Uranium-series ages of marine terraces,La Paz Peninsula,Baja California Sur,Mexico

Uranium-series dating of coral samples from raised marine terrace deposits between 1.5 and 10 m above sea level in the La Paz Peninsula area, Baja California Sur, yielded ages between 123 ka and 138 ka that are in agreement with previously reported results. The stratigraphy and ages of marine units near the El Coyote Arroyo indicate the presence of two high stands of the sea during the last interglacial or oxygen isotope substage 5e at about 140 ka and 123 ka. Accepting 5 m for the sea level during the last interglacial transgression, we calculate average uplift rates for the marine terraces of about 70 mm/ka and 40 mm/ka. These slow rates of uplift indicate a relative stability of the La Paz peninsula area for the past 140 000 years. In contrast, areas of Baja California affected by major faultf experienced higher rates of uplift. Rockwell et al. (1987) reported vertical uplift rates of 180 to 300 mm/ka at Punta Banda within the Aqua Blanea fault zone in northern Baja California.     

Palynology of a 250-m core from Lake Biwa: a 430,000-year record of glacial–interglacial vegetation change in Japan

Lake Biwa is situated in western Honshu, and is the largest and oldest freshwater lake in Japan. During 1982–1983, a long core was drilled to a bottom depth of 1422 m in order to investigate the palaeolimnological record, which contains 911 m of various sedimentary units overlying Palaeozoic–Mesozoic basements. A 249.5-m core of the uppermost bed (T Bed) was palynologically examined at intervals of ca. 2 m. The investigated part of the core covers approximately the last 430,000 years of the mid-Upper Pleistocene and Holocene, and five glacial–interglacial cycles can be recognized. Ten major vegetational zones could be recognized from the bottom to the surface. The zones bearing even numbers, BW-10, 8, 6, 4 and 2, matched glacial periods in which pollen of subarctic taxa (Pinaceae, Betula) and cool–temperate taxa (Fagus, Lepidobalanus) was dominant. In the glacial periods, high pollen values for temperate conifers such as Cryptomeria, Cupressaceae and Sciadopitys indicate interstadial periods. Zones bearing odd numbers, BW-9, 7, 5, 3 and 1, matched interglacial periods with high pollen values for the warm–temperate taxon Cyclobalanopsis, or showed the characteristic appearance of Lagerstroemia, and temperate coniferous taxa (Cryptomeria, Cupressaceae). There were two vegetational types in the interglacial periods. One was the type indicated by BW-9 and 1 zones, when warm–temperate evergreen broad-leaved trees such as Cyclobalanopsis and Castanopsis showed high pollen values, and the warm–temperate deciduous broad-leaved tree Lagerstroemia was lacking. The climate of these interglacial periods seems to have been cold and dry in winter, and warm and wet in summer. The other was the vegetational type recorded in BW-7, 5 and 3 zones, where Lagerstroemia showed low pollen values, and the warm–temperate evergreen broad-leaved trees mentioned above were poorly represented. The climate seems to have been mild and wet in winter, and cool and wet in summer. The dominant pollen values for cool–temperate deciduous broad-leaved taxa such as Fagus and Lepidobalanus are very important indicators of the initiation of both glacial and interglacial periods in western Japan.     

The chacma baboon (<Emphasis Type="Italic">Papio</Emphasis><Emphasis Type="Italic">ursinus</Emphasis>) through time: a model of potential core habitat regions during a glacial–interglacial cycle

The aim of this research is to understand changes in the biogeography of the chacma baboon (Papio ursinus) through time, by modelling potential habitat changes through the last glacial–interglacial cycle (last interglacial, glacial maximum and current conditions). An environmental envelope model in a geographic information system is used to produce a range of habitat distribution models for the chacma baboon. Initially it is modelled as a single taxon, following which the data are further divided and explored to model predicted habitats for the chacma clades during different stages of the glacial–interglacial cycle. An area of approximately 1,044,000 km² was identified as potentially having been within the environmental core habitat at some stage of the glacial–interglacial cycle. Of this, 63,700 km² of land was predicted to have been core habitat regardless of the stage of the glacial–interglacial cycle. Additionally, rainfall appears to be the environmental variable with the most limiting effect on habitat size. This is true for the current, last glacial maximum and last interglacial environmental conditions. The largest area that remains within the core habitat throughout the last glacial–interglacial cycle is found in the northern provinces of South Africa. The chacma clades appear to interact in a cyclic pattern of expansion and contraction, each clade being more prominent under different environmental conditions. It appears that grey footed chacma habitat periodically extends northward towards the yellow baboon. These findings suggest dynamic and varied progression of the chacma baboon palaeo-distributions.     

A 200-ka pollen and oxygen-isotopic record from two sediment cores from the eastern Arabian Sea

We present here a pollen record from the northern Indian Ocean that goes back to 200 ka, the boundary between marine isotopic stages (MIS) 7 and 6. Pollen, oxygen-isotopic composition and organic carbon have been examined for two sediment cores from the eastern Arabian Sea (15°02′N and 71°41′E, 13°16′N and 71°00′E), to reconstruct the long-term palaeoclimate and palaeovegetation of the Indian subcontinent. Oxygen-isotope data suggest that glacial periods (MIS 2, 4 and 6) are characterised by low precipitation because of a weak southwest monsoon and a strong northeast monsoon. In contrast, interglacial periods (MIS 1, 3 and 5) are marked by high fresh water input resulting from a strong southwest monsoon. During the last glacial-interglacial cycle, sea-surface temperature and surface salinity changed as a result of variations in the evaporation-precipitation (E-P) balance. Throughout the core, the dominant pollen types are Poaceae and Chenopodiaceae and/or Amaranthaceae (>50%). Their dominance during glacial periods (MIS 2, 4 and 6) suggests that the climate was cold and dry. This dominance is also suggestive of salinity-tolerant vegetation colonizing large areas near seashore due to lower sea level or high E-P conditions. During interglacial periods (MIS 1, 3 and 5) when there was high precipitation, the arid taxa were sparse, whereas Poaceae and Piperaceae were abundant. Hence, Chenopodiaceae and/or Amaranthaceae and Artemisia are suggestive of cold and arid/semi-arid climate, and Poaceae and Piperaceae of warm and wet conditions. Mangrove pollen is not well represented in the cores.     

宁波沿海平原Z02孔第四纪地层及古环境演变

宁波沿海平原第四纪沉积物属于海陆交互沉积,记录了良好的古气候变化信息,是研究古气候冷暖变化、沉积物沉积特征的良好载体.对位于宁波沿海平原东南部的Z02孔进行14C和古地磁测年,根据钻孔岩性、孢粉组合、有孔类和介形类组合、粒度等环境替代指标特征,确定了 Z02孔第四纪地层划分,揭示了研究区第四纪以来的古环境演变信息.结果...     

Late Quaternary clay mineral record in Central Lake Baikal (Academician Ridge, Siberia)

We investigated the mineralogical composition of two cores recovered on the Academician Ridge (Central Lake Baikal, Siberia). Sedimentological features show that the cores are unaffected by turbidity currents. However, hemipelagic deposition is not continuous, but intermittently disturbed by syn- or post-sediment reworking (e.g., bioturbation, slumps, faulting). Such modes of deposition are consistent with the complex uplift history of the ridge. Bulk mineralogy suggests that terrigenous sediment supplies are constant through glacial/interglacial stages, and diluted by diatom-rich intervals related to warmer interglacial stages. The core stratigraphy is based on the correlation of the diatom zonation and opal abundance with the marine oxygen isotope reference curve SPECMAP. The ∼8-m cores partly recover the last four interglacial/glacial cycles, i.e., since oxygen isotope stage 8. We test the use of clay minerals as a proxy for paleoclimatic reconstruction. The clays are more weathered during the diatom-rich intervals in agreement with warmer climate conditions. However, the mean clay composition does not change significantly through glacial/interglacial stages. This observation implies that, in the Academician Ridge sediments, a simple smectite/illite ratio (S/I) does not alone provide a reliable indicator of climatic variation. It reflects the complex clay assemblages, especially the smectite group, delivered to Central Lake Baikal. Smectites include primarily illite-smectite mixed layers, made of a mixture of montmorillonite and beidellite. According to their behavior after cation saturation, the illite-smectite mixed layers are primarily transformed smectites, with some neoformed smectites intermittently observed. In addition, Al-smectites occur in minor proportions. We conclude that the S/I ratio has a climatic significance only if it evolves in parallel with the weathering stage of the clays and is confirmed by a change in the composition of the smectites.     

Altitudinal variation in life cycle syndromes of California populations of the grasshopper,Melanoplus sanguinipes (F.)

Summary Life cycles of California populations of the grasshopper, Melanoplus sanguinipes, varied along an altitudinal gradient. Temperature records indicate a longer season at low altitude on the coast, based on computation of degree days available for development, even though summer air temperatures are cooler than at high altitude; this is a result of warm soil temperatures. At high and low altitudes there was a high proportion of diapause eggs oviposited, while intermediate proportions of diapause eggs occurred at mid altitudes. The low altitude, and especially sea level, populations diapaused at all stages of embryonic development, while at high altitudes most diapause occurred in the late stages just before hatch. Diapause was more intense at high altitudes. One result of diapause differences was delayed hatching in the sea level population. Nymphal development and development of adults to age at first reproduction were both accelerated at high altitude relative to sea level. At lower temperatures (27° C) there was a tendency for short days to accelerate development of sea level nymphs, but not high altitude nymphs. In both sea level and high altitude grasshoppers, short days accelerated maturation of adults to onset of oviposition at warm temperature (33° C); there was little reproduction at 27° C. Population differences for all traits studied appear to be largely genetic with some maternal effects possible. We interpret diapause variation at low and mid altitudes to be responses to environmental uncertainty and variations in development rates to be adaptations to prevailing season lengths.     

Pleistocene fluctuations in the Agulhas Current Retroflection based on the calcareous plankton record

Piston core (PS2487-6), recovered south of Cape Town, and sediment surface samples, recovered in the area of the Agulhas Current retroflection, were used to construct paleoceanographic scenarios for the late Quaternary in a region with an important role in global water mass transfer. Coccolithophore (calcareous nannofossil) and planktonic foraminifera assemblages and oxygen isotope data were collected. Stratigraphic control is based on calibration of the δ¹⁸O stratigraphic signals with calcareous nannofossil events that are thought to be synchronous over a broad range of latitudes. Study of the surface sediments permits the characterisation of the Agulhas Current, Subtropical Convergence and Subantarctic coccolithophore assemblages. The Agulhas Current assemblage has relatively high proportions of Florisphaera profunda, Gephyrocapsa oceanica and Umbilicosphaera spp. These species are absent or present in low proportions in subantarctic waters. The abundance of coccolithophores during isotope stages 1, 5 and 7 is characteristic of relatively warm, stratified surface waters, with a deep nutricline and chlorophyll maximum, which strongly suggests that the area was under the influence of the Agulhas Current retroflection. The incursion of Globigerinoides ruber, abundant today in the Agulhas Current, also supports this interpretation. Conversely, during glacial stages 2–4 and 6, a strong reduction in warm and stratified water indicators can be observed, together with an increase in cold-eutrophic species.The interval from isotope stages 8 to 12 displays an assemblage dominated by Gephyrocapsa caribbeanica, the highest values being seen in the so-called Mid-Brunhes event, accompanied by a clear reduction in subtropical Holocene species. During the glacial interval from isotope stages 10–12, G. caribbeanica dominated the assemblage. The ecological interpretation of this species is controversial due to a clear evolutionary overprint. Isotope stage 12 is here interpreted as having been the coldest one in the period studied. It is characterised by a strong increase in Neogloboquadrina pachyderma (dextral and sinistral) and a remarkable decrease in tropical and subtropical planktonic foraminifera. From isotope stage 13 to 18, a hiatus is interpreted. Below this hiatus the stratigraphic resolution is poorer, although the glacial–interglacial cyclicity is well defined in the Agulhas Current Retroflection area (Core PS2487-6) for the last 25 isotope stages. The glacial–interglacial cyclicity is thought to be due to a fluctuation in the Subtropical Convergence Zone, probably linked to the eastward and westward displacement of the Agulhas Current retroflection. In any case, the core studied was always in a subtropical environment, under the influence of the Agulhas Current, which was enhanced during interglacial periods. For the whole of the interval studied, increases in Calcidiscus leptoporus, Umbilicosphaera spp., and Syracosphaera spp. among the calcareous nannofossils, and in G. ruber and Globigerinoides sacculifer within the planktonic foraminifera, clearly respond to interglacial pulses, reaching maximum values during short periods close to the major deglaciations.     

Microrefugia and Shifts of Hippophae tibetana (Elaeagnaceae) on the North Side of Mt. Qomolangma (Mt. Everest) during the Last 25000 Years

Microrefugia at high altitudes or high latitudes are thought to play an important role in the post-glacial colonization of species. However, how populations in such microrefugia have responded to climate changes in alternating cold glacial and warm interglacial stages remain unclear. Here we present evidence to indicate the Rongbuk Valley of the Mt. Qomolangma (Mt. Everest) area, the highest region on earth, had microrefugia for Hippophae tibetana and discuss how this low shrub was adapted to the extreme climate fluctuations of the last 25,000 years by shifts. By integrating geological, glaciological, meteorological, and genetic information, we found that the Rongbuk Valley was not only a glacial microrefugium but also an interglacial microrefugium for H. tibetana: the former was located on the riverbank below 4800 m above sea level (asl) or lower area and the latter at ∼5000 m asl. Our results show that after the Last Glacial Maximum (LGM), H. tibetana in the valley has undergone upward and downward migrations around ∼5000 m driven by climate fluctuations and the population in the glacial microrefugium has suffered extinction or extreme contraction. Moreover, with the rise of temperature in the last four decades, the upper limit of H. tibetana has shifted at least 30 m upward. Combining population history and recent range shift of this species is important in predicting the fate of this endemic species to future climate changes.     

Revised paleoenvironmental analysis of the Holocene portion of the Barbados sea-level record: Cobbler’s Reef revisited

Sample elevations corrected for tectonic uplift and assessed relative to local modeled sea levels provide a new perspective on paleoenvironmental history at Cobbler’s Reef, Barbados. Previously, ¹⁴C-dated surface samples of fragmented Acropora palmata plotted above paleo sea level based on their present (uplifted) elevations, suggesting supratidal rubble deposited during a period of extreme storms (4500–3000 cal BP), precipitating reef demise. At several sites, however, A. palmata persisted, existing until ~370 cal BP. Uplift-corrected A. palmata sample elevations lie below the western Atlantic sea-level curve, and ~2 m below ICE-6G-modeled paleo sea level, under slow rates of sea-level rise, negating the possibility that Cobbler’s Reef is a supratidal storm ridge. Most sites show limited age ranges from corals likely damaged/killed on the reef crest, not the mixed ages of rubble ridges, strongly suggesting the reef framework died off in stages over 6500 yr. Reef crest death assemblages invoke multiple paleohistoric causes, from ubiquitous hurricanes to anthropogenic impacts. Comparison of death assemblage ages to dated regional paleotempestological sequences, proxy-based paleotemperatures, recorded hurricanes, tsunamis, European settlement, deforestation, and resulting turbidity, reveals many possible factors inimical to the survival of A. palmata along Cobbler’s Reef.

     

The distribution and structure of coral reefs: one hundred year since Darwin

Plate tectonic theory accounts for the steady subsidence of mid-plate oceanic islands by cooling of the lithosphere and so provides a sound basis for Darwin's theory of atoll formation. Now it is evident that because the lithosphere behaves elastically in response to loads such as islands, more localized subsidence and uplift patterns can also be explained. Tectonically active areas, where one plate is subducted beneath another, are also likely to contain regions of marked uplift, but are less amenable to modelling. These processes together provide a background motion framework for most reef settings with rates of vertical movement of the order of a few millimetres per year.
Reef forms are greatly influenced by the configuration of their foundations. Holocene reef foundations were essentially moulded by processes of deposition and erosion during the Pleistocene when global sea level changes were often greater than 1 cm year^-1.
We are now developing a sufficient understanding of the rates and nature of reef processes of growth and destruction to be able to see the manner in which the structural development of reefs responds to the complex interplay of tectonic uplift and subsidence plus changes of sea level and climate.     

Improved modelling of the impacts of sea level rise on coastal wetland plant communities

This study presents an enhanced methodology for modelling the impacts of sea level rise on coastal wetlands. The tool integrates dGPS-calibrated LiDAR data, isostatic uplift and sediment accretion rates to predict the location and extent of plant communities at three non-contiguous micro-topographical coastal wetlands in Estonia by 2100 in response to global sea level rise. Scenarios were run including sediment accretion, elevated sediment accretion and then discounting sediment accretion and dGPS calibration for comparison. Results showed an increase in surface elevation (related to sediment accretion and isostatic uplift) resulting in a decrease in local sea level in the majority of sites and scenarios in the north of the country, although a rise in local sea level is predicted in sites with limited allochthonous sediment supply, predominantly impacting higher elevation plant communities. Wetlands situated on the west coast are likely to maintain equilibrium with sea level as a result of lower sedimentation and isostatic uplift than more northerly sites. This study shows that dGPS-calibrated LiDAR data and sediment accretion are essential to maintain model validity in Baltic coastal wetlands due to their low relief and could considerably improve current sea level rise impact models for other regions.     

The roles of geological history and colonization abilities in genetic differentiation between mammalian populations in the Philippine archipelago

Aim To test hypotheses that: (1) late Pleistocene low sea‐level shorelines (rather than current shorelines) define patterns of genetic variation among mammals on oceanic Philippine islands; (2) species‐specific ecological attributes, especially forest fidelity and vagility, determine the extent to which common genetic patterns are exhibited among a set of species; (3) populations show reduced within‐population variation on small, isolated oceanic islands; (4) populations tend to be most highly differentiated on small, isolated islands; and (5) to assess the extent to which patterns of genetic differentiation among multiple species are determined by interactions of ecological traits and geological/geographic conditions. Location The Philippine Islands, a large group of oceanic islands in Southeast (SE) Asia with unusually high levels of endemism among mammals. Methods Starch‐gel electrophoresis of protein allozymes of six species of small fruit bats (Chiroptera, Pteropodidae) and one rodent (Rodentia, Muridae). Results Genetic distances between populations within all species are not correlated with distances between present‐day shorelines, but are positively correlated with distances between shorelines during the last Pleistocene period of low sea level; relatively little intraspecific variation was found within these ‘Pleistocene islands’. Island area and isolation of oceanic populations have only slight effects on standing genetic variation within populations, but populations on some isolated islands have heightened levels of genetic differentiation, and reduced levels of gene flow, relative to other islands. Species associated with disturbed habitat (all of which fly readily across open habitats) show more genetic variation within populations than species associated with primary rain forest (all of which avoid flying out from beneath forest canopy). Species associated with disturbed habitats, which tend to be widely distributed in SE Asia, also show higher rates of gene flow and less differentiation between populations than species associated with rain forest, which tend to be Philippine endemic species. One rain forest bat has levels of gene flow and heterozygosity similar to the forest‐living rodent in our study. Main conclusions The maximum limits of Philippine islands that were reached during Pleistocene periods of low sea level define areas of relative genetic homogeneity, whereas even narrow sea channels between adjacent but permanently isolated oceanic islands are associated with most genetic variation within the species. Moreover, the distance between ‘Pleistocene islands’ is correlated with the extent of genetic distances within species. The structure of genetic variation is strongly influenced by the ecology of the species, predominantly as a result of their varying levels of vagility and ability to tolerate open (non‐forested) habitat. Readily available information on ecology (habitat association and vagility) and geological circumstances (presence or absence of Pleistocene land‐bridges between islands, and distance between oceanic islands during periods of low sea level) are combined to produce a simple predictive model of likely patterns of genetic differentiation (and hence speciation) among these mammals, and probably among other organisms, in oceanic archipelagos.     

Periodicity of extinction and recolonization of the West Indian topshell Cittarium pica in the Quaternary of Bermuda (Gastropoda: Trochoidea)

Hermit‐crab transported shells of the West Indian top shell Cittarium pica occur in numerous terrestrial fossil deposits on Bermuda, which is the most remote outpost of this Caribbean species. Cittarium is so far known only from deposits of interglacial ages corresponding to marine isotope stages (MIS) 11, 9, 5e, and 1 (Holocene). In at least the cases of MIS 11 and 5e, Cittarium appears at the very beginning of the interglacial. The species is definitely absent from well‐stratified cave deposits of the last glacial (MIS 4–2). It is hypothesized that colder sea‐surface temperatures (SSTs) during glacial periods caused Cittarium to be extirpated on Bermuda, and that it has made at least four independent colonizations of the island in the past 400 000 years. Because of the limited larval life of Cittarium, the window for colonization may be a very narrow period at the onset of interglacials when the SST has risen sufficiently to make Bermuda habitable but the velocity of the Gulf Stream is still sufficiently rapid to transport viable larvae from the Bahamas. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 235–243.     

中国亚热带地区阔叶林植物的谱系地理历史

中国亚热带地区因丰富的植物物种多样性备受生物地理学研究关注,丰富的多样性与中新世以来的地质气候变化密切相关。谱系地理学已成为探讨植物分布模式和遗传格局受地质气候变化影响的主要手段。总结了该地区阔叶林植物对中新世以来地质气候变化的响应模式和种群分化的历史成因。在中新世和上新世时,由于全球变冷、青藏高原抬升和亚洲内陆干旱,阔叶林植物被迫向南退缩,形成不同的谱系。同时,亚洲季风的增强为遗传多样性的增加提供了良好的环境。在更新世冰期和间冰期时,大部分落叶阔叶林和常绿阔叶林植物在多个避难所间存在长期隔离,不同的避难所种群各自经历局部地区的收缩和扩张。长期的隔离使不同谱系间进一步分化,形成高水平的遗传多样性和遗传分化。少部分植物在冰期时向南退缩,并在间冰期时明显向北扩张。最后,就分化时间的准确估计和探究遗传格局背后的机制两方面展望了未来的研究趋势。     

Diversification in the Andes: age and origins of South American Heliotropium lineages (Heliotropiaceae, Boraginales)

The uplift of the Andes was a major factor for plant diversification in South America and had significant effects on the climatic patterns at the continental scale. It was crucial for the formation of the arid environments in south-eastern and western South America. However, both the timing of the major stages of the Andean uplift and the onset of aridity in western South America remain controversial. In this paper we examine the hypothesis that the Andean South American groups of Heliotropium originated and diversified in response to Andean orogeny during the late Miocene and a the subsequent development of aridity. To this end, we estimate divergence times and likely biogeographical origins of the major clades in the phylogeny of Heliotropium, using both Bayesian and likelihood methods. Divergence times of all Andean clades in Heliotropium are estimated to be of late Miocene or Pliocene ages. At least three independent Andean diversification events can be recognized within Heliotropium. Timing of the diversification in the Andean lineages Heliotropium sects.Heliothamnus, Cochranea, Heliotrophytum, Hypsogenia, Plagiomeris, Platygyne clearly correspond to a rapid, late Miocene uplift of the Andes and a Pliocene development of arid environments in South America.     

Towards a ‘Sea‐Level Sensitive’ dynamic model: impact of island ontogeny and glacio‐eustasy on global patterns of marine island biogeography

A synthetic model is presented to enlarge the evolutionary framework of the General Dynamic Model (GDM) and the Glacial Sensitive Model (GSM) of oceanic island biogeography from the terrestrial to the marine realm. The proposed ‘Sea‐Level Sensitive’ dynamic model (SLS) of marine island biogeography integrates historical and ecological biogeography with patterns of glacio‐eustasy, merging concepts from areas as diverse as taxonomy, biogeography, marine biology, volcanology, sedimentology, stratigraphy, palaeontology, geochronology and geomorphology. Fundamental to the SLS model is the dynamic variation of the littoral area of volcanic oceanic islands (defined as the area between the intertidal and the 50‐m isobath) in response to sea‐level oscillations driven by glacial–interglacial cycles. The following questions are considered by means of this revision: (i) what was the impact of (global) glacio‐eustatic sea‐level oscillations, particularly those of the Pleistocene glacial–interglacial episodes, on the littoral marine fauna and flora of volcanic oceanic islands? (ii) What are the main factors that explain the present littoral marine biodiversity on volcanic oceanic islands? (iii) How can differences in historical and ecological biogeography be reconciled, from a marine point of view? These questions are addressed by compiling the bathymetry of 11 Atlantic archipelagos/islands to obtain quantitative data regarding changes in the littoral area based on Pleistocene sea‐level oscillations, from 150 thousand years ago (ka) to the present. Within the framework of a model sensitive to changing sea levels, we discuss the principal factors affecting the geographical range of marine species; the relationships between modes of larval development, dispersal strategies and geographical range; the relationships between times of speciation, modes of larval development, ecological zonation and geographical range; the influence of sea‐surface temperatures and latitude on littoral marine species diversity; the effect of eustatic sea‐level changes and their impact on the littoral marine biota; island marine species–area relationships; and finally, the physical effects of island ontogeny and its associated submarine topography and marine substrate on littoral biota. Based on the SLS dynamic model, we offer a number of predictions for tropical, subtropical and temperate volcanic oceanic islands on how rates of immigration, colonization, in‐situ speciation, local disappearance, and extinction interact and affect the marine biodiversity around islands during glacials and interglacials, thus allowing future testing of the theory.     

MIS 21 and the Mid-Pleistocene climate transition: Climate and sea-level variation from a sediment core in Osaka Bay,Japan

We report climate and sea-level variation for the marine oxygen isotope stage (MIS) 21, encompassing the end of the Mid-Pleistocene climate transition (MPT), based on pollen, diatom, and sulfur records from a 50-m thick sequence in a core from Osaka Bay. An extremely warm climate coincided with the sea level highstand of substage 21.5, when the warm-temperate element Quercus (Cyclobalanopsis) exceeds 40% of total arboreal pollen. This was followed by a warm-temperate to temperate and humid climate that continued until the end of MIS 21. A linear age model shows that climate was dominated by precessional cyclicity, with an inverse correlation between temperature and precipitation. The postglacial sea-level rise reached its highest peak in substage 21.5, when paleo-Osaka Bay reached its maximum extent including Kyoto and Nara Basins. At this time pelagic diatoms were dominant in the central part of the bay. Sea level dropped below the Osaka Bay sill (about ? 60 m at present) during substage 21.4, followed by a rise above the sill in substage 21.3, and a drop at 21.2. Sea level remained below the sill during substage 21.1. The thermal maximum and sea level peak occurred just after the rapid postglacial sea level rise, after which there was a gradual decline in temperature and sea level accompanied by precession-related oscillations; these features are typical of the post-MPT interglacials dominated by 100-ka cyclicity. These features may be a sign of termination of the MPT.