Chamberlain PhD Thesis
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My phd thesis defense presentation.

My phd thesis defense presentation.

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  • I am particularly interested in the variation in species interactions
  • -for populations, communities, and evolution-
  • TRANSITION – I am particula rly interested in 3 factors in relation to variation in species interactions:
  • I am particularly interested in 3 factors in relation to variation in species interactions: 1) Differences in types of species interactions2) Differences due to the gradients along which species interactions occur3) Human causes of variation in species interactions--&AND& the evolutionary consequences of variation in interactions
  • -There’s some evidence for variation in outcomes driving selection, but not in agriculture
  • -My research: I am interested in exploring factors underlying variation in species interations && what consequences are for evolution of altered species interactions
  • -Why? This counterintuitive result is likely due to greater resource abundance for pollinators with crop sunflowers nearby, leading to greater spatial diversity
  • NS = any trait*whatever interactions not significantIf not an NS, then arrows give direction of selection, almost always positive. And Does not signify differece between near and far
  • -PC (principal component) 1 of both floral traits and inflorescence traits-proportional isophrictis damage-proportinoal midge damage-Pollen deposition per plant-relative fitness per plant
  • I am particularly interested in 3 factors in relation to variation in species interactions: 1) Differences in types of species interactions2) Differences due to the gradients along which species interactions occur3) Human causes of variation in species interactions--&AND& the evolutionary consequences of variation in interactions
  • -spp identity: predation is often a more specialized interaction, thus outcome varies more with different species, while mutualism more generalized so many interactions nearly equivalent-abiotic: predators mostly very mobile animals, so can decouple interaction from nutrients, etc., while competitors and mutualism often involved plants in our study, which are dependent on nutrients, and microhabitat changes
  • -spp identity: predation is often a more specialized interaction, thus outcome varies more with different species, while mutualism more generalized so many interactions nearly equivalent-abiotic: predators mostly very mobile animals, so can decouple interaction from nutrients, etc., while competitors and mutualism often involved plants in our study, which are dependent on nutrients, and microhabitat changes
  • -spp identity: predation is often a more specialized interaction, thus outcome varies more with different species, while mutualism more generalized so many interactions nearly equivalent-abiotic: predators mostly very mobile animals, so can decouple interaction from nutrients, etc., while competitors and mutualism often involved plants in our study, which are dependent on nutrients, and microhabitat changes
  • I am particularly interested in 3 factors in relation to variation in species interactions: 1) Differences in types of species interactions2) Differences due to the gradients along which species interactions occur3) Human causes of variation in species interactions--&AND& the evolutionary consequences of variation in interactions
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Chamberlain PhD Thesis Chamberlain PhD Thesis Presentation Transcript

  • Variation in species interactions and their evolutionary consequences Scott Alan Chamberlain Ph.D. Thesis Defense Wedenesday, 30 May, 2012
  • Species interactions are important across domains of ecology• Species interactions contribute to: – Population dynamics – Formation and dynamics of food webs – Evolutionary change through natural selection
  • Variation in species interactions• Not error variation in outcome in one context Site 1• The variation in outcomes among more than one context Site 1 Site 2
  • Variation in outcomes is common Mutualism Competition/Facilitation With Ants Without Ants Plants producing flowers or fruit (%) Low Elevation High Elevation Herbivory outcome for Acacia trees Outcomes vary from competition at low varies with ant species identity elevation to facilitation at high elevationPalmer et al. 2008, Callaway et al. 2002 More E.G.: Cushman and Whitham 1989, Thompson and Cunningham 2002, Pennings and Silliman 2005, Navarrete and Berlow 2006
  • Variation in outcomes is important Populations Communities EvolutionCactus Population Growth Effect of Herbviores on Less Stability Selection Strength Interaction Strength Lower species richness Variance Greater Stability Low Mid High Higher species richness Elevation Interaction Strength Site Mean Miller et al. 2009 Kokkoris et al. 2002 Rudgers & Strauss 2004
  • Questions1. What are the evolutionary consequences of variation in species interactions?2. How do types of species interactions differ in variation?3. How do gradients differ in importance for variation in species interactions?
  • What are the evolutionary consequences of variation in species interactions?• Variation in abundance and community structure lead to variation in species interactions• How is natural selection altered in response to these variable interactions?
  • How do types of species interactions differ in variation?Competition Predation Mutualism -/- +/- +/+
  • How do gradients differ in importance for variation in species interactions? ? Space Time
  • Outline• Part I : What are the evolutionary consequences of agriculturally altered species interactions?• Part II: How variable are species interaction outcomes?
  • Part I -- What are the evolutionaryconsequences of agriculturally altered species interactions?
  • 12Foley et al. 2005 Science
  • Mechanisms for altered evolution in agricultural landscapes • Gene flow from crops to wild/weed plants • Evolution of resistance to genetically modified crops (e.g., Bt cotton) • Evolution of resistance in plant weeds to chemical herbicides • Yet, little examination of altered natural selection via altered species interactions 13Ellstrand et al. 1999
  • Mutualists Antagonists VS. Natural selectionMeehan et al. 2011, Devictor et al. 2008,Ekroos et al. 2010, Dormann et al. 2007 14
  • Spatial variation in importance of mutualists and antagonists on selection Site 1 Site 2 Flower Flower Traits Traits Mutualists Mutualists Antagonists Plant Plant Fitness Fitness 15Gomez et al. 2009 Ecol. Monog.
  • Abundance and community structure Abundance Community Structure
  • QuestionsDoes proximity to crops:1. Alter abundance of mutualists and antagonists?2. Alter community structure of mutualists and antagonists?3. Affect selection on native plant floral traits?4. Alter contribution of mutualists and antagonists to selection on native plant floral traits?
  • Study System: Helianthus annuus Wild sunflower Mutualist Antagonists(H. annuus texanus) Pollinators Seed predators Halictus ligatus Neolasioptera (Diptera) Isophrictis (Lepidoptera) Megachile spp. Crop sunflower (H. annuus) Smicronyx (Coleoptera) Apis mellifera Folivores
  • Study Design Natural habitat Agricultural landscape Other Crop [corn/sorghum/wheat/cotton] Far Distance ~ 2.5 km Sunflower Crop Distance Near ≤ 10 mData Collected• Pollinators: pollinator Proximity to sunflowers (2 levels)observations X• Seed predators: counted Seed source (2 levels)damaged seeds• Folivores: leaf damage @ 5 sites in ‘10, @ 2 sites in ‘11
  • Abundance - mutualistsAbundance Greater Near vs. Far Far Near Far Abundance Visits inflorescence-1 min-1 Near Proximity to crop sunflowers
  • Abundance - antagonists Greater Far vs. NearAbundance Neolasioptera Far Near Far Abundance Near Isophrictis Proximity to crop sunflowers Smicronyx
  • Abundance Far NearSucking folivore abundance Chewing folivore abundance Greater Far vs. Near Abundance - antagonists
  • Community structure - mutualists & antagonists Differs Near vs. Far for both M and A Mutualists Far Near Antagonists
  • Abundance Beta-diversity Proximity to crop sunflowers Proximity, P = 0.004 • This pattern may be due to large crop sunflower Abundance Far resource pulse driving greater Near diversity among sites Proximity to crop sunflowers * No difference for antagonists
  • How does proximity to crop sunflowers affect selection on H.a. texanus flower traits? Disk diameter Ray width Ray length Number of rays -> Five of nine heritable in narrow- Petal size sense (sire-offspring regression) Throat width Throat length Proximal throat size Floral tube size
  • Phenotypic selection analysis• Total selection (s’) – Measures direct + indirect selection – Simple regression measures calculates covariance between standardized trait (mean=0, sd=1) and relative fitness• Direct selection (β) – Measures direct selection on a trait by removing indirect selection on all other traits in a multiple regression – Multiple regression with standardized traits (mean=0, sd=1) and relative fitness
  • Testing for differences in selection by proximity• Analysis of Covariance – 2010: five sites • Model: relative fitness ~ site * proximity * trait • trait * proximity • trait * site * proximity – 2010 & 2011: two sites • Model: relative fitness ~ year * site * proximity * trait • trait * year * proximity • trait * year * site * proximity – Total selection • Separate models for each floral trait – Direct selection • One model including all floral traits
  • Natural selection Differs Near vs. Far in some traits Total Selection (s’) Direct Selection (β) Far Near Far Near Disk diameter NS Ray width Ray length Number of rays ANCOVA NS trait * proximity trait * site * proximity NS trait * year * proximity Petal size trait * year * site * proximity Throat width NS NS NS NS Throat length Proximal throat size Floral tube size NS NS
  • Natural selection – Dispersion • This pattern may be due to Selection (s’ or β) large crop sunflower resource pulse driving greater Far Near diversity Proximity to crop sunflowers among sites
  • Do mutualists and antagonists contribute to selection on floral traits differently? Flower traits Antagonists Mutualists Plant fitness
  • Multi-group analysis to compare paths between treatments (Near vs. Far)Principal componentsAnalysis: reduced Floral Traits Inflorescence Traitsdimensionality, usingjust PC1 for eachSeed predators andpollen deposition Isophrictis sp Neolasioptera helianthi Pollenstandardized tomean = 0, sd = 1 W= Relative Plant Fitness
  • Far NearSite 1 -0.07 -0.06 0.02 0.0042011 0.002 -0.01Site 22011
  • Conclusions Part I• Sunflower mutualists more abundant near, antagonists more abundant far from crops• Beta-diversity of mutualists greater near crops• Natural selection altered by proximity to sunflower crops• Changes in mutualist/antagonist communities drive differences in selection near vs. far from crops• This is one of few studies to show agricultural effects on natural selection across a landscape in a native plant species
  • Implications• Mutualist-antagonist framework may be useful in understanding agricultural effects on plant evolution• Natural selection altered in agricultural landscapes, BUT contrary to expectation• These results may not be found in non- intensive agricultural landscapes
  • Questions1. What are the evolutionary consequences of variation in species interactions?2. How do types of species interactions differ in variation?3. How do gradients differ in importance for variation in species interactions?
  • Part II --How variable are species interaction outcomes?
  • Questions• A) How do different species interaction types differ in variation in outcomes?• B) What are relative importance of drivers of variation in outcomes?
  • Meta-analysis Web of Science search Experimental studies only Interaction outcome w/ & w/o competitor, predator, or mutualist Error estimates & sample sizes available Response variables: abundance, population growth, reproduction, etc. Responses measured over >1 year, population, or species, etc.Final dataset 353 papers
  • Site B Site C Site D Site E Site A Mean Interaction Outcome Negative RII = better w/o herbivory from Armas et al. (2004) Positive RII = better with herbivory RII = X C - X E X C + X E Variation in Interaction Outcome Magnitude Change in sign of Interaction Outcome Site A 0 Site A Site B 1 Site B SDRII Site CCVRII = ´100 0 or 1 -1 Site C X RII Site D -1 Site D Site E 0 Site E
  • Gradients that drive variation in interaction outcomeAbiotic NutrientsSpace Across sitesSpecies identity Sp. A interacts with either sp. B or sp. CTime Across hours, days, years3rd party presence Two species w/ or w/o 3rd species
  • How do different species interaction types differ in variation in outcomes?• Mean strength – Mutualisms weaker than antagonisms (Morris et al. 2007) – General sense in literature that mutualisms less important because so variable (Sachs & Simms 2006) – Weak interactions the most variable (Berlow et al. 1999)• Interaction complexity – Predation more specialized than mutualism (Gomez et al. 2010) – Strength greater with fewer interactions (Edwards et al. 2010)
  • How do different species interaction types differ in variation in outcomes? Predation Mean Strength Interaction Complexity Expected Varation Strong More specialized LowCompetition ?? ?? ??Mutualism Weak More generalized High
  • How do different species interaction types differ in variation in outcomes? A Predation Competition Mutualism CV*of Effect Size CV effect size 150 100 = = 50 0 B cProportion of studiesProportion of studies b with sign change 0.6 a 0.4 < < 0.2 (120) (143) (90) 0.0 p c m
  • What are relative importance ofdrivers of variation in outcomes? 250 ab aCV of Effect Size 200CV* effect size ab 150 100 b b 50 (53) (46) (117) (97) (40) 0 ic al ty ral ce iot ati nti po en ab sp ide s es tem pre ci rty spe pa rd thi
  • Variation highly dependent on context in which the interaction occurs abiotic spatial species identity temporal third party presence CV* Effect Size 400 CV ofeffect size 300 200 a ab 100 b 0 b aProportion of studies b with sign of studies 0.8 b b Proportion change a c b a b b 0.6 a a a a 0.4 0.2 (21) (26) (6) (11) (16) (19) (53) (37) (27) (26) (47) (24) (9) (17) (14) 0.0 p c m p c m p c m p c m p c m
  • Variation highly dependent on context in which the interaction occurs abiotic spatial species identity temporal third party presence Predation - Opposite of CV of Effect Size 400 prediction that CV* effect size 300 specialized predation 200 a may lead to less ab Mutualism variation 100 b 0 Proportion of studies - Instead, when you b a interact with moreProportion of studies b with sign change with sign of studies 0.8 b b Proportion change a c species, each b a b b 0.6 interaction is more a a a a 0.4 equivalent, and are not that variable 0.2 (21) (26) (6) (11) (16) (19) (53) (37) (27) (26) (47) (24) (9) (17) (14) 0.0 p c m p c m p c m p c m p c m
  • Variation highly dependent on context in which the interaction occurs abiotic spatial species identity temporal third party presence 400 CV* Effect Size - In predation studies, species CV ofeffect size 300 were largely animals, which are more mobile than plants 200 a ab 100 - In competition and mutualism b studies, species were largely 0 b a plants, which are immobileProportion of studies 0.8 b b with sign of studies b Proportion change c b 0.6 a a - Interactions involvingb b a a immobile plants may be more a a 0.4 variable along abiotic gradients as they cannot escape them 0.2 (21) (26) (6) (11) (16) (19) (53) (37) (27) (26) (47) (24) (9) (17) (14) 0.0 p c m p c m p c m p c m p c m
  • Conclusions• Types of species interactions differed in outcome variation > > – Implications: • We can’t treat different species interactions as equivalent • In interaction webs, it may be most important to understand variation in mutualistic links• Types of gradients differed in outcome variation Species identity > Abiotic Space > Time > 3rd party presence – Implications: • Some sources of variation in species interactions should be given priority (i.e., species identity), especially in new study systems
  • Future work• Add other species interaction types: herbivory, parasitism, facilitation• Do any variables correlate with variation in species interaction outcomes? – Do body size ratios predict variable outcomes?
  • Questions1. What are the evolutionary consequences of variation in species interactions?2. How do types of species interactions differ in variation?3. How do gradients differ in importance for variation in species interactions?
  • Thanks to• Committee • Microscopy – Jennifer Rudgers – John Slater – Ken Whitney – Robert Langsner – Volker Rudolf • Meta-analysis – Dennis Cox – Tens of authors who provided• Help data – Toby Liss • Discussion – Wael Al Wawi – The R-W lab – Charles Danan – Steve Hovick – Yosuke Akiyama – Tom Miller – Neha Deshpande • Of course: Katherine Horn – Rohini Sigireddi – Prudence Sun – Morgan Black – Edward Realzola
  • Mean / Variation Interaction Complexity Predation Argument Argument + - Competition - -Mutualism/Facilitation + - +
  • OK, BUT WHAT ARE THE CONSEQUENCES?
  • Consequences of Variation in Outcome Ecological Outcomes between membracids and ants varied with: - Time (among years) - Membracid life stage - Membracid abundance And these likely will influence population dynamics of the interaction Cushman & Whitham (1989)
  • Consequences of Variation in Outcome Evolutionary John Thompson - Distributed Outcomes Distributed Outcomes Raw Material for Evolution of Species Interactions Population 1 1% of Interactions β 0 -1 0 100 Population 2 Interaction Outcome CV (-) Antagonistic  Mutualistic (+) Thompson (2005), Bronstein (1994)
  • Drivers of Variation in Outcome? -An example of species identity variation Moth attack (% of fruits of Opuntia imbricata)Miller (2007)
  • What are the consequences of agriculture• Populations – ????????• Communities – Communities often simplified, made more similar across sites (decreased beta-diversity) – Interaction networks are simplified in agricultural landscapes• Evolution – Antagonists (predators, competitors) often XXXX – Mutualists often XXXX Ekroos et al. 2010, Tylianakis et al. 2007
  • PredationMutualism
  • Presence of both mutualists and antagonists may increase trait diversity Number of Trees Principal Component Axis (cone & seed traits) 59Siepielski & Benkman 2010