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

Across catchment – RCC predictions – Do organisms respond same to environmental gradient?

Analyses – patterns Heino et al 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 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 – tests Heino et al Indirect ordination: CA, PCA Direct ordination: CCA, RDA, RLQ Group test: MRPP Life history strategy: ANOVA Niche Model: Maximum Entropy Trait 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 – 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 Goldstein & Meador 2005 Hoeinghaus et al Frimpong & Angermeier 2010 Menezes et al Pyron et al Jacquemin & Pyron 2011 Pease et al Heino et al. 2013