Extinction Research Articles

Evolución de la biodiversidad amazónica: una revisión

ABSTRACT Amazonia (defined herein as the Amazon basin) is home to the greatest concentration of biodiversity on Earth, providing unique genetic resources and ecological functions that contribute to ecosystem services globally. The lengthy and complex evolutionary history of this region has produced heterogeneous landscapes and riverscapes at multiple scales, altered the geographic and genetic connections among populations, and impacted rates of adaptation, speciation, and extinction. In turn, ecologically diverse Amazonian biotas promoted further diversification, species coexistence, and coevolution, with biodiversity accumulating over tens of millions of years. Important events in Amazonian history included: (i) late Cretaceous and early Paleogene origin of major rainforest plant and animal groups; (ii) Eocene-Oligocene global cooling with rainforests contracting to tropical latitudes separating Atlantic coastal and Amazonian rainforests; (iii) Miocene uplift of central and northern Andes that separated Pacific coastal and Amazonian rainforests, spurred formation of mega-wetlands in the western Amazon, and contributed to the origin of the modern transcontinental Amazon River; (iv) late Neogene formation of the Panamanian Isthmus that facilitated the Great American Biotic Interchange; (v) Pleistocene climate oscillations followed by late Pleistocene-Holocene human colonization and megafaunal extinctions; and (vi) modern era of widespread anthropogenic deforestation, defaunation, and ecological transformations of regional landscapes and global climates. Amazonian conservation requires decade-scale investments into biodiversity documentation and monitoring to leverage existing scientific capacity, and strategic habitat planning to allow continuity of evolutionary and ecological processes now and into the future.

Toward a Procedure to Study Rule-Governed Choice: Preliminary Data

AbstractThe aim of this study was to model a situation that induced choice between following two incompatible rules, each associated with a different rate of reinforcement. In Experiment 1, eight undergraduate students were exposed to a two-component multiple schedule (training). In each component, there was a concurrent variable interval (VI)–extinction (EXT) schedule. Participants were given two rules that instructed them to respond to the VI alternative in the presence of different discriminative stimuli. The side of the VI schedule changed in each component and offered a different reinforcer rate according to the discriminative stimuli in the operation. When both discriminative stimuli were concurrently presented (test), participants favored the alternative previously instructed by the rule, which was associated with the greatest reinforcer rate, whereas indifference was observed in the absence of discriminative stimuli. Experiment 2 tested the effects of reinforcement rate using the same procedure without providing rules. During training, participants gradually developed a preference for the VI alternatives. In the choice test phase, participants favored the alternative associated with the stimuli with the highest reinforcer rate when both discriminative stimuli were present. Unsystematic preference was observed in the absence of discriminative stimuli. Two alternative explanations were provided for the findings.

BAMFORESTS: Bamberg Benchmark Forest Dataset of Individual Tree Crowns in Very-High-Resolution UAV Images

The anthropogenic climate crisis results in the gradual loss of tree species in locations where they were previously able to grow. This leads to increasing workloads and requirements for foresters and arborists as they are forced to restructure their forests and city parks. The advancements in computer vision (CV)—especially in supervised deep learning (DL)—can help cope with these new tasks. However, they rely on large, carefully annotated datasets to produce good and generalizable models. This paper presents BAMFORESTS: a dataset with 27,160 individually delineated tree crowns in 105 ha of very-high-resolution UAV imagery gathered with two different sensors from two drones. BAMFORESTS covers four areas of coniferous, mixed, and deciduous forests and city parks. The labels contain instance segmentations of individual trees, and the proposed splits are balanced by tree species and vitality. Furthermore, the dataset contains the corrected digital surface model (DSM), representing tree heights. BAMFORESTS is annotated in the COCO format and is especially suited for training deep neural networks (DNNs) to solve instance segmentation tasks. BAMFORESTS was created in the BaKIM project and is freely available under the CC BY 4.0 license.

How does the shape of the wing and hindlimb bones of aquatic birds relate to their locomotor abilities?

Aquatic birds represent diverse ecologies and locomotion types. Some became flightless or lost the ability for effective terrestrial locomotion, yet, certain species excel in water, on land, and in air, despite differing physical characteristics associated with each medium. In this exploratory study, we intend to quantitatively analyze the morphological variety of multiple limb bones of aquatic birds using 3D geometric morphometrics. Morphological variation is mainly driven by phylogeny, which also affects size and locomotion. However, the shape of the ulna, including the proportion and orientation of the epiphyses is influenced by size and aquatic propulsive techniques even when phylogeny is taken into consideration. Certain trends, possibly linked to functions, can be observed too in other bones, notably in cases where phylogenetic and functional signals are probably mixed when some taxa only englobe species with similar functional requirements: penguins exhibit the most distinctive wing bone morphologies, highly adapted to wing-propulsion; advanced foot-propellers exhibit femur morphology that reduces proximal mobility but supports stability; knee structures, like cnemial crests of varied sizes and orientations, are crucial for muscle attachments and efficient movement in water and on land; taxa relying on their feet in water but retaining terrestrial abilities share features enabling swimming and walking postures. Size-linked changes distinguish the wing bones of non-wing-propelled taxa. For hindlimbs, larger size relates to robust bones probably linked to terrestrial abilities, but robustness in femora can be connected to foot-propulsion. These results help us better understand birds' skeletal adaptation and can be useful inferring extinct species' ecology.

Limited herbivore migration during the Last Glacial Period of Kenya.

Eastern Africa is home to the largest terrestrial migrations on Earth. Though these migratory systems have been well studied for decades, little is known of their antiquity and evolutionary history. Serially sampled strontium stable isotopes (87Sr/86Sr) from tooth enamel can be used to track migration in mammals. Here we analyse 87Sr/86Sr for 79 bovid and equid individuals representing 18 species from four localities in Kenya to characterize prehistoric migratory systems during the Last Glacial Period (115-11.7 ka). Of the species analysed, 16 lack definitive evidence for migration, including blue wildebeest (Connochaetes taurinus), Thomson's gazelle (Eudorcas thomsonii) and plains zebra (Equus quagga), which are long-distance migrants today in the Greater Serengeti Ecosystem and historically in the Athi-Kapiti Plains. Only two species, the extinct wildebeests Rusingoryx atopocranion and Megalotragus sp., were migratory. These findings suggest a possible alternative narrative about ecosystem dynamics during the Last Glacial Period and shed light on the behaviour of both extant and extinct species at this time. In particular, these results indicate that migratory behaviour in extant species either emerged during the Holocene or was more spatiotemporally constrained in the past. Our results contribute to a growing body of evidence suggesting that the structure and function of geologically recent large mammal communities in eastern Africa differed considerably from those observed in the present day.

Predicting the responses of European grassland communities to climate and land cover change.

European grasslands are among the most species-rich ecosystems on small spatial scales. However, human-induced activities like land use and climate change pose significant threats to this diversity. To explore how climate and land cover change will affect biodiversity and community composition in grassland ecosystems, we conducted joint species distribution models (SDMs) on the extensive vegetation-plot database sPlotOpen to project distributions of 1178 grassland species across Europe under current conditions and three future scenarios. We further compared model accuracy and computational efficiency between joint SDMs (JSDMs) and stacked SDMs, especially for rare species. Our results show that: (i) grassland communities in the mountain ranges are expected to suffer high rates of species loss, while those in western, northern and eastern Europe will experience substantial turnover; (ii) scaling anomalies were observed in the predicted species richness, reflecting regional differences in the dominant drivers of assembly processes; (iii) JSDMs did not outperform stacked SDMs in predictive power but demonstrated superior efficiency in model fitting and predicting; and (iv) incorporating co-occurrence datasets improved the model performance in predicting the distribution of rare species. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'.

Coexistence and bistability of a modified Leslie–Gower predator–prey model with mixed movement for the predator and Holling-type II schemes

This paper centers on the analysis of the dynamics of a modified Leslie–Gower predator–prey model employing Holling-type II schemes, with the prey exhibiting pure random diffusion and the predator undergoing a mixed form of movement. The extinction of species and uniform persistence of this system are explored, and several conditions for the stability, uniqueness and multiplicity of positive steady-state solutions are derived. In contrast to the specialist and generalist predator–prey systems in open advective environments, the dynamics of this system are more intricate. It emerges that multiple positive steady-state solutions and the bistable phenomenon exist for this system when a small advection rate and a moderate predation rate are imposed. Numerical simulations reveal that the increase of diffusion rate for prey disadvantages the survival of itself and has no impact on predator invasion, while the increase of diffusion rate for predators favors the invasion of itself.

Forest conversion and timber certification in the public plantation estate of NSW: Implications at the landscape and policy levels

This paper investigates the clearance of native forests and native vegetation for plantation establishment, otherwise known as forest conversion, in the state-owned plantations of New South Wales, Australia. It begins by describing Australia’s forests, plantations, and forest conversion, continues with an outline of the history of public hardwood plantations in New South Wales, and explores the regulatory frameworks that allow this practice to happen, and the responses adopted by non-state environmental governance systems, notably forest certification, to address this problem. The paper presents a case study analysis of conversion in the hardwood plantations of northern NSW, and concludes that the current regulatory environment facilitates deforestation, with cumulative impacts at the landscape level, and that without government intervention, efforts to prevent this by non-state action will only be partially successful, leading to ongoing habitat and species loss. The failure of existing legislative and regulatory frameworks to adequately acknowledge, define, and prohibit conversion will remain an impediment to sustainable forest management, as the entry of such timber into the market contaminates supply chains, resulting in considerable reputation risk. Reform is needed in both public and private governance systems to ensure strong governance, effective planning, and ecosystem integrity at the landscape level. Recommendations are provided for policymakers.

The earliest large carpenter bee (Xylocopa) and its adhering pollen (Araliaceae, Theaceae)

AbstractThe association of pollinators with their host plants is a critical element of ecosystem functioning and one that is usually determined indirectly in the fossil record from specific morphological traits of flowers or putative pollinating animals. The exceptionally fine preservation at Messel, Germany, offers an excellent source of data on pollen from fossil flowers as well as preserved adhering to insects as direct evidence of their association with specific floral lineages. Here, we report on pollen recovered from the body and legs of a large carpenter bee (Apidae: Xylocopinae: Xylocopini) from the Eocene of Messel. The fossil is the earliest occurrence of the tribe Xylocopini and represents an extinct subgenus and species, described as Xylocopa (Apocolyx) primigenia subgen. et sp. nov. Two eudicot pollen types were recovered from the bee, one of the family Theaceae (Asterids: Ericales) and another of Araliaceae (Euasterids: Apiales). The pollen grains are compared with various extinct and extant pollen types, and data on floral visitors to modern theaceous and araliaceous flowers are explored in relation to understanding the association of the fossil carpenter with these floral types in the paratropical Eocene biota of Messel.

Deep lakes support higher zooplankton functional diversity than shallow lakes: A case study in lacustrine environments affected by mining tailings (lower Doce River basin, Brazil)

Abstract Tragic incidents involving mine tailings spills have impacted many aquatic ecosystems around the world. The massive mine tailings dam collapse of Fundão, which occurred in Brazil in 2015, affected several aquatic ecosystems, including shallow and deep lakes in the lower Doce River basin. Until now, the effects of mine tailings on the functional diversity of zooplankton remain poorly understood. We investigated the functional diversity of zooplankton (functional groups, functional richness [FRic] and functional evenness [FEve]) in shallow and deep lakes, exploring the influence of environmental variables and metals. In addition, trends in functional redundancy and functional vulnerability were also assessed to understand patterns of resilience in mining‐impacted ecosystems. Surveys were performed monthly on three deep and three shallow lakes affected by the dam failure, from October 2018 to September 2019. In the deep lakes, the zooplankton community was dominated by smaller filter‐feeders and omnivorous species, associated with cyanobacteria density and chlorophyll‐a. Medium‐sized filters were associated to iron, suspended particulate organic matter and total organic carbon in shallow lakes. The smaller filter‐feeders and omnivorous trophic groups had a higher contribution to increasing the functional diversity of zooplankton than medium‐sized filter‐feeders in both deep and shallow lakes. FRic and FEve were higher in deep lakes than in shallow lakes. Shallow lakes were highly vulnerable to species loss and functional diversity was modulated by environmental changes and metal pollution. Tropical shallow lakes impacted by mining tailings should receive particular attention in conservation plans, as a consequence of their high level of pollutant retention in comparison with deep lakes. In addition, we highlight the importance of using a functional approach to better understand the ecosystem changes resulting from the impacts of mine tailings on aquatic environments.

Eugenia <I>Singampattiana</I> Beddome (Myrtaceae) - its Status after Rediscovery from the Tirunelveli Hills, Tamil Nadu

Eugmia singampattiana Beddome, an endemic species of the Tirunelveli-Travancore Hills on the Western Ghats has been rediscovered after Beddome in the 1860s-1870s. Mature fruits and seeds are described for the first time. It is reportedly an endangered or possibly extinct species. Its present status is discussed and conservation measures are suggested.

The Ethnobotany of Amazon Indians: a Rapidly Disappearing Source of botanical Knowledge for Human Welfare

The Amazon Indians are a rich source of botanical information. Some 200 tribes each have their own unique botany with many different plant recipes for their common needs e.g. arrow poisons, narcotics, food and fibers. Examples from several tribes are given of the variety of arrow poisons, fish poisons and hallucinogenic drugs which arc used in Amazonia. The Indians have had thousands of years of management of the Amazon ecosystem. However, the rate of acculturation and extinction of tribes is accelerating-even faster than the 90 tribes which have gone extinct in the 20th Century. Information of great potential use to human welfare about unexploited plants and management of the forest ecosystem is rapidly becoming lost. A review is given of this destruction of the Indians and their forest and habitat and it is suggested that there is an urgent need to study these people and for biologists to be active in the efforts which are being made to protect the Amazon Indians.

Cortical and Trabecular Bone Modeling and Implications for Bone Functional Adaptation in the Mammalian Tibia.

Bone modeling involves the addition of bone material through osteoblast-mediated deposition or the removal of bone material via osteoclast-mediated resorption in response to perceived changes in loads by osteocytes. This process is characterized by the independent occurrence of deposition and resorption, which can take place simultaneously at different locations within the bone due to variations in stress levels across its different regions. The principle of bone functional adaptation states that cortical and trabecular bone tissues will respond to mechanical stimuli by adjusting (i.e., bone modeling) their morphology and architecture to mechanically improve their mechanical function in line with the habitual in vivo loading direction. This principle is relevant to various research areas, such as the development of improved orthopedic implants, preventative medicine for osteopenic elderly patients, and the investigation of locomotion behavior in extinct species. In the present review, the mammalian tibia is used as an example to explore cortical and trabecular bone modeling and to examine its implications for the functional adaptation of bones. Following a short introduction and an exposition on characteristics of mechanical stimuli that influence bone modeling, a detailed critical appraisal of the literature on cortical and trabecular bone modeling and bone functional adaptation is given. By synthesizing key findings from studies involving small mammals (rodents), large mammals, and humans, it is shown that examining both cortical and trabecular bone structures is essential for understanding bone functional adaptation. A combined approach can provide a more comprehensive understanding of this significant physiological phenomenon, as each structure contributes uniquely to the phenomenon.

A freshwater ecosystem once existed in the Rajasthan desert: evidence from a fossil of the aquatic herb Nelumbo

Nelumbonaceae encompasses aquatic plant lineages that represent major components in the modern tropical wetland ecosystems of India. The group is characterized by its distinctive reproductive receptacle incorporating in situ fruitlets and vegetative organs that are well-represented in the fossil record. Unusually, though, no Nelumbo reproductive fossils have yet been identified from the Cenozoic of India. Here, we report the first such fossil reproductive organ from the aquatic perennial herb Nelumbo, which was recovered in the lower Eocene Palana Formation at the Gurha lignite mine in Rajasthan, western India. The fossil preserves an aggregate fruit with 28 indehiscent, apocarpous and globose to oblong fruitlets embedded within an accrescent receptacle, and a single small central cavity or apical remains of a stigma in each fruitlet. Comparisons with extant and extinct Nelumbo species support attribution to Nelumbo sp. Our unexpected discovery of a fully aquatic plant in the Rajasthan Basin during the early Eocene indicates that a freshwater ecosystem existed there ca 55 ± 10 million years ago; this contrasts starkly with the arid climatic conditions predominant in Rajasthan today. Raman Patel† [ ramanpatel2142@gmail.com ], Department of Geology, Hemvati Nandan Bahuguna Garhwal University, Srinagar, 246174 Uttarakhand, India Ashif Ali† [ aashifli0011@gmail.com ], Palaeobotany, Palynology, and Plant Evolution Laboratory, Department of Botany, Sidho-Kanho-Birsha University, Ranchi Road, Purulia-723104, India Rajendra Singh Rana [ rajendra.rana1@gmail.com ], Department of Geology, Hemvati Nandan Bahuguna Garhwal University, Srinagar, 246174 Uttarakhand, India Mahasin Ali Khan* [ khan.mahasinali@gmail.com ], Palaeobotany, Palynology, and Plant Evolution Laboratory, Department of Botany, Sidho-Kanho-Birsha University, Ranchi Road, Purulia-723104, India.

Conservation of Sacred Groves of Rajasthan through Folkloric Beliefs

Sacred groves or sacred woods are groves of trees, related to traditional, religious & cultural beliefs & these areas are dedicated to local deities & ancestor spirits. They can be found as a section of a forest. They are excellent illustrations of in-situ conservation. These groves, which are around the nation in villages & cities, plains, and mountain areas, represent a priceless genetic diversity that helps to preserve our environment in many ways. Many extinct species that could have perished otherwise have been saved because of these virgin forest regions. Besides protecting biological diversity, the entire ecosystem aids in water & soil conservation. In the case of Rajasthan, sacred woods can be considered as one of the preservers of priceless ancient religious practices & traditional beliefs. Therefore, sacred forests offer humanity certain crucial ecological functions. In recent times, drastic changes around the globe have also impacted both religious practices and biological integrity. The destruction of the historic heritage has several causes, some of which need to be investigated, including changes in social beliefs, modernity, and the eroding of cultural practices. It becomes important to spread awareness of the management and conservation of various ecosystem services as well as to suggest management and conservation as an alternative strategy for the sustainability of forestry around human settlements.

Persistence and Stochastic Extinction in a Lotka–Volterra Predator–Prey Stochastically Perturbed Model

The classical Lotka–Volterra predator–prey model is globally stable and uniformly persistent. However, in real-life biosystems, the extinction of species due to stochastic effects is possible and may occur if the magnitudes of the stochastic effects are large enough. In this paper, we consider the classical Lotka–Volterra predator–prey model under stochastic perturbations. For this model, using an analytical technique based on the direct Lyapunov method and a development of the ideas of R.Z. Khasminskii, we find the precise sufficient conditions for the stochastic extinction of one and both species and, thus, the precise necessary conditions for the stochastic system’s persistence. The stochastic extinction occurs via a process known as the stabilization by noise of the Khasminskii type. Therefore, in order to establish the sufficient conditions for extinction, we found the conditions for this stabilization. The analytical results are illustrated by numerical simulations.

Recent Advances in Studies of Genomic DNA Methylation and its Involvement in Regulating Drought Stress Response in Crops

As global arid conditions worsen and groundwater resources diminish, drought stress has emerged as a critical impediment to plant growth and development globally, notably causing declines in crop yields and even the extinction of certain cultivated species. Numerous studies on drought resistance have demonstrated that DNA methylation dynamically interacts with plant responses to drought stress by modulating gene expression and developmental processes. However, the precise mechanisms underlying these interactions remain elusive. This article consolidates the latest research on the role of DNA methylation in plant responses to drought stress across various species, focusing on methods of methylation detection, mechanisms of methylation pattern alteration (including DNA de novo methylation, DNA maintenance methylation, and DNA demethylation), and overall responses to drought conditions. While many studies have observed significant shifts in genome-wide or gene promoter methylation levels in drought-stressed plants, the identification of specific genes and pathways involved remains limited. This review aims to furnish a reference for detailed research into plant responses to drought stress through epigenetic approaches, striving to identify drought resistance genes regulated by DNA methylation, specific signaling pathways, and their molecular mechanisms of action.

Evolution, Evil, Co-Creation and the Value of the World

This article builds on and supplements an earlier one in this journal about theodicy. It focuses on species extinctions and on the possible role of humanity as fallible co-creators. Christopher Southgate has suggested that co-creators might shoulder the task of curtailing extinctions. In appraising this view, I distinguish between extinctions resulting from evolution, which humans have limited power to reverse, but which are held to be indispensable for the evolution of complexity, consciousness and self-consciousness, and those caused by humanity itself, which humans should reduce, even if they cannot be halted. Human creativity, however, extends further to the development of skills, trades, the arts and literature. Church Fathers, such as Ambrose, Theodoret and Cosmas Indicopleustes, held that God left the creation incomplete so that humanity could enhance it; certainly, human creativity has introduced agriculture, navigation, technology and culture, adding to the value of the world. Granted belief in creation, this can be understood as co-creation. Granted the value that humanity continues to add to the world, the belief that such creativity flows from the creator’s overall plan emerges as a coherent one.

Regional differences of functional and taxonomic bird diversity in tropical agroforests of Peru

AbstractDiversity and functionality of bird communities in tropical agroforests are shaped by their surrounding landscape, particularly the extent and type of natural forest. However, most evidence comes from tropical rainforest landscapes, whereas the bearing of such trends in other forest types remains understudied. We compared functional and beta diversity of bird communities in 23 cacao agroforests embedded in landscapes of two contrasting Peruvian regions: seasonally‐dry tropical forests and subtropical rainforests from the Andean foothills. Strong climatic seasonality affects both landscapes, but forest vegetation structure and complexity differ. We found higher bird species richness (n = 179 spp) and higher species turnover in the subtropical forest than in the dry forest landscape (n = 64 spp). Only in the dry forest landscape, distance from forest increased dissimilarity driven by species loss, that is, the nestedness component of beta diversity. This points to the importance of conserving dry tropical forests within the broader landscape matrix, with known benefits for pest control and cacao yield. Functional diversity indices were not influenced by forest distance in either landscape, but the proportion of insects in birds' diet decreased by 27% along a 1 km distance gradient from forest in the subtropical forest landscape. In the dry forest landscape, however, it decreased by only 3% across the same distance gradient. Far from forest (≥1 km), forest specialization decreased by ~33% and 20% in the subtropical and dry forest landscapes, respectively. These differences indicate that regionally‐adapted agroforest management is paramount for conserving bird diversity and ecosystem services as pest control. Procuring high‐canopy shade trees and adequate microhabitats for insectivorous species is essential to maintain biocontrol services in the subtropical forest. Conversely, in the dry forest enhancing low‐canopy vegetation with a focus on frugivores and ensuring forest closeness to agroforests may maximize bird diversity and their ecosystem services. A complete version of this article is translated to Spanish in the supplements.

A new species of Eocene soldier beetle, a Malthodes (Coleoptera: Cantharidae: Malthininae) in Baltic amber

ABSTRACT A new species of soldier beetle (Cantharidae) from Eocene Baltic amber, Malthodes maierae sp. nov., is described and illustrated from a male specimen discovered in Russia. The new species differs from the hundreds of known extant and extinct species of Malthodes Kiesenwetter, 1852. The last abdominal segments, which are substantially modified on the male to hold the female during mating, differ considerably in Malthodes species and are very important diagnostic elements for this genus. The exact evolutionary forces driving these manifold modifications are unknown, but they are likely related to sexual selection, mate recognition, antagonistic coevolution, or varying habitats, or a combination of these factors. The Zoobank LSID for this is: urn:lsid:zoobank.org:pub:DC13FC31-BD71-4C3D-9536-B70AF65FB699