Variação sazonal e interespecífica na condição imunológica e corporal duas espécies de Elaenia (Passeriformes: Tyrannidae) no cerrado do Distrito Federal

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The immune system plays a decisive role in defending an animal against attack by pathogens and parasites. Its activation and maintenance demand nutritional and energetic costs, and may result in a trade-off with other demanding activities during stressfull periods. To verify this, I compared both body and immunological conditions of Elaenia cristata during non reproductive rainy season, non reproductive dry season and reproductive season. Elaenia cristata showed a typical stress leukocyte profile (decreased lymphocyte number, increased heterophil number and H:L ratio) during the dry season, but not at others seasons. However, it had no significant variation on body mass index (residual from the linear regression of body mass on tarsus length) among the seasons. As well, I compared both immunological and body conditions of E. cristata and E. chiriquensis (a migrant congener) during the reproductive season. I did not find differences for E. cristata, but E. chiriquensis starts the season with a stress leukocyte profile, reverses the condition at the intermediate months and returns to the stress profile at the end of the breeding season, before migration. I found weak correlations between immune condition and body condition for both species. I also compared immunological condition of E. cristata at different molt stages and I did not find significant variation. The results showed that leukocyte profile had changed due to stress conditions. It is apparently influenced by drought in E. cristata and by migration in E. chiriquensis, but not by reproductive condition in both species. The mounting of the immune system had no trade-off with molting, and both processes were not related to body mass.

ASSUNTO(S)

elaenia cristata immune condition condição corporal heterophil h:l ratio condição imunológica biologia geral stress razão h:l linfócito elaenia chiriquensis lymphocyte estresse heterófilo elaenia chiriquensis elaenia cristata body condition

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