But was it adaptive?Drift and adaptation in the radiation of the white proteas

Adaptive radiations• “the most common

syndrome in the origin of taxa” (Schluter 2000, p. 1)

Adaptive radiations• Adaptive (Schluter 2000; Gavrilets & Losos

2009)

• Divergent selection – among species

• Stabilizing selection – within species

Adaptive radiations• Adaptive (Schluter 2000; Gavrilets & Losos

2009)

• Divergent selection – among species

• Stabilizing selection – within species

• Explosive (Gavrilets & Vose 2005; Puebla et al. 2008)

Protea

Valente et al. (2009)

5 – 18 mya

Protea

Valente et al. (2009)

White protea0.34 – 1.2 mya

White protea

White proteaWinter rainfall Summer rainfall

White protea

Was it adaptive?

Was it adaptive?• Is variation correlated

with environment?

Sampling•35 populations•11-40 adults per population

Was it adaptive?• Is variation correlated

with environment? YES!•Is it genetic?

Sampling•35 populations•11-40 adults per population• 8 maternal lines per

population• Up to 15 seeds per

maternal line

Was it adaptive?• Is variation correlated

with environment? YES!•Is it genetic? YES!

Was it adaptive?• Is variation correlated

with environment? YES!•Is it genetic? YES!•Is it related to performance?

Logistic regression• “Selection” gradients

on garden survivorship• Convert logistic

regression coefficients to selection gradients

Kirstenbosch

Jonaskop

SLA -0.024 -0.017LWR -0.058 0.024Leaf area 0.389 -0.007Stomatal density

-0.061 -0.006

Growth rate 0.097 0.180

“Selection” gradients

Kirstenbosch

Jonaskop

SLA -0.024 -0.017LWR -0.058 0.024Leaf area 0.389 -0.007Stomatal density

-0.061 -0.006

Growth rate 0.097 0.180

“Selection” gradients

Large leaves favored in warm, moist garden

Kirstenbosch

Jonaskop

SLA -0.024 -0.017LWR -0.058 0.024Leaf area 0.389 -0.007Stomatal density

-0.061 -0.006

Growth rate 0.097 0.180

“Selection” gradients

Thick leaves favored in cold, dry garden

Was it adaptive?•Yes

Was it adaptive?•YesWas it explosive?

Microsatellites•36 populations•20 individuals per population•10 loci

FSC = among pops within speciesFCT = among species

FS

C

FCT

FSC = among pops within speciesFCT = among species

FS

C

FCT~50% of history associated with species divergence

Was it adaptive?•YesWas it explosive?•No

Structural equation model•Integrated response

Trait-environment associations•Among populations•Among species

Trait-environment associations•Among populations•Among speciesDo populations and species differ in the same ways?

Association differs among species•56 of 60 signs differ (P < 0.001)

Association differs among species•56 of 60 signs differ (P < 0.001)

Association differs among species•56 of 60 signs differ (P < 0.001)

Population divergence – adaptive

Population divergence – adaptiveSpeciation – non-adaptive?

Adaptive radiations• Not uniform• Adaptation and drift

Acknowledgments

Collaborators• John Silander• Guy Midgley

(SANBI)• Tony Rebelo

(SANBI)Post-doc• Jane CarlsonGraduate student• Rachel PrunierField assistants• Christopher Adams• Ann Marie Gawel

Undergraduates• Charles Berdan• David Fryxell• Sirenga Iyer• Susan Kim• Bronwen TombFacilities• Kirstenbosch National

Botanic GardenFunding• NSF

Acknowledgments

Collaborators• John Silander• Guy Midgley

(SANBI)• Tony Rebelo

(SANBI)Post-doc• Jane CarlsonGraduate student• Rachel PrunierField assistants• Christopher Adams• Ann Marie Gawel

Undergraduates• Charles Berdan• David Fryxell• Sirenga Iyer• Susan Kim• Bronwen TombFacilities• Kirstenbosch National

Botanic GardenFunding• NSF

Thank you!