Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer
It has been suggested that animals may escape attack from mobile parasites by aggregating in selfish herds. A selfish herd disperses the risk of being attacked among its members and the per individual risk of parasite infection should therefore decrease with increasing animal density through the enc...
Published in: | Oikos |
---|---|
Main Authors: | , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Wiley
2007
|
Subjects: | |
Online Access: | http://dx.doi.org/10.1111/j.0030-1299.2007.15390.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.0030-1299.2007.15390.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0030-1299.2007.15390.x |
id |
crwiley:10.1111/j.0030-1299.2007.15390.x |
---|---|
record_format |
openpolar |
spelling |
crwiley:10.1111/j.0030-1299.2007.15390.x 2024-06-02T08:06:35+00:00 Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer Fauchald, Per Rødven, Rolf Bårdsen, Bård‐Jørgen Langeland, Knut Tveraa, Torkild Yoccoz, Nigel G. Ims, Rolf A. 2007 http://dx.doi.org/10.1111/j.0030-1299.2007.15390.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.0030-1299.2007.15390.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0030-1299.2007.15390.x en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Oikos volume 116, issue 3, page 491-499 ISSN 0030-1299 1600-0706 journal-article 2007 crwiley https://doi.org/10.1111/j.0030-1299.2007.15390.x 2024-05-03T10:49:33Z It has been suggested that animals may escape attack from mobile parasites by aggregating in selfish herds. A selfish herd disperses the risk of being attacked among its members and the per individual risk of parasite infection should therefore decrease with increasing animal density through the encounter–dilution effect. Moreover, in a selfish herd, dominant and agile animals should occupy the best positions and thereby receive fewer attacks compared to lower ranked animals at the periphery. We tested these predictions on reindeer ( Rangifer tarandus tarandus ) parasitized by warble flies ( Hypoderma tarandi ). Warble flies oviposit their eggs on reindeer during summer and induce strong anti‐parasitic behavioural responses in the herds. In this period, reindeer are sexually segregated; females and calves form large and dense herds while males are more solitary. After hatching, the warble fly larvae migrate under the skin of their host where they encyst. In the present study encysted larvae were counted on newly slaughtered hides of male calves and 1.5 year old males from 18 different reindeer herds in Finnmark, northern Norway with large contrasts in reindeer density. In reindeer, body mass is correlated with fitness and social status and we hypothesized that individual carcass mass reflected the animal's ability to occupy the best positions within the herd. Larval abundance was higher among the 1.5 year old males than among the calves. For calves we found in accordance with the selfish herd hypothesis a negative relationship between larval abundance and animal density and between larval abundance and body mass. These relationships were absent for the 1.5 year old males. We suggest that these differences were due to different grouping behaviour where calves and females, but not males, aggregated in selfish herds where they escaped parasitism. Article in Journal/Newspaper Finnmark Northern Norway Rangifer tarandus Finnmark Wiley Online Library Norway Oikos 116 3 491 499 |
institution |
Open Polar |
collection |
Wiley Online Library |
op_collection_id |
crwiley |
language |
English |
description |
It has been suggested that animals may escape attack from mobile parasites by aggregating in selfish herds. A selfish herd disperses the risk of being attacked among its members and the per individual risk of parasite infection should therefore decrease with increasing animal density through the encounter–dilution effect. Moreover, in a selfish herd, dominant and agile animals should occupy the best positions and thereby receive fewer attacks compared to lower ranked animals at the periphery. We tested these predictions on reindeer ( Rangifer tarandus tarandus ) parasitized by warble flies ( Hypoderma tarandi ). Warble flies oviposit their eggs on reindeer during summer and induce strong anti‐parasitic behavioural responses in the herds. In this period, reindeer are sexually segregated; females and calves form large and dense herds while males are more solitary. After hatching, the warble fly larvae migrate under the skin of their host where they encyst. In the present study encysted larvae were counted on newly slaughtered hides of male calves and 1.5 year old males from 18 different reindeer herds in Finnmark, northern Norway with large contrasts in reindeer density. In reindeer, body mass is correlated with fitness and social status and we hypothesized that individual carcass mass reflected the animal's ability to occupy the best positions within the herd. Larval abundance was higher among the 1.5 year old males than among the calves. For calves we found in accordance with the selfish herd hypothesis a negative relationship between larval abundance and animal density and between larval abundance and body mass. These relationships were absent for the 1.5 year old males. We suggest that these differences were due to different grouping behaviour where calves and females, but not males, aggregated in selfish herds where they escaped parasitism. |
format |
Article in Journal/Newspaper |
author |
Fauchald, Per Rødven, Rolf Bårdsen, Bård‐Jørgen Langeland, Knut Tveraa, Torkild Yoccoz, Nigel G. Ims, Rolf A. |
spellingShingle |
Fauchald, Per Rødven, Rolf Bårdsen, Bård‐Jørgen Langeland, Knut Tveraa, Torkild Yoccoz, Nigel G. Ims, Rolf A. Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
author_facet |
Fauchald, Per Rødven, Rolf Bårdsen, Bård‐Jørgen Langeland, Knut Tveraa, Torkild Yoccoz, Nigel G. Ims, Rolf A. |
author_sort |
Fauchald, Per |
title |
Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
title_short |
Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
title_full |
Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
title_fullStr |
Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
title_full_unstemmed |
Escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
title_sort |
escaping parasitism in the selfish herd: age, size and density‐dependent warble fly infestation in reindeer |
publisher |
Wiley |
publishDate |
2007 |
url |
http://dx.doi.org/10.1111/j.0030-1299.2007.15390.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.0030-1299.2007.15390.x https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0030-1299.2007.15390.x |
geographic |
Norway |
geographic_facet |
Norway |
genre |
Finnmark Northern Norway Rangifer tarandus Finnmark |
genre_facet |
Finnmark Northern Norway Rangifer tarandus Finnmark |
op_source |
Oikos volume 116, issue 3, page 491-499 ISSN 0030-1299 1600-0706 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/j.0030-1299.2007.15390.x |
container_title |
Oikos |
container_volume |
116 |
container_issue |
3 |
container_start_page |
491 |
op_container_end_page |
499 |
_version_ |
1800751542651846656 |