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You searched for subject:( Afrotropics). Showing records 1 – 2 of 2 total matches.

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1. Ivande, Samuel T. Distribution ecology of Palearctic migrants in the humid Guinea savannah in West Africa .

Degree: 2015, University of St. Andrews

Declines in breeding populations of most migrants across much of the Palearctic have been linked to environmental conditions in their African non-breeding grounds. Studying winter distribution dynamics for these species is necessary to understand how factors in these areas may influence their overall population dynamics. This thesis explored in detail the distribution ecology of migrants in the Guinea savannah, the region from where wintering migrants currently show the greatest breeding population declines. In particular, I investigated some prevailing but hitherto little tested ecological hypothesis concerning impacts of geographical, vegetation and anthropogenic characteristics on the densities and winter distribution of migrants in Africa. Migrant distribution seemed to fit a pattern where decisions leading to winter habitat choice and association were hierarchical and jointly influenced by factors extrinsic and intrinsic to the habitats at large and finer scales respectively. Migrants were distributed in reasonable densities across a wide range of habitats. There was also evidence for an independent effect of latitude on densities and distribution, even after controlling for habitat characteristics. There was no evidence of large changes in latitudinal density patterns within a given winter season and site density patterns were generally consistent over the study duration. Migrants and taxonomically-related/ecologically similar Afrotropical residents showed similarities in habitat requirements and utilization, although migrants utilized habitats over a wider latitudinal range. Some migrants tended to show correspondence in site occurrence between consecutive winters but less so within a given winter season and there was an overall low transferability of habitat models for Palearctic migrants between sites in Nigeria. Collectively, the results describe distribution mechanisms typical for ecologically flexible species that can best be described as habitat generalists. As generalists, migrants are expected to show some resilience, especially in dealing with local and small scale changes on their wintering grounds such that these are unlikely to be the primary limiting factor in their population dynamics. However, the scale of ongoing habitat change across much of Africa is perhaps contributing to overcome the resilience engendered by their generalism. Conservation efforts for these mainly generalists species may therefore aim to preserve habitat on a large scale, perhaps through the promotion of sustainable land use practices. Advisors/Committee Members: Cresswell, Will (advisor).

Subjects/Keywords: Palearctic migrants; Species distribution; Afrotropics; Conservation

Page 1

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Ivande, S. T. (2015). Distribution ecology of Palearctic migrants in the humid Guinea savannah in West Africa . (Thesis). University of St. Andrews. Retrieved from http://hdl.handle.net/10023/7446

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Ivande, Samuel T. “Distribution ecology of Palearctic migrants in the humid Guinea savannah in West Africa .” 2015. Thesis, University of St. Andrews. Accessed November 22, 2019. http://hdl.handle.net/10023/7446.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Ivande, Samuel T. “Distribution ecology of Palearctic migrants in the humid Guinea savannah in West Africa .” 2015. Web. 22 Nov 2019.

Vancouver:

Ivande ST. Distribution ecology of Palearctic migrants in the humid Guinea savannah in West Africa . [Internet] [Thesis]. University of St. Andrews; 2015. [cited 2019 Nov 22]. Available from: http://hdl.handle.net/10023/7446.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ivande ST. Distribution ecology of Palearctic migrants in the humid Guinea savannah in West Africa . [Thesis]. University of St. Andrews; 2015. Available from: http://hdl.handle.net/10023/7446

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Dijkstra, Klaas-Douwe Benediktus. Demise and rise: the biogeography and taxonomy of the Odonata of tropical Africa.

Degree: 2007, Department of Biology, Faculty of Mathematics and Natural Sciences, Leiden University

Africa has a large and almost uninterrupted land surface that is isolated from surrounding continents. In the last 20 million years Africa had a variable and increasingly dry climate. As a result the Afrotropics have only half as many odonate species as tropical America or Asia. ‘Relict’ families are scarce and concentrated in five isolated, climatically stable areas: (1) the Cameroon highlands, (2) locally in East Africa, (3) the Cape region, (4) the granitic Seychelles, and especially (5) Madagascar. Most African odonate species, about two-fifths, are restricted to the Central and West African forests. The remainder is found, in three fairly equal parts, in (1) the highlands from Arabia to the Cape, (2) Madagascar and surrounding archipelagos, and (3) open habitats throughout the region. Most mainland species appear related to the relatively diverse fauna of tropical Asia, but have few relatives on Madagascar, suggesting that the modern continental fauna mostly diversified after the arrival of Asian ancestors. Being best adapted to change, Coenagrionidae and Libellulidae are the largest odonate families on Earth. Only in temperate regions, impacted strongly by the ice ages, is their dominance comparable to that in changeable Africa. The climatic influence is further seen in forest species ‘stranded’ in highlands by forest reduction, savanna species ‘trapped’ by forest expansion, and overseas colonisation of East Africa by island species. Traditional theory is that speciation took place in habitat fragments created by climatic change, especially in forest refuges, but such refuges seem to conserve old species rather than generate new ones. Abrupt habitat gradients in heterogeneous landscapes may be more important in speciation, especially close to areas where potential ancestors are conserved. The habitat mosaic on the Congo-Zambezi watershed is the best modern example of such an area. Phylogenetic research of various African plants and animals indicate that environmental and dispersal barriers are easily straddled, with savanna species radiating from a forest ancestors and vice versa. Species were eliminated with climatic change, but new ecological space was also constantly created. Such processes must also have lead to the ‘demise’ of most of Africa’s old odonate diversity and the ‘rise’ of a rich new fauna.

Subjects/Keywords: Odonata; Dragonflies; Damselflies; Biogeography; Systematics; Distributions; Dispersal; Africa; Afrotropics; Odonata; Dragonflies; Damselflies; Biogeography; Systematics; Distributions; Dispersal; Africa; Afrotropics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Dijkstra, K. B. (2007). Demise and rise: the biogeography and taxonomy of the Odonata of tropical Africa. (Doctoral Dissertation). Department of Biology, Faculty of Mathematics and Natural Sciences, Leiden University. Retrieved from http://hdl.handle.net/1887/11969

Chicago Manual of Style (16th Edition):

Dijkstra, Klaas-Douwe Benediktus. “Demise and rise: the biogeography and taxonomy of the Odonata of tropical Africa.” 2007. Doctoral Dissertation, Department of Biology, Faculty of Mathematics and Natural Sciences, Leiden University. Accessed November 22, 2019. http://hdl.handle.net/1887/11969.

MLA Handbook (7th Edition):

Dijkstra, Klaas-Douwe Benediktus. “Demise and rise: the biogeography and taxonomy of the Odonata of tropical Africa.” 2007. Web. 22 Nov 2019.

Vancouver:

Dijkstra KB. Demise and rise: the biogeography and taxonomy of the Odonata of tropical Africa. [Internet] [Doctoral dissertation]. Department of Biology, Faculty of Mathematics and Natural Sciences, Leiden University; 2007. [cited 2019 Nov 22]. Available from: http://hdl.handle.net/1887/11969.

Council of Science Editors:

Dijkstra KB. Demise and rise: the biogeography and taxonomy of the Odonata of tropical Africa. [Doctoral Dissertation]. Department of Biology, Faculty of Mathematics and Natural Sciences, Leiden University; 2007. Available from: http://hdl.handle.net/1887/11969

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