Past Habitat Research Articles

Imprints of Past Habitat Area Reduction on Extant Taxonomic, Functional, and Phylogenetic Composition

Past environmental changes have shaped the evolutionary and ecological diversity of extant organisms. Specifically, climatic fluctuations have made environmental conditions alternatively common or rare over time. Accordingly, most taxa have undergone restriction of their distribution to local refugia during habitat contraction, from which they could expand when suitable habitat became more common. Assessing how past restrictions in refugia have shaped species distributions and genetic diversity has motivated much research in evolutionary biology and biogeography. But there is still lack of clear synthesis on whether and how the taxonomic, functional and phylogenetic composition of extant multispecies assemblages retains the imprint of past restriction in refugia. We devised an original eco-evolutionary model to investigate the temporal dynamics of a regional species pool inhabiting a given habitat today, and which have experienced habitat reduction in the past. The model includes three components: (i) a demographic component driving stochastic changes in population sizes and extinctions due to habitat availability, (ii) a mutation and speciation component representing how divergent genotypes emerge and define new species over time, and (iii) a trait evolution component representing how trait values have changed across descendants over time. We used this model to simulate dynamics of multispecies assemblages that occupied a restricted refugia in the past and could expand their distribution subsequently. We characterized the past restriction in refugia in terms of two parameters representing the ending time of past refugia, and the extent of habitat restriction in the refugia. We characterized extant patterns of taxonomic, functional and phylogenetic diversity depending on these parameters. We found that extant relative abundances reflect the lasting influence of more recent refugia on demographic dynamics, while phylogenetic composition reflects the influence of more ancient habitat change. Extant functional diversity depends on the interplay between diversification dynamics and trait evolution, offering new options to jointly infer current trait adaptation and past trait evolution dynamics.

Chironomidae Morphological Types and Functional Feeding Groups as a Habitat Complexity Vestige

Chironomid (Diptera: Chironomidae) larvae play an important role in a wide range of aquatic ecosystems. The study focuses on Chironomidae trophic guilds and morphological types as indicator traits in reconstructions of habitat changes in shallow water bodies. Mentum and ventromental plates are important mouthparts whose shape depends on food type and feeding behavior. Chironomidae larvae strongly vary in the mode of life and feeding habits, representing almost every feeding group. Here we classified the mentum types into 16 groups and tested if they indicated similar past habitat changes as the Chironomidae functional feeding groups (FFGs), and tribes/subfamilies. Paleoecological data of biotic and abiotic proxies were derived from short sequences from a Late Glacial oxbow and a nearby medieval moat located in Central Poland. The study revealed that the habitat substratum structure, vegetation and physicochemical conditions are associated both with the feeding types and morphological traits. This provides a valuable tool for future reconstructions of habitat changes.

How do habitat amount and habitat fragmentation drive time-delayed responses of biodiversity to land-use change?

Land-use change is a root cause of the extinction crisis, but links between habitat change and biodiversity loss are not fully understood. While there is evidence that habitat loss is an important extinction driver, the relevance of habitat fragmentation remains debated. Moreover, while time delays of biodiversity responses to habitat transformation are well-documented, time-delayed effects have been ignored in the habitat loss versus fragmentation debate. Here, using a hierarchical Bayesian multi-species occupancy framework, we systematically tested for time-delayed responses of bird and mammal communities to habitat loss and to habitat fragmentation. We focused on the Argentine Chaco, where deforestation has been widespread recently. We used an extensive field dataset on birds and mammals, along with a time series of annual woodland maps from 1985 to 2016 covering recent and historical habitat transformations. Contemporary habitat amount explained bird and mammal occupancy better than past habitat amount. However, occupancy was affected more by the past rather than recent fragmentation, indicating a time-delayed response to fragmentation. Considering past landscape patterns is therefore crucial for understanding current biodiversity patterns. Not accounting for land-use history ignores the possibility of extinction debt and can thus obscure impacts of fragmentation, potentially explaining contrasting findings of habitat loss versus fragmentation studies.

Mammal species occupy different climates following the expansion of human impacts

Cities and agricultural fields encroach on the most fertile, habitable terrestrial landscapes, fundamentally altering global ecosystems. Today, 75% of terrestrial ecosystems are considerably altered by human activities, and landscape transformation continues to accelerate. Human impacts are one of the major drivers of the current biodiversity crisis, and they have had unprecedented consequences on ecosystem function and rates of species extinctions for thousands of years. Here we use the fossil record to investigate whether changes in geographic range that could result from human impacts have altered the climatic niches of 46 species covering six mammal orders within the contiguous United States. Sixty-seven percent of the studied mammals have significantly different climatic niches today than they did before the onset of the Industrial Revolution. Niches changed the most in the portions of the range that overlap with human-impacted landscapes. Whether by forcible elimination/introduction or more indirect means, large-bodied dietary specialists have been extirpated from climatic envelopes that characterize human-impacted areas, whereas smaller, generalist mammals have been facilitated, colonizing these same areas of the climatic space. Importantly, the climates where we find mammals today do not necessarily represent their past habitats. Without mitigation, as we move further into the Anthropocene, we can anticipate a low standing biodiversity dominated by small, generalist mammals.

Past, present and future habitat suitable for gaur (Bos gaurus) in Thailand

Past, present and future habitat suitable for gaur (Bos gaurus) in Thailand

Determinants of the nursery role of seagrass meadows in the sub-tropical Gulf of Mexico: inshore-offshore connectivity for snapper and grouper

Quantifying the nursery role of habitats or locations in supporting fisheries is central to understanding population-scale animal-habitat relationships, and in guiding ecosystem-based management. We assessed the nursery role of northern Gulf of Mexico seagrass meadows for gray snapper, lane snapper, and gag recruiting to Alabama’s extensive offshore reef complex. We accomplished this using broadscale juvenile trawl surveys and geochemical tags—indicative of past habitat use—stored in the otoliths of >2200 fishes. These natural tags revealed that 47-61% of snapper and gag recruits to Alabama reefs originated in Florida panhandle seagrass nurseries. Seagrass meadows in Alabama and Mississippi were also important nurseries for snappers and gag, contributing 26-46% of recruits. Despite high juvenile snapper and gag catches along the extensive Chandeleur Islands, Louisiana, relatively few of those fishes recruited to Alabama’s reefs (<13% of total recruits, across species), although they may have recruited to populations outside our sampling domain. Beyond the applied value of these data for resource management (i.e. interstate connectivity), our findings highlight broadscale drivers of the nursery role of juvenile habitats for coastal marine populations. These factors include: (1) juvenile habitat extent (i.e. extensive Florida panhandle meadows sourced the most recruits for Alabama fisheries); (2) proximity between juvenile and adult habitats (i.e. highest unit-area contribution from Alabama-Mississippi meadows); and (3) unidirectional, alongshore migration of egressing juveniles (i.e. primarily east-to-west movement, enhancing connectivity with Florida panhandle nurseries, and dampening connectivity with Chandeleur nurseries).

Changes in the Historical and Current Habitat Ranges of Rare Wild Mammals in China: A Case Study of Six Taxa of Small- to Large-Sized Mammals

Through history, the habitats of wild mammals have changed greatly in China. Habitat changes may reflect changes in the environment and human–wildlife conflicts. This study focused on how the habitat changed for six taxa of rare wild mammals (one family, one genus, and four species) in mainland China. Their historical and current habitats were estimated according to their historical and current presence occurrences and three sets of environmental data (climate data, topography data, and human activity data), using the Maximum Entropy Model. Then, spatial statistical methods were used to analyze the changes in their habitats, and how human activities have influenced changes in their habitat. The results suggest that the habitats of all six taxa of mammals have shrunk considerably, compared to their historical ranges. With regards to current or past habitats, on average, 68.3% of habitats have been lost. The Asian elephant, which is facing the most serious habitat losses, has lost 93.1% of its habitat. By investigating the relationship between the changes in habitats and the anthropogenic impacts for each taxa, human activities have an obvious negative influence on mammal habitats. The sensitivity of habitats to human activities varies among different mammals: the tiger, Asian elephant, Bactrian camel, and snub-nosed monkey are more sensitive to human activities than musk deer and Chinese water deer.

Evidence of plant–arthropod interaction in the fossil assemblage from Pitsidia (Messara Basin, Crete, Greece; Upper Miocene)

As major components of natural ecosystems, plants interact with the biotic and abiotic environment developing a spectrum of different responses at various biological levels. Such biotic interactions are detectible in the plant fossil record and provide an outline of ecological functions during the past. The recently described Late Miocene plant assemblage from Pitsidia in the Messara Basin was examined for arthropod mediated damage. Most of the damage was detected on abundant, more than 2.500 specimens, well-preserved material of Myrica lignitum foliage, providing a broad range of traces. Eighteen different types of leaf modifications were distinguished, with hole, margin, surface feeding, lamina distortion and possibly galls as the most common while mining and exophytic oviposition were rare. Among this damage, it appears that only a few represent host-specialist feeding. These findings could serve as a database for the component herbivore community on M. lignitum. Considerations of this insect damage regarding past habitats and vegetation at Pitsidia as well as on plant–arthropod co-association are discussed. Several forms of arthropod damage on other plant taxa in this assemblage are briefly mentioned.

Extinction–immigration dynamics lag behind environmental filtering in shaping the composition of tropical dry forests within a changing landscape

The impact of rapid habitat loss and fragmentation on biodiversity is a major issue. However, we still lack an integrative understanding of how these changes influence biodiversity dynamics over time. In this study, we investigate the effects of these changes in terms of both niche‐based and neutral dynamics. We hypothesize that habitat loss has delayed effects on neutral immigration–extinction dynamics, while edge effects and environmental heterogeneity in habitat patches have rapid effects on niche‐based dynamics.We analyzed taxonomic and functional composition of 100 tree communities in a tropical dry forest landscape of New‐Caledonia subject to habitat loss and fragmentation. We designed an original, process‐based simulation framework, and performed Approximate Bayesian Computation to infer the influence of niche‐based and neutral processes. Then, we performed partial regressions to evaluate the relationships between inferred parameter values of communities and landscape metrics (distance to edge, patch area, and habitat amount around communities), derived from either recent or past (65 yr ago) aerial photographs, while controlling for the effect of soil and topography.We found that landscape structure influences both environmental filtering and immigration. Immigration rate was positively related to past habitat amount surrounding communities. In contrast, environmental filtering was mostly affected by present landscape structure and mainly influenced by edge vicinity and topography.Our results highlight that landscape changes have contrasting spatio‐temporal influences on niche‐based and neutral assembly dynamics. First, landscape‐level habitat loss and community isolation reduce immigration and increase demographic stochasticity, resulting in slow decline of local species diversity and extinction debt. Second, recent edge creation affects environmental filtering, incurring rapid changes in community composition by favoring species with edge‐adapted strategies. Our study brings new insights about temporal impacts of landscape changes on biodiversity dynamics. We stress that landscape history critically influences these dynamics and should be taken into account in conservation policies.

Plant community assembly in suburban vacant lots depends on earthmoving legacy, habitat connectivity, and current mowing frequency.

In suburban regions, vacant lots potentially offer significant opportunities for biodiversity conservation. Recently, in Japan, due to an economic recession, some previously developed lands have become vacant. Little is known, however, about the legacy of earlier earthmoving, which involves topsoil removal and ground leveling before residential construction, on plant community composition in such vacant lots. To understand (dis)assembly processes in vacant lots, we studied 24 grasslands in a suburban region in Japan: 12 grasslands that had experienced earthmoving and 12 that had not. We surveyed plant community composition and species richness, and clarified compositional turnover (replacement of species) and nestedness (nonrandom species loss) by distance‐based β‐diversities, which were summarized by PCoA analysis. We used piecewise structural equation modeling to examine the effects of soil properties, mowing frequency, past and present habitat connectivities on compositional changes. As a result, past earthmoving, mowing frequency, soil properties, and past habitat connectivity were found to be the drivers of compositional turnover. In particular, we found legacy effects of earthmoving: earthmoving promoted turnover from native grassland species to weeds in arable lands or roadside by altering soil properties. Mowing frequency also promoted the same turnover, implying that extensive rather than intensive mowing can modify the negative legacy effects and maintain grassland species. Decrease in present habitat connectivity marginally enhanced nonrandom loss of native grassland species (nestedness). Present habitat connectivity had a positive effect on species richness, highlighting the important roles of contemporary dispersal. Our study demonstrates that community assembly is a result of multiple processes differing in spatial and temporal scales. We suggest that extensive mowing at local scale, as well as giving a high conservation priority to grasslands with high habitat connectivity at regional scale, is the promising actions to maintain endangered native grassland species in suburban landscapes with negative legacy effects of earthmoving.

Species recovery and recolonization of past habitats: lessons for science and conservation from sea otters in estuaries.

Recovering species are often limited to much smaller areas than they historically occupied. Conservation planning for the recovering species is often based on this limited range, which may simply be an artifact of where the surviving population persisted. Southern sea otters (Enhydra lutris nereis) were hunted nearly to extinction but recovered from a small remnant population on a remote stretch of the California outer coast, where most of their recovery has occurred. However, studies of recently-recolonized estuaries have revealed that estuaries can provide southern sea otters with high quality habitats featuring shallow waters, high production and ample food, limited predators, and protected haul-out opportunities. Moreover, sea otters can have strong effects on estuarine ecosystems, fostering seagrass resilience through their consumption of invertebrate prey. Using a combination of literature reviews, population modeling, and prey surveys we explored the former estuarine habitats outside the current southern sea otter range to determine if these estuarine habitats can support healthy sea otter populations. We found the majority of studies and conservation efforts have focused on populations in exposed, rocky coastal habitats. Yet historical evidence indicates that sea otters were also formerly ubiquitous in estuaries. Our habitat-specific population growth model for California’s largest estuary—San Francisco Bay—determined that it alone can support about 6,600 sea otters, more than double the 2018 California population. Prey surveys in estuaries currently with (Elkhorn Slough and Morro Bay) and without (San Francisco Bay and Drakes Estero) sea otters indicated that the availability of prey, especially crabs, is sufficient to support healthy sea otter populations. Combining historical evidence with our results, we show that conservation practitioners could consider former estuarine habitats as targets for sea otter and ecosystem restoration. This study reveals the importance of understanding how recovering species interact with all the ecosystems they historically occupied, both for improved conservation of the recovering species and for successful restoration of ecosystem functions and processes.

Brazilian montane rainforest expansion induced by Heinrich Stadial 1 event

The origin of modern disjunct plant distributions in the Brazilian Highlands with strong floristic affinities to distant montane rainforests of isolated mountaintops in the northeast and northern Amazonia and the Guyana Shield remains unknown. We tested the hypothesis that these unexplained biogeographical patterns reflect former ecosystem rearrangements sustained by widespread plant migrations possibly due to climatic patterns that are very dissimilar from present-day conditions. To address this issue, we mapped the presence of the montane arboreal taxa Araucaria, Podocarpus, Drimys, Hedyosmum, Ilex, Myrsine, Symplocos, and Weinmannia, and cool-adapted plants in the families Myrtaceae, Ericaceae, and Arecaceae (palms) in 29 palynological records during Heinrich Stadial 1 Event, encompassing a latitudinal range of 30°S to 0°S. In addition, Principal Component Analysis and Species Distribution Modelling were used to represent past and modern habitat suitability for Podocarpus and Araucaria. The data reveals two long-distance patterns of plant migration connecting south/southeast to northeastern Brazil and Amazonia with a third short route extending from one of them. Their paleofloristic compositions suggest a climatic scenario of abundant rainfall and relative lower continental surface temperatures, possibly intensified by the effects of polar air incursions forming cold fronts into the Brazilian Highlands. Although these taxa are sensitive to changes in temperature, the combined pollen and speleothems proxy data indicate that this montane rainforest expansion during Heinrich Stadial 1 Event was triggered mainly by a less seasonal rainfall regime from the subtropics to the equatorial region.

Habitat and History Influence Abundance of Bog Turtles

ABSTRACTConservation of rare and endangered species requires assessment of factors that influence the current habitat associations of a species and the role of past habitat degradation in limiting occupancy or abundance. The objective of our 2011–2014 study was to determine how habitat characteristics and wetland history can predict occupancy and abundance patterns of bog turtles (Glyptemys muhlenbergii) at the fringe of their range in the southeastern United States. We used a hurdle model to examine occupancy and abundance patterns while addressing problems associated with zero‐inflated data. Occupancy patterns were weakly related to percent of the wetland containing emergent vegetation, whereas abundance patterns were predicted by the percent silt in the wetland substrate, percent forest cover, amount of habitat degradation, and recovery time since past habitat degradation. The effect of historical habitat degradation on abundance rather than occupancy patterns has rarely been documented and its effect is rarely studied in vertebrate populations. Identification of predictors of occupancy and abundance patterns will aid discovery of new populations of bog turtles and improve management of occupied wetlands. © 2019 The Wildlife Society.

Blera miocenica: a new species of Early Miocene hoverfly (Diptera: Syrphidae) from the Czech Republic and its palaeoenvironmental significance

A new species of fossil hoverfly (Syrphidae: Eristalinae), i.e., Blera miocenica sp. nov. is described from the Early Miocene (Burdigalian) of Bílina mine in the Most Basin, Czech Republic. The species description is based on a well preserved compressed fossil and it represents the first known fossil record of the genus Blera Billberg, 1820 so far. B. miocenica sp. nov. diagnosis is based on the wing venation and other body characters like the coloration pattern of abdomen. The resemblance of the new fossil to extant species of Blera is briefly discussed. The previously suggested palaeoenvironmental conditions at the type locality are in agreement with the knowledge on autecology of recent representatives of the genus Blera (i.e., larval feeding strategy, adult habitat preferences and flower visitation). Thus, we conclude that fossil hoverflies could be a helpful tool for the indication of past habitats.

A process‐based model supports an association between dispersal and the prevalence of species traits in tropical reef fish assemblages

Habitat dynamics interacting with species dispersal abilities could generate gradients in species diversity and prevalence of species traits when the latter are associated with species dispersal potential. Using a process‐based model of diversification constrained by a dispersal parameter, we simulated the interplay between reef habitat dynamics during the past 140 million years and dispersal, shaping lineage diversification history and assemblage composition globally. The emerging patterns from the simulations were compared to current prevalence of species traits related to dispersal for 6315 tropical reef fish species. We found a significant spatial congruence between the prevalence of simulated low dispersal values and areas with a large proportion of species characterized by small adult body size, narrow home range mobility behaviour, pelagic larval duration shorter than 21 days and diurnal activity. Species characterized by such traits were found predominantly in the Indo‐Australian Archipelago and the Caribbean Sea. Furthermore, the frequency distribution of the dispersal parameter was found to match empirical distributions for body size, PLD and home range mobility behaviour. Also, the dispersal parameter in the simulations was associated to diversification rates and resulted in trait frequency matching empirical distributions. Overall, our findings suggest that past habitat dynamics, in conjunction with dispersal processes, influenced diversification in tropical reef fishes, which may explain the present‐day geography of species traits.

Reconstruction of the habitat range suitable for long-tailed goral (Naemorhedus caudatus) using fossils from the Paleolithic sites

Fossil data, which indicate the changing distribution of species, have been used to understand the responses of species to physical and social environmental changes. The current distribution of long-tailed goral (Naemorhedus caudatus, hereinafter “goral”), which is an endangered species in the Republic of Korea (ROK), is restricted to a few high mountain areas in the mid-eastern Korean Peninsula (KP). However, there is a discrepancy between their current distribution and the locations where the fossils of goral have been found. This discrepancy could explain the range shift of gorals on the KP in relation to environmental changes, climate change and human disturbances. The purposes of this research are 1) to reconstruct the past distribution of goral, 2) to explain the range shift of goral over time and 3) to understand the causes of the range shift in relation to environmental change, especially climate warming, and human disturbances. For this, we first reconstructed the past geographical range of goral with fossil data and analyzed the geomorphological characteristics of current and past habitats. Then, the current range and habitat characteristics were compared with the ones reconstructed from the fossil data. The results showed that the fossils of goral were found in 12 caves located at average elevations of 276.0 m calculated from the 1 km radius of the sites and 298.0 m from the 10 km radius of the sites. These sites were not only remote from the current goral habitats, but also had a significantly lower elevation than the elevational ranges of current habitats. Based on our analyses, the goral lived in much wider and lower areas on the KP during the Pleistocene. Climate warming since the Holocene era and increased human disturbances, mainly hunting by Paleolithic men, could explain the goral range shift toward higher elevations and steep slopes on the KP. In particular, considering the fact that the fossils were mostly found in caves, which were the homes of Paleolithic men, hunting could be more influential than climate warming in explaining the current distribution of goral on the KP. Our results could contribute to further goral research and provide the fundamental knowledge of alternative habitats for the endangered long-tailed gorals on the KP.

Evolutionary and demographic correlates of Pleistocene coastline changes in the Sicilian wall lizardPodarcis wagleriana

AbstractAimEmergence of coastal lowlands during Pleistocene ice ages might have provided conditions for glacial expansions (demographic and spatial), rather than contraction, of coastal populations of temperate species. Here, we tested these predictions in the insular endemic Sicilian wall lizardPodarcis wagleriana.LocationSicily and neighbouring islands.MethodsWe sampled 179 individuals from 45 localities across the whole range ofP. wagleriana. We investigated demographic and spatial variations through time using Bayesian coalescent models (Bayesian phylogeographic reconstruction, Extended Bayesian Skyline plots, Isolation‐with‐migration models) based on multilocusDNAsequence data. We used species distribution modelling to reconstruct present and past habitat suitability.ResultsWe found two main lineages distributed in the east and west portions of the current species range and a third lineage restricted to a small area in the north of Sicily. Multiple lines of evidence from palaeogeographic (shorelines), palaeoclimatic (species distribution models), and multilocus genetic data (demographic and spatial Bayesian reconstructions) indicate that these lineages originated in distinct refugia, located in the north‐western and south‐eastern coastal lowlands, during Middle Pleistocene interglacial phases, and came into secondary contact following demographic and spatial expansions during the last glacial phase.Main conclusionsThis scenario of interglacial contraction and glacial expansion is in sharp contrast with patterns commonly observed in temperate species on the continent but parallels recent findings on other Mediterranean island endemics. Such a reverse expansion–contraction (EC) dynamic has been likely associated with glacial increases of climatically suitable coastal lowlands, suggesting this might be a general pattern in Mediterranean island species and also in other coastal regions strongly affected by glacial marine regressions during glacial episodes. This study provides explicit predictions and some methodological recommendations for testing the reverseECmodel in other region and taxa.

Extinction debt in a biodiversity hotspot: the case of the Chilean Winter Rainfall-Valdivian Forests

Habitat fragmentation has become a major concern of conservation because of negative influences on plant species declines and extinctions. However, local extinction of species can occur with a temporal delay following habitat fragmentation, which is termed extinction debt. Many studies about extinction debt rely on community equilibrium from relationships between species richness and habitat variables. We assumed that the distribution of many vascular plant species in the coastal range of south-central Chile is not in equilibrium with the present habitat distribution. The aim of this research is to quantify patterns of habitat loss and to detect extinction debt from relationships between the current richness of different assemblages of vascular plants (considering longevity and habitat specialization) and both past and current habitat variables. The results showed that native forests have been fragmented and reduced by 53%, with an annual deforestation rate of 1.99%, in the study area between 1979 and 2011. Current richness of plant species was mostly explained by past habitat area and connectivity. Past habitat variables explained best richness of long-lived specialist plants, which are characterized by restricted habitat specialization and slower population turnover. We also showed that habitat fragmentation has resulted in a significant reduction in long-lived plant species’ “dwelling patch sizes (DPS)” between 1979 and 2011. Our analyses provide the first evidence of predicted future losses of plant species in a South American temperate biodiversity hotspot. Consequently, an unknown proportion of the plants in the study area will become extinct if no targeted restoration and conservation action is taken in the near future.

Nestedness-resultant community disassembly process of extinction debt in a highly fragmented semi-natural grassland

There are two major processes of species disassembly after landscape changes: non-random loss of species resulting in nested assemblages and species replacement resulting in spatial species turnover. Although time-lagged responses of species to landscape change have been widely recognized, few studies have empirically evaluated which of these two processes is more closely related to extinction debt (i.e., postponed species extinction following habitat loss). This study aimed to understand the underlying processes of extinction debt by partitioning β-diversity into components of species nestedness and species turnover. We measured grassland species richness at three spatial extents in a highly fragmented semi-natural grassland landscape in Japan. Dissimilarity-based β-diversity was partitioned into two components (i.e., nestedness-resultant dissimilarity [βsne] and turnover-resultant dissimilarity [βsim]), which were further analyzed using principal coordinates analyses (PCoA). The relationships between the variability of PCoA axis 1 scores and the current and past habitat proportions were evaluated. A significant positive relationship between current grassland species richness and past (i.e., the 1910s) grassland proportion was found at the largest spatial extent. The first axis of PCoA based on βsne showed significant correlation with past habitat proportions, whereas the PCoA axis based on βsim showed no significant correlation with either the current or past habitat proportions. A non-random loss of grassland species represented by nestedness underlay the extinction debt found at the landscape level. There is a chance of predicting the loss of species from the nested ranks of species which likely reflects the gradient of species vulnerability to historical landscape changes.

Unravelling habitat use of Coilia nasus from the Rokkaku River and Chikugo River estuaries of Japan by otolith strontium and calcium

The migratory history of the engraulid fish Coilia nasus in the Rokkaku and Chikugo River estuaries of the Ariake Sea, Japan was assessed using otolith strontium (Sr) X-ray intensity maps and strontium:calcium (Sr:Ca) ratio life history transects by an electron probe microanalyzer (EPMA). The results showed that seven of the ten specimens from the Rokkaku River Estuary (LJC) and all 15 specimens collected in the Chikugo River Estuary (ZHC) had low Sr:Ca ratios (⩽3) at the central otolith area, indicating their riverine origin and initial freshwater residence. After the first regime shift adjacent to natal regions, the Sr level mapping displayed a wide variety of color patterns, and the Sr:Ca ratios obtained by the line transect analysis could be divided into one to six significantly different phases indicative of gradual life history transition. The other three specimens from the Rokkaku River Estuary had high Sr:Ca ratios (3–6.7) at the central otolith area but showed alternating changes between low and high values outside the natal region, suggesting that estuarine-origin individuals occurred in the Rokkaku River Estuary. The two-dimensional maps of the Sr level and average of the otolith Sr:Ca ratios along the life-history transects could be used as effective tools for reconstruction of past habitat use of the tapertail anchovy in estuaries of the Ariake Sea, Japan.