title: Covarying variances: more morphologically variable populations also exhibit more diet variation.
abstract: Many ecologically generalized populations are composed of relatively specialized individuals that selectively consume a subset of their population's diet, a phenomenon known as 'individual specialization'. The Niche Variation Hypothesis posits that this individual specialization can arise during ecological release if niche expansion occurs mainly through diet divergence among individuals, leading to greater morphological variation. Most tests of this hypothesis have searched for correlations between niche width and morphological variance, but this approach rests on the untested assumption that within-population morphological diversity is highly correlated with ecological diversity. Here, we test whether intrapopulation diet variation is correlated with intrapopulation morphological variation, across 12 lacustrine populations of three-spine stickleback. First, we use behavioral observations, isotopes, and gut contents to show that, within populations, individuals differ in microhabitat use and diet. Second, we show that some populations exhibit more diet variation than others, as evidenced by differences in both isotopic and gut content variation among individuals. Finally, we confirm that populations with greater dietary variation are more morphologically variable. However, this relationship is only significant when total morphological variance is examined, not for individual morphological traits. This discordance may reflect among-population differences in the relationship between individual morphology and diet. Because morphology-diet relationships can differ among populations, morphological variance may be a poor predictor of actual diet variation when diverse populations are being compared.
authors: Department of Ecology, Evolution and Behavior, University of Texas at Austin, Austin, TX, 78712, USA, snowberg@utexas.edu.
authors: Lisa K
authors: LK
authors: Snowberg
authors: Kimberly M
authors: KM
authors: Hendrix
authors: Daniel I
authors: DI
authors: Bolnick
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D004032:Diet; D004463:Ecology; D005247:Feeding Behavior; D005260:Female; D008297:Male; D010641:Phenotype; D023701:Smegmamorpha
references: Oecologia. 2004 Jul;140(2):361-71
references: 15118902
references: Nature. 2009 Apr 30;458(7242):1167-70
references: 19339968
references: Ecology. 2011 Aug;92(8):1582-93
references: 21905425
references: Oecologia. 1985 Oct;67(3):338-341
references: 28311566
references: Oecologia. 1983 Mar;57(1-2):32-37
references: 28310153
references: Proc Natl Acad Sci U S A. 2010 Feb 23;107(8):3616-21
references: 20133670
references: Trends Ecol Evol. 2011 Apr;26(4):183-92
references: 21367482
references: Evolution. 1996 Apr;50(2):532-546
references: 28568934
references: Am Nat. 2003 Jan;161(1):1-28
references: 12650459
references: Philos Trans R Soc Lond B Biol Sci. 2009 Jun 12;364(1523):1483-9
references: 19414463
references: Am Nat. 2008 Dec;172(6):868-77
references: 18950275
references: Oecologia. 2005 Aug;144(4):647-58
references: 16041545
references: Ecology. 2010 Apr;91(4):1025-34
references: 20462117
references: Evolution. 1994 Oct;48(5):1723-1734
references: 28568405
references: Evolution. 2012 Jun;66(6):1819-32
references: 22671549
references: Science. 2011 Jan 28;331(6016):426-9
references: 21273479
references: Ecology. 2008 Jul;89(7):1981-93
references: 18705384
references: Proc Biol Sci. 2007 Mar 22;274(1611):839-44
references: 17251094
references: Proc Natl Acad Sci U S A. 2007 Jun 12;104(24):10075-9
references: 17537912
references: Am Nat. 2009 Aug;174(2):255-67
references: 19519220
references: Oecologia. 2002 Mar;131(1):61-70
references: 28547511
references: Ecol Lett. 2012 Oct;15(10):1189-98
references: 22897772
references: Am Nat. 1992 Jul;140(1):85-108
references: 19426066
references: J Evol Biol. 2005 Mar;18(2):464-73
references: 15715852
references: Proc Natl Acad Sci U S A. 2003 Jun 10;100(12):7169-74
references: 12740442
references: Philos Trans R Soc Lond B Biol Sci. 2009 Jun 12;364(1523):1629-40
references: 19414476
references: Am Nat. 2008 Jul;172(1):1-11
references: 18452402
references: Am Nat. 1993 Jun;141(6):880-96
references: 19425993
references: Evolution. 1987 Nov;41(6):1357-1369
references: 28563603
references: Am Nat. 2004 Sep;164(3):335-49
references: 15478089
references: Ecology. 2009 Feb;90(2):300-5
references: 19323211
references: Ecol Lett. 2010 Aug 1;13(8):989-97
references: 20528898
references: Am Nat. 2012 Aug;180(2):167-85
references: 22766929
references: Ecol Lett. 2011 Sep;14(9):948-58
references: 21790933
references: Proc Biol Sci. 2010 Jun 22;277(1689):1789-97
references: 20164100
references: Oecologia. 2007 Jul;152(4):643-54
references: 17356809
references: Evolution. 2010 Aug;64(8):2265-77
references: 20199566
references: Am Nat. 2008 Nov;172(5):733-9
references: 18834291
references: Evolution. 2004 Dec;58(12):2599-612
references: 15696740