The role of theoretical models explaining the relationships between brood parasites and their hosts

Fugo TAKASU

Department of Information and Computer Sciences, Nara Women's University, Nara 630-8506, Japan

S51: New models in avian host-brood parasitism systems. Convenors: Rｿskaft, E. & Soler, M.
In: Adams, N. J. & Slotow, R. H. (eds), 1999, Proceedings of 22nd International Ornithological Congress, Durban: 3146-3164.
Johannesburg: BirdLife South Africa

Copies of this CD-ROM may be ordered from the Natural History Book Service.
NHBS Web Site: http://www.nhbs.com
NHBS e-mail: bmercer@nhbs.co.uk

Abstract: Field researches have shown that some host individuals recognize and reject parasitism but the frequency of individuals that reject parasitism ranges from 0 % to 100 % depending on host population. Host populations that do not show perfect defense despite being parasitized have been a point of controversy. Do these hosts behave adaptively or do they only lack adaptive characteristics in evolutionary time scale? I constructed mathematical models to describe the relationships between brood parasites and their hosts and analyzed how the host defense spreads under selection pressure imposed by the parasite. The main results are 1) host may not establish perfect defense. 2) distribution of host defense levels is crucially affected by the parasite breeding strategy as specialized or generalized. Population dynamics is essential to these results. By measuring and estimating biological quantities (breeding parameters etc.), we would be able to resolve a long standing question - which hypotheses, evolutionary lag or equilibrium, better explain the well studied cases of the Common Cuckoo, Cuculus canorus, and the Brown-headed Cowbird, Molothrus ater. I suggest the usefulness of theoretical study to explore problems of brood parasitism with close cooperation with empirical study.

第２２回国際鳥類学会（南アフリカ共和国、ダーバン、１９９８年８月）の托卵鳥のシンポジウムで講演した内容です。托卵におけるホストの対抗手段の進化に関する一連の理論研究をまとめて発表しました。この内容は、１９９９年夏にナタール大学からCD-ROMの形式で出版されました。シンポジウム発表で使ったスライドをPDF形式で用意したので興味のある方はどうぞ。

Symposium Talk at 22nd International Ornithological Congress in Durban, South Africa, 1998:
The role of theoretical models explaining the relationships between brood parasites and their hosts (163kB in PDF format)

takasu@ics.nara-wu.ac.jp