Molecular Divergence Estimates Research Articles

Attenuated evolution of mammals through the Cenozoic.

The Cenozoic diversification of placental mammals is the archetypal adaptive radiation. Yet, discrepancies between molecular divergence estimates and the fossil record fuel ongoing debate around the timing, tempo, and drivers of this radiation. Analysis of a three-dimensional skull dataset for living and extinct placental mammals demonstrates that evolutionary rates peak early and attenuate quickly. This long-term decline in tempo is punctuated by bursts of innovation that decreased in amplitude over the past 66 million years. Social, precocial, aquatic, and herbivorous species evolve fastest, especially whales, elephants, sirenians, and extinct ungulates. Slow rates in rodents and bats indicate dissociation of taxonomic and morphological diversification. Frustratingly, highly similar ancestral shape estimates for placental mammal superorders suggest that their earliest representatives may continue to elude unequivocal identification.

Late Cretaceous hydrothermal vent communities from the Troodos ophiolite, Cyprus: systematics and evolutionary significance

AbstractModern hydrothermal vent communities are based on chemosynthesis by microbial primary producers. Molecular phylogenetic divergence estimates indicate that many of the dominant vent taxa arose during the Cenozoic and Cretaceous; however, the fossil record of vent communities from these time periods is poor. One occurrence of such Cretaceous vent communities pertains to six volcanogenic massive sulphide deposits in the Troodos ophiolite of Cyprus. These deposits represent hydrothermal activity on deep (2500–5000 m) arc‐related spreading ridge(s) in the Neotethyan Ocean over several million years during the late Cenomanian and earliest Turonian. The Cyprus vent communities consist of worm tubes, representing possible vestimentiferans and serpulids, together with a moderate diversity of abyssochrysoid gastropods, belonging to eight new species (Desbruyeresia kinousaensis sp. nov., Desbruyeresia memiensis sp. nov., Desbruyeresia kambiaensis sp. nov., Hokkaidoconcha morisseaui sp. nov., Ascheria canni sp. nov., Cyprioconcha robertsoni gen. et sp. nov., Paskentana xenophontosi sp. nov. and Paskentana dixoni sp. nov.) in five genera and three families; none of the species is shared between vent sites. A single gaudryceratid ammonite from one of the vent sites most likely represents a water‐logged shell that sank from surface waters. The gastropod fauna contains the first representatives of the genera Desbruyeresia, Hokkaidoconcha, Ascheria and Paskentana from hydrothermal vents, and also the youngest representative of the last‐named genus in any environment. The Cypriot vent communities share tube worms with slightly older (Cenomanian) and younger (Turonian–Santonian) vent communities elsewhere in the western part of the Neotethyan Ocean.

The second known stygomorphic freshwater crab from China, Phasmon typhlops gen. nov. et sp. nov. (Crustacea, Decapoda, Potamidae), diverged at the beginning of the Late Miocene.

A new genus and new species of blind freshwater cave crab are described from Chongzuo City, Guangxi Zhuang Autonomous Region, China based on morphology and mitochondrial 16S rDNA sequences. The new genus, Phasmongen. nov., is established for P. typhlopssp. nov., which is only the second blind cave crab known from China and East Asia. The combination of a very wide carapace, overall depigmentation, reduced orbits and vestigial unpigmented eyes of Phasmon immediately separates it from all known potamid genera. Molecular divergence estimates based on 16S rDNA suggest that the lineage to which the new genus belongs diverged from other potamids at the beginning of the Late Miocene (10.8 million years ago), much earlier than other Chinese cave crabs.

Early Oligocene chinchilloid caviomorphs from Puerto Rico and the initial rodent colonization of the West Indies.

By their past and present diversity, rodents are among the richest components of Caribbean land mammals. Many of these became extinct recently. Causes of their extirpation, their phylogenetic affinities, the timing of their arrival in the West Indies and their biogeographic history are all ongoing debated issues. Here, we report the discovery of dental remains from Lower Oligocene deposits (ca 29.5 Ma) of Puerto Rico. Their morphology attests to the presence of two distinct species of chinchilloid caviomorphs, closely related to dinomyids in a phylogenetic analysis, and thus of undisputable South American origin. These fossils represent the earliest Caribbean rodents known thus far. They could extend back to 30 Ma the lineages of some recently extinct Caribbean giant rodents (Elasmodontomys and Amblyrhiza), which are also retrieved here as chinchilloids. This new find has substantial biogeographic implications because it demonstrates an early dispersal of land mammals from South America to the West Indies, perhaps via the emergence of the Aves Ridge that occurred ca 35-33 Ma (GAARlandia hypothesis). Considering both this new palaeontological evidence and recent molecular divergence estimates, the natural colonization of the West Indies by rodents probably occurred through multiple and time-staggered dispersal events (chinchilloids, then echimyid octodontoids (spiny rats/hutias), caviids and lastly oryzomyin muroids (rice rats)).

Revision of Oligocene ‘Paraphiomys’ and an origin for crown Thryonomyoidea (Rodentia: Hystricognathi: Phiomorpha) near the Oligocene–Miocene boundary in Africa

Abstract‘Paraphiomys’ simonsi is a phiomorph rodent from the early Oligocene of Egypt (~29–30 Mya) that has historically been aligned with much younger (< ~20 Mya) Miocene species of the genera Paraphiomys and Neosciuromys. Here, we use Bayesian tip-dating analysis of a 109-character morphological matrix containing 57 living and extinct ctenohystricans to test these proposed placements for ‘Paraphiomys’ simonsi. Our analyses provide support for the exclusion of ‘Paraphiomys’ simonsi from both Paraphiomys and Neosciuromys and justify the establishment of a new genus (Monamys gen. nov.) for this stem thryonomyoid. These analyses also indicate that the divergence of the extant dassie rat Petromus from the extant cane rat Thryonomys (i.e. origin of crown Thryonomyoidea) occurred ~23.7 Mya, close to the Oligocene–Miocene boundary and in close agreement with recent molecular estimates for this split. Miocene Neosciuromys, Paraulacodus, Protohummus and the type species of Paraphiomys are identified as stem thryonomyids, whereas the Namibian species Apodecter stromeri, Tufamys woodi, ‘Paraphiomys’ australis and ‘Paraphiomys’ roessneri are identified for the first time as stem petromurids, raising the possibility of a long period of endemic petromurid evolution in south-west Africa. Comparison of molecular divergence estimates with our optimal tip-dated topology suggests that stem bathyergoids are most likely to have arisen from late Eocene and early Oligocene ‘phiomyids’.

Asmodochelys parhami, a new fossil marine turtle from the Campanian Demopolis Chalk and the stratigraphic congruence of competing marine turtle phylogenies.

Resolving the phylogeny of sea turtles is uniquely challenging given the high potential for the unification of convergent lineages due to systematic homoplasy. Equivocal reconstructions of marine turtle evolution subsequently inhibit efforts to establish fossil calibrations for molecular divergence estimates and prevent the accurate reconciliation of biogeographic or palaeoclimatic data with phylogenetic hypotheses. Here we describe a new genus and species of marine turtle, Asmodochelys parhami, from the Upper Campanian Demopolis Chalk of Alabama and Mississippi, USA represented by three partial shells. Phylogenetic analysis shows that A. parhami belongs to the ctenochelyids, an extinct group that shares characteristics with both pan-chelonioids and pan-cheloniids. In addition to supporting Ctenochelyidae as a sister taxon of Chelonioidea, our analysis places Protostegidae outside of the Chelonioidea crown group and recovers Allopleuron hofmanni as a stem dermochelyid. Gap excess ratio (GER) results indicate a strong stratigraphic congruence of our phylogenetic hypothesis; however, the highest GER value is associated with the phylogenetic hypothesis of marine turtles which excludes Protostegidae from the Cryptodira crown group. Ancestral range estimations derived from our phylogeny imply a European or North American origin of Chelonioidea in the middle-to-late Campanian, approximately 20 Myr earlier than current molecular divergence studies suggest.

Rapid morphological evolution in placental mammals post-dates the origin of the crown group.

Resolving the timing and pattern of early placental mammal evolution has been confounded by conflict among divergence date estimates from interpretation of the fossil record and from molecular-clock dating studies. Despite both fossil occurrences and molecular sequences favouring a Cretaceous origin for Placentalia, no unambiguous Cretaceous placental mammal has been discovered. Investigating the differing patterns of evolution in morphological and molecular data reveals a possible explanation for this conflict. Here, we quantified the relationship between morphological and molecular rates of evolution. We show that, independent of divergence dates, morphological rates of evolution were slow relative to molecular evolution during the initial divergence of Placentalia, but substantially increased during the origination of the extant orders. The rapid radiation of placentals into a highly morphologically disparate Cenozoic fauna is thus not associated with the origin of Placentalia, but post-dates superordinal origins. These findings predict that early members of major placental groups may not be easily distinguishable from one another or from stem eutherians on the basis of skeleto-dental morphology. This result supports a Late Cretaceous origin of crown placentals with an ordinal-level adaptive radiation in the early Paleocene, with the high relative rate permitting rapid anatomical change without requiring unreasonably fast molecular evolutionary rates. The lack of definitive Cretaceous placental mammals may be a result of morphological similarity among stem and early crown eutherians, providing an avenue for reconciling the fossil record with molecular divergence estimates for Placentalia.

Genetic Content of the Neo-Sex Chromosomes in Ctenonotus and Norops (Squamata, Dactyloidae) and Degeneration of the Y Chromosome as Revealed by High-Throughput Sequencing of Individual Chromosomes

Pleurodont lizards are characterized by an ancient system of sex chromosomes. Along with stability of the central component of the system (homologous to the X chromosome of Anolis carolinensis [Dactyloidae], ACAX), in some genera the ancestral sex chromosomes are fused with microautosomes, forming neo-sex chromosomes. The genus Ctenonotus (Dactyloidae) is characterized by multiple X₁X₁X₂X₂/X₁X₂Y sex chromosomes. According to cytogenetic data, the large neo-Y chromosome is formed by fusion of the ancestral Y chromosome with 2 microautosomes (homologous to ACA10 or ACA11 and ACA12), the X₁ chromosome is formed by fusion of the ancestral X chromosome with the autosome homologous to ACA10 or ACA11, and the X₂ chromosome is homologous to autosome ACA12. To determine more precisely the content and evolution of the Ctenonotus sex chromosomes, we sequenced flow-sorted chromosomes (both sex chromosomes and microautosomes as control) of 2 species with a similar system: C. pogus and C. sabanus. Our results indicate that the translocated part of the X₁ is homologous to ACA11, X₂ is homologous to ACA12, and the Y contains segments homologous to both ACA11 and ACA12. Molecular divergence estimates suggest that the ancestral X-derived part has completely degenerated in the Y of Ctenonotus, similar to the degeneration of the Norops sagrei Y chromosome (Dactyloidae). The newly added regions show loss of DNA content, but without degeneration of the conserved regions. We hypothesize that the translocation of autosomal blocks onto sex chromosomes facilitated rapid degeneration of the pseudoautosomal region on the ancestral Y.

A late Miocene (Hemphillian) freshwater fish (Osteichthyes) fauna from Mobile County, Alabama, USA

ABSTRACT Systematic descriptions of North American Miocene freshwater fishes are extremely uncommon, with those from the Gulf Coastal Plain region being completely absent. In this study we examined 324 historically collected freshwater fish elements derived from the late Miocene (Hemphillian) Mauvilla fossil site located in Mobile County, Alabama, USA. Analysis of these elements confirmed the presence of three unequivocal taxa including Atractosteus sp. cf. A. spatula, Ictalurus spp., and Aplodinotus grunninens. The preserved elements consisted of spines, pharyngeal bones, pharyngeal teeth, and scales, likely indicating a taphonomic bias towards large individuals with robust elements. The co-occurrence of these three taxa indicate they were derived from a medium-to-large river fish assemblage, suggesting that one or more of the rivers that constitute the nearby Mobile Basin may have been present in the region during the late Miocene. Molecular divergence estimates and morphological similarity to modern representatives both support the presence of these extant taxa in the late Miocene, and the examined remains represent some of the earliest fossil occurrences of these extant taxa. These three taxa also represent the first biogeographic occurrence of each in the late Miocene of both Alabama and the Gulf Coastal Plain of North America and helps to improve our understanding of Miocene freshwater fish assemblages.

Agathistrees of Patagonia's Cretaceous‐Paleogene death landscapes and their evolutionary significance

The fossil record of Agathis historically has been restricted to Australasia. Recently described fossils from the Eocene of Patagonian Argentina showed a broader distribution than found previously, which is reinforced here with a new early Paleocene Agathis species from Patagonia. No previous phylogenetic analyses have included fossil Agathis species. We describe macrofossils from Patagonia of Agathis vegetative and reproductive organs from the early Danian, as well as leaves with Agathis affinities from the latest Maastrichtian. A total evidence phylogenetic analysis is performed, including the new Danian species together with other fossil species having agathioid affinities. Early Danian Agathis immortalis sp. nov. is the oldest definite occurrence of Agathis and one of the most complete Agathis species in the fossil record. Leafy twigs, leaves, pollen cones, pollen, ovuliferous complexes, and seeds show features that are extremely similar to the living genus. Dilwynites pollen grains, associated today with both Wollemia and Agathis and known since the Turonian, were found in situ within the pollen cones. Agathis was present in Patagonia ca. 2 million years after the K-Pg boundary, and the putative latest Cretaceous fossils suggest that the genus survived the K-Pg extinction. Agathis immortalis sp nov. is recovered in a stem position for the genus, while A. zamunerae (Eocene, Patagonia) is recovered as part of the crown. A Mesozoic divergence for the Araucariaceae crown group, previously challenged by molecular divergence estimates, is supported by the combined phylogenetic analyses including the fossil taxa.

Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil record.

Simultaneously analysing morphological, molecular and stratigraphic data suggests a potential resolution to a major remaining inconsistency in crocodylian evolution. The ancient, long-snouted thoracosaurs have always been placed near the Indian gharial Gavialis, but their antiquity (ca 72 Ma) is highly incongruous with genomic evidence for the young age of the Gavialis lineage (ca 40 Ma). We reconcile this contradiction with an updated morphological dataset and novel analysis, and demonstrate that thoracosaurs are an ancient iteration of long-snouted stem crocodylians unrelated to modern gharials. The extensive similarities between thoracosaurs and Gavialis are shown to be an almost 'perfect storm' of homoplasy, combining convergent adaptions to fish-eating, as well resemblances between genuinely primitive traits (thoracosaurs) and atavisms (Gavialis). Phylogenetic methods that ignore stratigraphy (parsimony and undated Bayesian methods) are unable to tease apart these similarities and invariably unite thoracosaurs and Gavialis. However, tip-dated Bayesian approaches additionally consider the large temporal gap separating ancient (thoracosaurs) and modern (Gavialis) iterations of similar long-snouted crocodyliforms. These analyses robustly favour a phylogeny which places thoracosaurs basal to crocodylians, far removed from modern gharials, which accordingly are a very young radiation. This phylogenetic uncoupling of ancient and modern gharial-like crocs is more consistent with molecular clock divergence estimates, and also the bulk of the crocodylian fossil record (e.g. all unequivocal gharial fossils are very young). Provided that the priors and models attribute appropriate relative weights to the morphological and stratigraphic signals-an issue that requires investigation-tip-dating approaches are potentially better able to detect homoplasy and improve inferences about phylogenetic relationships, character evolution and divergence dates.

A Miocene pygmy right whale fossil from Australia.

Neobalaenines are an enigmatic group of baleen whales represented today by a single living species: the pygmy right whale, Caperea marginata, found only in the Southern Hemisphere. Molecular divergence estimates date the origin of pygmy right whales to 22–26 Ma, yet so far there are only three confirmed fossil occurrences. Here, we describe an isolated periotic from the latest Miocene of Victoria (Australia). The new fossil shows all the hallmarks of Caperea, making it the second-oldest described neobalaenine, and the oldest record of the genus. Overall, the new specimen resembles C. marginata in its external morphology and details of the cochlea, but is more archaic in it having a hypertrophied suprameatal area and a greater number of cochlear turns. The presence of Caperea in Australian waters during the Late Miocene matches the distribution of the living species, and supports a southern origin for pygmy right whales.

Barcoding and multi-locus phylogeography of the globally distributed calcareous tubeworm genus Hydroides Gunnerus, 1768 (Annelida, Polychaeta, Serpulidae)

Hydroides is a large and diverse group of calcareous tubeworms (Serpulidae, Annelida) recognised by a distinctive but variable two-tiered operculum. Despite considerable research using several species of Hydroides as models in ecological and biofouling studies, phylogenetic and biogeographic relationships within the genus are still poorly understood. Using combined mitochondrial (COI, cytochrome b) and nuclear (18S, 28S and ITS) gene markers for 284 individuals of 45 morphospecies of Hydroides, we investigated the global phylogenetic and biogeographic relationships within the genus. Phylogenetic topologies were well supported and indicated high genetic diversity within Hydroides, revealing potential cryptic species. Present results also include the first COI barcoding data enabling rapid and effective species identification of Hydroides on a global scale. Phylogenetic relationships within Hydroides were more concordant with geographical distributions than morphological similarity of their opercula. Molecular divergence estimates suggested the origin and subsequent diversification in the western Tethys Sea followed by a shift of the historical centre of diversity from the Indo-Mediterranean region to the central Indo-Pacific during the last 50 million years. Further studies on population genetics of species consisting of multiple lineages would provide a better understanding on the status of potential cryptic species. Furthermore, paleogeographic studies based on fossil Hydroides tubes would provide evidence to test this biogeographic hypothesis.

Molecular phylogenetics supports the origin of an endemic Balearic shrew lineage (Nesiotites) coincident with the Messinian Salinity Crisis

The red-toothed shrews (Soricinae) are the most widespread subfamily of shrews, distributed from northern South America to North America and Eurasia. Within this subfamily, the tribe Nectogalini includes the fossil species Nesiotites hidalgo recorded from the Late Pleistocene to Holocene of the Balearic Islands (Western Mediterranean). Although there is a consensus about the close relationship between the extinct red-toothed shrew genera Nesiotites and Asoriculus based on morphology, molecular data are necessary to further evaluate the phylogenetic relationships of the Balearic fossils. We obtained a near complete mitochondrial genome of N. hidalgo, allowing the first molecular phylogenetic analysis of this species. Analyses based on 15,167 bp of the mitochondrial genome placed N. hidalgo as close relative to the extant Himalayan shrew (Soriculus nigrescens), and a combined analysis using molecular and morphological data confirm that N. hidalgo and Asoriculus gibberodon are sister-taxa with S. nigrescens as the immediate outgroup. Molecular clock and divergence estimates suggest that the split between N. hidalgo and its closest living relative occurred around 6.44 Ma, which is in agreement with the previously proposed colonisation of the Balearic Islands from mainland Europe by nectogaline shrews during the Messinian Salinity Crisis (5.97–5.33 My ago). Our results highlight that it is possible to retrieve genetic data from extinct small mammals from marginal environments for DNA preservation. Additional finds from the fossil record of Soricinae from the Eurasian Late Miocene/Early Pliocene are needed to shed further light on the still confusing taxonomy and paleobiogeography of this clade.

Phylogeny and species diversity of Tasmanian mountain shrimps and their relatives (Crustacea, Anaspidesidae)

Anaspidacea is an enigmatic taxon within Malacostraca with uncertain phylogenetic affinities. One of the four families within Anaspidacea, the Anaspidesidae (representing in most respects the plesiomorphic conditions of the entire taxon), is endemic to Tasmania and shows a remarkable geographical and vertical distribution. Eleven species in three genera (Allanaspides, Anaspides and Paranaspides) are recognized to date, occurring in freshwater habitats such as lakes, rivers, streams, tarns and also in caves. We present the most detailed analyses to date of the phylogeny of Anaspidesidae including all eleven species based on molecular data (COI, 16S and 28S). In addition, the genetic differentiation within the morphologically recognized species is studied and a dating of speciation is given using a molecular clock approach (based on mt‐DNA only). A special focus is on the multiple instances of immigration into the subterranean habitat. Most of the morphologically delineated species are recognized by molecular data. Significantly, however, in at least two cases, the molecular data suggest more species than so far described, but further molecular sampling from a wider range of localities is required. Our molecular divergence estimates suggest the anaspidesids are younger than previously thought. Rather than having Eocene origins, our results suggest Early Miocene origins with primary diversification in Miocene and Pliocene. Entry into subterranean habitats appears to have occurred in the Pleistocene rather than Tertiary. Thus, rather than being a defensive response to rising temperatures in the Tertiary, entry into caves in the Pleistocene may represent opportunistic expansion into new habitats created by the action of glacial meltwaters on existing karst formations. As a result, environmental changes during the Pleistocene appear to have prompted ecological expansion of Anaspides by “opening” new subterranean habitats leading to increased diversification in the group.

The Tasmanian Lake Shrimps, Paranaspides Smith, 1908 (Crustacea, Syncarida, Anaspidesidae)

The Tasmanian Lake Shrimps of the genus Paranaspides Smith, 1908 (Syncarida: Anaspidesidae) are endemic to lakes on the eastern Central Plateau, Tasmania, namely Great Lake, Shannon Lagoon, Penstock Lagoon, Arthurs Lake and Woods Lake. Prior to the present study, only the type species, P. lacustris Smith, 1908, was recognized. Reconsideration of Paranaspides from throughout its range, however, showed that Paranaspides from Arthurs Lake and Woods Lakes are referrable to a new species, P. williamsi sp. nov. Morphometric differences in the uropodal exopod and maxilliped, and subtle differences in the morphology of the male pleopods 1 and 2, and colour-in-life distinguish the two species. Genetic divergence (p-distance) between the two species exceeds 10% in mitochondrial COI and 3% in 16S. Both species are described and illustrated, and a lectotype fixed for P. lacustris. Although P. lacustris and P. williamsi occur in relatively close proximity, they occupy different drainages. The Great Lake-Shannon Lagoon-Penstock Lagoon system drains to the southeast, and the Arthurs Lake-Woods Lake system to the northeast. The distributions of P. lacustris and P. williamsi precisely parallel those of a cognate pair of galaxiid fishes, Paragalaxias eleotroides and Paragalaxias mesotes. Given the geological history of the Central Plateau and molecular divergence estimates for Paragalaxias, Paranaspides may also have diverged prior to the Pleistocene glaciations. Species of Paranaspides are dependent on their shallow water algal bed habitat, making them highly susceptible to sudden or significant fluctuations in lake water levels as a result of hydroelectric operations. Both species of Paranaspides have small areas of occupancy and are prone to the effects of hydroelectric activities on their lake habitats; under IUCN Red List criteria, their conservation status corresponds to Vulnerable (D2).

A tale of the nearly tail‐less: the effects of Plio‐Pleistocene climate change on the diversification of the African avian genus Sylvietta

Sylvietta is a broadly distributed group of African species inhabiting a wide range of habitats and presents an interesting opportunity to investigate the historic mechanisms that have impacted the biogeography of African avian species. We collected sequence data from 50 individuals and used model‐based phylogenetic methods, molecular divergence estimates and ancestral area estimates to construct a time‐calibrated phylogeny and estimation of biogeographic history. We estimate a southern African origin for Sylvietta, with an initial divergence splitting the genus into two clades. The first consists of arid‐adapted species, with a southern African origin and subsequent diversification north into Ethiopia–Somalia. The second clade is estimated as having a Congolian forest origin with an eastward pattern of colonization and diversification as a result of Plio‐Pleistocene forest dynamics. Additionally, two members of the genus Sylvietta display interesting patterns of intraspecific diversification. Sylvietta rufescens is an arid‐adapted species inhabiting southern Africa, and we recover two subclades with a divergence dating to the Pleistocene, a unique pattern for avian species which may be explained via isolation in arid habitat fragments in the early Pleistocene. Second, Sylvietta virens, a species endemic to Afro‐tropical forests, is recovered with geographically structured genetic diversification across its broad range, an interesting result given that recent investigations of several avian forest species have found similar and substantial geographically structured genetic diversity relating to Plio‐Pleistocene forest fragmentation. Overall, Plio‐Pleistocene habitat cycling played a significant role in driving diversification in Sylvietta, and this investigation highlights the substantial impact of climate‐driven habitat dynamics on the history of sub‐Saharan species.

A novel Haemosporida clade at the rank of genus in North American cranes (Aves: Gruiformes)

The unicellular blood parasites in the order Haemosporida are highly diverse, infect many vertebrates, are responsible for a large disease burden among humans and animals, and have reemerged as an important model system to understand the evolutionary and ecological dynamics of host-parasite interactions. The phylogenetics and systematics of Haemosporida are limited by poor sampling of different vertebrate host taxa. We surveyed the Haemosporida of wild whooping cranes (Grus americana) and sandhill cranes (Grus canadensis) (Aves: Gruiformes) using a combination of morphological and molecular approaches. We identified Haemoproteus antigonis in blood smears based on published morphological descriptions. Phylogenetic analysis based on partial cytochrome b (cytb) and cytochrome oxidase (coI) sequences placed H. antigonis parasites in a novel clade, distinct from all avian Haemosporida genera for which cytb and/or coI sequences are available. Molecular clock and divergence estimates suggest this crane clade may represent a new genus. This is the first molecular description of H. antigonis and the first report of H. antigonis in wild whooping cranes, an endangered bird in North America. Further sampling of Haemosporida, especially from hosts of the Gruiformes and other poorly sampled orders, will help to resolve the relationship of the H. antigonis clade to other avian Haemosporida genera. Our study highlights the potential of sampling neglected host species to discover novel lineages of diverse parasite groups.

Oligocene Termite Nests with In Situ Fungus Gardens from the Rukwa Rift Basin, Tanzania, Support a Paleogene African Origin for Insect Agriculture.

Based on molecular dating, the origin of insect agriculture is hypothesized to have taken place independently in three clades of fungus-farming insects: the termites, ants or ambrosia beetles during the Paleogene (66–24 Ma). Yet, definitive fossil evidence of fungus-growing behavior has been elusive, with no unequivocal records prior to the late Miocene (7–10 Ma). Here we report fossil evidence of insect agriculture in the form of fossil fungus gardens, preserved within 25 Ma termite nests from southwestern Tanzania. Using these well-dated fossil fungus gardens, we have recalibrated molecular divergence estimates for the origins of termite agriculture to around 31 Ma, lending support to hypotheses suggesting an African Paleogene origin for termite-fungus symbiosis; perhaps coinciding with rift initiation and changes in the African landscape.

Lines in the land: a review of evidence for eastern Australia's major biogeographical barriers to closed forest taxa

The influence of climatic changes occurring since the late Miocene on Australia’s eastern mesic ecosystems has received significant attention over the past 20 years. In particular, the impact of the dramatic shift from widespread rainforest habitat to a much drier landscape in which closed forest refugia were dissected by open woodland/savannah ecosystems has long been a focal point in Australian ecology and biogeography. Several specific regions along the eastern coast have been identified previously as potentially representing major biogeographical disjunctions for closed forest taxa. Initially, evidence stemmed from recognition of common zones where avian species/subspecies distributions and/or floral communities were consistently separated, but the body of work has since grown significantly with the rise of molecular phylogeographic tools and there is now a significant literature base that discusses the drivers, processes and effects of these hypothesised major biogeographical junctions (termed barriers). Here, we review the literature concerning eight major barriers argued to have influenced closed forest taxa; namely, the Laura Basin, Black Mountain Corridor, Burdekin Gap, Saint Lawrence Gap, Brisbane Valley Barrier, Hunter Valley Barrier, Southern Transition Zone and East Gippsland Barrier. We synthesise reported phylogeographical patterns and the inferred timing of influence with current climatic, vegetation and geological characteristics for each barrier to provide insights into regional evolution and seek to elicit common trends. All eight putative biogeographical barriers are characterised currently by lowland zones of drier, warmer, more open woodland and savannah habitat, with adjacent closed forest habitats isolated to upland cool, wet refugia. Molecular divergence estimates suggest two pulses of divergence, one in the early Miocene (~20–15 Mya) and a later one from the Pliocene–Pleistocene (~6–0.04 Mya). We conclude with a prospectus for future research on the eastern Australian closed forests and highlight critical issues for ongoing studies of biogeographical barriers worldwide.