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This chapter describes the duty of States to respect and protect the right to life in the context of assemblies, including demonstrations, marches, and protests. The right to assembly peacefully is a fundamental human right. General Comment 37 on the right of peaceful assembly, adopted by the United Nations Human Rights Committee in July 2020, is an important normative reference.
We used a standardised transect method to compare lowland forest termite assemblages in Buton Island, Sulawesi, with transects in Sundaland. The four Buton transects were extremely depauperate with species density ranging from 1 to 6 species, which is around 10% of the species density in 11 described Sundaland transects. Soil-feeding species were absent from the Buton transects but represent some 43% of species in the Sundaland transects. The Buton transects have relatively high soil pH (6.7–7.9), which may be associated with depauperate termite assemblages. Most termite genera recorded in Sulawesi are wood nesters that can raft in floating wood, which is probably how they arrived in Sulawesi. The Macrotermitinae (fungus-growers) do not raft and probably flew across serendipitously. Geographic isolation, both on Buton and in Sulawesi more generally, and Buton’s underlying geology causing high soil pH, may account for the near-absence of soil-nesters and soil-feeders, none of which are known to raft.
Site 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.
The end of the twentieth century saw a significant change – quantitatively and qualitatively – in refugees coming to Britain. As the post-Cold War world saw growing numbers fleeing a constellation of state collapse, civil war, environmental disaster and economic stagnation, 1990s Britain saw an absolute increase in the number of asylum applications. It also saw a shift away from the entry of distinct blocks of refugees towards the piecemeal entry of individuals seeking refuge. These two trends came together, combining with Britain’s continued restriction of extra-European immigration, to ensure two things. First, that Britain’s stated commitment to refugee rights via the Refugee Convention became undermined by a determination to reduce the number of successful asylum applications. Through repeated legislation, the burden of proof an individual needed to make a successful application became ever greater. Second, despite assertive grassroots activism, new measures – dispersal, detention and ever-more restricted access to welfare support and legal employment – all served to marginalise asylum seekers from the mainstream population. While these sought to underline the difference between, and the competing claims of, asylum seekers and the ‘hard working poor’, in fact both faced the consequences of a retreating state, shrinking affordable housing and the erosion of universal welfare.
We review trophic biogeography theory, a growing sub-discipline in ecology that seeks to merge food web ecology with the theory of island biogeography. We start by presenting a deliberately provocative theory, extending neutral community theory to multi-trophic systems, where one does not pay attention to the details of interactions across trophic levels, but rather emphasizes the consequences of traits associated with trophic rank, such as dispersal rates. Our results suggest that the effect of trophic rank on dispersal rates is a key driver of trophic rank effects on species–area relationships. We then examine effects of trophic specialization on species–area relationships, after which we turn to the implications of trophic generalization. An important arena of recent work is elucidating the impact of top down effects in food webs on species–area relationships. Lastly, we offer insights into key avenues for future research including the impact of cross-ecosystem subsidies in driving patterns of biodiversity in heterogeneous landscapes, the need to consider how species coexistence mechanisms may shift across islands or habitat patches varying in area and isolation, and assessing the evolutionary dimension of trophic influences on species–area relationships.
Ecological neutral theory refers to a suite of neutral models that all assume the demographic properties of an individual are independent of its species identity. This is a strong assumption that precludes explicit ecological niches or trophic interactions. Nevertheless, neutral models have been historically successful in replicating classic ecological patterns and linking these to mechanisms in insightful ways. Here we review the species–area relationship (SAR) predicted by various neutral models in different contexts. We discuss ‘mainland SARs’ relevant to large swathes of uninterrupted habitat and show that neutral theory predicts a triphasic SAR shape across broad spatial scales. We discuss ‘island SARs’ relevant to isolated patches of habitat and show that neutral theory predicts no effect of area and a single species for small islands and potentially rich behaviour for larger islands which may harbour endemic species. We also discuss two more complex types of SAR corresponding to cases where the areas sampled and sometimes the habitat itself are distributed unevenly across space in a fragmented pattern. We conclude by demonstrating specific applications of neutral SARs, including calculating extinction debt as well as optimal design of sampling schemes and nature reserves.
By taking advantage of spatially explicit modelling and network analysis, we investigated how species–area relationships (SARs) emerge and are maintained by dispersal and how the spatial arrangement of islands affects colonization/extinction dynamics of SARs. In particular, we generated different archipelagos characterized by varying geometric properties and then we simulated inter-island dispersal/colonization patterns. As the model proceeds through time, species accumulate on different islands according to their dispersal ability and depending on island size and isolation. During each time step, the model fit a power function that thus enabled us to track the emergence of island SARs (ISARs). After equilibrium was reached, we simulated a phase of reduced dispersal. Each simulated archipelago was analysed as a network in which each island was a node connected to other nodes (islands) based on pairwise spatial distances. We found that basic properties of the underlying connectivity network were correlated with ISAR properties, although the best predictor of richness was almost always island area. In nearly all simulations, the ISAR weakened after reducing the dispersal ability of the species. Our study demonstrates that a spatially explicit dispersal simulation model and network analysis can provide meaningful insight into the evolution and robustness of ISARs.
Epiphytic lichens are sensitive to deteriorating air quality, but levels of nitrogen and especially sulphur deposition have been in decline over most of Europe in recent decades. We assessed the response of epiphytic lichens to this decline, using data from long-term monitoring sites in Sweden. We analyzed 20 years of data to investigate temporal trends in lichen communities’ sensitivity to sulphur, nitrogen preference, species richness and alpha and beta diversity. We found only limited and partial evidence of recovery in the area that previously had high levels of deposition, and a decline in mean sulphur sensitivity at a northern site with low deposition levels throughout the monitoring period. The slow recolonization of sensitive species, even where environmental conditions are now suitable, is probably a result of impoverished regional species pools and the inherent limited dispersal capacity of many lichen species. We suggest due consideration of these factors in the use of epiphytic lichens as environmental indicators in a period of improving air quality.
Dispersal is a key ecological process affecting community dynamics and the maintenance of populations. There is increasing awareness of the need to understand individual dispersal potential to better inform population-level dispersal, allowing more accurate models of the spread of invasive and beneficial insects, aiding crop and pest management strategies. Here, fine-scale movements of Poecilus cupreus, an important agricultural carabid predator, were recorded using a locomotion compensator and key movement characteristics were quantified. Net displacement increased more rapidly than predicted by a simple correlated random walk model with near ballistic behaviour observed. Individuals displayed a latent ability to head on a constant bearing for protracted time periods, despite no clear evidence of a population level global orientation bias. Intermittent bouts of movement and non-movement were observed, with both the frequency and duration of bouts of movement varying at the inter- and intra-individual level. Variation in movement behaviour was observed at both the inter- and intra- individual level. Analysis suggests that individuals have the potential to rapidly disperse over a wider area than predicted by simple movement models parametrised at the population level. This highlights the importance of considering the role of individual variation when analysing movement and attempting to predict dispersal distances.
Following the continual decline of the Cape vulture Gyps coprotheres since the 1960s, captive breeding and rehabilitation programmes have been established to reinforce populations across southern Africa. This study examines the spatial ecology of captive-bred and rehabilitated vultures following release. Our analysis used 253,671 GPS fixes from 20 captive-bred and 13 rehabilitated birds to calculate home range sizes using kernel density estimation. We found that home range size did not differ significantly between captive-bred and rehabilitated birds. The location of home ranges differed: captive-bred birds showed greater site fidelity, remaining close to their release site, whereas rehabilitated birds dispersed more widely across the species' native range. By remaining close to their release site within a protected area, captive-bred birds had a significantly higher per cent of their GPS fixes within protected areas than did rehabilitated birds. Despite fidelity to their release site, captive-bred birds demonstrated innate capabilities for natural foraging behaviours and the same habitat selection strategy as rehabilitated individuals. These findings suggest that captive breeding and reinforcement of populations at declining colonies could provide localized benefits. Future long-term studies should seek to analyse survivorship and identify the breeding behaviour of these captive-bred birds once they reach sexual maturity.
Common kestrels are defined as partial migrants because they have variable migratory strategies over their geographic distribution, from obligate migrants in the north of Europe to more sedentary habits in central and southern regions. Migratory strategies are subject to a multiplicity of external and internal drivers, which are still not well understood. Many individual kestrels also disperse, rather than migrate, from the breeding or birth area. Dispersal distances are longer in females than in males and in yearlings than in older individuals. The dispersal is influenced by a number of factors, such as individual propensity and food availability. The deployment of GPS data-loggers and geolocators on kestrels will greatly improve our understanding of their movement ecology and help to discriminate between migration and dispersal.
Wetlands embedded in agroecosystems provide vital ecosystem services (i.e., freeze protection, water retention, nutrient cycling, biodiversity support). However, they are particularly susceptible to invasion by nonnative species. West Indian marsh grass [Hymenachne amplexicaulis (Rudge) Nees] is a major wetland invader in Florida. Despite the documented consequences of H. amplexicaulis invasions, the landscape factors influencing the spread of this species are poorly understood. In this study, we asked whether landscape factors associated with wetland isolation, connectivity, and land management influence the presence of H. amplexicaulis among wetlands embedded in pastures. We recorded the presence or absence of H. amplexicaulis in 158 seasonal wetlands embedded in different pasture types (semi-natural vs. intensively managed). Wetland area, isolation from neighboring wetlands, isolation from the nearest source ditch, and connectivity were determined using a geographic information system (GIS). We related landscape factors to H. amplexicaulis using generalized linear models and model selection based on the second-order Akaike information criterion. Hymenachne amplexicaulis was first detected at the study site in the early 2000s. By 2018, we observed this species in 66% of the surveyed wetlands. The likelihood of observing H. amplexicaulis was higher in wetlands embedded in semi-natural pastures and higher in less isolated wetlands, especially when connected to a ditch. These results indicate that H. amplexicaulis spreads both overland (during seasonal flooding) and via the ditch network. Future work is needed to understand whether seeds or stolons are the primary invasion propagule and whether the species forms a persistent seed bank that could slow down restoration efforts. Additionally, further research is required to understand the ecological impact of this highly invasive plant in Florida wetlands.
Globally, little is known about the dispersal abilities of carnivores, their survival in non-protected areas, and the connectivity between protected and non-protected populations. More than a decade of sighting data for 496 known African lions Panthera leo, with 189 individuals engaging in dispersing activities plus an exchange of cross-site information, has provided unique insight into connectivity and survival in unprotected and protected areas in Kenya. In particular, three individuals, across two generations residing solely in unprotected landscapes, demonstrated connectivity between three protected areas that, to our knowledge, have not previously been recognized as harbouring connected populations. These observations suggest that unprotected areas and the human communities that reside in them may successfully create corridors of tolerance that facilitate connectivity and the long-term persistence of lion populations, both within and outside protected areas.
To better understand the role of seed banks in ecological succession of dry forests, we compared similarities between vegetation and seed banks and assessed the relative contributions of seed dispersal and persistence in chronosequences in the Brazilian semi-arid region. To sample the standing vegetation and the seed bank, we collected data in three sites with three successional ages in each one (5 y, 25 y and 45 y). A total of 180 soil samples (three sites × three successional ages × 10 plots × two components) were collected. The composition of the seed bank was assessed by the seedling emergence method. Of 166 species identified in the standing vegetation, only 50 (30.1%) were also present in the seed bank, resulting in low similarity (Jaccard index = 0.02–0.21) and reflecting the rarity of woody species and the dominance of annuals (71% of richness). The relative importance of seed persistence and seed dispersal to seed banks composition were balanced in most cases (difference was not rejected in four out six comparisons). Those results suggest that seed banks in tropical dry forests are largely the result of high dispersal rates and the persistence of allochthonous annual species that contribute to decoupling seed bank and vegetation composition.
Habitat fragmentation is a major cause of biodiversity loss in agricultural landscapes. Studying habitat connectivity in fragmented landscapes is therefore pivotal for better understanding the factors that shape faunal communities in anthropogenic landscapes. Amphibians have limited dispersal abilities, strong site fidelity and often perform seasonal movements to reach relatively distant breeding habitats. This calls for a better knowledge of which landscape features might promote dispersal, especially in crops. We applied graph-theoretic network analyses to a set of 35 waterbodies embedded in 10 rice fields in a savanna–rain forest ecotone, Tocantins, Brazil, to assess the importance of landscape features (forest patches, waterbodies) for anuran functional connectivity within the entire network. We used taxonomic, functional and phylogenetic diversity as proxies of anuran functional connectivity (i.e. dispersal ability intrinsic to the taxa), based on previous associations uncovered between species diversity metrics and landscape connectivity. We found that, assuming individuals belonging to each of the 14 amphibian species recorded are unable to disperse over 800 m, forest and waterbody area and abundance are the most important predictors of waterbody importance for connectivity. Hence, pond network connectivity for amphibians in rice crops depends on (1) abundant and large forest patches in the area surrounding waterbodies, and (2) a network of abundant waterbodies.
Habitat fragmentation creates habitat edges, and ecological edge effects can cause major changes in the ecology and distribution of many taxa. However, these ecological changes may in turn influence animal movements and lead to molecular edge effects and edge-related genetic structure, matters that are largely unexplored. This study aims to infer molecular edge effects and to test three possible underlying mechanisms in the Endangered golden-brown mouse lemur Microcebus ravelobensis, a nocturnal species in the dry deciduous forest of the Ankarafantsika National Park in north-western Madagascar. Mouse lemurs were sampled in one edge and two interior habitats in close proximity to each other (500–1,400 m) in a continuous forest. A total of 41 mouse lemur samples were genotyped with seven nuclear microsatellites, and a fragment of the mitochondrial control region was sequenced for all samples. The overall genetic diversity (allelic richness, heterozygosity, haplotype richness, nucleotide diversity) was lower in the edge habitat compared to the two interior sites and all subpopulations showed signals of relatively low genetic exchange and significant genetic differentiation between them despite the short geographical distances, supporting the local preference model. These findings can be interpreted as preliminary signals of a molecular edge effect and suggest the potential for local adaptation. They are highly relevant for the conservation of fragmented populations, because a further subdivision of already small populations may increase their vulnerability to stochastic demographic changes and collapse.
There are a number of studies describing the gross range of morpho-anatomical variability in epiphytic Tillandsia species, but the interspecific variation in seed traits remain largely unexplored, although these play an important role in determining dispersal and establishment success. In order to evaluate interspecific variation in seed morphology, anatomy and germination, we sampled six Tillandsia species from the Yucatan peninsula, Mexico, distributed along a precipitation gradient. We studied morpho-anatomical traits (seed length, seed mass, ratio of coma to seed, ratio of embryo to endosperm), seed terminal velocity in still air, and performed histochemical analyses and germination trials under controlled conditions. Tillandsia recurvata differs from the other five species in the structure of the plumose coma; it was the only species lacking an endosperm and showed distinct seedling development. Among the species, bigger seeds were related to longer comas, and had higher germinability. Overall, seed terminal velocity was invariably slow, compared with reports of other anemochorous species, suggesting a high dispersal potential. Taxonomical and ecological implications of our results are discussed.
The main phases of plant dispersal into, and out of the South-East Asian region are discussed in relation to plate tectonics and changing climates. The South-East Asian area was a backwater of angiosperm evolution until the collision of the Indian Plate with Asia during the early Cenozoic. The Late Cretaceous remains poorly understood, but the Paleocene topography was mountainous, and the climate was probably seasonally dry, with the result that frost-tolerant conifers were common in upland areas and a low-diversity East Asian aspect flora occurred at low altitudes. India's drift into the perhumid low latitudes during the Eocene brought opportunities for the dispersal into South-East Asia of diverse groups of megathermal angiosperms which originated in West Gondwana. They successfully dispersed and became established across the South-East Asian region, initially carried by wind or birds, beginning at about 49 Ma, and with a terrestrial connection after about 41 Ma. Many Paleocene lineages probably went extinct, but a few dispersed in the opposite direction into India. The Oligocene was a time of seasonally dry climates except along the eastern and southern seaboard of Sundaland, but with the collision of the Australian Plate with Sunda at the end of the Oligocene widespread perhumid conditions became established across the region. The uplift of the Himalaya, coinciding with the middle Miocene thermal maximum, created opportunities for South-East Asian evergreen taxa to disperse into north India, and then with the late Miocene strengthening of the Indian monsoon, seasonally dry conditions expanded across India and Indochina, resulting eventually in the disappearance of closed forest over much of the Indian peninsula. This drying affected Sunda, but it is thought unlikely that a ‘savanna’ corridor was present across Sunda during the Pleistocene. Some dispersals from Australasia occurred following its collision with Sunda and following the uplift of New Guinea and the islands of Wallacea, Gondwanan montane taxa also found their way into the region. Phases of uplift across the Sunda region created opportunities for allopatric speciation and further dispersal opportunities. There is abundant evidence to suggest that the Pleistocene refuge theory applies to the South-East Asian region.
Mitochondrial and nuclear sequence data from two Antarctic ameronothroid mites, Halozetes belgicae and Alaskozetes antarcticus, were used to address three key questions important for understanding both the evolution of biodiversity and its future conservation in the Antarctic Peninsula Region: i) Do populations of mites across the Antarctic Peninsula and Scotia Arc constitute distinct genetic lineages? ii) What implications does the spatial genetic structure in these species have for current understanding of the region’s glacial history? iii) What are the conservation implications of these findings? Our results indicate that both mite species have been present in the Antarctic since at least the Pliocene. At the regional scale, both species are comprised of a number of divergent, but sympatric, lineages that are genetically as distinct as some species within the genera Halozetes and Alaskozetes. At the local scale, complex structure suggests limited and stochastic post-Holocene dispersal. For both species, considerable spatial genetic structure exists across the region, similar to that found in other terrestrial invertebrates. These results support the implementation of stringent biosecurity measures for moving between the Scotia Arc islands and the Antarctic Peninsula, and throughout the latter, to conserve both evolutionary history and future evolutionary trajectories.
Although roads are often assumed to be barriers to the dispersal of arboreal species, there has been little empirical testing of this assumption. If arboreal animals are unable to cross roads, population subdivision may occur, or resources may become inaccessible. We tested the hypothesis that Route Nationale 4 (RN4), a paved highway, was a barrier to movement and dispersal of the Endangered golden-brown mouse lemur Microcebus ravelobensis in Ankarafantsika National Park, in north-west Madagascar. During June–August 2015 we conducted a capture–mark–recapture study at three sites: two adjacent to RN4 and one within intact forest without a potential barrier. During 2,294 trap nights we captured 120 golden-brown mouse lemurs 1,032 times. In roadside habitats we captured significantly more males than females, whereas the opposite was the case in interior forest habitat. We detected eighteen crossings of highway transects by nine individuals; however, all potential dispersal events involved males. In roadside habitat, movement was significantly inhibited in both males and females. We present some of the first data on the effects of roads on movement patterns in arboreal Malagasy mammals, showing species- and sex-biased effects of roads as dispersal barriers. Our findings indicate that roads may not be complete barriers to dispersal in lemurs. We recommend that conservation managers and scientists examine explicitly the effects of roads and natural arboreal bridges in Madagascar in future studies.