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Divergent hormonal responses to social competition in closely related species of haplochromine cichlid fish

Dijkstra, Peter D.; Verzijden, Machteld LU ; Groothuis, Ton G. G. and Hofmann, Hans A. (2012) In Hormones and Behavior 61(4). p.518-526
Abstract
The diverse cichlid species flocks of the East African lakes provide a classical example of adaptive radiation. Territorial aggression is thought to influence the evolution of phenotypic diversity in this system. Most vertebrates mount hormonal (androgen, glucocorticoid) responses to a territorial challenge. These hormones, in turn, influence behavior and multiple aspects of physiology and morphology. Examining variation in competition-induced hormone secretion patterns is thus fundamental to an understanding of the mechanisms of phenotypic diversification. We test here the hypothesis that diversification in male aggression has been accompanied by differentiation in steroid hormone levels. We studied two pairs of sibling species from Lake... (More)
The diverse cichlid species flocks of the East African lakes provide a classical example of adaptive radiation. Territorial aggression is thought to influence the evolution of phenotypic diversity in this system. Most vertebrates mount hormonal (androgen, glucocorticoid) responses to a territorial challenge. These hormones, in turn, influence behavior and multiple aspects of physiology and morphology. Examining variation in competition-induced hormone secretion patterns is thus fundamental to an understanding of the mechanisms of phenotypic diversification. We test here the hypothesis that diversification in male aggression has been accompanied by differentiation in steroid hormone levels. We studied two pairs of sibling species from Lake Victoria belonging to the genera Pundamilia and Mbipia. The two genera are ecologically differentiated, while sibling species pairs differ mainly in male color patterns. We found that aggression directed toward conspecific males varied between species and across genera: Pundamilia nyererei males were more aggressive than Pundamilia pundamilia males, and Mbipia mbipi males were more aggressive than Mbipia lutea males. Males of both genera exhibited comparable attack rates during acute exposure to a novel conspecific intruder, while Mbipia males were more aggressive than Pundamilia males during continuous exposure to a conspecific rival, consistent with the genus difference in feeding ecology. Variation in aggressiveness between genera, but not between sibling species, was reflected in androgen levels. We further found that M. mbipi displayed lower levels of cortisol than M. lutea. Our results suggest that concerted divergence in hormones and behavior might play an important role in the rapid speciation of cichlid fishes. (C) 2012 Elsevier Inc. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Testosterone, 11-Ketotestosterone, Cortisol, Teleost, Cichlid, Steroid, Male-male competition, Speciation
in
Hormones and Behavior
volume
61
issue
4
pages
518 - 526
publisher
Elsevier
external identifiers
  • wos:000302763700008
  • scopus:84859101511
ISSN
1095-6867
DOI
10.1016/j.yhbeh.2012.01.011
language
English
LU publication?
yes
id
e99af5ab-efd1-4ed3-aba8-d803f80ab69a (old id 2574858)
date added to LUP
2012-06-04 12:47:58
date last changed
2017-07-23 03:10:21
@article{e99af5ab-efd1-4ed3-aba8-d803f80ab69a,
  abstract     = {The diverse cichlid species flocks of the East African lakes provide a classical example of adaptive radiation. Territorial aggression is thought to influence the evolution of phenotypic diversity in this system. Most vertebrates mount hormonal (androgen, glucocorticoid) responses to a territorial challenge. These hormones, in turn, influence behavior and multiple aspects of physiology and morphology. Examining variation in competition-induced hormone secretion patterns is thus fundamental to an understanding of the mechanisms of phenotypic diversification. We test here the hypothesis that diversification in male aggression has been accompanied by differentiation in steroid hormone levels. We studied two pairs of sibling species from Lake Victoria belonging to the genera Pundamilia and Mbipia. The two genera are ecologically differentiated, while sibling species pairs differ mainly in male color patterns. We found that aggression directed toward conspecific males varied between species and across genera: Pundamilia nyererei males were more aggressive than Pundamilia pundamilia males, and Mbipia mbipi males were more aggressive than Mbipia lutea males. Males of both genera exhibited comparable attack rates during acute exposure to a novel conspecific intruder, while Mbipia males were more aggressive than Pundamilia males during continuous exposure to a conspecific rival, consistent with the genus difference in feeding ecology. Variation in aggressiveness between genera, but not between sibling species, was reflected in androgen levels. We further found that M. mbipi displayed lower levels of cortisol than M. lutea. Our results suggest that concerted divergence in hormones and behavior might play an important role in the rapid speciation of cichlid fishes. (C) 2012 Elsevier Inc. All rights reserved.},
  author       = {Dijkstra, Peter D. and Verzijden, Machteld and Groothuis, Ton G. G. and Hofmann, Hans A.},
  issn         = {1095-6867},
  keyword      = {Testosterone,11-Ketotestosterone,Cortisol,Teleost,Cichlid,Steroid,Male-male competition,Speciation},
  language     = {eng},
  number       = {4},
  pages        = {518--526},
  publisher    = {Elsevier},
  series       = {Hormones and Behavior},
  title        = {Divergent hormonal responses to social competition in closely related species of haplochromine cichlid fish},
  url          = {http://dx.doi.org/10.1016/j.yhbeh.2012.01.011},
  volume       = {61},
  year         = {2012},
}