Sex ratio and morphological polymorphism in an isolated, endemicTeladorsagia circumcinctapopulation

Journal of Helminthology - Tập 84 Số 2 - Trang 208-215 - 2010
Barbara Craig1, Jill G. Pilkington2, Josephine M. Pemberton2
1Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
2Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh,

Tóm tắt

AbstractTeladorsagia circumcinctais a polygamous nematode that exhibits morphological polymorphism. Sex ratio is typically female biased and the male nematodes occur in association with the genetically similar, minor morphotypesTeladorsagia davtianiandTeladorsagia trifurcata. In experimental infections, sex ratio (proportion male) and the proportion of minor male morphs observed have been shown to be influenced by both host and nematode-related factors. As similar investigations from natural systems are rare, this study examined whether sex ratio and minor male morph frequency were associated with host age and sex and nematode infra-population size in the isolated Soay sheep population on St Kilda. Count data forTeladorsagiawere analysed for sheep of all age classes and both sexes from the winters of three consecutive population crashes (1999, 2002 and 2005). Generally, the intensity ofTeladorsagianematodes increased with host age until the age of 2 years before decreasing. In 2005, abundance of nematodes was generally higher than in the previous crashes, nematode sex ratio was negatively associated with host age and tended to be negatively associated with nematode intensity. Within the male nematode subpopulation,T. circumcinctaalways predominated, followed byT. davtianiand thenT. trifurcata, with little variation in the relative proportions between hosts. The presence of each minor morph was primarily associated with the intensity of maleT. circumcinctaand, in those hosts where all three male morphs were detected, intensity of each minor morph was most associated with intensity ofTeladorsagiafemales. Therefore, in a year when the nematode was generally more abundant, sex ratio appeared to be influenced by both host and nematode-related factors, whereas in all years examined, the frequency of morphological polymorphism was primarily density dependent.

Từ khóa


Tài liệu tham khảo

Wilson, 2004, Soay sheep: dynamics and selection in an island population, 113

10.1017/CBO9780511542053.004

10.1016/0020-7519(78)90034-6

10.1016/0020-7519(95)00049-8

10.1016/S0020-7519(96)80013-0

10.1016/S1090-0233(97)80049-4

10.1126/science.1167345

Rose, 1962, Differentiation of the sheep stomach worms Teladorsagia davtiani (Andreeva and Satubaldin, 1954) and Ostertagia trifurcata (Ransom, 1907), Research in Veterinary Science, 3, 304, 10.1016/S0034-5288(18)34904-X

10.1016/0304-4017(93)90029-M

Poulin, 2007, Evolutionary ecology of parasites, 134, 10.1515/9781400840809

10.1007/s004420050248

10.1017/S0031182000079269

10.1016/0304-4017(93)90046-P

10.1645/0022-3395(2002)088[0135:NMETTC]2.0.CO;2

Leignel, 2001, Are Teladorsagia (Nematoda) morphs equally able to survive under anthelmintic treatment in sheep on pastures, Parasitology Research, 87, 687, 10.1007/s004360100387

Lancaster, 1983, Concepts in nematode systematics, 22, 293

10.1016/j.molbiopara.2008.01.001

Fowler, 1990, Practical statistics for field biology

10.1007/BF00009507

10.1017/S0031182006000618

10.1051/parasite/1984596607

10.2307/3277904

10.2307/3275219

10.1017/S0022149X00012311

10.1016/0020-7519(96)00058-6

10.1046/j.0269-8463.2001.00567.x

10.1079/9780851998183.0127

Clutton-Brock, 2004, Soay sheep: dynamics and selection in an island population

10.1007/978-1-349-02667-8_6

Crawley, 2003, Statistical computing: an introduction to data analysis using S-Plus

10.1016/0304-4017(84)90109-2

10.1016/j.vetpar.2006.04.006

10.1098/rsif.2007.1104

Thông tin
Thông tin xuất bản

Journal of Helminthology

Tập 84 Số 2

208-215

Thông tin tác giả