Anthropogenic Habitat Fragmentation Research Articles

Efficient purging of deleterious mutations contributes to the survival of a rare conifer

Abstract Cupressaceae is a conifer family rich in plants of horticultural importance, including Cupressus, Chamaecyparis, Juniperus and Thuja, yet genomic surveys are lacking for this family. Cupressus gigantea, one of the many rare conifers that are threatened by climate change and anthropogenic habitat fragmentation, plays an ever-increasing role in ecotourism in Tibet. To infer how past climate change has shaped the population evolutionary of this species, we generated a de novo chromosome-scale genome (10.92 Gb) and compared the species’ population history and genetic load to that of a widespread close relative, C. duclouxiana. Our demographic analyses, based on 83 re-sequenced individuals from multiple populations of the two species, revealed a sharp decline of population sizes during the first part of the Quaternary, however, populations of C. duclouxiana then started to recover, while C. gigantea populations continued to decrease until recently. The total genomic diversity of C. gigantea is smaller than that of C. duclouxiana, but contrary to expectations, C. gigantea has fewer highly and mildly deleterious mutations than C. duclouxiana, and simulations and statistical tests support purifying selection during prolonged inbreeding as the explanation. Our results highlight the evolutionary consequences of decreased population size on the genetic burden of a long-lived endangered conifer with large genome size and suggest that genetic purging deserves more attention in conservation management.

Edge history modulates the depth of edge influence: Evidence from ground beetles with different feeding traits

Anthropogenic habitat loss and fragmentation are major concerns to conservationists, since these processes lead to species decline and extinction. Edge effect is one of the most important causes of biodiversity losses in fragmented habitats. The depth of edge influence, the distance over which the edge effect penetrates into the adjacent habitat is a central issue, as it fundamentally determines whether the habitat fragment has any remaining core habitat, which is essential for the survival of habitat specialist species. We reviewed 204 edge studies on ground beetles (Coleoptera: Carabidae) of different feeding habits, in forests, one of the habitats most impacted by humans. Meta-analysing 1814 abundance data of 351 ground beetle species from forest edges and their adjoining interiors, we showed that forest edges had significantly higher abundance of herbivorous, omnivorous, and predatory ground beetles than their interiors. Edge history considerably affected the depth of edge influence which on all trophic groups was similar in natural edges and those maintained by agriculture (≤ 10–20 m), while it was wider (> 300 m) when created by forestry or other anthropogenic activities. Consequently, the minimum area of a forest fragment should be ∼ 330 ha in order to keep half of it as core habitat to preserve forest-interior species.

Variations in the plasticity of functional traits indicate the differential impacts of abiotic and biotic factors on the structure and growth of trees in tropical dry forest fragments

Abiotic and biotic factors have considerable impact on the plasticity of plant functional traits, which influences forest structure and productivity; however, their inter-relationships have not been quantified for fragmented tropical dry forest (TDF) ecosystems. We asked the following questions: (1) what are the variations in the plasticity of functional traits due to soil moisture availability in TDF fragments? (2) what are the roles of soil nutrients and forest disturbances in influencing variations in the plasticity of functional traits in the TDF fragments? and (3) how do the variations in the plasticity of functional traits influence the structure and productivity of TDF fragments? Based on linear mixed-effects results, we observed significant variations among tree species for soil moisture content (SMC) under the canopy and selected functional traits across forest fragments. We categorized tree species across fragments by principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) analyses into three functional types, viz., low wood density high deciduous (LWHD), high wood density medium deciduous (HWMD), and high wood density low deciduous (HWLD). Assemblage of functional traits suggested that the LWHD functional type exhibits a drought-avoiding strategy, whereas HWMD and HWLD adopt a drought-tolerant strategy. Our study showed that the variations in functional trait plasticity and the structural attributes of trees in the three functional types exhibit contrasting affinity with SMC, soil nutrients, and disturbances, although the LWHD functional type was comparatively more influenced by soil resources and disturbances compared to HWMD and HWLD along the declining SMC and edge distance gradients. Plasticity in functional traits for the LWHD functional type exhibited greater variations in traits associated with the conservation of water and resources, whereas for HWMD and HWLD, the traits exhibiting greater plasticity were linked with higher productivity and water transport. The cumulative influence of SMC, disturbances, and functional trait variations was also visible in the relative abundance of functional types in large and small sized fragments. Our analysis further revealed the critical differences in the responses of functional trait plasticity of the coexisting tree species in TDF, which suggests that important deciduous endemic species with drought-avoiding strategies might be prone to strategic exclusion under expected rises in anthropogenic disturbances, habitat fragmentation, and resource limitations.

Factors associated with Paddlefish (Polyodon spathula) restoration success in Oklahoma

AbstractThe Paddlefish (Polyodon spathula) has been extirpated from portions of its native range due to anthropogenic habitat degradation and fragmentation, most notably the impoundment of rivers. To mitigate some of these losses in Oklahoma, Paddlefish have been stocked into reservoirs throughout the state, with variable success in establishing self‐sustaining populations. Two factors thought to contribute to success of Paddlefish stocking are spawning substrate and prey availability, which were quantified in six reservoirs and nine reservoir tributaries. Side‐scan sonar and supervised classification of aerial imagery were used to classify 4517‐ha of river substrate upstream of the river‐reservoir interface in reservoir tributaries. Zooplankton community structure, water clarity, and nutrient availability were also assessed in the same reservoirs and tributaries. One tributary had suitable spawning substrate (>40%), and the rest had minimal (<1.5%), which suggested that availability of suitable spawning substrate was not directly correlated with Paddlefish stocking success. Reservoirs with self‐sustaining Paddlefish populations had higher abundance of large zooplankton (copepods and cladocerans) than reservoirs without a reproducing population. Notably, tributaries associated with Lake Texoma, the one known example of failed restoration, were much more turbid than other rivers. We conclude that abiotic factors such as water clarity may contribute more to variable recruitment than spawning substrate or zooplankton abundance by mediating foraging success of Paddlefish post‐larvae.

Can't pass or won't pass: the importance of motivation when quantifying improved connectivity for riverine brown trout Salmo trutta.

Reversing the negative impacts that anthropogenic habitat fragmentation has on animal movement is a key goal in the management of landscapes and conservation of species globally. Accurate assessment of measures to remediate habitat fragmentation, such as fish passage solutions in rivers, are imperative but are particularly challenging for territorial species, which are less likely to leave their existing home range, or populations composed of both migratory and resident individuals (i.e., partial migration). This investigation quantified the movements of translocated (captured upstream of the impediment and released downstream) and non-translocated (captured and released downstream of the impediment) riverine brown trout (Salmo trutta L.), a species known to perform a homing movement, through a fish pass using passive integrated transponder (PIT) telemetry. A significantly higher proportion of translocated fish approached, entered, and passed (on a wider range of flows) compared to non-translocated fish, consistent with the theory that motivation is a key driver in fish pass use. Translocated fish that entered the pass were significantly larger than those that approached but did not enter, presumably due to physiological capability. Translocated fish were a more reliable indicator of the fish passage solution effectiveness than non-translocated fish. Our findings hence imply that many fish passage solutions globally, and potentially measures to remediate habitat fragmentation for other taxa, may have been mistakenly assessed for unmotivated animals. Studying both non-translocated and translocated fish is recommended to provide more accurate and cost-effective fish passage solution assessments.

System evolution model of human disturbances in panda habitats

Anthropogenic associated habitat fragmentation has had a profound impact on great panda populations and their geographical distribution. Quantifying how panda disturbances manifest temporally and to what extent spatially can be challenging to model given the complexity of data structures and predictor variables involved. To inform future panda protection efforts and research in conservation ecology, we adopted a new approach to modeling the spatial patterns of simultaneously occurring panda disturbances over time using a system evolution model. Based on the 3rd (1999–2003) and 4th (2011–2014) National Wild Giant Panda field surveys, we analyzed the development and spatial trends of local and regional habitat disturbances affecting panda populations in China. Between 1999 and 2014, human disturbances in Minshan and Xiaoxiangling decreased by 16.15% and 36.62%, respectively, while increasing trends of 7.59%, 0.89%, and 34.49% were observed in Qionglaishan, Daxiangling, and Liangshan respectively. Ecological protection measures have also increased in Minshan, Xiaoxiangling, and Liangshan by 4.10%, 19.01%, and 4.56%, respectively, whilst a reverse trend was identified in Qionglaishan (-3.52%) and Daxiangling (-8.09%). The regional imbalance of human disturbances in Minshan, Xiaoxiangling, and Liangshan increased by 46.36%, 33.59%, and 18.82%, respectively, whilst decreasing in Qionglaishan (-4.81%) and Daxiangling (-36.39). Our findings demonstrate the utility of information entropy theory in examining cross-sectional data of multiple disturbances affecting wildlife populations. Application of this method in the context of panda habitat fragmentation has helped identify unique temporal and spatial characteristics of human disturbances impacting panda habitats over time.

A haplotype-resolved genome assembly of Rhododendron vialii based on PacBio HiFi reads and Hi-C data

Rhododendron vialii (subgen. Azaleastrum) is an evergreen shrub with high ornamental value. This species has been listed as a plant species with extremely small populations (PSESP) for urgent protection by China’s Yunnan provincial government in 2021, due to anthropogenic habitat fragmentation. However, limited genomic resources hinder scientifically understanding of genetic threats that the species is currently facing. In this study, we assembled a high-quality haplotype-resolved genome of R. vialii based on PacBio HiFi long reads and Hi-C reads. The assembly contains two haploid genomes with sizes 532.73 Mb and 521.98 Mb, with contig N50 length of 35.67 Mb and 34.70 Mb, respectively. About 99.92% of the assembled sequences could be anchored to 26 pseudochromosomes, and 14 gapless assembled chromosomes were included in this assembly. Additionally, 60,926 protein-coding genes were identified, of which 93.82% were functionally annotated. This is the first reported genome of R. vialii, and hopefully it will lay the foundations for further research into the conservation genomics and horticultural domestication of this ornamentally important species.

Do habitat fragmentation and degradation influence the strength of fine-scale spatial genetic structure in plants? A global meta-analysis.

As primarily sessile organisms, plants often show a non-random spatial distribution of genotypes over distance. This process known as fine-scale spatial genetic structure (FSGS) has been suggested through systematic reviews to depend on life form, mating system, and pollen and seed dispersal vectors, while there is no consensus on its behaviour due to external factors, such as anthropogenic habitat changes. By conducting a systematic review and global meta-analysis of empirical FSGS studies, we aimed to evaluate how anthropogenic habitat fragmentation and degradation influence the strength of FSGS in plant populations by means of the Sp statistic. Moreover, we tested how pollination and seed dispersal vectors contribute to the variation of the Sp statistic. We retrieved 243 FSGS studies from 1960 to 2020 of which only 65 were informative for the systematic review. Most empirical studies comprised outcrossers (84%) and trees (67%), with few herbs (23%) and scarce annual species (2%). In weighted meta-analyses for 116 plant populations (31 studies), we did not detect significant effects in the magnitude of effect sizes for the Sp statistic among undisturbed, degraded and fragmented habitats. Results showed significant effects for seed dispersal vectors, but not for pollination. Overall, we observed high variation among the effect sizes (not related to the goodness-of-fit of mixed models) of habitat status, pollination and seed dispersal categories, which precludes identifying biological trends on the Sp statistic. More empirical studies are needed that contrast multiple plant populations in disturbed versus undisturbed habitats, and by increasing the taxonomic groups, such as herbs and annual plants.

Human footprint effects on the distribution of the spotted lowland paca (Cuniculus paca)

Human activity has caused the decrease of about 20 % of the planet's vertebrate diversity and 25 % in their abundance. Many large and medium-sized herbivore mammals have gone extinct locally, unleashing a cascade of ecosystem changes. The spotted paca (Cuniculus paca) is impacted by hunting and anthropogenic habitat fragmentation and loss. To protect spotted pacas, it is essential to estimate anthropogenic effects on their geographic distribution. Through the use of primary biodiversity data, bioclimatic data, land-cover data, and a human footprint index, we modeled the distribution of C. paca. From 105 candidate models, only one model met our selection criteria. The variables with the highest contribution were the human footprint and annual precipitation. According to the model's performance curves, the spotted paca has low to medium tolerance of anthropogenic pressure. Cuniculus paca tolerates low to medium anthropogenic disturbance, which we hypothesize is related to reduced predator pressure in habitats modified by humans. Accounting for the costs and benefits of anthropogenic disturbance is essential to paca conservation.

The vegetation cover dynamics and potential drivers of habitat change over 30 years in the Free State National Botanical Garden, South Africa

As a conservation strategy, the South African National Biodiversity Institute (SANBI) establishes biodiversity gardens in areas with unique vegetation types that are vulnerable to extinction. The study aimed to (1) determine the vegetation cover dynamics of the Free State National Botanical Garden (FSNBG) over a 30-year period (1987–2017), focusing on different vegetation classes; (2) evaluate the ecological integrity of the Critical Biodiversity Area 1 (CBA1) vegetation using species abundance and vegetation cover; and (3) quantify potential conservation threats that may be drivers of vegetation cover changes. The “moderate vegetation cover” and “dense vegetation cover” had increased by 25.1 ha and 8.6 ha respectively in the FSNBG. Woody vegetation cover expanded significantly over the past 30-year period, suggesting “bush” encroachment. Shannon–Wiener diversity indices showed high overall plant species diversity of CBA1 vegetation type (H = 3.5), with the vegetation cover remaining high (79.6 ± 15.9%), 50 plant species no longer existing, suggesting reduced taxonomic richness. Major conservation threats included the presence of 27 alien and invasive plant species interspersed within different vegetation patches and anthropogenic habitat fragmentation in the past 19 years (i.e. covering ~ 18% of the buffer zone). We conclude that increased vegetation cover is associated with bush encroachment and we recommend interventions to reduce the population density of woody plants and establish permanent vegetation monitoring plots.

Projected stream fish community risk to climate impacts in the Northeastern and Midwestern United States

Climate change is expected to alter stream fish habitat potentially leading to changes in the composition and distribution of fish communities. In the Northeastern and Midwestern United States we identified the distribution and characteristics of those fish communities most and least at risk of experiencing changes in climate which deviate from the climate they are associated with. We classified stream fish communities based on a suite of climate and environmental variables with multivariate regression trees under both recent and future conditions based on eight climate models. Our findings showed that some areas, such as the majority of the Illinois, Wisconsin, and Iowa), have high levels of risk of change in stream class, while much of Kentucky, West Virginia, Virginia, Pennsylvania, Eastern Ohio, Southern Michigan, and the Atlantic Coast are at relatively low risk. Stream class shifts ranged from over 75% of segments lost (associated with cooler temperatures) to gains of over 40% (associated with warmer temperatures). Common warmwater species such as green sunfish (Lepomis cyanellus), bluegill (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) are expected to have the largest net gains in associated stream classes, while species associated with cooler streams such as Southern redbelly dace (Chrosomus erythrogaster), slimy sculpin (Cottus cognatus), and Eastern blacknose dace (Rhinichthys atratulus) were expected to experience the largest proportional losses. By pairing our climate risk predictions with other stressors such anthropogenic land use, habitat fragmentation, and water quality impairment, we identified opportunities for preservation (low risk due to all threats), restoration (low risk due to climate, high risk due to other stressors), and adaptation (high climate risk with low risk from other stressors). Understanding which communities are at risk due to climate change will aid in developing adaptation strategies to help sustain them in the future.

Sex‐specific shifts in morphology and diet in a frog after 50 years of anthropogenic habitat fragmentation

AbstractAimPhenotypic shifts are commonly observed when animals face insular habitat change and may reflect ongoing stresses on individuals. However, the generality and the driving processes of this ‘island rule’ remain equivocal, notably in amphibians. Here, we investigate both morphological and dietary shifts in a frog using a mosaic of human‐created islands to assess the potential operating mechanisms underlying these phenotypic responses.LocationThousand Island Lake, China.TaxonThe Chinese piebald odorous frog,Odorrana schmackeri.MethodsWe compared body size between insular and mainland populations and between sexes. We examined the potential underlying mechanisms regarding body size shifts using structural equation modelling (SEM). Finally, we analysed changes in diet composition and compared intersexual diet overlap between islands and mainland sites.ResultsWe found insular dwarfism in female but not male frogs. Meanwhile, insular females also had smaller gape widths than mainland females after accounting for snout‐vent lengths (SVLs). According to SEMs, resource availability had a direct positive effect on body size. Finally, diet composition differed between the island and mainland populations but only in females. Males and females on islands exhibited greater overlaps in the diet.Main conclusionsIn contrast with most studies in amphibians, we found insular dwarfism rather than gigantism in females. The smaller gape width after accounting for SVL in insular females suggests potential changes in prey utilization or food availability on these human‐created islands. This notion is further supported by the differentiation of diet composition between island and mainland females. The higher diet overlap between sexes implies stronger intersexual competition for food resources after habitat fragmentation. Overall, we found rapid shifts in morphology and diet in frogs, which might result from habitat fragmentation in only 50 years and underscore the need to consider intersexual differences when assessing responses of species to anthropogenic disturbances.

Genetic diversity and population structure of the Western European hedgehog, Erinaceus europaeus: conservation status of populations in the Iberian Peninsula

Anthropogenic habitat fragmentation and roadkill mortality are considered important threats to European hedgehogs. Habitat fragmentation isolates hedgehog populations and, as a consequence, reduces their genetic diversity and leads the populations to vulnerable situations. The hedgehog populations in the Iberian Peninsula represent the southern limit of the species. We used microsatellite markers to estimate the genetic diversity and population structure of Erinaceus europaeus on the Iberian Peninsula. The obtained results indicated the presence of two differentiated groups, north-western and north-eastern, which coincided with the distribution of the two phylogeographic mitochondrial lineages described in the Peninsula. Moreover, in the north-eastern group, three genetically different clusters (Girona, Central Catalonia and Zoo) were identified. The highest genetic diversity (Hs = 0.696) was detected in the north-western region. Significant genetic differentiation (FST range = 0.072–0.224) was found among the clusters, indicating that these groups are well differentiated and present low gene flow. We concluded that the north-western group is genetically stable, whereas in the north-eastern region, despite some contact among groups, some populations are isolated and vulnerable.

Occupancy patterns of prey species in a biological corridor and inferences for tiger population connectivity between national parks in Bhutan

AbstractSite occupancy models, accounting for imperfect detection and the influence of anthropogenic and ecological covariates, can indicate the status of species populations. They may thus be useful for exploring the suitability of landscapes such as biological corridors, to ensure population dispersal and connectivity. Using occupancy probability models of its principal prey species, we make inferences on landscape connectivity for the movement of the tiger Panthera tigris between protected areas in Bhutan. We used camera-trap data to assess the probability of site occupancy (Ψ) of the sambar Rusa unicolor, wild boar Sus scrofa and barking deer Muntiacus muntjak in biological corridor no. 8, which connects two national parks in central Bhutan. At least one prey species was recorded at 17 out of 26 trapping locations. The probability of site occupancy was highest for the barking deer (Ψ = 0.52 ± SE 0.09) followed by sambar (Ψ = 0.49 ± SE 0.03) and wild boar (Ψ = 0.45 ± SE 0.07). All three species had higher occupancy probability at lower altitudes. Sambar occupancy was greater farther from settlements and on steeper and/or south-facing slopes. Barking deer also had higher occupancy on south-facing slopes, and wild boar occurred mainly close to rivers. Our findings suggest that this biological corridor could facilitate dispersal of tigers. Protecting prey species, and minimizing anthropogenic disturbance and habitat fragmentation, are vital for tiger dispersal and thus functional connectivity amongst populations in this area.

Temporal edge effects structure the assemblages of Drosophilidae (Diptera) in a Restinga forest fragment in Southern Brazil

Anthropogenic habitat fragmentation directly affects ecological processes, leading to negative biodiversity impacts for insects and other biota. Increased edge effects are one consequence of fragmentation, and may alter the composition or abundance of species in the remaining habitat fragments. Understanding the ways in which edge effects impact upon the biota is essential for conservation decision-making in fragmented landscapes. Therefore, the aim of this study was to analyze the seasonal patterns of abundance, richness, and composition of Drosophilidae in a Restinga forest fragment in the extreme south of Brazil, as a function of the distance from the edge to the interior of the fragment. The data were analyzed using SIMPER analyses, which showed that the edge and the forest interior were most dissimilar during winter, followed by spring, autumn and summer. An NMDS and the SIMPER analyses showed that the lower dissimilarity between the edge and interior in spring, autumn and summer, compared to winter, is driven by immigration of individuals from outside of the forest fragment. Furthermore, some species were asymmetrically distributed in the fragment, with some species restricted to the edge of the fragment and others to the interior. This information aids in the understanding of the functioning and dynamics of fragmentation, which is fundamental for the maintenance and integrity of environments and their fauna.

Genetic divergence between isolated populations of the North Island New Zealand Rifleman (Acanthisitta chloris granti) implicates ancient biogeographic impacts rather than recent habitat fragmentation.

This research investigates the extent and causal mechanisms of genetic population divergence in a poorly flighted passerine, the North Island Rifleman or Titipounamu (Acanthisitta chloris granti). While this species has a historically widespread distribution, anthropogenic forest clearance has resulted in a highly fragmented current distribution. We conducted analyses of mitochondrial DNA (COI and Control Region) and 12 nuclear DNA microsatellites to test for population divergence and estimate times of divergence. diyabc and biogeobears were then used to assess likely past dispersal scenarios based on both mtDNA and nDNA. The results reveal several significantly divergent lineages across the North Island of New Zealand and indicate that some populations have been isolated for extensive periods of time (0.7–4.9 mya). Modeling indicated a dynamic history of population connectivity, with a drastic restriction in gene flow between three geographic regions, followed by a more recent re‐establishment of connectivity. Our analyses indicate the dynamic influence of key geological and climatological events on the distribution of genetic diversity in this species, including support for the genetic impact of old biogeographic boundaries such as the Taupo Line and Cockayne's Line, rather than recent anthropogenic habitat fragmentation. These findings present a rare example of an avian species with a genetic history more like that of flightless taxa and so provide new general insights into vicariant processes affecting populations of passerines with limited dispersal.

Genetic Diversity in the Threatened Freshwater Mussel Lampsilis powellii

North America is home to the greatest share of the world's freshwater mussel diversity; however, more than 70% of its ∼300 species are endangered or threatened. Lampsilis powellii, the Arkansas Fatmucket, is endemic to Arkansas and is now restricted to upstream reaches of the Ouachita and Saline rivers, but the species is declining within this small range. Conservation actions such as augmenting or reintroducing populations may be necessary, but they require knowledge of the distribution of genetic variation within and among extant populations. We analyzed population structure between the South Fork Ouachita River and Saline River using a 607-base-pair region of the mitochondrial COI gene and 14 microsatellites designed for Lampsilis abrupta. COI sequences showed little variation, and the most common haplotype was present in both rivers. Our mtDNA sequences were indistinguishable from those of L. siliquoidea deposited on GenBank, but we were unable to make conclusions about the taxonomic distinctiveness of L. powellii. Microsatellites showed heterozygote deficiencies for most loci and revealed little evidence of population structure between the two rivers. Overall, our results show low genetic diversity in L. powellii, which may reflect its small population size due to its long history of geographic isolation compounded by anthropogenic habitat destruction and fragmentation. Further genetic analyses of lampsiline taxa are needed to establish species limits for Lampsilis in the Interior Highlands.

Do Anthropogenic Activities Affect Floristic Diversity and Vegetation Structure More Than Natural Soil Properties in Hyper-Arid Desert Environments?

Egypt is characterized by its hyper-arid desert environment with high temperature, scanty rainfall, high evapotranspiration rate, and patchy scattered precipitation-dependent vegetation. Located in this peculiar ecosystem, the northeastern part of the eastern desert occupies vast areas where this study was conducted. Despite some protection in this area, destruction of plant cover, soil erosion, and degradation of natural habitat are still occurring. Among the complex array of anthropogenic disturbances that directly affect species diversity, over-grazing, road construction, over-collection of plants, salinization, over-cutting, military activities, urbanization, and industrialization were encountered. The aim of this study was to assess the effect on long-lasting anthropopressure on the current floristic and ecological status of the unprotected area in comparison to the protected one. Two areas were chosen for detailed studies: protected (Wadi Degla; WD) and unprotected (Cairo-Suez road, SR). Fourteen soil variables were used to assess the soil–vegetation relationships in the two areas. An assessment of seven human activities (over-grazing, over-collection, introduced species, land degradation, urbanization, solid wastes, and military activities) was carried out at four levels of disturbance intensities. A floristic presence/absence data set of 25 plots × 56 species, including 14 plots for SR and 11 plots for WD, was employed in the analyses. The application of multivariate analysis techniques such as cluster analysis (for classification), indicator species analysis (ISA) and the multi-response permutation procedure (MRPP), canonical correspondence analysis (CCA), and redundancy analysis (RDA) for ordination were performed in the data analysis. Generally, a total of 85 plant species belonging to 68 genera and 30 families was recorded. Asteraceae, Chenopodiaceae, Fabaceae, Zygophyllaceae, Poaceae, Brassicaceae, and Geraniaceae were the largest families, constituting more than 50% of the total flora. Chamaephytes, therophytes, hemicryptophytes, and phanerophytes prevail in the life form spectrum. Chorological analysis showed that the Saharo-Arabian element, whether pure or combined with other chorotypes, dominated the current flora, whereas the Mediterranean chorotype was very poorly represented. Application of cluster analysis yielded eight vegetation groups: I–IV for the Cairo-Suez road, and V–VIII for Wadi Degla. This study indicated the disappearance of several plant communities that were previously of common occurrence such as Retama raetam, Anabasis articulata, Ephedra alata, Artemisia monosperma, Zygophyllum decumbens, Lasiurus hirsutus, and Panicum turgidum. Partial CCA (pCCA) for the unprotected area revealed that most of the variance (45.7%) was attributed to the anthropogenic variables more than soil factors (14.5%). Like what was revealed in other unprotected areas, a clear relationship between anthropogenic pressure and habitat fragmentation was observed. Long-term, intensive human activities caused vegetation degradation, species loss, and a decline in plant richness. Hence, the highest species richness value was recorded in the protected area. Over-grazing, land degradation, and military activities were not correlated with the diversity indices, whereas over-collection of plant species, urbanization, and solid wastes were significantly negatively correlated with both α-diversity and the Shannon–Wiener index. Suitable protection measures should be taken to reduce the anthropogenic pressures in this ecosystem as well as some conservation programs and management plans should be implemented to save biodiversity.

A rocky heart in a spinifex sea: occurrence of an endangered marsupial predator is multiscale dependent in naturally fragmented landscapes

Research on the impacts of anthropogenic habitat fragmentation has dominated landscape ecology for decades, yet our understanding of what drives species’ distributions in naturally fragmented landscapes remains limited. We aimed to (i) determine whether rocky patches embedded within a ‘matrix’ of fire prone grasslands act as naturally fragmented landscapes for an endangered marsupial predator, the northern quoll (Dasyurus hallucatus), and (ii) reveal the extent to which within-patch, patch, landscape variables, and matrix condition drive the occurrence of northern quolls. We deployed remote sensing cameras for a total of 200 nights, at 230 sites spanning rocky and grassland habitats across 6000 km2 of the Pilbara bioregion of Western Australia. We examined the influence of within-patch, patch, landscape variables, and matrix condition on northern quolls using Generalised Linear Mixed Models. We found strong evidence that northern quoll habitat is naturally fragmented, observing higher occurrence and abundance of quolls in rocky patches than the surrounding grassland matrix. Within rocky patches, quolls were more likely to use patches with higher vegetation cover and den availability (within-patch), lower amounts of edge habitat relative to patch area (patch), and larger amounts of surrounding rocky habitat (landscape). When quolls entered the matrix, they tended to remain in areas with high vegetation cover, close to rocky patches. Species occurrence in naturally fragmented landscapes is influenced by factors operating at multiple scales. Rocky habitats are naturally fragmented and vital to the conservation of a range of taxa around the world, including the northern quoll.

Ocean Currents Drove Genetic Structure of Seven Dominant Mangrove Species Along the Coastlines of Southern China.

Mangrove forest ecosystems, which provide important ecological services for marine environments and human activities, are being destroyed worldwide at an alarming rate. The objective of our study was to use molecular data and analytical techniques to separate the effects of historical and contemporary processes on the distribution of mangroves and patterns of population genetic differentiation. Seven mangrove species (Acanthus ilicifolius, Aegiceras corniculatum, Avicennia marina, Bruguiera gymnorrhiza, Kandelia obovata, Lumnitzera racemosa, and Rhizophora stylosa), which are predominant along the coastlines of South China, were genotyped at nuclear (nSSR) and chloroplast (cpSSR) microsatellite markers. We estimated historical and contemporary gene flow, the genetic diversity and population structure of seven mangrove species in China. All of these seven species exhibited few haplotypes, low levels of genetic diversity (HE = 0.160–0.361, with the exception of K. obovata) and high levels of inbreeding (FIS = 0.104–0.637), which may be due to their marginal geographical distribution, human-driven and natural stressors on habitat loss and fragmentation. The distribution patterns of haplotypes and population genetic structures of seven mangrove species in China suggest historical connectivity between populations over a large geographic area. In contrast, significant genetic differentiation [FST = 0.165–0.629 (nSSR); GST = 0.173–0.923 (cpSSR)] indicates that populations of mangroves are isolated from one another with low levels of contemporary gene flow among populations. Our results suggest that populations of mangroves were historically more widely inter-connected and have recently been isolated, likely through a combination of ocean currents and human activities. In addition, genetic admixture in Beibu Gulf populations and populations surrounding Hainan Island and southern mainland China were attributed to asymmetric gene flow along prevailing oceanic currents in China in historical times. Even ocean currents promote genetic exchanges among mangrove populations, which are still unable to offset the effects of natural and anthropogenic fragmentation. The recent isolation and lack of gene flow among populations of mangroves may affect their long-term survival along the coastlines of South China. Our study enhances the understanding of oceanic currents contributing to population connectivity, and the effects of anthropogenic and natural habitat fragmentation on mangroves, thereby informing future conservation efforts and seascape genetics toward mangroves.