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Eseb meeting switzerland 2015_jose m iriondo

  1. 1. Local adaptation versus inbreeding depression in marginal populations of a Mediterranean alpine plant: are they worthy of conservation in a context of climate change? Morente-López, J., García-Fernández, A., Lara-Romero, C., Rubio-Teso, M.L., Ruiz, R., Sánchez, A., Iriondo, J.M. Área de Biodiversidad y Conservación, Universidad Rey Juan Carlos, E-28933 Móstoles, Madrid, Spain.
  2. 2. • Genetically impoverished populations • Inbreeding depression • Maladaptation • Not necessarily depauperate for variation in ecologically relevant traits. • Locally adapted Introduction Aims Materials & Methods Results & Discussion Conclusions Marginal populations: • grow under suboptimal environmental conditions • great fluctuations and high probability of extinction Soulé (1973) ? Kawecki, T. J. 2008. Annu. Rev. Ecol. Evol. Syst. 39:321–342. Soulé M. 1973. Annu. Rev. Ecol. Sys. 4:165-187 Lande R. 1994. Evolution 48: 1460–1469. Whitlock MC. 2003. Genetics 164: 767–779. Lande (1994), Whitlock (2003) Kawecki (2008)
  3. 3. Mediterranean alpine environments: highly vulnerable to global warming Introduction Aims Materials & Methods Results & Discussion Conclusions Marginal populations Central populations temperature rainfall
  4. 4. Experimental gene flow between populations: • assessment of inbreeding depression and geneflow of adaptive/maladaptive value • management tool to assist marginal populations Introduction Aims Materials & Methods Results & Discussion Conclusions Marginal populations Central populations central – marginal geneflow: • Genetic diversity (Holt & Gomulkiewicz, 1997) • Maladaptive alleles or gene combinations (Kirkpatrick & Barton, 1997) Holt RD, Gomulkiewicz R. 1997. Am Nat 149:563-572 Kirkpatrick M, Barton NH. 1997. Am Nat 150:1-23
  5. 5. Experimental gene flow between populations: • assessment of inbreeding depression and geneflow of adaptive/maladaptive value • management tool to assist marginal populations Introduction Aims Materials & Methods Results & Discussion Conclusions Marginal populations Central populations marginal-marginal geneflow • Genetic diversity & adaptive alleles or gene combinations (Sexton et al. 2011) Sexton JP, Strauss SY, Rice KJ. 2011. PNAS 108:11704-11709
  6. 6. Aim: • To assess whether marginal populations at the lowest elevation of Mediterranean alpine plants are locally adapted/maladapted to the environmental conditions that will prevail with global warming Introduction Aims Materials & Methods Results & Discussion Conclusions
  7. 7. • Circum-mediterranean alpine chamaephyte • Central System at the lowest latitude of the distibution range: • Sierra de Béjar • Sierra de Gredos • Sierra de Guadarrama • Elevation range: 1900 – 2500 m Introduction Aims Materials & Methods Results & Discussion Conclusions Silene ciliata Pourret
  8. 8. Introduction Aims Materials & Methods Results & Discussion Conclusions • Central population • Marginal populations GuadarramaGredosBéjar Central vs. marginal populations (Giménez-Benavides et al. 2011) Giménez-Benavides, L., Albert, M.J., Iriondo, J.M. & Escudero, A. Ecography (2011) 34:85-93
  9. 9. Introduction Aims Materials & Methods Results & Discussion Conclusions Central population from same mountain range Marginal population Marginal population from same mountain range X 6 marginal populations F1 F2 F3 Experimental design: • Seeds obtained in common garden conditions from artificial crossings simulating different types of geneflow
  10. 10. Experimental design: • Ex situ sowing experiment at optimum conditions in growth chamber and greenhouse environment (mother plant x type of cross x block x pop. = 8640 seeds). • In situ sowing experiment at the locations of the 6 marginal populations (mother plant x type of cross x block x pop. = 24000 seeds) Introduction Aims Materials & Methods Results & Discussion Conclusions
  11. 11. Introduction Aims Materials & Methods Results & Discussion Conclusions Ex situ germination experiment F1<F2, F3 F1=F2, F3 Germination = geneflowi + populationj + (geneflow x population)ij + motherplantk(j)
  12. 12. Introduction Aims Materials & Methods Results & Discussion Conclusions Ex situ germination experiment RUI AGI CAM SES NAJMOR F1<F2,F3F1<F2,F3 F1=F2,F3 F1=F2,F3F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2,F3 Inbreeding depression F1 F2 F3 GuadarramaGredosBéjar
  13. 13. Introduction Aims Materials & Methods Results & Discussion Conclusions In situ germination experiment F1<F3 F1>F2 F1=F2,F3 F1<F2 Germination = geneflowi + populationj + (geneflow x population)ij + motherplantk(j)
  14. 14. Introduction Aims Materials & Methods Results & Discussion Conclusions In situ germination experiment RUI AGI CAM SES NAJMOR F1>F2F1<F3 F1=F2,F3 F1=F2,F3F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2 Adaptation from MOR F1 F2 F3 Maladaptation from RUI GuadarramaGredosBéjar
  15. 15. Introduction Aims Materials & Methods Results & Discussion Conclusions In situ germination experiment RUI AGI CAM SES NAJMOR Local adaptation (Giménez-Benavides et al., 2007) Inbreeding depression (García-Fernández et al., 2012) GuadarramaGredosBéjar Giménez-Benavides L, Escudero A, Iriondo JM. 2007. Ann Bot 99:723-734. García-Fernández A, Iriondo JM, Escudero A.2012. Oikos 121: 1435-1445.
  16. 16. Introduction Aims Materials & Methods Results & Discussion Conclusions RUI AGI CAM SES NAJMOR F1 F2 F3 F1>F2F1<F3 F1=F2,F3 F1=F2,F3F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2 Adaptation from MOR Maladaptation from RUI In situ F1<F2,F3F1<F2,F3 F1=F2,F3 F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2,F3 Inbreeding depression Ex situ F1=F2,F3
  17. 17. Introduction Aims Materials & Methods Results & Discussion Conclusions RUI AGI CAM SES NAJMOR F1 F2 F3 F1>F2F1<F3 F1=F2,F3 F1=F2,F3F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2 Adaptation from MOR Maladaptation from RUI In situ F1<F2,F3F1<F2,F3 F1=F2,F3 F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2,F3 Inbreeding depression Ex situ F1=F2,F3 He= 0.63 FIS= 0.33 Ne= 10 He= 0.75 FIS= 0.32 Ne= 25 He= 0.66 FIS= 0.19 Ne= 12 He= 0.70 FIS= -0.12 Ne= inf He= 0.70 FIS= 0.39 Ne= 66 He= 0.51 FIS= 0.31 Ne= 131
  18. 18. Introduction Aims Materials & Methods Results & Discussion Conclusions RUI AGI CAM SES NAJMOR F1 F2 F3 F1>F2F1<F3 F1=F2,F3 F1=F2,F3F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2 Adaptation from MOR Maladaptation from RUI In situ F1<F2,F3F1<F2,F3 F1=F2,F3 F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2,F3 Inbreeding depression Ex situ F1=F2,F3 He= 0.63 FIS= 0.33 Ne= 10 He= 0.75 FIS= 0.32 Ne= 25 He= 0.66 FIS= 0.19 Ne= 12 He= 0.70 FIS= -0.12 Ne= inf He= 0.70 FIS= 0.39 Ne= 66 He= 0.51 FIS= 0.31 Ne= 131
  19. 19. Introduction Aims Materials & Methods Results & Discussion Conclusions RUI AGI CAM SES NAJMOR F1 F2 F3 F1>F2F1<F3 F1=F2,F3 F1=F2,F3F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2 Adaptation from MOR Maladaptation from RUI In situ F1<F2,F3F1<F2,F3 F1=F2,F3 F1=F2,F3 Inbreeding depression No inbreeding depression F1<F2,F3 Inbreeding depression Ex situ F1=F2,F3 He= 0.63 FIS= 0.33 Ne= 10 He= 0.75 FIS= 0.32 Ne= 25 He= 0.66 FIS= 0.19 Ne= 12 He= 0.70 FIS= -0.12 Ne= inf He= 0.70 FIS= 0.39 Ne= 66 He= 0.51 FIS= 0.31 Ne= 131 Leimu R , Fischer M. 2008. PLoS ONE 3: e4010
  20. 20. Introduction Aims Materials & Methods Results & Discussion Conclusions RUI AGI CAM SES NAJMOR F1 F2 F3 • Seedling survival and size (up to July): No differences between geneflow treatments • On-going experiment In situ
  21. 21. Introduction Aims Materials & Methods Results & Discussion Conclusions Marginal populations Central populations F1F2 F3 Little evidence of adaptive geneflow between marginal populations: • Mimulus laciniatus (Sexton et al., 2011) Sexton JP, Strauss SY, Rice KJ. 2011. PNAS 108:11704-11709
  22. 22. Introduction Aims Materials & Methods Results & Discussion Conclusions • Some evidence of central populations providing genetic diversity that reduces inbreeding depression (Holt & Gomulkiewicz, 1997) • No evidence of maladaptive alleles or gene combinations from central populations (Kirkpatrick & Barton, 1997) Marginal populations Central populations F1F2 F3 Holt RD, Gomulkiewicz R. 1997. Am Nat 149:563-572 Kirkpatrick M, Barton NH. 1997. Am Nat 150:1-23
  23. 23. Introduction Aims Materials & Methods Results & Discussion Conclusions Marginal populations Central populations F1F2 F3 Genetic differentiation in functional traits between central and marginal populations: • Tolerance to water stress (García-Fernández et al. 2013). • Flowering phenology: S. ciliata (unpublished results), Armeria caespitosa (Lara- Romero et al., 2014) García-Fernandez A, Iriondo JM, Bartels D, Escudero A.2013 Plant Biol 15:93-100. Lara-Romero C, García-Camacho R, Escudero A, Iriondo JM. 2014. Bot J Linn Soc 176:384-395.
  24. 24. Introduction Aims Materials & Methods Results & Discussion Conclusions Conclusions 1. High incidence of inbreeding depression in marginal populations. 2. Both adaptive/maladaptive geneflow between marginal populations at the germination stage. 3. No maladaptive geneflow between central and marginal populations at the germination stage. 4. Variation of responses to geneflow depending on the marginal population are probably associated to differences in effective population size, genetic diversity and population inbreeding. 5. Response to geneflow in a given marginal population is also dependent on temporal variation of environmental conditions
  25. 25. Local adaptation versus inbreeding depression in marginal populations of a Mediterranean alpine plant: are they worthy of conservation in a context of climate change? Acknowledgements: • C. Diaz, G. Escribano, S. Prieto, P. Tabares, S. Eleazar, L. Cano & L. Martinez • Parque Nacional de la Sierra de Guadarrama • Parque Regional de la Sierra de Gredos • Reserva de la Biosfera de la Sierras de Béjar y Francia • AdAptA Project CGL2012-33528, Spanish National R&D&I Plan

Editor's Notes

  • I am going to talk about the presence of adaptation or maladaptation and inbreeding depression in marginal populations
  • If we consider that marginal populations are those the grow under suboptimal environmental conditions within the ecological range of the species and in terms of population dynamics experience great fluctuations and higher probability of extinction, we can see that marginal populations have traditionally been seen under two perspectives: they are populations normally located a the end of the distribution range, genetically impoverished and subject to inbreeding depression, and, therefore, maladapted to the conditions that they are experiencing, or, on the contrary, and in spite of some limitations, they are locally adapted to the reigning marginal environmental conditions.
    Lande R, 1994: Risk of population extinction from fixation of new deleterious mutations. Evolution 48: 1460–1469.
  • Mediterranean alpine environments are highly vulnerable to global warming and in this sense marginal populations may be of interest, because they are currently experiencing the environmental conditions of higher temperatura and lower rainfall that central populations are going to experience in the future.
  • Experimental gene flow between populations can be a way of assessing inbreeding depression in populations and the existence of geneflow of adaptive or maladaptive value and could actually be used as a way to assist wild plant populations affected by global change.
    Historically the geneflow between central and marginal populations has been proposed to be beneficial for marginal populations as it provides much needed genetic diversity in marginal populations to evolve. On the contrary, and based on the theory on the evolution of the limits of distribution (Kirkpatrick & Barton, 1997), central to marginal geneflow can transfer maladaptive alleles or gene combinations.
    Complement to the traditional reciprocal transplant experiments used to determine local adaptation…
  • More recently, Sexton et al. have highlighted the possible benefits of geneflow between marginal populations subject to the same environmental conditions as they can provide both genetic diversity and adaptive alleles or gene combinations.

    Complement to the traditional reciprocal transplant experiments used to determine local adaptation…
  • Thus, in this context, the aim of our study was…
  • We based our study on Silene ciliata, Caryophyllaceae, a species of circum-mediterranean distribution found in the iberian, italic and balkan penínsulas as well as in France. We worked on the populations of the Central System located at the westernmost lowest latitude of the distribution range on three sierras, covering an elevation range between 19 hundred and 25 hundred meters.
  • We generated an ecological niche model with Maxent to objectively identify the marginal populations we worked on. We defined as marginal those populations whose hábitat suitability index was in the lowest quartile. We selected 6 populations, two in each sierra, located at the lowest elevations. Previous studies of our group showed that these populations were smaller and had lower population growth rates and reproductive success than the populations identified as central populations.
    Lower demographic performance and reproductive success in low elevation populations (Giménez-Benavides et al. 2007, 2011).

    Marginal populations are those in the first quartile of hábitat suitability in a Maxent model
  • With plant material gathered from each of these marginal populations and grown in common garden conditions we obtained seeds from artificial crossings simulating different types of genelow. Specifically we cross the plants of our focal marginal population with F1 pollen from the same population., F2 pollen from another marginal population from the same mountain range and F3 pollen from a central population of the same mountain range. These was done for the 6 marginal populations we chose.
  • With these seeds we carried out an ex situ sowing experiment at optimum conditions in a growth chamber and subsequently in a greenhouse, and a main in situ sowing experiment at the locations of the 6 marginal populations. In both cases we considered the identity of the mother plant, type of cross, block and population and used over 8000 seeds in the ex situ experiment and 24000 seeds in the in situ experiment.
    In situ: 10 seeds/mother plant x 20 mother plants/type of cross x 5 types of cross /block x 4 blocks/population x 6 populations = 24000 seeds
    Ex situ: 24 seeds/mother plant x 4 mother plants/type of cross x 5 types of cross/block x 3 blocks/population x 6 populations =8640 seeds
  • With the ex situ experiment we aim to detect the most extreme cases of inbreeding depression, which would not be able to germinate even at optimal environmental conditions and with no wáter limitation. In half the populations the progeny of F1 had lower germination capacity.
  • Therefore, we interpreted that these populations, that were located at the edges of the Central System were experiencing inbreeding depression.

    The ex situ germination experiment aimed at determining the germination capacity of each cohort by incubating seeds at optimum conditions. The lower the germination capacity, the greater the inbreeding depression.

    Mean comparison by Dunnett test against F1.

    Similar results were obtained when we used Mean Germination Time
  • The in situ germination experiment provided 4 different types of responses that took place at the environmental conditions of the marginal populations
  • In RUI population F1 had lower germination than F3, which again indicated a situation of inbreeding depression. In AGI population the higher value of F1 over F2 could be interpreted as a maladaptive carry over by F2, whereas in NAJ we found the opposite situation where the higher germination of F2 could be seen as adaptive alleles and gene combinations carried from the other marginal population MOR.
  • Interesting to note that in MOR population in which we did not detect differences between treatments, we had detected in previous years evidences of both local adaptation and inbreeding depression.

    Inbreeding depression in MOR population (García-Fernández et al., 2012a).
  • There was a high congruence between the results of ex situ and in situ germination experiments.

    Inbreeding depression in MOR population (García-Fernández et al., 2012a).
    Najarra: He y Fis de los cuatro primeros marcadores de Carlos (uno de ellos distinto al utilizado en el resto del estudio)
    Ne calculado para los 8 marcadores de Najarra
  • In parallel we conducted a genetic characterization of the marginal populations using microsatellite markers


    Inbreeding depression in MOR population (García-Fernández et al., 2012a).
    Najarra: He y Fis de los cuatro primeros marcadores de Carlos (uno de ellos distinto al utilizado en el resto del estudio)
    Ne calculado para los 8 marcadores de Najarra
  • It is interesting to note that the populations in which we detected inbreeding depression were associated to low genetic diversity values and effective population sizes,

    Inbreeding depression in MOR population (García-Fernández et al., 2012a).
    Najarra: He y Fis de los cuatro primeros marcadores de Carlos (uno de ellos distinto al utilizado en el resto del estudio)
    Ne calculado para los 8 marcadores de Najarra
  • And conversely, the populations in which we did not detect inbreeding depression were associated to low inbreeding values and high effective population size estimates. This is in accordance to Leimu and Fischer’s metanalysis in which they found that population size was a critical factor in local adaptation.

    Inbreeding depression in MOR population (García-Fernández et al., 2012a).
    Najarra: He y Fis de los cuatro primeros marcadores de Carlos (uno de ellos distinto al utilizado en el resto del estudio)
    Ne calculado para los 8 marcadores de Najarra
  • In the in situ experiment we have been monitoring seedling survival and size and so far we have found no differences between geneflow treatments.

    Inbreeding depression in MOR population (García-Fernández et al., 2012a).
  • Therefore, so far we have found Little evidence of adaptive geneflow between marginal populations, as Sexton et al did in a similar experiment with Mimulus laciniatus (just in one population out of 6).

    In 1 population out of 6. Worthy to note that there was another population that experimented maladaptation from geneflow of the other marginal population.
  • Similarly, we have found no evidence of maladaptive alleles or gene combinations from central populations. On the contrary, we have found some evidence of central populations providing genetic diversity that reduces inbreeding depression.

    Complement to the traditional reciprocal transplant experiments used to determine local adaptation…
  • And all this is happening in a study system in which we had previously detected genetic differentiation in functional traits between central and marginal populations in terms of tolerance to wáter stress and flowering phenology. Obviously, we need to follow the experiment through the complete life cycle to extract definite results.

    Complement to the traditional reciprocal transplant experiments used to determine local adaptation…
  • In conclusión, we found….

    Management actions based on assisted geneflow to mitigate the effects of climate change should not be taken lightly. An in-depth case by case study will be needed to determine the usefulness of these actions.
  • But first of all I would like to acknowledge the help of these fellow collaborators in the study, the support of the authorities and managers of the protected áreas where we conducted the study and the research Project that has funded it.
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