Habitat Fragmentation Research Articles

Extreme events and ichthyofauna: case report of a neotropical river

The increasing frequency and intensity of extreme weather events and their impact on aquatic ecosystems and fish species is concerning. This manuscript reports and analyzes two events, a drought in 2019 and a flood in 2024, providing valuable insights into the consequences of these events. The rescue of 269 individuals of 19 fish species during the 2019 drought highlights the significant impact of the extreme conditions on the ichthyofauna. Rising temperatures, isolation, and habitat fragmentation must have posed severe challenges for the fish species during this period. On the other hand, the observation of 53 dead individuals of 5 species during the 2024 flood indicates the detrimental effects of this event on the fish population. The association of mortality and dispersal of several species with the existing dam further underscores the complexity of the challenges faced by fish during extreme flood events. The correlation between rainfall, river regime, and the impact of land use and occupation provides an important context for understanding the dynamics of these extreme events. The low rainfall during the 2019 drought and the gradual increase in rainfall between 2022 and 2024 leading to the flood demonstrate the significant role of precipitation patterns in shaping the outcomes for fish species. Additionally, the analysis of land use and occupation, particularly the substantial increase in urbanization in the drainage basin over the last 30 years, highlights the human-induced factors contributing to the stress on aquatic ecosystems. Both extreme floods and droughts have significant implications for fish species. Extreme floods can alter riverbeds, cause direct mortality, and disrupt isolated populations, while extreme droughts can lead to fish kills, and habitat fragmentation, and exacerbate environmental stressors. This analysis emphasizes the urgent need for comprehensive measures to mitigate the impact of extreme weather events on aquatic ecosystems and fish species. Addressing factors such as land use and occupation, water management, and climate change adaptation strategies is crucial for promoting the resilience of fish populations in the face of ongoing environmental challenges. Keywords: drought, Ipanema National Forest, rainfall.

Effect of Genotype and Altitude on the Germination of Freshly Collected Seeds from Wild-Growing Populations of Campanula pelviformis Lam. and Petromarula pinnata (L.) A. DC. (Campanulaceae)

The genetic wealth of range-restricted species is threatened by human activities such as habitat fragmentation or alteration. This research focused on the genotype effect in sexual propagation with freshly collected seeds of vulnerable local endemic plants in Crete, namely, Campanula pelviformis and Petromarula pinnata (Campanulaceae), which can be sustainably utilized for agro-alimentary, medicinal, and ornamental purposes. The morphological characteristics of seed length, width, and weight of freshly collected seeds from five wild-growing populations of C. pelviformis and seven wild-growing populations of P. pinnata from lowlands (<500 m) and semi-mountainous (>500 m) altitudes were measured and subjected to germination experiments at four incubation temperature treatments (10, 15, 20, and 25 °C). The effects of temperature, genotype, and their interactions were statistically significant for seed germination, with the results similar to those of previous studies on stored seeds of the same populations. Freshly collected seeds of both species germinated best at incubation temperatures of 10 °C and 15 °C (>68.13% for all population of C. pelviformis and >80.63% for six out of seven populations of P. pinnata), while significant differences were detected among genotypes for both species at each incubation temperature and among genotypes, even from similar altitudes. A statistically significant effect of altitude on germination percentages was observed at an incubation temperature of 20 °C between lowland and semi-mountainous genotypes for both species. The data produced in this study may enhance conservation efforts and lead to species-specific information that can be exploited in the future for their introduction as novel multi-purpose crops.

Landscape-level analysis of disturbance regimes in Chinnar Wildlife Sanctuary, a protected area of Western Ghats, India

ABSTRACT The degradation, fragmentation, and depletion of forests have occurred all over the world, simultaneously, with the exponential growth of the human population. The present study assesses the forest disturbance regime of Chinnar Wildlife Sanctuary (CWS), an ecologically significant biodiversity hotspot of Western Ghats (WG) through satellite image-based forest and land cover mapping and landscape metric analysis. The on-screen analysis based on field knowledge, facilitated, mapping of seven types of vegetation cover. The majority of forest area was covered by dry deciduous forest (39.2 km2 or 43.15%), whereas the minimum area was covered by disturbed forest (2.05 km2 or 2.26%). The disturbance index (DI) was calculated by linearly combining the land use land cover (LULC), road and settlement closeness, fire risk, porosity, patchiness interspersion, normalized difference vegetation index (NDVI), and fragmentation through a probabilistic weight-based linear additive model. The values of the DI (120–310) reclassified into four classes viz. low, moderate, high, and very high. The results revealed that 74.62 km2 (82.52%) of the forest area has low to moderate disturbance, while the rest of the forest area that is 15.8 km2 (17.48%) has high to very high disturbance. These analyses are based on remote sensing and GIS crucial for forest conservation and management strategies formulation.

Functional traits as an indicator of urbanization impact on the scorpion assemblage in Neotropical forest

Currently, natural forests face significant loss of vegetation cover linked to habitat loss due to urban expansion. Therefore, we investigated the effects of changes in different land uses and land cover at the landscape scale resulting from the urbanization process on the functional traits of the body of scorpions in the Brazilian Atlantic Forest. In 10 forest fragments in Paulista, Pernambuco, we observed that forest cover had a statistically significant negative relationship with the average functional body traits of the scorpion assemblage. Distinct functional body traits were associated with the conditions of the surrounding landscape. Forest units with lower forest cover harbored species with higher average functional body traits, indicating adaptation to the urban scenario. Conversely, in areas with greater forest cover, species with smaller functional body traits predominated, suggesting habitat sensitivity and dependence on less disturbed environments. Our results indicate that scorpions may be indicators of changes in functional body traits due to land use change. These findings highlight significant implications for biodiversity conservation in the Atlantic Forest in the face of urban expansion, emphasizing the role of scorpions as key indicators of changes in functional body traits in response to the altered landscape.

Biodiversity and plant-insect interactions in fragmented habitats: A systematic review

Abstract Fragmentation is threatening insect biodiversity and intricate interactions in various ecosystems. Ecological interactions – especially those involving plants and insects – are significantly impacted by fragmented habitats. Because of fragmentation, edge effects and reduced habitat connectivity and quality affect insect species diversity, abundance, behavior, movement, life cycles, and interactions with plants, e.g., pollination, herbivory, and seed distribution. To a large degree, ecosystem services or processes are mediated by these interactions. While fragmented habitats create suitable conditions for invasive alien plants (IAPs), such invasions modify native plant composition and herbivorous insect communities because they cause a decline or loss in insect biodiversity. A systematic review was conducted by reviewing eighty-eight (88) articles to gather evidence for fragmentation effects on insect biodiversity, insects’ behavior and adaptations, plant-insect interactions (i.e., pollination, herbivory, and seed dispersal), and its influence on IAP invasions. This review deduced that any change in insect community composition and diversity due to fragmentation can have cascading effects on ecosystem processes within habitats. It further contends that successful conservation and management of fragmented habitats requires an understanding of the intricate dynamics of plant-insect interactions. However, the long-term resilience and health of ecosystems can be guaranteed by supporting sustainable land use, improving connectivity, and restoring habitats. These actions may help stop and/or reduce the effects of fragmentation on insect biodiversity and support the livelihoods and well-being of millions of people.

Assessing Climate Change Impact on Habitat Suitability and Ecological Connectivity of Wych Elm (Ulmus glabra Huds.) in Türkiye

Understanding how climate change influences the geographical distribution of species within an ecological niche is essential for predicting habitat shifts and informing conservation efforts. This study evaluates the impact of climate change on habitat suitability and ecological connectivity of wych elm (Ulmus glabra Huds.) in Türkiye. The study explores the future distribution of U. glabra and how its connectivity is affected by habitat fragmentation arising from changing climatic conditions. Contextually, this paper aims to achieve two primary objectives: estimating the potential geographical ranges of U. glabra under different climate scenarios and assessing alterations in ecological connections between current and future habitats. The maximum entropy (MaxEnt) model was used along with Morphological Spatial Pattern Analysis (MSPA), and the Probability of Connectivity (PC) index was applied to show possible transformations in distribution patterns of U. glabra over time. The findings suggest that there will be a reduction in the suitability of locations for the species. Moreover, it is expected that under future climate scenarios, ecological connectivity will decline, especially from 2061 to 2100 in the SSP585 scenario. Notably, significant alterations are anticipated during the latter half of the twenty-first century, mainly outside the coastal areas of the Black Sea, where extensive regions would become unsuitable. Additionally, the species is projected to shift its range, decreasing its presence in inland regions while expanding along the coasts. The results show the vulnerability of this species against climate change, thereby demanding adaptive conservation measures to preserve it within the forest ecosystems of Türkiye.

Evaluating the IUCN conservation status of Tritaxis kurnoolensis (R.R.V.Raju & Pull.) R.Y.Yu. & Welzen (Euphorbiaceae), an endemic tree species found in the Eastern Ghats region of Andhra Pradesh, India

Tritaxis kurnoolensis, a small tree of the Euphorbiaceae family, is endemic to a valley within the Sullavai Sandstone plateau in close proximity to the Paleru Reservoir (Owk dam). The species is a narrow endemic. No documented sightings of this species have been recorded beyond the type locality since its description in 1994 by Venkataraju & Pullaiah as Dimorphocalyx kurnoolensis from the Nandyal District of Andhra Pradesh. In this study, the authors applied the grid method for quantification and subjected the species to a meticulous analysis aligning with IUCN Red List Criteria. The distribution was found to be restricted due to habitat (valley) fragmentation, reservoir which is arresting seed dispersal, and destruction caused by tunnel construction civil works. The area of occupancy (AOO) at 16 km² and the extent of occurrence (EOO) at 0.474 km², were systematically computed using GeoCAT. The species is assessed here using the Red List methodology for evaluating extinction risk. Based on its AOO, EOO, and population size, it has been classified as Critically Endangered.

Habitat Fragmentation Affects Richness—A View Through a Metacommunity Lens

Habitat fragmentation is often assumed to negatively impact species diversity because smaller, more isolated populations on smaller habitat patches are at a higher extinction risk. However, some empirical and theoretical studies suggest that landscapes with numerous small habitat patches may support higher species richness, although the circumstances remain elusive. We used an agent-based metacommunity model to investigate this and simulate landscapes of the same total area but diverse patch sizes. Our model, as generic and unbiased by specific assumptions as possible, aimed to explore which circumstances may be more conducive to supporting higher biodiversity. To this end, most parameters and behaviors were random. The model included generalized species traits, dispersal, and interactions to explore species richness dynamics in fragmented landscapes of distinct patch sizes. Our results show that landscapes with many small patches maintain higher species richness than those with fewer large patches. Moreover, the relationship between patch connectivity and species richness is more pronounced in landscapes with smaller patches. High connectivity in these landscapes may support species diversity by preventing local extinctions and facilitating recolonization. In contrast, connectivity is less significant in large-patch landscapes, where generalist species dominate. The findings highlight the complex interplay between patch size quality, connectivity, species traits, and diverse interactions among species in determining species richness. We suggest the patterns produced by the model represent null predictions and may be useful as a reference for a diversity of more specialized questions and predictions. These insights may also have specific implications for conservation strategies, suggesting that maintaining a mosaic of small, well-connected patches could enhance biodiversity in fragmented landscapes.

Population genomics of a specialized insect, Tetraopes texanus (Coleoptera: Cerambycidae), across a fragmented grassland system

AbstractSpecialist insects are especially susceptible to loss of genetic diversity in the face of habitat destruction and fragmentation. Implementing effective conservation practices for specialist insects will benefit from knowledge of population structure and genetic diversity. Because insects are hyper-diverse, characterizing the population structure of all species within the insect community is untenable, even if focused within a particular habitat type. Thus, concentrating on a single species specialized to a particular habitat type is needed to infer general trends. Here, we investigate the range-wide population genetics of Tetraopes texanus Horn 1878 (Coleoptera: Cerambycidae), which provides a useful model of grassland insects due to its’ habitat specificity and unique biology. Tetraopes texanus occurs primarily in Texas and Oklahoma, into Northern Mexico, and possibly into eastern New Mexico but also occurs in Black Belt prairies of Mississippi and Alabama. Mitochondrial and nuclear DNA (RAD-seq) analysis identified two distinct population clusters of T. texanus corresponding to the Texas and Oklahoma population and the Mississippi and Alabama population. Demographic models indicate ongoing, though incomplete, isolation of the two populations, with estimated dates of divergence in the mid-Pleistocene, coinciding with the end of a glacial period and a shift in glacial interval. These results can inform conservation of grassland adapted insects and offers insight to the biogeography of the Gulf Coastal Plain.

Variation in species-specific responses to habitat fragmentation and land cover structure in urban small mammal communities

Abstract Urbanization is a key driver of habitat loss and fragmentation worldwide, yet many urban ecosystems contain vegetated habitat patches that support diverse wildlife communities. Managing urban systems to support robust wildlife communities requires us to understand the mechanisms that drive the response of species to the urban environment. Small mammals are key components of terrestrial ecosystems (e.g., seed predators, prey) and likely also carry out these roles in urban ecosystems; however, the effects of urbanization on small mammal communities are understudied. To identify how species-specific responses to urban environments shape community composition, we quantified both overall community and species-specific changes in small mammal abundance across an urbanization gradient in a Midwestern US metropolitan area. We combined small mammal trapping and land cover data to generate a hierarchical community abundance model. Species diversity increased with increasing proportional cover of human-modified land cover (i.e., impervious surfaces and turfgrass). This finding is driven by high species diversity on sites bordering streams in mowed parks and low diversity on sites with high tree canopy closure. Additionally, modeling results indicated that species responded differently to landscape attributes, leading to variation in small mammal community composition across the urbanization gradient: prairie-associated species tended to be more abundant in tall vegetation bordering mowed parks while habitat generalists tended to be more abundant on sites with greater canopy closure and shrub cover. Our results suggest that studies that focus on community-level responses (e.g., species richness) to urbanization may miss important species-specific responses. It may be particularly important to assess both species-specific and community-level responses in cities at ecotones (e.g., between forest and grassland) where species with different habitat requirements may replace one another in different types of green spaces, thereby changing community composition without affecting species diversity or richness. Our findings also indicate that vegetated urban patches, especially patches with tall vegetation cover and low canopy cover, are important habitat for prairie-associated small mammal communities, providing conservation options in heavily altered landscapes.

Desarrollo de puentes aéreos para el desplazamiento seguro de monos en Costa Rica

Monkey mortality in Costa Rica is due, in most cases, to anthropogenic factors, such as deforestation, forest fragmentation, lack of tree connectivity, and tourism development in most coastal areas. The latter factor has caused the death of at least 450 monkeys per year due to electrocution, as a result of the increase in electrical wiring that has arisen in the different regions with urban development. Faced with this threat, proposals have been developed to avoid the danger, such as the construction of appropriate passage infrastructure for monkeys, the placement of insulated wiring, and the protection of electrical transformers. Using the morphometric measurements of the four species of monkeys native to Costa Rica (Alouatta palliata, Ateles geoffroyi, Saimiri oerstedii, and Cebus imitator), a model of safe and functional aerial passages or bridges for them was designed, the foundations of which are discussed in this article.

Local heterogenisation and regional homogenisation linked to habitat loss induced by dams in riparian forests of the Brazilian Atlantic Forest

Riparian forests are crucial for biodiversity, but dam construction for hydroelectric power disrupts these ecosystems, causing habitat loss and altering river dynamics. Our study investigates the impacts of dams on tree diversity in the southern Brazilian Atlantic Forest. We sampled trees along riverbanks and uplands across 15 dam-affected fragments, analysing the relationship between habitat loss (i.e. loss of riparian zones by permanent flooding due to dam filling), elevation difference, fragment size, and dam implementation time with alpha and beta diversity using mixed models and redundancy analyses. Habitat loss had a more significant impact on beta diversity, leading to shifts in species composition and reduced uniqueness of communities as the impact’s intensity, spatial extent, and duration increased. Alpha diversity only increased in response to local elevation differences between plots located on uplands and riverbanks. Our sampling design can be applied to other inadequately monitored systems to provide insights into beta diversity, a component often neglected in dam licensing and mitigation processes. Our findings reveal a transient local heterogenisation, transitioning into regional homogenisation due to dam-induced habitat loss in riparian forests of the Brazilian Atlantic Forest.

Whole Genome Analysis Reveals Evolutionary History and Introgression Events in Bale Monkeys

Background/Objective: The Bale monkey (Chlorocebus djamdjamensis) is a threatened primate species endemic to Ethiopia and, in contrast to other members of the genus Chlorocebus, lives at high altitudes and feeds mainly on bamboo. Two populations of the species are present, one in continuous bamboo forest (CF) in the eastern part of the species’ range, and the other in fragmented forest (FF) in the western part. Based on mitochondrial DNA and phenotypic characteristics, previous studies have suggested introgression by parapatric congeners into the FF population but not into the CF population. The objective of this study was to gain insights into the evolutionary history of Bale monkeys and their potential genetic adaptations to high altitudes and for bamboo consumption. Methods: We sequenced the whole genomes of individuals from both populations and compared their genomes with those of the other five Chlorocebus species. We applied phylogenetic methods and conducted population demographic simulations to elucidate their evolutionary history. A genome-wide analysis was conducted to assess gene flow and identify mutations potentially associated with adaptations to high altitudes and for bamboo metabolism. Results: Our analyses revealed Bale monkeys as the sister clade to Chlorocebus aethiops and showed that gene flow occurred between C. aethiops and FF but not between C. aethiops and CF. In addition, we detected non-synonymous mutations in genes potentially associated with the adaptation to high altitudes (EPAS1) in both populations and with the adaptation for bamboo metabolism (TAS2R16, MPST, and TST) mainly in the CF population. Conclusions: Our study provides insights into the evolutionary history of a threatened primate species and reveals the genetic basis for its adaptions to unique environments and for diet specialization.

Differential responses of woodland caribou to fire and forestry across boreal and montane ecosystems—a literature review

Abstract Ecosystem-based management (EBM) is a landscape-level management and planning process that is common across North America. A primary tenet of EBM is that the area and intensity of anthropogenic disturbance should mimic the historical natural disturbance of the focal ecosystem. Biodiversity should persist, at least at a coarse scale, where anthropogenic disturbance, such as forest harvesting, matches natural disturbance. However, EBM is failing some species, particularly those that are dependent on old forest. Across many areas of Canada, woodland caribou (Rangifer tarandus caribou) are declining because of the direct and indirect effects of habitat loss and fragmentation. This is even though forest management often follows the principles of EBM. We conducted a qualitative comparison of the responses of woodland caribou to wildfire and forest harvesting, considering a broad range of responses, including habitat selection and distribution, forage, movement patterns, and population dynamics. We found that while wildfire and forest harvesting both influence caribou, the negative effects are generally greater following forest harvesting. For example, wildfire and forest harvesting result in the loss of habitat, but caribou are more likely to shift, abandon or contract their range in response to harvest. The literature also suggested a stronger negative population response of caribou to forest harvest when compared to wildfire. This difference could be the result of greater residual forest structure associated with wildfire as well as the extensive resource roads that are necessary for forestry operations. Although there is sound theoretical support for EBM, the practice, as implemented, may not be effective for maintaining the habitat and ultimately populations of woodland caribou.

Diurnal Activity Budgets and Feeding Habits of Grivet Monkey (Chlorocebus aethiops aethiops) in Fragmented Moist Afromontane Forest

ABSTRACTGrivet monkeys (Chlorocebus aethiops aethiops) are opportunistic omnivores and extremely adaptable in both rural and urban environments. A study was conducted out in human‐dominated fragmented moist Afromontane forest of wondo genet to investigate the diurnal activity budgets and feeding habits of grivet monkey. Data collection was carried out from February to September 2022 covering both wet and dry seasons. During each scan, individuals were recorded as performing one of the following activities: feeding, moving (searching for food), resting, grooming, playing and others such as drinking, vocalisation and defecation, or aggression and sexual activity. Dietary composition and preferences were assessed using scan sampling method. Proximate analysis was conducted to examine the nutritional makeup of feeding food items. The greatest proportion of the activity time budget of the grivet monkey was devoted to feeding, resting and moving, with relatively higher time devoted to feeding and moving and less time devoted to resting when compared with grivet monkeys inhabiting natural habitats. Grivet monkey utilised 42 food items grouped into 41 plant species and 1 insect. Psidium guava and Desmodium intortum, relatively with higher crude protein and less fibre, were the most preferred plants consumed. The study has pointed out that grivet monkeys in the human‐dominated landscape of Wondo Genet remnant moist afromontane forest tend to prefer to consume on fruit tress such as Persea americana, Mangifera indica and Psidium guava, which contain high nutritional content that are planted and managed around homesteads. It is recommended to plant and sustainably manage grivet monkeys' natural foods in human‐dominated landscape of Wondo Genet remnant moist afromontane forest to sustainably conserve the species and avoid/reduce human‐grivet monkey conflict.

Genetic diversity loss in the Anthropocene will continue long after habitat destruction ends.

Genetic diversity within species is the basis for evolutionary adaptive capacity and has recently been included as a target for protection in the United Nations' Global Biodiversity Framework (GBF). However, there is a lack of reliable large-scale predictive frameworks to quantify how much genetic diversity has already been lost, let alone to quantitatively predict future losses under different conservation scenarios in the 21st century. Combining spatio-temporal population genetic theory with population genomic data of 18 plant and animal species, we studied the dynamics of genetic diversity after habitat area losses. We show genetic diversity reacts slowly to habitat area and population declines, but lagged losses will continue for many decades even after habitats are fully protected. To understand the magnitude of this problem, we combined our predictive method with species' habitat area and population monitoring reported in the Living Planet Index, the Red List, and new GBF indicators. We then project genetic diversity loss in 13,808 species with a short-term genetic diversity loss of 13-22% and long-term loss of 42-48% with substantial deviations depending on the level of habitat fragmentation. These results highlight that protection of only current habitats is insufficient to ensure the genetic health of species and that continuous genetic monitoring alone likely underestimates long term impacts. We provide an area-based spatio-temporal predictive framework to develop quantitative scenarios of global genetic biodiversity.

Is reinforcement a viable conservation strategy for the endangered perennial herb, Astragalus applegatei?

Reinforcing imperiled plant populations with transplanted individuals is a conservation tool that is increasingly used to counter the negative effects of land use change and habitat fragmentation. A reinforcement project's success is dependent on the survival of planted individuals and the support of the extant population's growth; thus, demographic comparisons of planted and extant individuals within the same population are critical to quantify success. We assessed long‐term demographic data from planted (9 years) and extant (7 years) individuals of a rare perennial herb, Astragalus applegatei, to quantify the success of a reinforcement project. We compared cumulative survival among extant and planted cohorts and constructed generalized mixed‐effect models to understand how age affected survival, flowering, and plant size of both planted and extant individuals. Overall, 9.7% of planted individuals survived after 9–11 years. Although young planted individuals had higher flowering percentages than extant individuals, our models for survival, flowering, and plant size were similar in planted and extant individuals as they aged. Cumulative survival curves among planted cohorts varied while they were similar among extant cohorts. Furthermore, there was evidence of recruitment by planted individuals, an essential benchmark of successful translocation projects. Combined, these results suggest that reinforcement can be a successful conservation tool for A. applegatei under the right conditions and may be used to inform conservation strategies for other imperiled herbaceous perennials.

Applications of Primate Genetics for Conservation and Management

Conservation genetics is the use of genetics to understand and mitigate the threats caused by anthropogenic activities, including habitat loss and fragmentation, wildlife trafficking, and emerging diseases. In this review, we discuss the role of primate conservation genetics in the development of effective conservation strategies, emphasizing the importance of maintaining genetic diversity to enhance adaptive potential and prevent extinction. First, we discuss studies of various primate species that exemplify how genetic data have been instrumental in accurately assessing threat levels, identifying trafficked animals and tracing their geographic origin, and studying how habitat loss affects primate populations. Subsequently, we describe the various molecular tools and analytical approaches employed in these studies. Lastly, we provide a bibliographic review of research in conservation genetics over the last 20 years. We conclude with a brief discussion of the limitations and challenges in this field in developing countries and recommendations for future research.

Spatiotemporal variations and driving factors of fine-scale habitat use by the Yangtze finless porpoise population in the Yangtze River.

The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critically endangered and has suffered from extensive habitat loss and fragmentation. Knowledge of its habitat preference could assist the conservation of the species and associated ecosystem. In the present study, spatiotemporal variations and driving factors of habitat use of a Yangtze finless porpoise population were studied in a 30-km section of the Yangtze mainstream. Seasonal variation in porpoise occurrences was observed based on visual surveys conducted from 2022 to 2023, with five surveys during the dry season and seven surveys during the wet season. Biological and environmental factors were synchronously sampled in both seasons. The maximum entropy model (MaxEnt) was applied to get the effects of biological and environmental variables on porpoise habitat preference. Within the study area, high-suitability habitats of the finless porpoises accounted for 19.0% and 15.4% of the area during the dry and wet seasons, respectively. The high-suitability habitat shifted from the mainstream in the dry season to the sandbar head and tributary area in the wet season. In the dry season, variables influencing the distribution were phytoplankton biomass, water velocity, and zooplankton biomass, which contributed 97.05% variation in the MaxEnt modeling. In the wet season, water depth, surface water temperature, and zooplankton biomass accounted for 97.69% variation of the distribution. Above results highlight that food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. This is because plankton is the primary food source for filter-feeding and omnivorous fish, especially those in the upper-middle layer which are frequently preyed on by finless porpoises. Suitable areas for finless porpoises, particularly those with high suitability, differed significantly across seasons at a fine-scale in the Yangtze mainstream. Seasonal variations in habitat were driven by different factors. But food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. These results suggest prioritizing conservation of the finless porpoise in the dry season when fish resources are relatively scarce. Measures including monitoring and evaluating prey resources should be considered. More attention should also be paid on management of shipping in the dry season given that the high-suitability habitat of the finless porpoises shifts to the mainstream.

Habitat amount interacting synergistically with cattle intrusion drives pervasive changes in leaf-litter ant assemblages in Amazonian Forest remnants

Deforestation driven by the expansion of cattle ranching activities towards the southern edge of the Amazon Forest transforms the landscape and is a threat to biological diversity. A secondary impact associated with this kind of fragmentation is cattle intrusion in Legal Reserves. To assess the fragmentation effect (habitat amount) and cattle intrusion on forest remnants, we sampled ground-dwelling ants in 24 forest remnants and the matrix adjacent to each remnant, in Meridional Amazon, Brazil. In all, we recorded 3,156 occurrences of ants, comprising 262 species. In addition to the natural characteristics of the areas (leaf-litter weight), the changes resulting from fragmentation (habitat amount) and cattle intrusion act synergistically affecting ground-dwelling ants’ assemblage. This result shows that the pervasive effect of habitat reduction due to forest fragmentation combined with habitat degradation (habitat quality) in the ground-dwelling ants’ assemblage.