Trait-based Analyses for Fishes and Invertebrates in Streams

Mark Pyron

Stoeckerecological.com

River Habitat Templet

Ideas for species traits-environmental filters

(from Southwood 1977; used by Poff 1997)

Why Traits?

• Compare evolutionarily distinct systems• Species-habitat relationships

• Ecosystem processes

Major assumption!

Present day habitat conditions match present day traits in organisms

Which traits?Which analyses?What are results?What are problems?

Which traits?

• Spatial and temporal heterogeneity of habitat define where and when the organisms use habitat

Traits:

• Should vary with ecological gradients

and . . .

• Organisms with same traits occur in multiple biogeographical regions

– Different taxa

Traits of macroinvertebrates

• Trophic– Shredders, filterer-collector, grazer, predator

• Locomotion

• Body size

• Voltinism

• Respiration technique

Traits of macroinvertebrates

• Life history: reproductive strategies– Body size– Egg size, number, shape, attachment– Generations / year– Oviposition period -season– Incubation time– Clutch number

Traits of fishes

• Habitat preferences:– Stream size (small, medium, large)– Discharge– Temperature– Depth– Substrate size– Canopy

Traits of fishes

• Life history– Body size– Lifespan– Age at maturity– Egg size– Fecundity

Traits of fishes

• Dispersal ability

• Colonization ability

Traits of fishes

• Reproductive guilds

• IBI metrics

• Feeding and ecosystem interactions

• Morphology

Analyses – patterns Heino et al. 2013

Analyses – patterns Heino et al. 2013

• Across catchment– RCC predictions– Do organisms respond same to environmental

gradient?

Analyses – patterns Heino et al. 2013

• Across catchment

• Among region differences or convergence– Same traits in different local communities?– Compare trait responses to same gradients in

different geographical regions

Analyses – patterns Heino et al. 2013

• Across catchment• Among region differences or convergence• Across community – large extent or w/in

catchment– Trait variation across local communities in

drainage basin at large geographical extent

Analyses – testsHeino et al. 2013

Indirect ordination: CA, PCADirect ordination: CCA, RDA, RLQGroup test: MRPPLife history strategy: ANOVANiche Model: Maximum EntropyTrait diversity: regression, ANOVA

Results: macroinvertebrate traits

• Human impacts– Traits discriminate river reaches– Taxonomy could not – Genus level or family level sufficient – Gayraud et al. 2003

Results: macroinvertebrate trait richness

• Increases along local, catchment, and geographical gradients

• Bêche & Statzner 2009

Results: macroinvertebrate traits studies

• Trait richness correlated with genus richness Beche & Statzner 2009

Results: fish traits

• Hydrologic variability:

– Resource generalists vs. specialists – Poff & Allan 1995

Results: fish traits

• Hydrologic variability:

– Life-history traits – Tedesco et al. 2008; Mims & Olden 2012

Results: fish traits studies

• Taxonomy explains regional / geographic distributions of fishes

• Traits better explain local habitat type and stability, and regional distribution

• Hoeinghaus et al. 2006

Results: fish traits studies

• Difference in fish traits across river basins– Result of glaciation: filter– Colonizers had opportunistic traits: small body size,

brief lifespan, low age maturity, small eggs

– Mims et al. 2010– Jacquemin and Pyron 2011

Traits vs. taxa

• respond similarly to gradients?

– Predicted by Heino et al. 2013:

– Traits insensitive to geographical variation

– Taxa more geographically structured

• Depends on spatial extent of study

Problems with traits

• Developmental trophic changes

• Poorly known taxa; broad family characterizations often incorrect

• Traits are intercorrelated: not independent

Problems with traits

• Data quality of traits varies– Fuzzy coding, continuous variables, categories

Summary

• Functional traits are useful

• Tend to respond more strongly to environmental gradients than taxonomy

– Taxonomy is successful at distinguishing large-scale assemblage variation

Traits studies

• Gayraud et al. 2003• Goldstein & Meador

2005• Hoeinghaus et al.

2007• Frimpong &

Angermeier 2010• Menezes et al. 2010

• Pyron et al. 2011• Jacquemin & Pyron

2011• Pease et al. 2012• Heino et al. 2013