Region, species with legs as elongate as those of M. mainae have not been reported. ...
The behaviour and natural history of Megaloastia mainae, a long- legged salticid spider that appears to be endemic to northwest Australia, was investigated under natural conditions in the Kimberley Region of Western Australia. Megaloastia mainae is commonly found on rock escarpments, where it spends most of its time on downward-facing horizontal surfaces of large rocks. The diet of M. mainae comprises a variety of insects and spiders, including other salticids and web-building spiders. Megaloastia mainae builds large nests on the surface of the rock escarpment, which are generally occupied for at least several weeks. Contrary to previous reports, we found no evidence that M. mainae builds a prey-capture web or uses its nest as a predatory device. Megaloastia mainae is active during the day, and usually remains within 2 m of its nest. Megaloastia mainae orients to face prey from up to 1.2 m, and can move very quickly across the rock escarpment. Hunting is generally by slow stalking approaches, followed by rapid attacks. The elongated legs of M. mainae may be the result of selection for rapid locomotion in inverted environments. We also found that M. mainae that built nests close to conspecifics were more likely to be missing legs, suggesting that agonistic interactions might be an important source of injury for these spiders.
... This is a large clade of primarily Australasian salticids (Maddison et al. 2008, Hill 2010. There is strong evidence that a common ancestor of the the Astioida and Marpissoida lived on a great southern continent (Australamerica) comprised of South America, Antarctica and Australia, in the Eocene after the breakup of Gondwanaland (Hill 2009b). According to this hypothesis, the marpissoids and astioids would represent parallel lines of descent from this common ancestor, after the separation of Antarctica at the end of the Eocene. ...
... This is a large group with two primary centers of diversity, one Neotropical, where they are particularly diverse in the Caribbean (making up the majority of the salticid fauna), and the other Australasian (Hill 2009a, Zhang 2012, Zhang & Maddison 2012a, 2012b. This distribution suggests that the 'first' euophryine lived in Australamerica after the breakup of Gondwana (Hill 2009b). ...
The origin of every major group or clade of North American salticid spiders can be explained by its origin
in, and subsequent introduction from, either the Neotropical or Palaearctic regions. Although the more ancient
salticid fauna represented by Eocene fossils from the Baltic Amber of Europe (~45Ma) was probably present in
North America, we have no record of a North American fauna predating that represented by Miocene fossils in the amber of Chiapas, Mexico (~23-15Ma). Before completion of the Panamanian Land Bridge (~2.5-2.3Ma), Antillean and Central American volcanic island arcs could have supported an early introduction of dendryphantine and marpissine ancestors from South America. Throughout the Cenozoic, the Beringia Land Bridge was generally available to support the introduction of the other important North American group, the pellenines, from Eurasia. Since the Pleistocene, cycles of glaciation have repeatedly altered the distribution of the North America fauna.
... This scenario involves late major dispersal events from the Australia-New Zealand complex to South America, at a time before the separation of Australia and Antarctica. Such migrations were still possible as an Antarctic land bridge remained in place until the Eocene, and was associated with a relatively moderate climate (Hill 2009). Even in the Miocene, short-term warming events were possible. ...
The biogeographic relationships among the Cantacaderinae (Heteroptera) are revisited in the light of a genus and species recently described. The results are reasonably congruent with previous studies, but with some differences. The common ancestor of Cantacaderinae may not be restricted to Australia but to a more widely distributed taxon. The Cantacaderinae evolved into two lineages: the Ceratocaderini + Carldrakeanini, originating in the Australia–New Zealand complex; and the Cantacaderini, originating in the Oriental region and dispersing through a south-eastern arc of continental fragments but not through the Asian peninsula.
... Consequently , consensus on a biogeographic scenario to explain the microhylid distribution pattern has not been reached. Furthermore, although these studies proposed different colonization scenarios for many microhylid taxa, they agree on a similar Antarctic route scenario for the Australian-New Guinean taxon (Asterophryinae), as suggested in other vertebrate taxa distributed in Australia (e.g., marsupials, ratite bird, chelid turtles, and hyloid frogs [7]). It is generally considered that employing long sequence data, and increased taxon sampling in molecular phylogenetic inference, can clarify problematic phylogenetic relationships8910. ...
Microhylidae is a geographically widespread family of anurans. Although several extensive molecular analyses have attempted to elucidate their subfamilial relationships, and correlate these with Mesozoic and Cenozoic continental drifts, consensus has not been reached. Further, generic level relationships have not been well investigated in some microhylid subfamilies, and therefore subfamilial affiliations of some genera are still unclear. To elucidate the phylogenetic positions of two mysterious Asian genera, Gastrophrynoides and Phrynella, and to better understand the trans-continental distributions of microhylid taxa, we performed molecular phylogenetic and dating analyses using the largest molecular dataset applied to these taxa to date.
Six nuclear and two mitochondrial genes (approx. 8 kbp) were sequenced from 22 microhylid frog species representing eight subfamilies. The maximum likelihood and Bayesian analyses could not fully elucidate the subfamilial relationships, suggesting a rapid radiation of these taxa between 85 and 66 million years ago. In contrast, generic relationships of Asian microhylines were generally well resolved.
Our results clearly showed that one of two problematic Asian genera, Phrynella, was nested in the clade of the Asian subfamily Microhylinae. By contrast, Gastrophrynoides occupied the most basal position of the Australian-New Guinean subfamily Asterophryinae. The estimated divergence of Gastrophrynoides from other asterophryine was unexpectedly around 48 million years ago. Although a colonization scenario via Antarctica to the Australian-New Guinean landmass has been suggested for Asterophryinae, our finding suggested a novel colonization route via Indo-Eurasia.
