Browsing by Author "Virani, Munir"

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    Assessment of pesticide concentrations in environmental and biological parameters from two Kenyan Rift Valley Lakes
    (2012) Gudka, Masumi; Simmons, Robert E; Virani, Munir
    In the last two decades Kenyan agriculture has developed rapidly. In particular, horticultural and floricultural activities have intensified on the riparian fringe of Lake Naivasha, a RAMSAR site. The lake supports a large variety of wildlife and avifauna in particular. In the 1980s, the African Fish-Eagle (Haliaeetus vocifer) population on the lake was the densest in Africa. As a top predator resident in the Kenyan Rift Valley Lakes the African Fish-Eagle is a good indicator of general ecosystem health but is also highly susceptible to toxic effects of pesticide contamination...Globally, most organochlorine pesticides have been banned, but endosulfan, HCH and methoxychlor are widely used in Kenya, while aldrin, dieldrin and lindane are restricted and DDT, endrin, and heptachlor banned. Studies examining residue levels of these harmful chemicals in African Fish-Eagles are limited to small sample sizes examined in the 1970s and 1980s. This study is the first comprehensive investigation of organochlorine residue contamination in biological and environmental parameters from Lake Naivasha and the control water body at Lake Baringo.
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    Tracing the colonization history of the Indian Ocean scops-owls (Strigiformes: Otus) with further insight into the spatio-temporal origin of the Malagasy avifauna
    (BioMed Central Ltd, 2008) Fuchs, Jerome; Pons, Jean-Marc; Goodman, Steven; Bretagnolle, Vincent; Melo, Martim; Bowie, Rauri; Currie, David; Safford, Roger; Virani, Munir; Thomsett, Simon; Hija, Alawi; Cruaud, Corinne; Pasquet, Eric
    BACKGROUND:The island of Madagascar and surrounding volcanic and coralline islands are considered to form a biodiversity hotspot with large numbers of unique taxa. The origin of this endemic fauna can be explained by two different factors: vicariance or over-water-dispersal. Deciphering which factor explains the current distributional pattern of a given taxonomic group requires robust phylogenies as well as estimates of divergence times. The lineage of Indian Ocean scops-owls (Otus: Strigidae) includes six or seven species that are endemic to Madagascar and portions of the Comoros and Seychelles archipelagos; little is known about the species limits, biogeographic affinities and relationships to each other. In the present study, using DNA sequence data gathered from six loci, we examine the biogeographic history of the Indian Ocean scops-owls. We also compare the pattern and timing of colonization of the Indian Ocean islands by scops-owls with divergence times already proposed for other bird taxa. RESULTS: Our analyses revealed that Indian Ocean islands scops-owls do not form a monophyletic assemblage: the Seychelles Otus insularis is genetically closer to the South-East Asian endemic O. sunia than to species from the Comoros and Madagascar. The Pemba Scops-owls O. pembaensis, often considered closely related to, if not conspecific with O. rutilus of Madagascar, is instead closely related to the African mainland O. senegalensis. Relationships among the Indian Ocean taxa from the Comoros and Madagascar are unresolved, despite the analysis of over 4000 bp, suggesting a diversification burst after the initial colonization event. We also highlight one case of putative back-colonization to the Asian mainland from an island ancestor (O. sunia). Our divergence date estimates, using a Bayesian relaxed clock method, suggest that all these events occurred during the last 3.6 myr; albeit colonization of the Indian Ocean islands were not synchronous, O. pembaensis diverged from O. senegalensis about 1.7 mya while species from Madagascar and the Comoro diverged from their continental sister-group about 3.6 mya. We highlight that our estimates coincide with estimates of diversification from other bird lineages. CONCLUSION: Our analyses revealed the occurrence of multiple synchronous colonization events of the Indian Ocean islands by scops-owls, at a time when faunistic exchanges involving Madagascar was common as a result of lowered sea-level that would have allowed the formation of stepping-stone islands. Patterns of diversification that emerged from the scops-owls data are: 1) a star-like pattern concerning the order of colonization of the Indian Ocean islands and 2) the high genetic distinctiveness among all Indian Ocean taxa, reinforcing their recognition as distinct species.