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Completing the global inventory of plants : species discovery and diversityGoodwin, Zoe A. January 2017 (has links)
To complete an online world Flora by 2020 rapid progress is required towards understanding the taxonomy and distributions of the world's plants. This ambitious target set by the Global Strategy for Plant Conservation is hampered by two facts; first, many species of seed plant remain poorly known and second, the process of improving taxonomy and discovering species is not well understood. Here I investigate in detail the taxonomy and process of species discovery in a genus of tropical plants, Aframomum by examining specimens, taxonomic literature and authors of specimen determinations. I demonstrate that >50% of Aframomum specimens did not have the correct name prior to a recent comprehensive revision, that the number of specimens in herbaria doubled between 1970 and 2000, and that these results are also found in other taxa. I deconstruct the process of âspecies discovery' by identifying four key events: Initial collection, publication, conservation assessment, and distribution mapping. The time lags between the initial collection and completion of a) an accurate conservation assessment (101 years) and b) a comprehensive distribution map (115 years) demonstrate that many seed plant species published in the last 100 years are not fully understood. This is partly due to the fact that most species protologues (>90%) cite too few specimens at publication to produce an accurate conservation assessment. Furthermore, I explore variation in species' distribution patterns over time, taking account of specimen misidentification. Taken together the thesis identifies the lack of taxonomic capacity to efficiently deal with the tremendous influx of specimens since 1970, the poor current state of taxonomic knowledge of many taxa, and three significant time lags in the process of species discovery. Focused taxonomic effort is required for the successful completion of a world online Flora with conservation assessments to meet the 2020 GSPC target.
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Are Species’ Geographic Ranges Mainly Determined by Climate?Rich, Johnathan January 2017 (has links)
Aim
It is commonly asserted that climate presents the primary constraint on species’ geographic distributions, and therefore, that species' ranges shift in response to changing climate given their specific climatic tolerances. However, supporting evidence is surprisingly inconsistent. Alternatively, spatially structured processes (e.g., dispersal) could more strongly determine species’ geographic distributions. Is climate the primary determinant of species’ geographic distributions, or might non-climatic, spatial processes constitute a stronger influence, such that the effect of climate is indirect? This study tests a number of predictions made by each of these hypotheses, during a single period of time.
Location
Contiguous United States and southern Canada.
Methods
We used 19 species of passerine birds whose distributions fall entirely within the area sampled by the North American Breeding Bird Survey from 1990-2000. We related these distributions to the mean breeding season climate, geographic locations and neighbourhood effects. Two spatial scales were addressed to assess the geographic location of species’ ranges and species' distributions within ranges.
Results
On average, geographic coordinates and a model representing neighbourhood occupancy outperform a simple climatic model. After controlling for geographic coordinates, species occupancy is poorly related to climate. A neighbourhood model on average accounts for the majority of variance captured by geographic coordinates within ranges, and more for the continental placement of ranges. Spatially explicit variables are more important than macroclimatic variables in a predictive model of species occupancy on average.
Main Conclusions
The geographic distributions of wide-spread North American passerine birds appear not to be primarily determined by climate. Our results are consistent with the hypothesis that localized spatial processes such as dispersal are stronger determinants of both continental range placement and within-range distributions of North American birds.
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Como o comportamento animal pode influenciar a distribuição das espécies / The influence of animal behavior on species distributionsLima, Herlander Correia de 21 March 2018 (has links)
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Previous issue date: 2018-03-21 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Research in animal personality is increasing our understanding of what prevents a species from
colonizing new areas, which is one of the outstanding questions in biogeography. Some
behavioral types can perform better than others in specific stages involved in range expansion.
For example, a high exploratory behavior increases the chances of finding new resources in novel
environments. However, inconsistent results in the literature hindered a definite recognition of the
role of animal personalities on species distributions. I collected data available in the literature and
performed a bayesian meta-analysis to assess which behavioral types are driving range expansion
in the following biogeographical processes: dispersal, migration and invasion. I used several
moderators to try to discern context-dependencies in effect sizes. A hierarchical model, with
effect sizes nested within studies, revealed that more exploratory and bolder behaviors facilitate
range expansion. Also, I found that invasive individuals are more likely to be more exploratory
and more active than natives, while dispersers are generally bolder and more exploratory than
non-dispersers. Yet, the low study sample size obtained for analysis stresses the need to conduct
more primary studies. Results highlight the role of behavioral traits in species distributions and
increase our knowledge about which ecological characteristics might prepare species to endure
the current global environmental challenges. / A pesquisa em personalidade animal está aumentando o nosso conhecimento sobre o que
previne uma espécie de colonizar novas áreas, sendo esta uma das principais questões em
biogeografia. Alguns tipos de comportamento podem resultar em melhor desempenho que outros
em específicos estágios de expansão do território. Por exemplo, um comportamento mais
exploratório facilita a descoberta de recursos em um novo meio. Contudo, resultados
inconsistentes na literatura estão dificultando um reconhecimento do papel da personalidade
animal na distribuição das espécies. Coletei dados da literatura e realizei uma meta-análise
bayesiana para determinar que tipos de comportamento são responsáveis pela expansão do
território através dos processos biogeográficos de: dispersão, invasão e migração. Fiz ainda uso
de vários moderadores na tentativa de identificar contexto-dependências nos tamanhos de efeito.
Em um modelo hierárquico, usando tamanhos de efeito aninhados dentro dos estudos, mostro que
um comportamento mais ousado e mais exploratório facilita o sucesso na expansão do território.
Para além disso, eu demonstro que invasores são mais exploratórios e mais ativos que nativos, e
dispersores são mais exploratórios e ousados que não-dispersores. Contudo, o baixo tamanho
amostral obtido para as análises demonstra a necessidade de conduzir mais estudos primários. Os
resultados realçam o papel dos traços comportamentais na distribuição das espécies e aumentam
o nosso conhecimento sobre que características ecológicas podem preparar as espécies para
resistir aos desafios das mudanças ambientais.
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Assessing factors influencing the spatial distribution of species diversity in ground dwelling ant assemblages in lowland, wet forest of southwest Sri LankaGunawardene, Nihara R January 2008 (has links)
Tropical forests of the world are fast disappearing and there is a race to understand patterns of species distribution in space and time. Studying species distributions can provide better frameworks for conservation of these ecologically important patches of floral and faunal diversity. The island of Sri Lanka is a well known harbour of unique and highly threatened biodiversity. Tropical lowland forest is remnant in the south-west of the island now mainly existing in small patches. While most are small disturbed fragments, Sinharaja Forest Reserve represents one of the largest remaining patches of this important ecosystem. As a UNESCO World Heritage Site and a Man and Biosphere Reserve, it has a dual role as a conservation area and a historically important resource forest. While the distribution of vegetation diversity has been well documented, analyses of invertebrate species distributions are lacking. This thesis investigated a key arthropod group, ground dwelling ants, in relation to environmental gradients within the forest. Cumulative results demonstrate the high diversity of the forest patch. In an area representing less than half the reserve, over 173 ground dwelling ant species were found in distinct assemblages throughout the forest. Since the forest is located upon a series of parallel ridges, ant species distribution was first analysed in terms of this small elevation change. Species richness declined over a vertical incline from 430 m to 660 m, highlighting a possible small-scale, mountain mass effect. This section of the reserve is also characterised by a patch of once-logged forest (30 years previously). A study was undertaken to investigate whether there were residual effects of selective logging on the reserve. / Significant differences between species assemblages in once-logged forest and unlogged forest add to growing evidence that selectively logged forests continue to remain distinct from unlogged forest even after decades of regeneration. Ant distribution was then analysed for their relationship with habitat heterogeneity and tree species distribution. Long-term research on tree species in the SFR has demonstrated a close relationship to habitat complexity. Ant species appear to respond more to the structural heterogeneity of the vegetation than to actual topographic variation within the forest. From a conservation perspective, maintaining the integrity of this highly diverse forest is imperative. The impact of anthropogenic land uses surrounding the forest was investigated in terms of ant assemblages along the forest edges. Significant differences were found between assemblages within the edges bordered by different matrix types. Even relatively large forest remnants can be affected by the surrounding matrix land uses and encouraging the growth of structurally similar vegetation and maintaining low disturbance along the borders should attenuate the effect of the edge. Overall, the highly heterogeneous distribution of ant assemblages within the SFR demonstrates the potential for other small patches to be harbours of further species diversity. Future research should be undertaken to assess the diversity and distribution of ant species within this region and encourage the protection of this remnant diversity.
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Conserving Moving Species under Changing Landscapes and ClimatesLoarie, Scott Robbins 04 August 2008 (has links)
<p>To conserve biodiversity, it is critical to understand the dynamic landscapes and climates through which species move and how the environment influences movement choices. In particular, I am interested in how species respond to human modifications to landscapes and climates. Chapter 1 uses datasets on the spatial and temporal coverage of remotely sensed land cover datasets to examine gaps in the monitoring of environmental priorities. Temporal gaps in Landsat and spatial gaps in commercial high resolution satellites such as QuickBird may hinder land cover change monitoring efforts.</p><p>Chapter 2 uses Global Climate Models and museum specimens to projects the impact of climate change on the flora of California, a global biodiversity hotspot. With anticipated climate change, up to 66% may experience >80% reductions in range size within a century. These projections are less severe if plants are able to disperse in time. With no constraints on dispersal, plant centroids move an average of up to 150 km. The projections identify regions where species undergoing severe range reductions may persist. Protecting these potential future refugia and facilitating species dispersal may be essential to maintain biodiversity in the face of climate change.</p><p>Chapter 3 analyzes the movements of 73 elephants fitted with GPS collars against 4 remotely sensed datasets spanning a strong rainfall gradient across 7 southern African countries. Movements show strong seasonal and geographic differences across the study area. Two major human interventions, artificial water and fences, distort these movement patterns by increasing dry season ranging patterns and increasing the density of wet season movements.</p><p>Chapter 4 uses the datasets described in chapter 3 to explore elephant vegetation preferences. Elephants consistently prefer greener vegetation throughout the year. Vegetation preferences vary seasonally. Elephants prefer less variable vegetation such as forests in the dry season and ephemeral vegetation such as grasslands in the wet season.</p><p>Chapter 5 uses telemetry and remotely sensed landcover data to ask how climatic factors - snow cover - and land cover - agriculture and roads - influence pronghorn movements in South Eastern Alberta. Analysis using a Bayesian movement model reveals that each of these features significantly influences pronghorn movement choices.</p> / Dissertation
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Evaluating the influence of ecosystem characteristics and species traits on exotic species distributionsLázaro-Lobo, Adrián 06 August 2021 (has links) (PDF)
Natural dispersal mechanisms and biogeographical barriers have shaped species' native distributional ranges over millions of years. However, over the last few centuries, humans have dispersed species beyond their natural ranges. Those species that undergo explosive population growth and rapid expansion in the introduced region are considered as invasive because they have the potential to cause negative effects on desirable species and/or ecosystem services. In chapter II, I identified what ecosystem characteristics are more closely associated with successful establishment of exotic and native species, to have a better idea of where to concentrate our efforts and resources to prevent invasion events while preserving native species. I found that native and exotic species were differently affected by ecosystem properties. Exotic species were favored by human activities and low native species abundance and diversity. However, in Chapter III, I found that species functional traits, such as growth form and phenology, are more important to explain their response to ecosystem characteristics than native status under certain circumstances. The abundance and reproductive capacity of the evaluated plants were reduced when disturbances occurred during their respective active growing periods. This finding suggests that we need to have into account species-specific responses to ecosystem characteristics when managing biological invasions. Chapter IV examined phenotypic differentiation of native, expansive, and introduced populations of Baccharis halimifolia L. occurring in different regions of the world. The results suggest that there are significant phenotypic differences in germination and early growth among native, expansive, and introduced populations, which could have contributed to the success of B. halimifolia in the introduced and expansive ranges. Finally, in Chapter V, I used the information that I learned in the past projects to predict the spread of 45 exotic plants across southeastern United States and evaluated what landscape factors make an area more susceptible to be invaded. I found that the influence of landscape composition and configuration on invasion risk is species-specific. This result suggests that not only we have to consider species functional traits when managing biological invasions, as we saw earlier in the experiment with disturbance timing, but also species habitat preferences.
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Ecological analysis of large floristic and plant-sociological datasets – opportunities and limitationsGoedecke, Florian 04 May 2018 (has links)
No description available.
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The Genus Milnesium (Tardigrada: Eutardigrada: Milnesiidae) in the Great Smoky Mountains National Park (North Carolina and Tennessee, USA), With the Description of Milnesium Bohleberi sp. Nov.Bartels, Paul J., Nelson, Diane R., Kaczmarek, Łukasz, Michalczyk, Łukasz 30 June 2014 (has links)
For many decades the genus Milnesium was thought to consist of a single, cosmopolitan species: Milnesium tardigradum Doyere, 1840. However, recently the genus has been re-evaluated, and numerous new species have been described. Cur-rently, over twenty extant species and one fossil are recognised, and most appear to have very narrow geographic ranges. It is doubtful that M. tardigradum sensu stricto is truly cosmopolitan, but to evaluate this hypothesis, specimens previously identified as M. tardigradum must be re-examined using newly proposed taxonomic characters. As part of the All Taxa Biodiversity Inventory (ATBI) we collected Milnesium specimens from various locations in the Great Smoky Mountains National Park (GSMNP). Two Milnesium species have been evaluated, and one of them, Milnesium bohleberi sp. nov., is new to science. The new species is most similar to M. eurystomum but differs by shorter claws and a shorter, narrower, and more cylindrical buccal tube. The other Milnesium species, very rare in our collection, is morphologically indistin-guishable from Milnesium granulatum Ramazzotti 1962, which was previously known only from Chile, Italy and Roma-nia. Based on the recently revised description of M. tardigradum sensu stricto, this nominal species for the genus has not been found in the GSMNP samples.
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Comparison of MaxEnt and boosted regression tree model performance in predicting the spatial distribution of threatened plant, Telephus spurge (Euphorbia telephioides)Mainella, Alexa Marie 29 April 2016 (has links)
No description available.
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Species Endemism: Predicting Broad-Scale Patterns and Conservation PrioritiesZuloaga Villamizar, Juan Gerardo January 2018 (has links)
Do thermal barriers limit biotic composition and community similarity, potentially helping to shape biodiversity patterns at continental scales? Are environmental variables responsible for broad-scale patterns of species endemism? Are these patterns predictable? And, how can patterns of endemism can inform global conservation strategies? These are some of the questions that I attempted to answer during my doctoral research.
In the first chapter, I tested one of the most contentious hypotheses in ecology: Do thermal barriers, which grow stronger along elevational gradients across tropical mountains, create a dispersal barrier to organisms and consequently contribute to the isolation and divergence of species assemblages? If so, do patterns potentially generated by this mechanism detectably relate to dissimilarity of biotic assemblages along altitudinal gradients across the mountains in the Americas? We found that mountain passes are not only higher in tropical realms, as initially thought by Janzen (1967), and extensively popularized and assumed in further research, but they are also present in temperate regions along the western coast of North America. We also found that the stronger the thermal barrier, the higher the dissimilarity between communities. However, the variance explained was low, suggesting thermal barriers play a minor role in creating and maintaining patterns of biodiversity.
The second chapter raises the question of why are there more small-ranged species in some places than in others. I tested four macroecological hypotheses (H1: climate velocity; H2: climate seasonality; H3: climate distinctiveness or rarity; and, H4: spatial heterogeneity in contemporary climate, topography or habitat) to predict broad-scale patterns of species endemism, using a cross-continental validation approach. We found that there is no empirical reason, from the standpoint of model fitting, parameter estimates, and model validation, to claim that any of these hypotheses creates and maintains broad-scale patterns of endemism. Although we found statistically significant relationships, they failed stronger tests of a causal relationship, namely accurate prediction. That is, the hypotheses did not survive the test of cross-continental validation, failing to predict observed patterns of endemism. Climate velocity was dropped from some models, suggesting that early correlations in some places probably reflect collinearity with topography. The effect of richness on endemism was in some cases negligible, suggesting that patterns of endemism are not driven by the same variables as total richness. Despite low explained variance, spatial heterogeneity in potential evapotranspiration was the most consistent predictor in all models.
The third chapter is aimed to evaluate the extent to which global protected areas (PAs) have included endemic species (species with small range size relative to the median range size). We measure the relative coverage of endemic species by overlapping species geographic ranges for amphibians, mammals, and birds, with the world database of PAs (1990-2016). Then we measure the rate of expansion of the global PA network and the rate of change in endemic species coverage.
We found that ~30% of amphibian, ~6% of bird and ~10% of mammal endemic species are completely outside PAs. Most endemic species’ ranges intersect the PA network (amphibian species = 58%; birds = 83%; mammals = 86%), but it usually covers less than 50% of their geographic range. Almost 50% of species outside the PA network are considered threatened (critically endangered, endangered and vulnerable). We identified that ecoregions in tropical Andes, Mesoamerica, Pacific Islands (e.g., New Guinea, Solomon), Dry Chaco, and Atlantic forests are major conservation priorities areas.
The historic rates of new PAs added every year to the network is between ~6,000 to ~15,000. In contrast, we found that rates of including endemic species within the PA network have been fairly slow. Historic data shows that every year, the entire geographic range of 3 (amphibians) to 6 (birds and mammals) endemic species is 100% included inside the PA network (amphibians = from 162 to 233; mammals = 10 to 84; and, amphibians = 16 to 99). Based on these trends, it is very unlikely PAs will include all endemic species (14% total endemic species, that is ~1,508 out of 11,274) currently outside the PA network by 2020. It will require five times the effort made in the last two decades. However, projections also showed that is very likely that some portions of the geographic ranges for all endemic birds and mammals, but not for all endemic amphibians, will be covered by the future PA network.
I sum, I found that none of the hypotheses tested here can explain broad-scale patterns of total species richness and total species endemism. My main contribution on this research area is clearly rejecting these hypotheses from potential candidates that may explain biodiversity patterns. By removing them, we advance in this field and open possibilities to test new hypotheses and evaluate their mechanisms. I proposed that other drivers and mechanisms (whether biotic and biotic) acting at local scales, and escaping the detection of macroecological approaches, might be responsible for these patterns. Finally, in terms of conservation planning, I proposed that the international community has an opportunity to protect a great number of endemic species and their habitats before 2020, if they strategically create new PAs.
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