Use this URL to cite or link to this record in EThOS:
Title: Avian life in a seasonally arid tropical environment : adaptations and mechanisms in breeding, molt and immune function
Author: Nwaogu, Chima Josiah
ISNI:       0000 0004 7972 2080
Awarding Body: University of St Andrews
Current Institution: University of St Andrews
Date of Award: 2019
Availability of Full Text:
Access from EThOS:
Access from Institution:
There is a growing appreciation of the diversity and uniqueness of tropical organisms, but evidence about the selection pressures that shape this diversity remains sketchy. In this thesis, I investigated how variation in life history traits arises from tropical environmental seasonality, starting with the exploration of the annual cycle of the Common Bulbul Pycnonotus barbatus in Nigeria. This revealed that breeding was not seasonal, but moult was timed almost entirely to the wet season with only few individuals extending moult into the dry season This confirmed that breeding and to a lesser extent moult, are decoupled from season, thus, allowing me to test how breeding and moult affect immune function independent of seasonal environmental conditions. On testing this, I found that season explained variation in immune function better than breeding or moult, but unexpectedly, immune indices were higher in the dry season and during breeding, contrary to what I would expect if infection risk is higher in the wet season, and if breeding constrains resources for immune function. Furthermore, I compared immune indices along the cool-wet to hot-dry environmental gradient in Nigeria and found that immune indices were rather similar. I then tested the effect of diet alteration on immune function, body mass and moult of Common Bulbuls in captivity and found that bulbuls fed on fruits had a more immune function, body mass and onset of moult than those fed on invertebrates. These findings together suggest that environmental conditions affect immune function more directly than via resource allocation trade-offs, but that variation in immune function does not follow simple environmental productivity pattern as previously expected.
Supervisor: Tieleman, B. Irene Sponsor: Rijksuniversiteit Groningen ; Leventis Conservation Foundation ; University of St Andrews ; Koninklijke Nederlandse Akademie van Wetenschappen
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Life history strategies ; Annual cycle ; Tropical environment ; Diet ; Self-maintenance ; Reproduction ; Ecological immunology ; Common bulbul ; QL696.P268N8 ; Bulbuls ; Birds--Reproduction ; Birds--Immunology ; Animal life cycles--Tropics ; Molting