Research

Evolution of sperm morphology and sperm competition in Afrotropical songbirds

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Extreme variation exists in sperm morphology (sperm length and components) across the animal kingdom. In birds, most studies of sperm diversity originated from Northern Temperate regions, leaving us with doubt about the extent of sperm variation in Afrotropical avian species. Knowledge of avian sperm morphology and sperm competition is limited in tropical birds, thus needing paramount attention. This project focused on investigating the evolution of sperm morphology and sperm competition in birds from the African Continent using comparative analysis. The specific objectives are to determine variation within and between male variation in sperm morphology at the intra- and inter-specific level across birds; and determine levels of variation in sperm competition across the avian species and associated effects socio-ecological traits. This also extends to analysis of evolutionary rates in sperm morphology using evolutionary models. 

[Principal Investigator: Dr. Taiwo Crossby, EU & APLORI]

[Collaborators: Prof. Jan T. Lifjeld, Norway; Prof. Ulf Ottosson, APLORI; Prof. Tomas Abrecht, Czechia]

[Funder: RCN, IFS, CSF]

The interaction between avian malaria, immunity and gross sperm morphology

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Few studies have shown the impact of pathogens on sperm ultra-structure. In birds, this understanding is limited including that of sexually transmitted diseases. It is not uncommon to observe physiological or anatomical deformity in sperm cells within an ejaculate but whether disease causing pathogens can jeopardize ability to produce normal and viable sperm cells and thus reduce individual fitness, is unclear. Specifically, avian malaria -vector-transmitted disease- is caused by protozoa (Genera: Plasmodium and Haemoproteus); host are infected vectors (mosquitoes-Culicidae, biting midges-Ceratopogonidae, and louse flies obtain blood meals from host. Through an interdisciplinary collaborative approach, we investigate the relationship between haemosporidian infection, host immunity and gross sperm morphology. The objectives are to assess factors influencing exposure of bird species to malaria infection, and evaluate the immuno-responses of birds to avian malaria infection, and determine the sperm quality of avian malaria infected in comparison to non-infected.

[Principal Investigator: Dr. Taiwo Crossby, EU & APLORI]

[Collaborators: Tsomafo Constance, Ghana; Leonce Kouakanou, Benin; and Dr. Jesca Nakayima, Uganda] 

[Funder: IFS, NHM]

Colonial breeding and genetic diversity in the Village Weaver, Ploceus cucullatus 

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Population genetic and conservation effort are mostly focused on genetically depleted and isolated populations with little or no attention to wide, continuous, and spatially structured meta-population. Colonial breeding local populations of widely distributed species are scarcely studied in term of population structure and genetic diversity. Perhaps on the presumption that such population are genetically healthy due to widespread distribution. However, Some species may thrive in spite of poor genetic diversity; and widely distributed may not imply high genetic diversity. We adopt the Village weaver Ploceus cucullatus as a model system for this study through population genetic framework, with the intention to investigate sperm competition, genetic structure and diversity at the colonial (subpopulation) alongside other socio-ecological parameters in Nigeria and neighboring countries.

[Principal Investigator: Dr. Taiwo Crossby, EU & APLORI] 

[Collaborators: Prof. Jan T. Lifjeld, Dr. Lars E. Johannessen, Norway] 

[Funder: Fund seeking]

Spatio-temporal preference and variation in diet of tropical birds using metabarcoding

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Food resources are unevenly distributed in time and space, and at the same time season-bound (Oscillational-model). This compels most species to adjust food preference accordingly. Species migration and migration-driven food requirement may lead to food replacement and supplementation. As a consequent, diet composition may vary between seasons year-in and year-out, especially across the avian feeding guilds. We aim to investigate using metabarcoding pipeline, diet switches, supplementation and preference in the avian feeding guilds within the Afrotropical landscape.

[Principal Investigator: Taiwo Crossby, EU & APLORI] 

[Collaborators: None] 

[Funder: Fund seeking phase]

DNA Barcoding of birds and their ectoparasites in tropical Africa 

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DNA Barcoding has taken center-stage recently in helping to facilitate species identification; flag specimens that may represent new species; and provide insight into the evolutionary history of life on earth. The approach enables identifications where traditional methods are unrevealing; at the same time, encourage new technologies for DNA analysis which are faster, better, cheaper, and usable in field biology. Based on the little variation within species, and large distance between species  in a 'marker', species can be identified. This has recieved wide spectrum of application in forensic science, and environmental monitoring.  Limited capacities and facilities within tropical Africa lags the progress of work in this field especially in barcode libraries preparation and availability for species in the region.  As part of the International Barcode of Life (iBOL) project, and collaboration with NHM Oslo, the aim is to generate barcode libraries for birds and their parasite in tropical Africa, and at the same time build capacity in this area.

[Principal Coordinator: Dr. Taiwo Crossby, EU & APLORI] 

[Collaborators: Prof Jan Lifjeld, Norway] 

[Funder: Fund seeking phase]