The Effect of Niche Construction: A Digital Experiment

1. The Effect of Niche Construction: A Digital Experiment A population of Avidians evolved (mutations yield new instructions) over three periods, each defined by which tasks were rewarded (the environment). Runs with negative niche construction in the middle trimester ended with significantly higher fitness than paired static runs. first middle third reference reference reference STATIC reference alternate reference EXO. alternate reference reference N.C. time time • Both the presence and form of niche construction affected adaptation. Static Environment Runs Negative Niche Construction Transplant (into Negative Niche Construction) Positive Niche Construction

2. Niche Construction • Lecture Outline • Introduction to niche construction • Niche construction and adaptive landscapes • Rekindling an old flame • Experiment on mutual niche construction • Summary

3. Fire and Plants • Wildfire is a recurring event in many vegetation systems. • Plants in fire-prone ecosystems have a remarkable suite of traits to persist: • Survival traits (e.g., lignotubers, thick bark) • Reproductive traits (serotiny, fire-cued flowering or germination) • Such traits have been interpreted as adaptations to cope with the presence of fire. E. moorei P. rigida (Lyne, 1996) (Little, 1990) B. attenuata W. borbonica (Bond & van Wilgen 1996) (Bond & van Wilgen 1996)

4. Flammability • Certainly climate affects the fire regime of a given vegetation • However, as fuel, the plants also influence the nature and intensity of fire. • Traits exist in many fire-prone species which enhance their flammability: • Retention of dead branches • Possession of volatile compounds • Fine branching patterns • Schleromorphic leaf structure E. globulus A. fasciculatum (Simpson, 2003) (Boden & Fagg, 2003)

5. The Mutch Hypothesis D D D D D D D D D D D D D T D D D D D D D D D D D If plants possess traits to persist in a fire-prone environment, then there may be selection for characteristics that enhance flammability. (Mutch, 1970) • Mutch ado about nothing? Criticisms of the Mutch hypothesis: • It is difficult to see how a more flammable variant would invade a less flammable population of conspecifics • (Snyder 1984, Troumbis & Trabaud 1989) • Flammability is a side-effect of selection for other traits (e.g., volatile oils are selected because they deter herbivores) • (Snyder 1984, Bond & van Wilgen, 1996) • Flammability is not a trait of individuals, but an emergent property of populations. • (Snyder 1984, Troumbis & Trabaud 1989) E. ficifolia (Monroe & Clark, 2003)

6. A Bright Idea: Testing Flammability as Niche Construction Dylan Schwilk pyrometer calorimeter • Can the traits of plants influence the intensity and biological effects of wildfire at a local scale? • Schwilk (2003) executed a field experiment to gauge whether the retention of dead branches by chamise shrubs (Adenostoma fasciculatum) affected fire intensity and effects. • Four replicated treatments were established: • Unmanipulated • Removal • Clip and leave • Addition Clip & Leave Removal • Prescribed burns were set and temperature and plant response were measured. Un-manipulated Addition

7. Field Results 2000 2001 • Schwilk found that treatments with intact dead branches (un-manipulated and addition) had significantly higher temperatures than treatments with dead branches removed. • Schwilk found that the density of seedlings of another species (C. cuneatus) was highest in treatments with dead branches. • This is evidence that flammability is a niche construction trait. Discuss the role of niche construction in management and conservation: How might the results of this experiment influence fire management policy? Conservation of fire-adapted plant species?

8. Niche Construction • Lecture Outline • Introduction to niche construction • Niche construction and adaptive landscapes • Rekindling an old flame • Experiment on mutual niche construction • Summary

9. Coevolution as Mutual Niche Construction environment (t) population (t) population (t) niche construction natural selection niche construction ecological inheritance genetic inheritance genetic inheritance population (t+1) environment (t+1) population (t+1) • The new view of evolution incorporating niche construction emphasizes the effects organisms have on their environment. • However, one major part of the environment is other organisms (e.g., predators, pathogens, competitors, mutualists). • In this light, coevolutionary dynamics can be recast as mutual niche construction. • Here, we focus on cases where two interacting species have an antagonistic interaction. • Niche construction by one species induces new niche construction in the other (i.e., a construction arms race).

10. Red Queen Dynamics in Microbial Populations • Red Queen principle: • When a population is interacting (antagonistically) with another evolving population, continual evolutionary change is necessary just to “stay in the game” • The effects of a coevolutionary arms race on the rate of molecular evolution can be explored with phage. “Now, here, you see, it takes all the running you can do, to keep in the same place.” • Paterson, Brockhurst and colleagues (2010) propagated phageF2 with Pseudomonas fluorescens under two treatments: • “Evolution”: Phage evolves against a constant host. • “Coevolution”: Phage evolves against a co-evolving host. • Compared to the Evolution treatment, coevolved phage: • Possessed a higher rate of molecular evolution • Displayed greater divergence between and within replicates • Displayed greater variation at loci involved in host adhesion S. Paterson M. Brockhurst EVOLUTION COEVOLUTION … …

11. Niche Construction • Lecture Outline • Introduction to niche construction • Niche construction and adaptive landscapes • Rekindling an old flame • Experiment on mutual niche construction • Summary

12. Summary • Through their physiology, development and behavior, organisms alter the world in which they live– this process is called “niche construction.” • Incorporation of niche construction offers a different evolutionary perspective, where the effects organisms have on their environment can feed back to influence future evolution. • Niche construction can involve physical perturbation or relocation, can be inceptive or counteractive, and can have negative or positive fitness consequences. • Niche construction is now being explored in mathematical modeling, computer simulations, laboratory experiments and field studies: • Niche construction can affect the evolution of cognition. • Niche construction can affect the process of adaptation. • Niche construction can be demonstrated in the field. • Coevolution can be seen as a form of mutual niche construction and shown to affect rates of evolution in antagonistic interactions.

13. Thank you E3!