Habitat Fragmentation Research Articles

Genetic diversity and structure of Hopea bilitonensis, an endemic Dipterocarp from Belitung Island, Indonesia

Hopea bilitonensis Ashton (Dipterocarpaceae) is a small tree endemic to some islands on the east coast of Sumatra, particularly Belitung Island, Indonesia, and the northwest of Malaysia. Forest fragmentation and degradation in Belitung Island could affect population and genetic diversity of this species. The main objectives of this study are to examine genetic diversity and structure of H. bilitonensis on Belitung Island, Sumatra. Multiplexed ISSR genotyping by sequencing (MIG-seq) is used for genotyping and SNP detection. Genetic diversity and structure were determined using STRUCTURE analysis. We found that genetic diversity of H. bilitonensis is lower in seedlings than in juvenile and mature individuals. In contrast, inbreeding coefficient is lower in mature individuals than in the seedlings and juveniles. Genetic clusters (K=3) are detected in the early regeneration stages. These genetic structure separates the population of seedling and juvenile stages more clearly than in the mature individuals. Representation of these genetic clusters is essential when collecting propagation material for ex-situ conservation and establishing new populations of this threatened species to ensure its sustainability.

Microallopatric speciation in the relict dung beetle genus Grebennikovius (Coleoptera: Scarabaeidae) in the Eastern Arc Mountains

Abstract The Eastern Arc Mountains (EAMs) in Tanzania and Kenya are renowned for their exceptional species endemism often restricted to isolated mountain blocks. Forest fragmentation during the Pliocene–Pleistocene played a significant role in shaping the EAMs’ biodiversity by facilitating allopatric speciation between different mountains. However, only a few studies focused on species diversification within the same mountain block. In this article, we investigated the taxonomy and evolution of the dung beetle genus Grebennikovius, endemic to the Uluguru Mountains. Our goal was to unravel factors promoting allopatric speciation within a confined geographic area like the Ulugurus. We used an integrative taxonomic approach, combining phenotypic data and COI barcodes to delimit species and reconstructed a timetree of the genus. Molecular and morphological evidence consistently recovered 4 distinct Grebennikovius species, of which 3 are new to science: G. armiger n. sp., G. basilewskyi (Balthasar, 1960), G. lupanganus n. sp., and G. pafelo n. sp. Grebennikovius represents a rare case of microallopatry, with all species occurring in close proximity within different regions of the limited Uluguru forest (∼230 km2). We infer that speciation was driven by the interplay between climate fluctuations during the Miocene and mid-Pleistocene, Uluguru topography, and the stability of rainforest ecological conditions. The latter factor probably favored the loss of wings and a specialization for Uluguru microhabitats, reinforcing population isolation and divergence. This study highlights a unique instance of diversification resulting from small-scale speciation events, providing valuable insights into the evolution of Eastern African rainforest arthropods and underscoring the importance of microhabitats conservation.

Conserving diversity, distinctiveness and connectivity in the Sunshine Coast heathlands, Queensland, Australia

AbstractAustralia is committed to global area‐based conservation targets whilst ensuring its National Reserve system is representative of ecosystem types. However, concern remains for the increasing habitat loss and fragmentation, and the possible impacts of loss of connectivity between remnant vegetation. This study uses a range of diversity metrics to examine the biodiversity conservation status of the Sunshine Coast heathlands, in the South Eastern Queensland bioregion. The pre‐clearing and remnant extent, and the protection status of the nine heath Regional Ecosystems were calculated. Fragmentation and connectivity were examined by comparing heath patch sizes, and by calculating the distance between patches, from pre‐clearing estimates, until 2019. Diversity metrics for the Regional Ecosystems, including phylogenetic metrics, were tested for correlation with habitat extent, patch size, patch number and distance between patches. Of the pre‐clearing extent, 62% of Sunshine Coast heathlands remain and 46% is protected in National Parks. Levels of protection in National Parks vary across the Local Government Areas, and between Regional Ecosystems, and the priority Regional Ecosystems for further protection were identified. There has been habitat loss resulting in reduced patch sizes, and fragmentation due to urbanization, but the number of patches of heath remains intact, and connectivity in terms of distance between patches remains stable. Phylogenetic dispersion, but not diversity, was correlated with the extent of heath and the number of patches. This highlights the opportunity to maintain biodiversity in these heathlands, with the value of small patches of heath identified as key to maintaining connectivity in the coastal lowlands, distinctiveness in the montane heaths and dunes, and overall phylogenetic dispersion. This study has shown how a variety of diversity metrics and landscape analyses can inform on priority areas for biodiversity conservation in the heathlands of an increasingly urbanized region.

Plant functional traits and abundance jointly shape keystone plant species in a plant–ectomycorrhizal fungus network

AbstractKeystone species are more important than others for community dynamics and stability. Keystone species can be identified and evaluated by their centrality (i.e., a relative ranking of the topological positional importance of a species) in ecological networks. Studies of node centrality of plant–fungus bipartite networks, for example, have identified the keystone species that are important for maintaining network structure and stability. However, the underlying drivers of the importance of species in a network have rarely been examined. We assessed the centrality (degree, closeness, and betweenness) of plant and fungal species in a plant–ectomycorrhizal fungus network in a subtropical forest in southern China. Based on the phylogenies of plants and fungi and plant traits, we explored ecological factors that led to a species taking a central position or not. We found one plant species (Ternstroemia gymnanthera) and four species of ectomycorrhizal fungi (Russula citrina, Scleroderma sp., and two Cenococcum sp.) were characterized by the highest centrality of degree, closeness, and betweenness among the bipartite network nodes and thus played key roles in maintaining network structure. Centrality for fungi (not for plants) was phylogenetically constrained. Plant traits and abundance together explained 46.36%, 46.0%, and 43.7% of variation in the centrality of degree, closeness, and betweenness of plant species in the bipartite network, respectively. When plant or fungal species were sequentially removed on the order of higher to lower centrality, network was less stable than randomly removed. We suggest that abundance and traits determine the positional importance of plant species in a network. This work helps understand how plant–fungus association networks will respond to species extinction and changes in species abundance and functional traits due to habitat fragmentation and human activities.

Revisiting the effectiveness of biodiversity offsets in coastal wetlands of China through landscape connectivity

We modified the landscape connectivity calculation method and applied it to assess changes in temporal connectivity under different offsetting scenarios in the Yellow River Delta High-efficiency Ecological Economic Zone of China. We evaluated landscape connectivity based on resistance surfaces, least-cost distances, habitat areas, and the probability of dispersal between wetland patches in the landscape. The landscape connectivity declined between 1980 and 2015, with the degree of decline varying with the type of wetland. The cumulative percentages of freshwater marsh, salt marsh, and tidal marsh habitat areas that could be offset were 100 %, 100 %, and 34 %, respectively. However, the maximum landscape connectivity that was compensated for was only 1.2–10.4 %. When the offset patches were restored to freshwater marsh, the highest connectivity of coastal wetlands was achieved. There were substantial gaps between the area of habitat restoration offset required to achieve no net loss and the landscape connectivity that would ensure ecological effectiveness. The compensation area required to achieve no net loss of landscape connectivity was greater than that required to achieve no net loss of habitat area. We provide guidance for policy makers on how to implement offsetting to develop and manage green corridors, thus allowing movement that will ensure species’ survival. It was suggested that the passive restoration of isolated coastal wetland may be difficult to achieve. Policies that seek to increase landscape connectivity offsets can effectively promote population diffusion and migration, avoid habitat fragmentation, and are key to improving no net loss effectiveness.

Emerging patterns of genetic diversity in the critically endangered Malayan tiger (Panthera tigris jacksoni)

Southeast Asia experiences some of the highest deforestation in the world. Loss of tropical forest typically leads to widespread habitat fragmentation, with detrimental effects on dispersal ability and gene flow—particularly for large carnivores. We conducted mtDNA and microsatellite analysis to assess—for the first time—contemporary patterns of genetic diversity in the Malayan tiger. We collected 295 suspected carnivore samples in Peninsular Malaysia, from which we identified 26 as originating from tiger using 16 polymorphic microsatellite loci, comprising 22 individual tigers. Despite limitations of the study, our findings suggest tiger subpopulations in the north of the peninsula maintain some genetic connectivity and migration between two putative geographic subpopulations in the Main Range and Greater Taman Negara, with negligible population segregation due to dispersal barriers such as road infrastructure. We identified consistently lower levels of genetic diversity in tigers in the Greater Taman Negara region compared to tigers in the Main Range and small but emerging differences in nuclear and mitochondrial genetic diversity. Our mtDNA haplotype and nuclear DNA analyses suggest the levels of genetic diversity in Malayan tigers may be amongst some of the lowest of the surviving tiger subspecies, though the study is limited both in scale and genomic loci. Our findings are consistent with an expected lag between the rapid decline of tigers in Peninsular Malaysia by over 95% in the last 70 years and observed differences in their levels of genetic diversity.

Vegetation structure and relative humidity drive the diurnal foraging activity of Malaysian giant ant workers in urban fragmented forests

Abstract The impacts of urban forest fragmentation on tropical ant foraging activity are poorly understood. The Malaysian giant ant (Dinomyrmex gigas) is among the largest ant species worldwide. Colonies of this species contribute to important ecosystem processes such as predation and nutrient cycling in the tropical forests of Southeast Asia. Here, we compared the diurnal foraging activity of D. gigas workers in urban‐fragmented and contiguous forests, and investigated how this was shaped by key environmental factors such as vegetation structure and microclimate. Specifically, we sampled ground‐foraging D. gigas workers in four urban/semi‐urban forest patches and two contiguous forests in Peninsular Malaysia across the wet and dry seasons. Surprisingly, we found that some urban forest patches, irrespective of area, supported greater foraging activity of D. gigas workers than contiguous forests. These differences in foraging activity were explained by differences in multiple stand‐level variables between urban forests patches and contiguous forests. Specifically, the abundance of foraging D. gigas workers increased with number of trees with Diamater at breast height (DBH) 5–30 cm, but it decreased with relative humidity, canopy cover, number of palms, number of shrubs and trees with DBH <5 cm. Our study highlights the importance of urban forest patches, microclimate and vegetation structure for driving the diurnal foraging activity of Malaysian giant ant. Small and relatively large forest patches were of comparable importance for the maintenance of biodiversity in urban landscapes. In the absence of landscape connectivity, reforestation is the most feasible option to restore the natural habitat of D. gigas in urban forest patches and mitigate microclimatic edge effects.

Influence of environmental factors on the occurrence of gastrointestinal and cardiopulmonary nematodes in the red fox in the semi-arid Mediterranean areas of the Iberian Peninsula

Human-induced ecosystem fragmentation is one of the drivers causing wildlife migration from their natural habitats to urban areas, among other reasons. The red fox (Vulpes vulpes) is the most abundant wild canid in the semi-arid Mediterranean areas of the Iberian Peninsula. Water scarcity may result in areas shared by synanthropic fox populations and domestic animals becoming hotspots for parasite transmission. This study describes the gastrointestinal and cardiopulmonary nematode species affecting fox populations in these semi-arid areas and the influence of environmental variables on parasite abundance. A total of 167 foxes collected from 2015 to 2021 in the Region of Murcia (SE Spain) were analysed. Parasite abundance and spatial distribution were evaluated using environmental variables and host characteristics with a Generalised Linear Model and the Moran index. Eleven species (seven from the gastrointestinal tract and four from the cardiopulmonary tract) were described. The influence of biotic and abiotic variables was studied for Angiostrongylus vasorum, Crenosoma vulpis, Uncinaria stenocephala, Toxocara canis and Toxascaris leonina. Temperature, humidity and areas of forest or agricultural land influenced the abundance of these parasites, providing optimal conditions for free-living stages of the direct life cycle nematodes and intermediate hosts. Absolute abundance distribution maps showed defined locations for C. vulpis, T. canis and T. leonina. The results for U. stenocephala, T. canis and T. leonina were particularly important as their higher abundance levels were found close to anthropized areas, which need to be carefully evaluated to prevent transmission of these nematodes between domestic and wild canids and human health.

Lack of pollinators selects for increased selfing, restricted gene flow and resource allocation in the rare Mediterranean sage Salvia brachyodon

Range contraction and habitat fragmentation can cause biodiversity loss by creating conditions that directly or indirectly affect the survival of plant populations. Fragmented habitats can alter pollinator guilds and impact their behavior, which may result in pollen/pollinator limitation and selection for increased selfing as a mechanism for reproductive assurance. We used Salvia brachyodon, a narrowly distributed and endangered sage from eastern Adriatic, to test the consequences of range contraction and habitat fragmentation. Molecular data indicate a severe and relatively recent species range reduction. While one population is reproductively almost completely isolated, moderate gene flow has been detected between the remaining two populations. The high pollen-to-ovule ratio and the results of controlled hand pollination indicate that S. brachyodon has a mixed mating system. Quantitative and qualitative differences in the community and behaviour of flower visitors resulted in limited pollination services in one population where no effective pollinator other than pollen and nectar robbers were observed. In this population, self-pollination predominated over cross-pollination. Various environmental factors, in which plant-pollinator interactions play a pivotal role, have likely created selection pressures that have led to genetic and phenotypic differentiation and different resource allocation strategies among populations.

Foray movements are common and vary with natal habitat for a highly mobile bird.

Understanding dispersal is central to interpreting the effects of climate change, habitat loss and habitat fragmentation, and species invasions. Prior to dispersal, animals may gather information about the surrounding landscape via forays, or systematic, short-duration looping movements away from and back to the original location. Despite theory emphasizing that forays can be beneficial for dispersing organisms and that such behaviors are predicted to be common, relatively little is known about forays in wild populations. Theory predicts that individuals that use forays may delay dispersal and such behaviors should increase survival, yet empirical tests of these predictions remain scarce. We tested these predictions in a natural system using the critically endangered snail kite (Rostrhaumus sociabilis), a wetland-dependent raptor. We GPS tracked 104 snail kites from fledging through emigration from the natal site across their breeding range to understand the demographic consequences of movement. We found that forays were common (82.7% of individuals tracked), and natal habitat played an important role in the initiation, execution, and outcome of foray behavior. The effect of foraying on survival was indirect, where forayers emigrated later than non-forayers, and individuals that emigrated later had the highest survival. Poor hydrological conditions in the natal environment were especially important for eliciting forays. Finally, females responded more strongly to natal hydrology than males, making more forays and significantly longer, more distant trips. These results emphasize the fundamental role of natal habitat for determining behavioral patterns, strengthen links between individual movement decisions and their demographic consequences, and provide an important behavioral focal point for interpreting movement tracks that would not otherwise be captured by conventional movement models.

Irrigation dams threaten Brazilian biodiversity.

Brazil is among the main contributors to global biodiversity, which, in turn, provides extensive ecosystem services. Agriculture is an activity that benefits greatly from these ecosystem services, but at the same time is degrading aquatic and terrestrial ecosystems and eroding Brazilian biodiversity. This conflict is growing, as emerging unsustainable legislative proposals that will benefit the agricultural sector are likely to accelerate the decline of biodiversity. One such initiative (Bill 1282/2019) would change Brazil's "Forest Code" (Law 12,651/2012) to facilitate construction of irrigation dams in Permanent Preservation Areas, a category that includes strips (with or without vegetation) along the edges of watercourses. Two other similar bills are advancing through committees in the Chamber of Deputies. Here we provide details of these three bills and discuss their consequences for Brazil's biodiversity if they are approved. Expected negative impacts with changes in the legislation include: increased deforestation; siltation; habitat fragmentation; introduction of non-native species; reduction in the availability of aquatic habitats; and changes in biogeochemical process. These proposals jeopardize biodiversity and may compromise the negotiations for an agreement between Mercosur and the European Union.

Precipitation explains Wood Thrush (Hylocichla mustelina) occupancy patterns in Northern Costa Rica

Introduction: The Wood Thrush is a migratory bird that has experienced dramatic declines in its populations in recent decades. This species overwinters in forest fragments with intermediate levels of habitat modification in Central America. However, more studies detailing the use of remnant forests through time are needed to elucidate the threats this species faces in the wintering grounds. Objective: To understand the effects of environmental and forest structure variables on the occupancy of Wood Thrush in Northern Costa Rica. Methods: The study area was the Área de Conservación Guanacaste (ACG), located in Northern Costa Rica, in December 2016, and during the 2018-2019 migration season. We estimated Wood Thrush occupancy and detection probability in four locations of ACG (dry forest, cloud forest, and two locations in the wet forest) using single-season occupancy models. We also estimated Wood Thrush occupancy and probability of persistence in different months in three vegetation types (open area, secondary forest, and old-growth forest) in the wet forest of ACG using a multi-season occupancy model approach. Results: Wood Thrush occupancy was best described by precipitation in the four locations of the ACG; the probability of occupancy increased with precipitation. The average occupancy of Wood Thrushes varied with vegetation type: open area with shrubs and forest edge (0.69 ± 0.09), secondary forest (0.46 ± 0.1), and old-growth forest (0.61 ± 0.1). Wood Thrush probability of persistence responded partially to changes in precipitation, with an unexpected increase in persistence when the rainfall continued decreasing in the season. Conclusion: Wood Thrush occupancy was best predicted by changes in precipitation considering a larger spatial scale. Its probability of persistence partially varied with precipitation. An increase in persistence closer to Spring migration might be explained by the start of the breeding season of resident birds, potentially reducing territorial conflicts and conserving energy before migration. The long-term protection of wet forests in Northern Costa Rica is of paramount importance for the conservation of Wood Thrushes in their wintering grounds.

Last stand: Application of a criteria-based framework to inform conservation of a critically threatened tropical lowland forest fragment

Investing resources into protecting small, isolated tropical forest fragments can require considerable justification, especially in the context of limited resources and competing development pressures. Nevertheless, fragments may be suitable targets for conservation if they offer irreplaceable biodiversity outcomes and align with conservation aspirations. This is particularly true for island systems such as Oceania, where tropical lowland forest fragments may be the last remaining representatives of critical habitat due to agriculture or urban expansion on limited flat land. Despite this urgency, the decision to invest significant resources into a permanent conservation investment should be informed by a systematic framework to evaluate relevant conservation criteria for one or multiple sites. Here we present a case study where we applied the criteria-based framework of the Forest Legacy Program of the United States Forest Service, to assess the importance, threat, and strategic benefits of the last known remnant (9.33 ha) of lowland lava flow forest in American Samoa (Polynesia). We expounded on the FLP framework by providing examples of potential evidence and corresponding datasets that could inform the conservation criteria. For the case study, we conducted a comprehensive high-precision tree census to quantify forest structure and composition and compare with other forest types in the country, which revealed high conservation importance based on unique community composition and irreplaceable tree species representations, including Pometia pinnata, Dendrocnide harveyi, and two banyan figs Ficus obliqua and F. prolixa. Analysis of historical (70-year) aerial imagery and recent land cover maps, evidence of recent small-scale incursions, documented attempts by the landowners to obtain development permits, and the need for a court-imposed injunction and a conservation lease to prevent further encroachment, all indicated a high likelihood of conversion (threat) if left unprotected. Finally, we found that protection of this fragment would strategically align with the conservation, management, and education portfolios of the American Samoa government, and provide significant cultural and well-being benefits to the public, specific to the fact that this is the last representative of lava flow forest and is easily accessible to the public. We conclude that there is strong justification for conservation of Naumati forest, which in this case would be through a land purchase. More broadly, criteria-based approaches are often broad and flexible and can be widely applied, but they require significant work to collect data and generate evidence that is meaningful to conservation practitioners working on-the-ground. Effectively linking data to evidence to criteria and ultimately to decision-making is key to justifying sound conservation investments.

Integrative approach for landscape demography analysis of Plakad-Pa Pak-Tawan-Ok (Betta siamorientalis): Deciphering genetic and environmental factors in Eastern Thailand's conservation efforts

In recent decades, a global acceleration of urbanization has been observed, leading to significant habitat loss and fragmentation. Economic development in eastern Thailand has been promoted, but this has often coincided with unsustainable exploitation of natural resources. The expansion of urban and industrial areas in the region puts many organisms at risk of extinction owing to habitat loss. Plakad-Pa Pak-Tawan-Ok (Betta siamorientalis) is an endemic species found only in the eastern Thailand. In this study, the genetic diversity and population structure of 17 B. siamorientalis populations were analyzed using microsatellite genotyping. High genetic variability was observed. The STRUCTURE plot reveals large, distinct gene pools in the lower Prachin River and Phra Prong River Part 2. Migration analyses showed that the estimated gene flow between populations aligned with the dominant water flow in the flooding direction toward the mouth of the Bang Pakong River on the western side of eastern Thailand. Thus, this area must be considered a vital genetic resource. The pairwise fixation index values were statistically significant for all populations, including those within the same sub-watershed, indicating genetic differentiation among populations. This suggests relatively low gene flow between ecologically divergent populations. Mean annual total precipitation was also significantly correlated with genetic diversity. We propose the need for careful consideration and awareness of the planning and implementation of industrial development within eastern Thailand. Resource allocation in management efforts may be most effective when directed toward the preservation of habitat suitability, specifically in relation to precipitation and water resources, rather than prioritizing enhancements in landscape connectivity for B. siamorientalis.

Relevance of forest fragments and synanthropic habitats for the maintenance of non-phyllostomid bats in an anthropogenic matrix

Relevance of forest fragments and synanthropic habitats for the maintenance of non-phyllostomid bats in an anthropogenic matrix

Impact Of Beekeeping On The Wild Bee Diversity In Northern Cote D'Ivoire (West Africa)

In Cote d’Ivoire, beekeeping takes an important place among the major economic activities. It contributes to improve the population livelihoods thanks to its derived products which are honey, propolis, wax and royal jelly. However, the installation of honey bee hives could put pressure on wild bee species which are live often alone (solitary bees). However, these wild bees are excellent pollinators of cultivated and wild plants. Our study aimed to assess the effect of honey bee hives on the diversity of wild bee. The methodology approach consisted to capture bees in three different plots within the forest fragment of the university Peleforo Gon Coulibaly. The first plot was located near the apiary containing ten hives. The two other plots, far to the apiary, were located to 200 m and 400 m from the first plot, respectively. Bees were captured once a month for three months using pan traps (UV - blue, yellow and white). A total of 17 bee species belonging to three families (Apidae, Megachilidae and Halictidae) were identified. The furthest plot from the apiary was the most diverse (H’ = 2.49) and that near the apiary was the least diverse (H’ = 0.11). Only, two wild bee species, Hypotrigona sp and Thrinchostoma petersi, persisted inside the plot near the apiary where honey bee was most abundant. The furthest plots from the apiary seems to have the highest diversity of wild bees. These findings are very relevant because they can play an essential role in the policies of wild bee communities’ conservation and in the beekeeping activities management in our regions.

Analyzing Habitat Suitability of Bird Species in Urban Areas to Changes in Biotope Level: Case Study of Seoul

Background and objective: Rapid urbanization has led to habitat degradation and fragmentation in urban ecosystems, negatively impacting biodiversity. Various natural spaces and green areas, particularly urban biotopes, are essential to foster an environment for diverse species within urban areas. The increase in biotope grades is a crucial factor in enhancing biodiversity and expanding wildlife habitats in urban areas, thereby improving the overall health and sustainability of urban ecosystems. This study focuses on environmentally sensitive bird species, applying scenarios of biotope grade elevation to derive efficient methods for improving biotope grades. The goal is to support projects and policy decisions to increase urban biodiversity and sustain ecosystems within the city.Methods: The analysis model employed the MaxEnt species distribution model, and 11 environmental variables tailored to bird characteristics were considered. Additionally, four scenarios for upward adjustments in biotope grades were examined: (1) current biotope grades, (2) upgrading second-grade areas to first-grade, (3) upgrading third-grade areas to second-grade, and (4) upgrading second and third-grade areas to first-grade. The study aimed to derive the efficiency of potential habitats in response to biotope grade increases under each scenario.Results: The results of the biotope grade upward scenarios showed an increase in efficiency of 81% for Scenario(2), 38.6% for Scenario (3), and 54.6% for Scenario (4). This reveals the efficiency of potential habitat expansion for urban birds with improved biotope grades. The findings underscore the significant role of biotope grade enhancement in securing bird habitats within the city.Conclusion: Focusing on birds in Seoul, this study concluded that higher biotope ratings significantly increase potential habitats. Limitations of the study include the omission of specific bird species when considering environmental variables and the lack of reflection of habitat characteristics like meteorological factors. Future research aims to develop a more in-depth and accurate model for evaluating the efficiency of biotope rating change scenarios.

High effects of climate oscillations on population diversity and structure of endangered Myricaria laxiflora.

Exploring the effects of climate oscillations on the population diversity and structure of endangered organisms in the Three Gorges Reservoir (TGR) area is essential for hydrological environment changes on endangered organism evolution. Myricaria laxiflora is an endemic and endangered shrub restricted to the TGR along the banks of Yangtze River, China. Recently, six natural populations of this species were newly found upstream and downstream of the TGR, whose habitats have been dramatically changed by the summer flooding regulated by large dams. To study the water level fluctuations and climatic shifts on the genetic diversity and genetic differentiation of the six natural populations, 303 individuals from six populations were analyzed based on one nuclear DNA (ITS) and four chloroplast fragments (trnL-F, psbA-trnH, rps16, and rpl16). The phylogenetic tree and significant genetic divergence identified in the cpDNA and ITS with genetic isolation and limited gene flow among regions suggested that the six populations separated well to two groups distributed upstream and downstream. The MaxEnt modeling results indicated that obvious unidirectional eastward migration via Yangtze River gorges watercourse mediated from Last Interglacial to Last Glacial Maximum were showed with the narrow scale distributions of six remnant populations and nine extirpated populations. The initial habitat fragmentation could be triggered by the accumulation of local habitat loss of the impoundment of the TGR during the Present period and might remain stable restoration with bidirectional diffusion in the Future. Divergences among M. laxiflora populations might have been induced by the drastic changes of the external environment and limited seed/pollen dispersal capacity, as the results of long-term ecological adaptability of summer flooding stress. The haplotypes of nuclear gene could be used for population's differentiation and germplasm protection. This identified gene flow and range dynamics have provided support for the gene-flow and geology hypothesis. It is also crucial for rescuing conservation to understand the impact of environmental dynamics on endangered organism evolution.

A comparison of forest structural methods of semiarid mangrove species using a field-based approach

The data obtained from field-based forest inventories, mainly basal area and stem density, are relevant for the analysis of aboveground biomass and forest fragmentation. Due to its persistently flooded ground, fieldwork in mangrove forests is time-consuming and complicated. Since mangroves are sensitive to the effects of climate change, selecting a reliable field method is of utmost importance. To this end, we analyzed 4 mangrove classes: Rhizophora mangle (RM), Laguncularia racemosa (LR), Avicennia germinans (AG), and AG shrub. We georeferenced and counted all mangrove stems within four 0.04 ha (20 × 20 m square). We analyzed data from 3 circular area plots and the plotless point-centered quarter method (PCQM) based on the original square plots. Depending on the mangrove class, PCQM overestimated basal area by up to 34% and stem density by 21%. The 3 circular plot surveys underestimated basal area from –1% to –29% and stem density from –3 to –25%. Based on the results, we suggest using a circular plot of 0.04 ha (r = 11.28 m) in less dense forests (RM and AG) and a circular plot of 0.015 ha (r = 6.9 m) with forest densities greater than 3,500 stems/ha (LR and AG shrub). The advantages of using the circular plot approach over PCQM are that mangrove inventories can be quantified quickly and do not require a minimum number of sampling points.

Unearthing calf burials among Asian Elephants Elephas maximus Linnaeus, 1758 (Mammalia: Proboscidea: Elephantidae) in northern Bengal, India

Rampant environmental changes and forest destruction push elephants, both Asian and African, to explore human spaces to fulfil their dietary and ecological requirements and, consequently in shared spaces many ‘novel’ elephant behaviors come into the limelight. Elephant calf burial is reported in African literature but remains absent from the Asian context. We report calf burials by Asian Elephants in the eastern Himalayan floodplains of the northern Bengal landscape. The study area consists of fragmented forests, tea estates, agricultural lands, and military establishments. Tea estates form the majority of elephant corridors, and we explain the burial strategy of elephants in the irrigation drains of tea estates. We present five case reports of calf burials by elephants. We aimed to understand the perimortem strategy and postmortem behavior of the Asian Elephants. The major findings reflect that the carcasses were carried by trunks and legs for a distance before being buried in a ‘legs-upright-position’. We further investigated the underlying reason for calf deaths through postmortem examinations. Direct human intervention was not recorded in any of the five deaths. Through opportunistic observation, digital photography, fieldnotes, and postmortem examination reports, we suggest that the carcasses were buried in an abnormal recumbent style irrespective of the reason for the calf’s death. Through long-term observation, we further report that the elephants in this region clearly avoid the paths where carcasses were buried. We discuss and connect the literature of two distinct elephant species and also compare thanatological studies of other sentient nonhuman species.