Ecological & Evolutionary Physiology

Coordinator

Assoc. Prof. Andrew McKechnie

Research Team

Dr Susan Cunningham (PFIAO)
Prof. Phil Hockey (PFIAO)
Dr Rowan Martin (PFIAO)
Prof. Mark Brigham (University of Regina, Canada)
Dr Blair Wolf (University of New Mexico, USA)
Prof. Barry Lovegrove (University of KwaZulu-Natal)
Dr Justin Boyles (University of Pretoria)
Dr Nomakwezi Mzilikazi (Nelson Mandela Metropolitan University)
Dr Stephan Woodborne (CSIR, Pretoria)
Mr Ben Smit (PhD student, University of Pretoria)
Ms Fadzai Matsvimbo (MSc student, University of Pretoria)

Overview

Research in the area of Ecological and Evolutionary Physiology focuses on the interactions between birds and their physical environments. We are particularly interested in the ways in which birds match their energy and water requirements to the availability of resources, and how natural selection has operated on the physiological machinery of species inhabiting various habitats. Another key focus area at present is climate change; many of the impacts of warmer temperatures are going to be driven by from changes in energy and water requirements, and physiological research tools will be vital for predicting and mediating these impacts.

Related Publications

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Climate change and birds in hot deserts

Research Team: Prof. Phil Hockey, Assoc. Prof. Andrew McKechnie, Dr Rowan Martin, Mr Ben Smit

Collaborators: Dr Blair Wolf

Climate change is having profound impacts on biological systems. Desert birds are particularly vulnerable to rising temperatures, since many species inhabit areas characterized by extremely hot weather in summer. For these birds, the rates at which they must evaporate water to keep cool increase rapidly with increasing air temperature, and may exceed 5 % of body mass per hour during extremely hot weather. Birds are thought to be able to tolerate dehydration levels of 10-20% of body mass, but during very hot weather they can rapidly reach these limits and become fatally dehydrated. These challenges are compounded in desert environments, since water demands are high but water resources are scarce and highly unpredictable. Catastrophic mortality events among desert bird communities during extreme heat waves have been recorded in the past, particularly in the Australian deserts. Our research into the impacts of climate change on desert birds uses several complementary approaches to model the impacts of increased temperatures on avian behaviour and physiology. Most of this research is currently taking place in Tswalu Kalahari Private Game Reserve.

Acknowledgments: E. Oppenheimer & Son allowed this work to take place at Tswalu Kalahari Private Game Reserve, and provided generous logistical support.

Torpor and hibernation in southern African birds

Research Team: Assoc. Prof. Andrew McKechnie, Mr Ben Smit

Collaborators: Prof. Mark Brigham, Dr Justin Boyles, Prof. Barry Lovegrove

This project addresses three questions that are essential for a better understanding of avian facultative hypothermic responses. The first of these questions concerns the phylogenetic distributions of hibernation, torpor, and shallow rest-phase hypothermia in southern African birds, and the consequences for understanding the evolution of these responses. The second question relates to the ecological consequences of facultative hypothermia, and defining these responses in ecologically meaningful ways. Most studies of torpor in endotherms have focused on whether or not torpor occurs in a particular species and/or the energetic benefits of torpor. Far less effort has been invested in understanding the potential costs of torpor. The third question our research will address concerns the energetic benefits of facultative hypothermia under natural conditions

Phenotypic plasticity in avian metabolic rates

Research Team: Assoc. Prof. Andrew McKechnie

Collaborators: Dr Nomakwezi Mzilikazi, Prof. Barry Lovegrove

There is increasing evidence that individual birds can reversibly adjust their metabolic rates and evaporative water loss rates though time in response to changing environmental demands. Phenotypic plasticity in physiological parameters has profound implications for the interactions between birds and biotic and abiotic environments, and the ways in which natural selection acts on physiological systems. Understanding the functional and mechanistic correlates of phenotypic adjustments that affect avian energy and water fluxes has emerged as a prerequisite for progress in several fields of avian ecological and evolutionary physiology, and for linking physiology to behavioural ecology and life-history evolution. The primary aim of this research is to examine the consequences of phenotypic flexibility on the allometric scaling of physiological parameters such as basal metabolic rate, and to assess the role of phenotypic flexibility as a contributor to "adaptive" variation in physiological traits.

Conservation biology of the Blue Swallow

Research Team: Assoc. Prof. Andrew McKechnie, Ms Fadzai Matsvimbo

Collaborators: Mr James Wakelin, Dr Stephan Woodborne

The Blue Swallow (Hirundo atrocaerulea) is in imminent danger of extinction in South Africa, due to rampant transformation of its mistbelt grassland habitat, and the fact that very little of its local range is formally conserved. A complicating factor is that the swallow is an intra-African migrant, and spends part of the year in central Africa. Conservation efforts need to be coordinated across the areas that birds occupy at different times of the year, but we currently have very little knowledge of the migratory connections between non-breeding populations in central Africa and breeding populations in southern Africa. In collaboration with the late James Wakelin (Ezemvelo KZN Wildlife) and Stephan Woodborne (CSIR), we have been using biochemical signatures in the swallows’ feathers to infer links between birds on the breeding and non-breeding ranges. Early in 2009, we travelled to Nyika National Park in northern Malawi and collected feathers from the largest Blue Swallow breeding population. Analyses of these feathers have allowed us to identify a unique isotopic “featherprint” for each breeding population. We also analysed feathers from eight non-breeding birds caught on the shores of Lake Victoria in Uganda, and were able to establish the origins of these individuals.

Acknowledgements

Tswalu Kalahari Private Game Reserve, E Oppenheimer & Son.