Dr Res Altwegg

South African National Biodiversity Institute
Email: res [dot] altwegg [at] gmail [dot] com

My research interests

I study the connection between life-history evolution and population/community ecology. The dynamics of food webs are the result of things that happen at the level of the individuals: their survival rates, their reproductive success, their movements, their life-history decisions, the habitat choices they make, how effective they are at gathering food and at avoiding predators. In all these traits, there is variation among individuals in natural populations; genetic variation that can lead to evolutionary change over multiple generations, and phenotypic plasticity that can result in very fast changes within one generation. My main interest is to understand the connection between this variation at the individual level and community processes.

Conceptually, I strive to combine field observations with controlled experiments and theoretical concepts. If possible, I aim to directly connect theory and data through statistical methods, and I often use the Akaike Information Criterion (AIC) to evaluate how well my data support different models corresponding to different biological hypotheses.

Short description of current research

My main project aims at understanding the range dynamics of Southern African birds. Many of these birds are presently expanding their range, while others are losing ground. I examine the demography of these species to learn what may drive their local population dynamics, and I’m developing methods to quantify range changes more reliably. This work is in collaboration with Dr Birgit Erni at the Department of Statistical Science (UCT) and my colleagues in the Global Change Research Group here at SANBI, Dr Guy Midgley and Dr Phoebe Barnard.

One of the bird species I’m currently working on is the Hadeda (Bostrychia hagedash), which is a relative newcomer to the Cape Town area. Their western limit was near Port Elizabeth about 100 years ago, while they are really abundant throughout most of the Western Cape Province now. Together with Doug Harebottle, we are collecting demographic data on this species to understand what makes them so successful. Other species I’m working on are Blue Cranes (with Mark Anderson, Northern Cape provincial ornithologist), weavers (with Dr Dieter Oschadleus, ADU), Peregrines (with Dr Andrew Jenkins at the Fitz), Pale Chanting Goshawks (with Prof Gerard Malan, Technical University Tshwane), and some more.

Some of my recent projects used capture-mark-recapture methods and matrix population models for demographic analyses of wild populations of Barn Owls (Tyto alba), asp vipers (Vipera aspis), and bull frogs (Rana catesbeiana). I estimate age-specific survival, reproduction, and emigration, examine how much these rates are affected by weather, and quantify the effects on population growth. As a general result, these analyses have shown that weather differentially affects different age classes. The connection between weather and population dynamics therefore depends on the demographic composition of these populations, and ultimately on the life history of the species involved.

For my PhD, I investigated predator-induced plasticity in the life history of water frogs (Rana lessonae / esculenta). Using artificial ponds and terrestrial outdoor enclosures, I was able to manipulate the growth environment and examine the reaction of these animals during two different stages in their complex life cycle. For my Diploma (MSc), I investigated dispersal between local populations within a metapopulation of House Sparrows (Passer domesticus), and examined how the decision to disperse depended on an individual's age, sex, and morphological characteristics.

Education and occupations

Since 2008: Specialist scientist at the South African National Biodiversity Institute.

2005 – 2008: Postdoctoral Research fellow, University of Cape Town, South Africa, mentor: Prof. Les G. Underhill, fellowship from the National Research Foundation of South Africa (NRF) and the Swiss National Science Foundation (SNF).

2002 – 2005: Postdoctoral Research fellow, University of Victoria, Canada, mentor: Prof. Bradley R. Anholt, fellowship from the Swiss National science Foundation (SNF)

2001 – 2002: Civil service at the Swiss Ornithological Institute, Sempach: statistical analysis of ring recovery data, and fieldwork

1997 – 2001: PhD dissertation at the Zoology Institute, University of Zürich, Switzerland: 'Complex life cycles and predation risk: plastic growth and life-history strategies in water frogs', supervisor: Prof. H.-U. Reyer.

1996 – 1997: Diploma thesis (equivalent to Masters degree) at the Norwegian University of Science and Technology, Trondheim (NTNU), Norway, and University of Basel, Switzerland: 'Causes and consequences of dispersal within a metapopulation of house sparrows (Passer domesticus) in northern Norway', supervisors: Prof. B.-E. Sæther, NTNU, and Prof. S.C. Stearns, University of Basel.

1991 – 1997: Study of Biology I at the University of Basel, Switzerland. Study directions: population biology (supervisor: Prof. S.C. Stearns), invertebrate biology (supervisor: Prof. H. Rowell), plant ecology (supervisor: Prof. C. Körner), vertebrate biology (supervisor: Dr. D.G. Senn), conservation biology (supervisor: Prof. B. Baur).

Publications

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