Plant-animal interactions Co-evolution? Herbivory Plant defense Pollination Seed dispersal Interactions across the life cycle Conservation: butterflies/host plants Photos: Ricklefs (Economy of Nature), Bradshaw & Schemske, Kalko,

TODAY: Interactions across the life cycle Definitions and issues – Life cycle diagram – Interactions happen at certain stages – Fitness components – Fitness – Constant world – (Variable world) – Traits Example

LIFE CYCLE DIAGRAM a population dynamics model Individuals in each stage, from one year to the next, may survive (Survival) may change life stage (Growth) may reproduce by a certain amount (Reproduction) The probabilities/rates are written on these arrows

STAGE SPECIFIC INTERACTIONS Interactions influence particular rates and probabilities

FITNESS COMPONENTS FITNESS : representation in future population Depends upon ALL probabilities/rates Each probability/rate is a FITNESS COMPONENT

FITNESS FITNESS : Per capita rate of increase for a population that has these rates Calculated using matrix analysis represented by λ

Sequence of environments … … … … Environmental transition probabilities Life cycle probabilities/rates & animals vary among environments

Sequence of environments … … … … Environmental transition probabilities Life cycle probabilities/rates & animals vary among environments

FITNESS : Per capita rate of increase for a population in this changing environment Calculated using stochastic sequence matrix analysis Represented by λ s

So… Animals - affect  Rates on arrows Rates on arrows -  Fitness Animals - affect  Fitness

TRAITS? Plant traits may influence the effects of animals Animals - affect  Rates on arrows Rates on arrows -  Fitness Animals - affect  Fitness

TODAY: Interactions across the life cycle Definitions and issues – Life cycle diagram – Interactions happen at certain stages – Fitness components – Fitness – Constant world – (Variable world) – Traits Example

Part I. The effects of animals on fruit production and fates of a neotropical herb

Calathea ovandensis (Marantaceae )

Laguna encantada Laguna Encantada, Los Tuxtlas Veracruz, MEXICO

Effects of animals on “fitness components”  Within the year natural variation among individuals: fruit production  Between years natural variation among individuals: fates the subsequent year  Within the year experimentally induced variation in herbivores and antguards: fruit production

Natural variation in parameters quantified for individual plants in the field

Effects of animals & covariates Pollinator visits, antguards, herbivory of reproductive tissues -> flowers, initiated and mature fruits Schemske & Horvitz, Ecology 69: Size, herbivory of leaves, competition, fruits -> survival, growth, inflorescence production Horvitz & Schemske Journal of Ecology 90:

Animals & covariates Antguards Herbivory of reproductive tissues Pollinators Size Herbivory of leaf tissues Neighbors Fruits

Animals & covariates  Antguards  Herbivory of reproductive tissues  Pollinators  Size  Herbivory of leaf tissues  Neighbours  Fruits

Flowers Path analysis: effects of animals on reproduction Initiated fruits Mature fruits Ants Eurybia Pol 1 Pol 2 Pol 3

Antguards at EFN

Eurybia elvina (Riodinidae)

Eurybia elvina (Riodinidae)

Flowers with trigger

Animals influencing fruit production within a season  Antguards (many taxa)  Herbivory of reproductive tissues  Eurybia elvina (Riodinidae)  Number of visits by pollinators  Euglossa spp  Eulaema cingulata  Eulaema polychroma  Exaerete smaragdina  Rhathymus sp

Conclusions: effects of animals on flower and fruit production Ants: + direct on flower production, both yrs Ants: + indirect on fruit production, both yrs Eurybia: - direct on flower production, both yrs Eurybia: - direct on fruit production, both yrs Pollinators: + direct on fruit initiation, 1 yr only (the year with more abundant high quality visitors)

Animals & covariates Antguards Herbivory of reproductive tissues Pollinators Size Herbivory of leaf tissues Neighbors Fruits

Animals & covariates in one year acting on fates the following year Current size (leaf area, cm 2 ) Herbivory of leaf tissues (% leaf area gone) Neighborhood competition (leaf area, cm 2 ) Fruits produced

Size Herbivory Neighbors [Fruits] Survival Path analysis for effects of animals & covariates on survival probability

Size Herbivory Neighbors [Fruits] Relative growth Path analysis for effects of animals & covariates on growth rate

Size Herbivory Neighbors [Fruits] Inflore- scences Path analysis for effects of animals & covariates on reproduction

Separate analyses for each dependent variable by stage and year (total of 55 analyses!)  Seedlings  Juveniles  Pre- reproductives  Reproductives  1982  1983  1984  1985  1986 

Conclusions: effects of animals (& covariates) on probabilities/rates Size: important for all stages, improving survival (of smallest ones) and improving reproduction, but slowing down relative growth. Herbivory: very low in general; it had mysterious negative effects in 1985, not the year it was highest. Competition: strongest negative impact on seedlings, but also had temporal pattern (partially) consistent with its strength. Fruit production: positive impacts on future growth and future reproduction.

Effects of herbivores and antguards on fitness: experimental results combined with population study Maron, Horvitz &Williams J. Ecol. 98: based on data in experiment : 600 plants for 9 wks: Horvitz & Schemske Ecology 65: population: >5,000 plants over 6 yrs : Horvitz & Schemske Ecological Monographs. 65:

Part II. Selection on traits affecting interactions of animals with plants in variable environments

“Tripping” mechanism Insects with short tongues have to get heads deeper in Short floral tubes ?=? higher fruit set Yes, if short-tongued insects are abundant No, if short-tongued insects are absent

Short-tongued visitors = efficient pollinators Rarely seen One year: More abundant That year: Counts of visits by pollinators explained significant variation in fruit production Schemske & Horvitz Science 225: Schemske & Horvitz Ecology 69: >21,000 floral visits observed 1984, 1985, 1986

a small tropical Mexican herb Floral tube length (pollinator related) 3 yrs of selection gradients Fruit production Demographic projection matrices for 4 yrs Regional environmental dynamics

SELECTION Relative fitness regressed against quantitative trait value The slope of the regression = selection gradient for the trait (Lande and Arnold 1983 Evolution) fitness something quantitative

FITNESS : Per capita rate of increase for a population in this changing environment Calculated using stochastic sequence matrix analysis Represented by λ s

SELECTION across the life cycle stage-specific elasticity, e ij = change in λ due to a change in one element of the matrix X selection gradient = change in one element of the matrix due to a change in the trait value = regression of fitness component on trait (van Tienderen 2000 Ecology, Coulson et al Evolution)

SELECTION ACROSS THE LIFE CYCLE in variable environments Environment-specific elasticity, e ijβ = change in λ S due to a change in one matrix element in one state of the environment X selection gradient = change in one matrix element in one state of the environment due to a change in the trait value = regression of fitness component on trait Horvitz, Coulson, Tuljapurkar, Schemske (2010)

Environmental variation in stage-specific demographic rates Environmental variation in stage-specific selection gradients* *Slopes for analyses of fitness components regressed against trait.

Rainfall in the Dry Season,mm [9.3, 111.7] μ = 57.1, σ = 25.2: mean monthly precipitation (mm) records Nov-May town of San Servicio Nacional de Meterologia of Mexico. Data are expressed as the annual deviation from the mean divided by the standard deviation ENVIRONMENTAL TRANSITION RULES FROM HISTORY Study years (open bars) in context of long-term climate data Assign each historical year a set of rates from one study year Let historical sequence determine environmental transition rules

… … climate :Dry Season Rainfall …… … one alternative: Environmental Stasis Sequences for hypothetical environmental drivers

INTEGRATED SELECTION FORMALLY Environment-specific elasticity X Environment-specific selection gradient (summed across all life history and environmental transitions, weighted by the frequency of each environment) Horvitz, Coulson, Tuljapurkar, Schemske (2010)

Environment-specific integrated selection Environment-specific elasticity Environmental driver alters elasticity of λ s and integrated selection Climate driven dynamics One alternatively driven set of dynamics

Integrated selection summed across all environments by life-history rate Climate driven dynamics One alternatively driven set of dynamics Stages 3-8:

Climate driven dynamics One alternatively driven set of dynamics Integrated selection summed across all life-history rates by environment

Stochastic Growth Rate ( λ S ) & Total Integrated Selection Driver of Environmental Change (Cervus) Climate*Alternative NAO ** 26-yr cycle Stochastic Growth Rate ( λ s ) Total Integrated Selection *Precipitation during dry season ** North Atlantic Oscillation Index

Conclusions: Selection across the life cycle in variable environments Historical climate data combined with a few years of demographic observations: plausible long run patterns Stronger (1.7 X) selection by pollinators for short tubes in climate-driven scenario of environmental change The force of selection on a trait depends upon environmental dynamics

TODAY: Interactions across the life cycle Definitions and issues – Life cycle diagram – Interactions happen at certain stages – Fitness components – Fitness – Constant world – (Variable world) – Traits Example