The freshwater fish of Neogene Africa (Miocene–Pleistocene): systematics and biogeography

According to when they attained high diversity, major taxa of marine animals have been clustered into three groups, the Cambrian, Paleozoic, and Modern Faunas. Because the Cambrian Fauna was a relatively minor component of the total fauna after mid-Ordovician time, the Phanerozoic history of marine animal diversity is largely a matter of the fates of the Paleozoic and Modern Faunas. The fact that most late Cenozoic genera belong to taxa that have been radiating for tens of millions of years indicates that the post-Paleozoic increase in diversity indicated by fossil data is real, rather than an artifact of improvement of the fossil record toward the present.Assuming that ecological crowding produced the so-called Paleozoic plateau for family diversity, various workers have used the logistic equation of ecology to model marine animal diversification as damped exponential increase. Several lines of evidence indicate that this procedure is inappropriate. A plot of the diversity of marine animal genera through time provides better resolution than the plot for families and has a more jagged appearance. Generic diversity generally increased rapidly during the Paleozoic, except when set back by pulses of mass extinction. In fact, an analysis of the history of the Paleozoic Fauna during the Paleozoic Era reveals no general correlation between rate of increase for this fauna and total marine animal diversity. Furthermore, realistically scaled logistic simulations do not mimic the empirical pattern. In addition, it is difficult to imagine how some fixed limit for diversity could have persisted throughout the Paleozoic Era, when the ecological structure of the marine ecosystem was constantly changing. More fundamentally, the basic idea that competition can set a limit for marine animal diversity is incompatible with basic tenets of marine ecology: predation, disturbance, and vagaries of recruitment determine local population sizes for most marine species. Sparseness of predators probably played a larger role than weak competition in elevating rates of diversification during the initial (Ordovician) radiation of marine animals and during recoveries from mass extinctions. A plot of diversification against total diversity for these intervals yields a band of points above the one representing background intervals, and yet this band also displays no significant trend (if the two earliest intervals of the initial Ordovician are excluded as times of exceptional evolutionary innovation). Thus, a distinctive structure characterized the marine ecosystem during intervals of evolutionary radiation—one in which rates of diversification were exceptionally high and yet increases in diversity did not depress rates of diversification.Particular marine taxa exhibit background rates of origination and extinction that rank similarly when compared with those of other taxa. Rates are correlated in this way because certain heritable traits influence probability of speciation and probability of extinction in similar ways. Background rates of origination and extinction were depressed during the late Paleozoic ice age for all major marine invertebrate taxa, but remained correlated. Also, taxa with relatively high background rates of extinction experienced exceptionally heavy losses during biotic crises because background rates of extinction were intensified in a multiplicative manner; decimation of a large group of taxa of this kind in the two Permian mass extinctions established their collective identity as the Paleozoic Fauna.Characteristic rates of origination and extinction for major taxa persisted from Paleozoic into post-Paleozoic time. Because of the causal linkage between rates of origination and extinction, pulses of extinction tended to drag down overall rates of origination as well as overall rates of extinction by preferentially eliminating higher taxa having relatively high background rates of extinction. This extinction/origination ratchet depressed turnover rates for the residual Paleozoic Fauna during the Mesozoic Era. A decline of this fauna's extinction rate to approximately that of the Modern Fauna accounts for the nearly equal fractional losses experienced by the two faunas in the terminal Cretaceous mass extinction.Viewed arithmetically, the fossil record indicates slow diversification for the Modern Fauna during Paleozoic time, followed by much more rapid expansion during Mesozoic and Cenozoic time. When viewed more appropriately as depicting geometric—or exponential—increase, however, the empirical pattern exhibits no fundamental secular change: the background rate of increase for the Modern Fauna—the fauna that dominated post-Paleozoic marine diversity—simply persisted, reflecting the intrinsic origination and extinction rates of constituent taxa. Persistence of this overall background rate supports other evidence that the empirical record of diversification for marine animal life since Paleozoic time represents actual exponential increase. This enduring rate makes it unnecessary to invoke environmental change to explain the post-Paleozoic increase of marine diversity.Because of the resilience of intrinsic rates, an empirically based simulation that entails intervals of exponential increase for the Paleozoic and Modern Faunas, punctuated by mass extinctions, yields a pattern that is remarkably similar to the empirical pattern. It follows that marine animal genera and species will continue to diversify exponentially long into the future, barring disruption of the marine ecosystem by human-induced or natural environmental changes.

The freshwater and marine fish faunas of South America are the most diverse on Earth, with current species richness estimates standing above 9100 species. In addition, over the last decade at least 100 species were described every year. There are currently about 5160 freshwater fish species, and the estimate for the freshwater fish fauna alone points to a final diversity between 8000 and 9000 species. South America also has c. 4000 species of marine fishes. The mega-diverse fish faunas of South America evolved over a period of >100 million years, with most lineages tracing origins to Gondwana and the adjacent Tethys Sea. This high diversity was in part maintained by escaping the mass extinctions and biotic turnovers associated with Cenozoic climate cooling, the formation of boreal and temperate zones at high latitudes and aridification in many places at equatorial latitudes. The fresh waters of the continent are divided into 13 basin complexes, large basins consolidated as a single unit plus historically connected adjacent coastal drainages, and smaller coastal basins grouped together on the basis of biogeographic criteria. Species diversity, endemism, noteworthy groups and state of knowledge of each basin complex are described. Marine habitats around South America, both coastal and oceanic, are also described in terms of fish diversity, endemism and state of knowledge. Because of extensive land use changes, hydroelectric damming, water divergence for irrigation, urbanization, sedimentation and overfishing 4-10% of all fish species in South America face some degree of extinction risk, mainly due to habitat loss and degradation. These figures suggest that the conservation status of South American freshwater fish faunas is better than in most other regions of the world, but the marine fishes are as threatened as elsewhere. Conserving the remarkable aquatic habitats and fishes of South America is a growing challenge in face of the rapid anthropogenic changes of the 21st century, and deserves attention from conservationists and policy makers.

If we restrict the use of Homo sapiens in the fossil record to specimens which share a significant number of derived features in the skeleton with extant H. sapiens, the origin of our species would be placed in the African late middle Pleistocene, based on fossils such as Omo Kibish 1, Herto 1 and 2, and the Levantine material from Skhul and Qafzeh. However, genetic data suggest that we and our sister species Homo neanderthalensis shared a last common ancestor in the middle Pleistocene approximately 400-700 ka, which is at least 200 000 years earlier than the species origin indicated from the fossils already mentioned. Thus, it is likely that the African fossil record will document early members of the sapiens lineage showing only some of the derived features of late members of the lineage. On that basis, I argue that human fossils such as those from Jebel Irhoud, Florisbad, Eliye Springs and Omo Kibish 2 do represent early members of the species, but variation across the African later middle Pleistocene/early Middle Stone Age fossils shows that there was not a simple linear progression towards later sapiens morphology, and there was chronological overlap between different 'archaic' and 'modern' morphs. Even in the late Pleistocene within and outside Africa, we find H. sapiens specimens which are clearly outside the range of Holocene members of the species, showing the complexity of recent human evolution. The impact on species recognition of late Pleistocene gene flow between the lineages of modern humans, Neanderthals and Denisovans is also discussed, and finally, I reconsider the nature of the middle Pleistocene ancestor of these lineages, based on recent morphological and genetic data.This article is part of the themed issue 'Major transitions in human evolution'.

The cranial morphology of fossil hominids between the end of the Early Pleistocene and the beginning of the Middle Pleistocene provides crucial evidence to understand the distribution in time and space of the genus Homo. This evidence is critical for evaluating the competing models regarding diversity within our genus. The debate focuses on two alternative hypotheses, one basically anagenetic and the other cladogenetic. The first suggests that morphological change is so diffused, slow, and steady that it is meaningless to apply species names to segments of a single lineage. The second is that the morphological variation observed in the fossil record can best be described as a number of distinct species that are not connected in a linear ancestor‐descendant sequence. Today much more fossil evidence is available than was in the past to test these alternative hypotheses, as well as intermediate variants. Special attention must be paid to Africa because this is the most probable continental homeland for both the origin of the genus Homo (around 2.5–2 Ma),1 as well as the site, two million or so years later, of the emergence of the species H. sapiens.2 However, the African fossil record is very poorly represented between 1 Ma and 600 ka. Europe furnishes recent discoveries in this time range around the Matuyama‐Brunhes chron boundary (780,000 years ago), a period for which, at present, we have no noteworthy fossil evidence in Africa or the Levant. Two penecontemporaneous sources of European fossil evidence, the Ceprano calvaria (Italy)3 and the TD6 fossil assemblage of Atapuerca (Spain)4 are thus of great interest for testing hypotheses about human evolution in the fundamental time span bracketed between the late Early and the Middle Pleistocene. This paper is based on a phenetic approach to cranial variation aimed at reviewing the Early‐to‐Middle Pleistocene trajectories of human evolution. The focus of the paper is on neither the origin nor the end of the story of the genus Homo, but rather its chronological and phylogenetic core. Elucidation of the evolutionary events that happened around 780 ka during the transition from the Early to Middle Pleistocene is one of the new frontiers for human paleontology, and is critical for understanding the processes that ultimately led to the origin of H. sapiens.

AimAssessing the consequences of a future increase in non‐native species introductions and native species extirpations on taxonomic similarity among fish faunas.LocationWorld‐wide.MethodsWe designed 42 scenarios of future species introductions and extirpations to simulate future fish composition for 1054 river basins. Using these simulated future compositions, we computed the change in taxonomic similarity among pairs of fish faunas from historical to future situation at the river basin, biogeographic realm and world scales.ResultsAccording to all our scenarios, taxonomic similarity among fish faunas will strongly increase in the future at the three spatial scales considered. Fish faunas from the Southern Hemisphere, which are currently the less affected by taxonomic homogenization, are forecasted to show the steepest changes. Our scenarios also reveal that non‐native species introductions will account for most of the predicted changes, whereas the effect of native species extirpations will be weak.Main conclusionsThe predicted future taxonomic homogenization will blur the current high level of taxonomic dissimilarity among freshwater fish faunas, and therefore, imperil the conservation programmes based on beta‐diversity mapping.

Évolution des grands Carnivores au Plio Pléistocène en Afrique et en Europe occidentale

The current study focuses on the emblematic Myopus/Lemmus species complex (tribe Lemmini) in the European Pleistocene fossil record. The members of the two genera occupy distinct ecological niches and have different external appearances, but they are remarkably similar in their dental morphology, so that they were commonly thought of as undistinguishable in the fossil record. Thus, more or less all European Lemmini fossils have been assigned to the genus Lemmus. In the Early Pleistocene site of Schernfeld (Germany), the species Lemmus kowalskii had been described. It was thought by some authors that all Lemmini from Early to late Middle Pleistocene belong to this species.In the current study, we investigated Lemmini molar morphology from Western and Central European sites including Schernfeld (Early Pleistocene), Sackdillinger Höhle (Sackdilling Cave), and Koněprusy C718 (both early Middle Pleistocene), as well as other fossil localities with fewer specimens, formerly assigned to Lemmus kowalskii. Using an extensive modern referential material of Lemmus and Myopus, this study proposes to re-evaluate taxonomic status of the Middle and Early Pleistocene Lemmini. This modern referential also allows a better understanding of the morphology of Lemmus kowalskii specimens and its variability.Our results highlight the very high variation within fossil populations, as well as significant statistical differences between populations of the Early and Middle Pleistocene localities. A large part of these fossil specimens is firmly identified as Myopus sp., including the L. kowalskii holotype. Our identifications demonstrate that in most Early and Middle Pleistocene sites considered in this study, both genera (Lemmus and Myopus) are present. Possible interpretations and consequences for current view of lemming history are discussed, as well as some of the paleoecological and paleoenvironmental implications.

Effects of urbanization on California’s fish diversity: Differentiation, homogenization and the influence of spatial scale

The faunal succession of Japanese Quaternary mammals is described within the stratigraphic framework provided mainly by KAMEI, KAWAMURA and TARUNO (1988). Descriptions are given separately for Hokkaido, Honshu-Shikoku-Kyushu and the Ryukyu Islands.In Hokkaido, Pleistocene mammalian remains are too scarce to provide a detailed faunal succession, but abundant remains of Holocene age suggest that the fauna was almost identical to that of the present day. Large mammals recorded for the Late Pleistocene are therefore considered to have been extinct by the Holocene.In Honshu-Shikoku-Kyushu, the Early Pleistocene fauna is of temperate forest type, and related to those of north China. Almost all the components are, however, assigned to extinct endemic species. The Middle Pleistocene fauna is characterized by the presence of extant species. In fact, they exceed half of the components in the middle Middle Pleistocene fauna, and are still more common in the later faunas. This fauna is also dominated by temperate forest elements and endemic species. Immigration from south China in the middle Middle Pleistocene is more limited than previously thought, and only a few forms migrated from north and northeast China in the late Middle Pleistocene. The Late Pleistocene fauna is basically identical with that of the Middle Pleistocene except for the absence of several extinct species and several exotic species which still survive in other regions. Although the fauna seems to have been isolated from those of the adjacent continent in the early Late Pleistocene, immigration of large herbivores from the northern part of the continent was recognized in the late Late Pleistocene. Most of the extinct and exotic species were eliminated from the fauna between 20, 000 and 10, 000 years BP, and thus the fauna became almost identical with that of the present day by the early Holocene.In the Ryukyu Islands, Early and Middle Pleistocene faunas are almost unknown, while Late Pleistocene and Holocene ones are relatively well recorded. The Late Pleistocene fauna is of insular type, and includes several species endemic to the islands. Some of them are extinct species. From the end of the Pleistocene to the Holocene, insularity of the fauna was enhanced by the extinction of major species and by extreme reduction in habitat areas of the survivors.

Evolutionary dynamics in the fish faunas of the Mediterranean basin during the Plio-Pleistocene

Carboniferous continental strata in eastern Canada are classed into (1) fanglomerate, (2) fluvial, (3) lacustrine, and (4) mixed fluvial and lacustrine facies. Each facies contains formations that are widely distributed geographically and vertically within the Carboniferous strata; each is related genetically to a rift valley framework, basement mobility, and climate. The fanglomerate facies grade laterally into the fluvial facies. They are poorly sorted and crudely stratified. Angular to subrounded clasts, ranging in size from 2 mm to over 1,220 mm, correspond in composition to underlying or nearby upfaulted basement. The fluvial facies contain thick sandstone units alternating with lutite and thin sandstone units. Many thick sandstone units contain one or more cycles of primary structure sequences suggestive of fluvial channel deposits. A typical cycle consists of (1) mud-pebbles at base, (2) cross-stratified sandstone, (3) horizontally stratified sandstone, and (4) ripple-laminated sandstone at top. This sequence suggests fluctuating velocities during the formation of bedforms such as subaqueous dunes, plane bed, channel bars, point bars, or ripples. Horizontal stratification is considered upper flow regime; cross-stratification and ripples, lower flow regime. Channel sandstone units contain as many as four cycles. Rate of valley floor subsidence, rate of lateral channel migration (or rate of channel jumping), rate of base-level changes, and climatic fluctuations are possible controls on the number of cycles within a channel sandstone unit. The interchannel units consist of lutite with persistently uniform sandstone interbeds, and contain mud cracks, current ripples, flutes, grooves, raindrop impressions, amphibian trackways, and horizontal stratification. The sandstone interbeds are interpreted as the basal member of the overbank cycle. The lutite is interpreted as the upper member of the overbank cycle. The lacustrine facies consist of dark- to medium-gray calcareous lutite with interbeds of medium-gray fine-grained sandstone and of dusky-red lutite and sandstone. In addition to the typical lithology described, 6 of the 10 formations assigned to the lacustrine facies are known to contain less typical units of dark-gray calcareous lutite with interbeds of tan-weathering calcilutite. These less typical units contain hopper-shaped casts, mud cracks, red lutite beds, algal biolithites, and a sparse fauna of conchostracans and pelecypods, and are interpreted as a fluctuation from deeper to a shallower water (and perhaps partially subaerial), more saline environment. The more typical rock units of gray calcareous lutite and sandstone show graded and current-worked laminae, plant detritus, pyrite, and contain a fauna of fresh-water fish, pelecypods, and arthropods, which are interpreted as a deeper water, less fluctuating environment of deposition. The lakes thus fluctuated in depth and salinity and covered up to 11,000 square miles during lower Cansoan (middle Carboniferous) time. Hortonian (lower Carboniferous) and lower Cansoan lake deposits exceed 1,000 feet in thickness and pass laterally over short distances into fine and eventually coarse fluvial facies near the margin of the depositional basins. Fine-grained facies of mixed origin consist of intertonguing fine fluvial and lacustrine deposits. These were laid down during the expansion and contraction of the lakes within what was probably a flat central-basin region. A proposed model of Carboniferous continental deposition consists of fanglomerates at the basin margin (or above pre-Carboniferous basement) grading laterally basinward into coarse and then to fine fluvial facies that grade ultimately into basin-center lacustrine facies.

AimHuman‐mediated species introductions and extirpations have resulted in the homogenization of biotas over time. However, there remains considerable uncertainty in our understanding of homogenization process for megadiverse regions of the world. Here, we investigate the consequences of widespread species invasions and extirpations for the biogeography of China's unique freshwater fish fauna.LocationChina.MethodsBy assembling a comprehensive dataset for distribution of Chinese freshwater fishes, we quantify how non‐native fish species, from both overseas introductions and domestic translocations, has led to taxonomic homogenization of fish faunas at watershed, basin, ecoregion and country scales. We explore how the observed patterns in homogenization vary geographically, and identify those species most responsible for the faunal changes. Lastly, we simulate how China's fish fauna may continue to homogenize according to different scenarios of anticipated species introductions and extirpations.ResultsWe demonstrate that species introductions and extirpations have homogenized freshwater fish faunas across China. Overall compositional similarity of watersheds increased by 7.0% (from a historical 14.9% to 21.9% in the present day; Sørensen index). Compositional similarity of 96 of 103 (93.2%) watersheds increased, with western basins exhibiting the highest magnitude. Translocated non‐native species associated with aquaculture practices contributed the most to faunal homogenization when compared to alien species (7.3% and 0.4%, respectively). Furthermore, faunal homogenization is predicted to intensify an additional 0.5–4.2% with increasing numbers of new non‐native species introductions and the extirpation of native species.Main conclusionsSpecies introductions and extirpations have resulted in the significant impoverishment, and thus the loss of antiquity, of China's freshwater fish fauna over the past century. In the light of the growing realization that species composition (not richness) defines the role that biodiversity plays in maintaining ecosystem function, our study highlights the need for conservation strategies in China that consider changing patterns of β diversity.

Aim This paper describes known patterns in the distributions and relationships of Hawaiian freshwater fishes, and compares these patterns with those exhibited by Hawaii's terrestrial biota.Location The study is based in Hawaii, and seeks patterns across the tropical and subtropical Indo‐west Pacific.Methods The study is based primarily on literature analysis.Results The Hawaiian freshwater fish fauna comprises five species of goby in five different genera (Gobiidae). Four species are Hawaiian endemics, the fifth shared with islands in the western tropical Pacific Ocean. All genera are represented widely across the Indo‐west Pacific. All five species are present on all of the major Hawaiian islands. All five species are amphidromous – their larval and early juvenile life being spent in the sea. Although there has been some local phyletic evolution to produce Hawaiian endemics, there has been no local radiation to produce single‐island endemics across the archipelago. Nor is there evidence for genetic structuring among populations in the various islands.Main conclusions In this regard, the freshwater fish fauna of Hawaii differs from the well‐known patterns of local evolution and radiation in Hawaiian Island terrestrial taxa. Amphidromy probably explains the biogeographical idiosyncrasies of the fish fauna – dispersal through the sea initially brought the fish species to Hawaii, and gene flow among populations, across the archipelago, has hitherto inhibited the evolution of local island endemics, apparently even retarding genetic structuring on individual islands.

Xenocyon lycaonoides is a well-represented large canid known from the middle Early Pleistocene to Middle Pleistocene in Europe, central Asia, and Alaska, yet its fossil record in eastern Asia is extremely poor. Here we report a well-preserved palatal part of the skull of this species from Jinyuan Cave of Luotuo Hill, Puwan, Dalian of Liaoning Province, northeastern China. The new material confirms the presence of this species in eastern Asia during the early Middle Pleistocene, supporting a Holarctic distribution of this lineage during the Mid-Pleistocene climate change. The morphology of the new material suggests that the Middle Pleistocene X. lycaonoides is more derived than the late Early Pleistocene population, and is distinct from the living Lycaon pictus, and imply the different evolutionary direction from Lycaon. Our analyses support a generic distinction of the Xenocyon from Lycaon. X. lycaonoides can not be the direct ancestor of Lycaon, but is a related taxon that lived in Eurasia and North America. The lineage includes Xenocyon, and Lycaon Brookes, 1827, and partially contributes to Cynotherium Studiati, 1857, showing two independent Island specialisation events, making it one of the most successful lineages of canids ever known.

Creation of reservoirs by regulation of the Dnieper River and small rivers caused significant changes in the conditions of existence and affected on fish biodiversity of pondsof Prydniprovya. To the anthropogenic factors influencing the species composition of fish fauna factors of technical and fishery character can be included. Technical impact on water bodies is associated with the creation of new artificial lakes, ecosystems of which are not stable and are influenced by invasive processes. Fisheries management measures include work on the introduction of new species of fish that primarily have economic importance for the development of industrial fishing. Work on the introduction of new species have both positive and negative effects, but nevertheless new species affect natively on fish fauna. This transforms biota of reservoir and creates conditions for further spread of new species, increasing their numbers, creating new ecological relationships in the ecosystem of the pond. In the formation of the Dnieper (Zaporizhia) reservoir`s fish fauna it is traditionally defined five stages: the first stage is before building a dam to the Dnieper (until 1931) when there was a natural Dnieper rapids area, inhabited by migratory, semi-migratory and local fish; the second stage is the beginning of formation of reservoir`s fish fauna with the gradual disappearance of reophilic and dominance of limnophilic species (1931–1941); the third stage is the restoration of fish populations of Dnieper rapids due to destruction of dam during the Second World War (1941–1947); fourth stage is the secondary formation of ichtiocenosis of reservoir after recovery of dam (1947–1960); fifth stage is reforming of the structure of fish fauna in terms of cascade (creation of Dnieper reservoirs) and anthropogenic pressures (from 1961 to the present period). The first stage is defined by period of filling the reservoir. After the construction of Zaporozhye hydroelectric station the process of rebuilding fish fauna took place. In the early years of the reservoir existence migratory and semi-migratory fish have naturally disappeared. The species composition of fish fauna has decreased by 11 taxons. The number of reophilic species has markedly reduced and remained predominantly in the upper river part of the reservoir. The lower part of reservoir with sustained hydrological regime has been being actively assimilated by fish of limnophilic complex. The second and third stages are associated with the destruction of the dam during the Second World War and the short restoration of hydrobiological regime of Dnieper rapids, until the re-filling of the reservoir and its final transformation into a regulated pond. The flow of these two phases has not influenced significantly the structure of industrial ichtyocomplex total number of species at that time was 38 taxons. The fourth stage involves fishery exploitation of reservoir. With the aim of the purposeful impact on formation of industrial fish fauna of the Dnieper (Zaporizhia) reservoir, considering sufficient development of natural fodder the works on artificial introduction of new species were carried out in the years 1950-1960. The fifth stage of development and current state of fish fauna of reservoir is characterized by the emergence and spread of invasive species. During the period of existence of the Dnieper (Zaporizhia) reservoir ichthyofauna of the reservoir has substantially transformed. In the modern fish fauna of reservoir there are 52 species of fish which are representatives of 14 families. Compared with the period of existence of Dnieper River before its regulation the number of species remained at the same level, but the species composition and structure of fish fauna changed drastically due to the loss of some species and the emergence of other species, mostly unwanted invaders. Changing the number of species is related to several factors. Firstly, process of spread of species upstream took place after the disappearance of Dnieper Rapids and rise of mineralization. Secondly, with the deliberate introduction of fish with purpose of fishery exploitation of the reservoir, and as a consequence randomly invasion of some species that came from fish farms. Thirdly, emergence of new species is also connected with the deliberate release of fish to the open water, similarly Pumpkinseed Sunfish Lepomis gibbosus (Linnaeus, 1758) has appeared in the Dnipro (Zaporizhia) reservoir, which is well acclimatized and has broadly extended its habitat in reservoirs of Dnipropetrovsk region. Today about 31 % of fish species of Dnieper (Zaporizhia) reservoir is adventitious. The process of genesis of fish fauna of the Dnieper (Zaporizhia) reservoir is still ongoing and it is connected with the subsequent emergence of new species and rise of their numbers. Such changes in the fish fauna of reservoir can harm fisheries because the vast majority of fish aliens are competitors by food for young commercially valuable fish species.