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Jarryd Alexander

Other affiliations: University of the Witwatersrand
Bio: Jarryd Alexander is an academic researcher from University of KwaZulu-Natal. The author has contributed to research in topics: Biodiversity & Species evenness. The author has an hindex of 5, co-authored 8 publications receiving 52 citations. Previous affiliations of Jarryd Alexander include University of the Witwatersrand.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the effects of changing land use, and especially urbanisation, on species and functional diversity are of global concern, and the influence of differing land-cover covariates on all three components of functional diversity (functional richness, evenness, and divergence) were determined through a series of general linear models.
Abstract: The effects of changing land use, and especially urbanisation, on species and functional diversity are of global concern. Eco-estates are a form of urban housing development that is suggested to partially negate the effects of landscape development. We assessed avian functional diversity at four eco-estates (previously sugarcane plantations) and one sugarcane plantation site along the north coast of KwaZulu-Natal (KZN), South Africa. We determined whether the differing development, management types, and the effects of land-cover configuration and composition at the respective study sites influenced avian functional diversity. Fixed-radius point-count surveys were conducted within varying levels of land cover (natural, semi-natural, golf course and urban) at each eco-estate, and at a control sugarcane plantation site (natural, sugarcane-natural, and sugarcane land cover). The influence of differing land-cover covariates on all three components of functional diversity (functional richness, evenness, and divergence) were determined through a series of general linear models. Sections of the respective study sites with increased natural land cover, mainly in the form of indigenous forest and coastal thicket/dense bush, showed improved avian functional diversity in comparison to those with increased building and road density. Negative effects of increased building density may be offset through an interconnection with or incorporation within natural land cover. Each component of functional diversity was influenced dynamically by seasonal changes and depending on land-cover type. Eco-estates improved avian functional diversity if natural habitats are emphasised and connected. We suggest future development and management for eco-estates and agricultural land in coastal KZN follow ecological land-use complementation, to improve local ecosystem functioning.

21 citations

Journal ArticleDOI
TL;DR: In this article, the authors assessed whether eco-estates along the coast of KwaZulu-Natal (KZN) were ecologically connected to a) one another, and b) the surrounding natural landscape.

13 citations

Journal ArticleDOI
TL;DR: This paper reviewed case studies of vertebrate species' responses to urbanisation in KwaZulu-Natal, South Africa, to determine trends and presented a novel modification to the final of three phases of the framework described by Evans et al. (2010).
Abstract: Urbanisation is rapidly transforming natural landscapes with consequences for biodiversity. Little is documented on the response of African wildlife to urbanisation. We reviewed case studies of vertebrate species' responses to urbanisation in KwaZulu-Natal, South Africa to determine trends. Connected habitat mosaics of natural and anthropogenic green spaces are critical for urban wildlife persistence. We present a novel modification to the final of three phases of the framework described by Evans et al. (2010), which documents this sequence for vertebrate species persistence, based on the perspective of our research. Species in suburbia exhibit an initial phase where behavioural and ecological flexibility, life-history traits and phenotypic plasticity either contribute to their success, or they stay at low numbers. Where successful, the next phase is a rapid increase in populations and distribution; anthropogenic food resources and alternate breeding sites are effectively exploited. The modified third phase either continues to spread, plateau or decline.

12 citations

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TL;DR: It is suggested that further analyses of feathers, across a range of spatial and temporal scales, will enhance stable isotope analyses as a valuable tool in monitoring and combatting the trade of African grey parrots.
Abstract: Stable isotope analyses are a powerful tool in understanding diets, defining trophic networks, inferring geographical origins of animals and in forensic tracing of the origins of deceased humans or illegally traded animal and plant material. African grey parrots Psittacus erithacus are one of the most traded animal species in the world, and the origin of confiscated illegal or deceased specimens are often unknown. We measured stable isotope values (δ¹³C, δ¹⁵N and δ²H) in different African grey parrots (n = 32) and determined feather type (i.e. primary, tail, breast) standardization values for comparing individuals. δ¹³C and δ²H values differed between known wild (n = 42) and captive (n = 50) birds when standardized for feather type, but not for δ¹⁵N. δ¹³C and δ²H values in feathers from a consignment of African grey parrots (n = 100), all of which were deceased, aligned significantly with that of known wild birds. We suggest that further analyses of feathers, across a range of spatial and temporal scales, will enhance stable isotope analyses as a valuable tool in monitoring and combatting the trade of African grey parrots. Furthermore, the use of stable isotope analyses may improve the monitoring of illegally traded bird species, and other wildlife, across the globe.

11 citations

Journal ArticleDOI
TL;DR: In this article, a multi-taxa assessment of the three components of functional diversity (functional richness, functional evenness, and functional divergence) suggested that eco-estate development was improving certain components for each of the taxa assessed.

10 citations


Cited by
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Journal ArticleDOI
TL;DR: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols used xiii 1.
Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

14,171 citations

01 Jan 1980
TL;DR: In this article, the influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition and found that the variability of the relationship between the δ^(15)N values of animals and their diets is greater for different individuals raised on the same diet than for the same species raised on different diets.
Abstract: The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition. The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ^(15)N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ^(15)N values. The variability of the relationship between the δ^(15)N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ^(15)N relative to the diet, with the difference between the δ^(15)N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ^(15)N values of collagen and chitin, biochemical components that are often preserved in fossil animal remains, are also related to the δ^(15)N value of the diet. The dependence of the δ^(15)N values of whole animals and their tissues and biochemical components on the δ^(15)N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ^(15)N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources. The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ^(15)C and δ^(15)N values of bone collagen suggest that C_4 and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.

5,548 citations

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TL;DR: The first comprehensive global meta-analysis on the effects of human disturbances on functional diversity of birds is provided, indicating a consistent negative effect of disturbances on bird functional diversity, regardless of the variability caused by the different predictor variables considered.

47 citations

Journal ArticleDOI
TL;DR: In this article, the authors conducted a systematic literature review to explore how an ecological justice perspective can advance the understanding of nature-based solutions, and argued that ecological justice, which builds on the equitable distribution of environmental goods and bads, social-ecological interconnectedness, nature's agency and capabilities, and participation and inclusion in decision-making, provides a transformative framework for rethinking naturebased solutions in and for cities.
Abstract: Planning for and implementing multifunctional nature-based solutions can improve urban ecosystems' adaptation to climate change, foster urban resilience, and enable social and environmental innovation. There is, however, a knowledge gap in how to design and plan nature-based solutions in a nonanthropocentric manner that enhances co-benefits for humans and nonhuman living organisms. To address this gap, we conducted a systematic literature review to explore how an ecological justice perspective can advance the understanding of nature-based solutions. We argue that ecological justice, which builds on the equitable distribution of environmental goods and bads, social-ecological interconnectedness, nature's agency and capabilities, and participation and inclusion in decision-making, provides a transformative framework for rethinking nature-based solutions in and for cities. A qualitative analysis of 121 peer-reviewed records shows a highly human-centred worldview for delivering nature-based solutions and a relationship to social justice with no direct reference to the dimensions of ecological justice. There is, however, an underlying recognition of the importance of nonhumans, ecosystem integrity and well-being, and a need to consider their needs and capacities through multispecies nature-based solutions design and planning. We conclude with a discussion of the critical aspects for designing and planning ecologically just cities through nature-based solutions and future research directions to further integrate these fields.

28 citations

Journal ArticleDOI
TL;DR: The use of stable isotope approaches to examine the movements and ecology of wildlife has been widespread over the past two decades as mentioned in this paper, and there are few guides for how to best employ these methods for management.

27 citations