Mattias Hagman Heydon-Laurence Building, A08 University of Sydney NSW 2006 Room: 447 Ph: (02) 9351 8679 Fax: (02) 9351 5609 e-mail: mattias.hagman@bio.usyd.edu.au

Research Interests Current Research Publications Conferences Grants and Awards

For as long as I can remember, reptiles  and amphibians have fascinated me. This interest has had a great influence on my life and it has taken me from my home country, Sweden, to various places in the world. One of my favourite trips was a visit to the Komodo Islands, home of the famous Komodo dragon (Varanus komodoensis, below).
 

 

The colourful and highly toxic poison frogs (Dendrobatidae, below) of Central- and South America are also long time favourites and I have been to the rainforests of Costa Rica, Panama and Peru to study them. These frogs have some interesting aspects of life-history. Many species, for example, have evolved higly specialised reproduction strategies. The most obvious thing about them however, is their extremely potent skin toxins and conspicuous colouration. The vivid colouration presumably serves as a signal that warns potential predators about their toxicity. Experimental studies have shown that the avoidance inducing effect of conspicuous prey colouration increases with increasing size of pattern elements and with increasing body size. In collaboration with Professor Anders Forsman I used poison frogs to test predictions from these findings, i.e., that conspicuous colouration will evolve in tandem with body size. The results from our study were consistent with this hypothesis.

In the first quarter of 2004  I was in the rainforests of north-eastern Peru researching a flesh fly (Sarcophagidae) whose parasitic larvae prey on poison frogs from the family Epipedobates. The invasion of fly larvae in vertebrate tissues is a phenomenon commonly refered to as myiasis. The phenomenon is well documented in many animals, predominantly mammals and birds. Amphibians worldwide are also parasitised by numerous fly species. This however, is a poorly studied area of amphibian biology. In collaboration with Dr Thomas Pape and Rainer Schulte, I provided the first evidence of flies causing myiasis on frogs from Peru as well as the first evidence of fly larvae parasitising poison frogs. Some of the papers I published on poison frogs are available as PDF files from my list of publications.

 

 
 

Top

---

Current Research

Potential short-term control measures for cane toads
I am very fortunate to have been able to come to Australia, where I am currently employed as a postdoc in Professor Shine's lab at the University of Sydney. Most of my research is focused on the invasive cane toad (Chaunus marinus), which was introduced to Australia more than 70 years ago in a futile attempt to control pests on cane fields in Queensland. Since its introduction the cane toad has spread, and continues to spread, across vast areas of Australia. Because is is toxic in all life-stages it is causing declines (and perhaps, local extinctions) of native predator populations. Although the cane toad thus is widely believed to be a major pest, very little is known about ecological processes at the toad invasion front. I am studying the ecology of the cane toad, with emphasis on early life stages. My overall aim is to identify life-history traits that potentially could be exploited for control. For example, cane toads like many other water breeding amphibians rely upon waterbodies for reproduction. Waterbodies in many landscapes are a scarce resource. Hence, one of my initial studies was an investigation of spawning site selection by cane toads at an invasion front in tropical Australia. In March 2005 I surveyed waterbodies for signs of breeding in an area between Darwin and Kakadu. I recorded a range of variables from breeding- and non-breeding sites that may influence toads in their choice of spawning site. Collecting this data was exciting as crocodiles and water buffalos inhabited many of the waterbodies I examined. Another phenomenon that made this study an interesting experience was "Ingrid" - the hurricane - who was in the neighbourhood at the time of my visit. Anyway, when I compared variables from the two sets of sites (breeding vs non-breeding) I found that it was habitat variables that differed. Since some of these habitat variables could be manipulated there is potential for control. By manipulating waterbodies it would be possible to either discourage oviposition or to attract toads spatially and have concentrated communal breeding. The latter option would not only facilitate trapping and removal, but also exploit density-dependent mechanisms such as intraspecific competition and cannibalism for control of feral toad populations. Cannibalism is widespread among toad populations and my be an important viability reducing agent. Indeed, my research has shown that toads have evolved specific behaviours that facilitate cannibalism. By waving the middle toe of their rear feet up and down, medium-sized cane toads can attract smaller conspecifics within striking-range. Click here for a video of a toe-waving toad.

 

I have also studied effects of toads on native mosquito species. This investigation yielded some very interesting and surprising results. Current research also involves behavioural responses by toad tadpoles to different stimuli and fitness costs of plastic traits (phenotypic plasticity). I believe that simple but effective control methods can be developed from a sound knowledge of basic toad ecology. It is my hope that in addition to conservation applications, my research will also yield new knowledge about the ecology of cane toads and contribute to the general science of biology.
 
 

Apart from studying the ecology of reptiles and amphibians I am also interested in photography, which I think combines very well with my research. I have taken numerous pictures during field work and travels. On this page I have included a few of them.

                                                                                  Mattias Hagman
 
 

Top