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Evolution of the niche in protozoan Communities William Bartram, ~1780.

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Presentation on theme: "Evolution of the niche in protozoan Communities William Bartram, ~1780."— Presentation transcript:

1 Evolution of the niche in protozoan Communities William Bartram, ~1780

2 Outline 1.Who am I? 1.What QUESTIONS am I interested in? 2.What TECHNOLOGY do I use? 3.Example of a project 4.Motivation: Why I use (or want to use) the individual-based approach? 5.Challenges: What prevents me from (or makes it difficult to) use the individual-based approach? 6.Opportunities: What (else) the individual-based approach could be used for?

3 Ecology and Evolution of Species Patterns using Pitcher Plants

4 Food web within Pitcher Plants Studied by: Addicot, Istock, Bradshaw, Ellison and Gotelli, Kneitel and Miller, Hoekman, many others Bacterivores

5 Dominant Bacterivores Species in Sarracenia Colpoda (CA) Eimeriidae (BFC) Bodo (BO) Poterioochromonas (CH) flagellates ciliates Mosquito larvae bacteriovores bacteria dead bugs Habrotrochus Sarraceniopus gibsonii

6 Evolution in ecological time scale What role does past or current evolution play in determining species patterns? In this system, we can quantify evolution over successional time scales because of the fast generations times.

7 Competitive Hierarchy in Protozoa in Two Week-old Community Mosquito larvae protozoa bacteria dead bugs CH < BO < BFC = CA competitive ability rank CHBOBFCCA CH -1.00* BO *-0.14* BFC CA0.13* Effect of Effect on

8 CHBOBFCCA CH -1.00* BO *-0.14* BFC CA0.13* WEEK 2WEEK 7 WEEK 12 CHBOBFCCA CH *-0.50* BO *-0.10* BFC CA CHBOBFCCA CH -0.36* BO *-0.02 BFC-0.14* * CA *-0.16* Evolution of Interaction Strengths less competitive effect increased competitive effect

9 Conclusions There is no evidence for pairwise niche convergence or divergence among competitors in this community. Our fundamental view of species’ niche overlap driving evolution of competitors may need revision. What is really evolving? While we measure interaction traits, we have no knowledge of the mechanisms involved. NIMBioS Question 1: At the level of individual cells, what traits or characters are actually evolving?

10 species Resource-use matrixPer-capita interaction matrix Population growth resources A model of evolution with substitutable resources

11 species Resource-use matrixPer-capita interaction matrix Population growth.1 resources A model of evolution with substitutable resources

12 resources species Resource-use matrixPer-capita interaction matrix Population growth.1

13 terHorst, Miller, and Power model One species diverges to specialize on Resource 1 Two species converge to specialize on Resource 1 terHorst, Miller, and Powers Evol. Ecol. Res. 12:

14 Convergence is an evolutionary outcome of competition of >2 species Convergence or divergence can occur when there is sufficient selection and genetic variation to converge before extinction occurs. terHorst, Miller, and Power model terHorst, Miller, and Powers Evol. Ecol. Res. 12:

15 terHorst, Miller, and Power model A problem is that the model essentially acts through group selection. It creates variation in resource use among populations, then selections the population that has the highest growth rate. This form of modeling competitors has been shown to be inaccurate. NIMBioS Question 2: What is the best way to model the simultaneous evolution of competitors, based on selection on individuals?

16 Outline 1.Who am I? 1.What QUESTIONS am I interested in? 2.What TECHNOLOGY do I use? 3.Example of a project 4.Motivation: Why I use (or want to use) the individual-based approach? 5.Challenges: What prevents me from (or makes it difficult to) use the individual-based approach? 6.Opportunities: What (else) the individual-based approach could be used for?

17 This work has been significantly supported by the National Science Foundation Thanks to the many students that either marked leaves and sucked up pitcher plants out in the miserable heat or counted protozoa in the very cold Miller lab, including Amber Roman, Casie Reed, Fani Gruber, John Mola, and Heather Wells.

18 CHBOBFCCAPred CH -1.00* -0.48* BO *-0.14*-0.24* BFC CA0.13* WEEK 2WEEK 7 WEEK 12 CHBOBFCCAPred CH *-0.50*-0.15 BO *-0.10*-0.14 BFC * CA CHBOBFCCAPred CH -0.36* * BO * BFC-0.14* *-0.29* CA *-0.16* -0.37* Evolution of Predation Tolerance Less effect Increased effect

19 Biogeography detail on community

20 Buckley, et al Community Patterns within a Field

21 WEEKS High Predation Low Competition Low Predation High Competition Mosquito larvae protozoa bacteria dead bugs Succession in Sarracenia leaves

22 terHorst selection experiments in the laboratory show that Colpoda evolve faster growth rates and smaller size when in competition. Evolution of Colpoda in competition terHorst, J. Evol. Biol. 24:36-46

23 terHorst selection experiments in the laboratory show that Colpoda evolve when in predation. Evolution of Colpoda with predation by Wyeomyia terHorst, Miller and Levitan, Ecology 91:

24 Poorer get rich and rich get poorer

25 Results, again Poorer competitors evolve to be better competitors (effect and response) Better competitors evolve to be poorer competitors (effect and response) All the species are converging on an intermediate competitive ability But, NOT convergence as described before, driven by reciprocally increased competitive interactions No evidence of a competition/predation trade-off.


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