1 / 31

What makes a species invasive? c) Micro-evolutionary change hypothesis

What makes a species invasive? c) Micro-evolutionary change hypothesis. Micro-evolutionary change hypothesis Frequent colonizing events are a central feature of invasive plants. What makes a species invasive? c) Micro-evolutionary change hypothesis. Micro-evolutionary change hypothesis

meira
Download Presentation

What makes a species invasive? c) Micro-evolutionary change hypothesis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events are a central feature of invasive plants

  2. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects = founders of a new population carry only a fraction of the total genetic variation of the source populations

  3. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks = loss of genetic variation when population size drastically decreases; often associated with catastrophic events that result in mass mortality

  4. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift = loss of genetic variation by chance when populations are small and do not have complete, random interbreeding

  5. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection: strong selective forces often apply to successful colonizers

  6. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment – rapid adaptive responses over short times and within short distances to new environment

  7. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment – shifts in relative proportions of competition vs. defense pressures

  8. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization – a natural process that occurs in plants

  9. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization – a natural process that occurs in plants • ↑ genetic diversity

  10. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization – a natural process that occurs in plants • ↑ genetic diversity • ↓reproductive barriers

  11. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization – a natural process that occurs in plants • ↑ genetic diversity • ↓reproductive barriers • Transfers or originates adaptations

  12. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization – a natural process that occurs in plants • 2834 plant species in the British Isles • Of these, 715 (25%) are hybrids • 74 are native X alien • 21 are alien X alien • 95 (13% of hybrids) involve aliens

  13. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization • Interspecific – often with other species in new environment

  14. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Micro-evolutionary change hypothesis • Frequent colonizing events • Founder effects • Genetic bottlenecks • Genetic drift • Natural selection • New abiotic environment • New biotic environment • Hybridization • Interspecific • Intraspecific – often with populations from native range that would not normally occur

  15. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Hybridization Evidence: • Stabilized introgressants • Introgression = back cross with 1 or more parents • P1 X P2 → F1 • F1 X {P1, P2} → F2 introgressant

  16. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Hybridization Evidence: • Stabilized introgressants • Introgression = back cross with 1 or more parents • Stabilized = viable, fertile hybrids

  17. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Hybridization Evidence: • Stabilized introgressants • Hybrids form new Intraspecific taxa

  18. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Hybridization Evidence: • Stabilized introgressants • Hybrids form new intraspecific taxa • Hybrids form new Species – Note: all examples are alien X alien

  19. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Hybridization Evidence: • Stabilized introgressants • Allopolyploids = hybrid between different species in which chromosomes of both parents are retained

  20. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Hybridization Evidence: • Stabilized introgressants • Allopolyploids • Hybrids form new Species – Note: both Tragopogon’s are alien X alien

  21. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Rhododendron ponticum in British Isles • *Milne & Abbott (2000) Molecular Ecology 9:541-556 • Natural distribution: south of Black Sea with disjunct populations in Lebanon, Spain, & Portugal

  22. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Rhododendron ponticum in British Isles • *Milne & Abbott (2000) Molecular Ecology 9:541-556 • Natural distribution: south of Black Sea with disjunct populations in Lebanon, Spain, & Portugal • Extensively naturalized throughout British Isles

  23. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Rhododendron ponticum in British Isles • *Milne & Abbott (2000) Molecular Ecology 9:541-556 • Natural distribution: south of Black Sea with disjunct populations in Lebanon, Spain, & Portugal • Extensively naturalized throughout British Isles • Origin unclear: • Earliest known introduction (1763) from Spain • But subsequent introductions likely, especially from Black Sea area • Also can’t tell from morphological information where it came from, but know from morphology that had to hybridize at some time • R. ponticum cultivated along with other introduced species

  24. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study:Rhododendron ponticum in British Isles • *Milne & Abbott (2000) Molecular Ecology 9:541-556 • Most individuals from naturalized populations had genotypes from Spain (88%), followed by Portugal (10%) • No genotypes from Black Sea region

  25. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study:Rhododendron ponticum in British Isles • *Milne & Abbott (2000) Molecular Ecology 9:541-556 • Most individuals from naturalized populations had genotypes from Spain (88%), followed by Portugal (10%) • No genotypes from Black Sea region • Small number of individuals had hybridized with at least 3 other species • Occurrence of R. catawbiense genotypes most common in Scotland (coldest area of British Isle) • Introgression with catawbiense appears to have conferred cold tolerance into ponticum

  26. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Tamarix in US • *Gaskin & Schaal (2002) PNAS 99:11256-11259 • Native range: 54 species across Europe & Asia • Introduced range: originally 8-12 species into US for shade & for erosion control • 2 species particularly invasive: • Tamarix ramosissima & T. chinensis

  27. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Tamarix in US • *Gaskin & Schaal (2002) PNAS 99:11256-11259 • In native ranges: T. ramosissima & T. chinensis overlap • But different genotypes from DNA sequencing • T. chinensis: Haplotype 2 (red); primarily homozygous • T. ramosissima: Haplotype 1 (blue) most abundant, but also others; fewer homozygotes, many heterozygotes • No T. ramosissima -T. chinensis hybrids (red-blue combinations)

  28. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Tamarix in US • *Gaskin & Schaal (2002) PNAS 99:11256-11259 • In US: • ~20% genotypes are T. ramosissima homozygotes (blue-blue) • ~20% genotypes are T. chinensis homozygotes (red-red) • ~20% genotypes are T. ramosissima -T. chinensis hybrids (red-blue) • Also get novel genotypes plus hybrids with other Tamarix species

  29. What makes a species invasive? • c) Micro-evolutionary change hypothesis • Case Study: Tamarix in US • *Gaskin & Schaal (2002) PNAS 99:11256-11259 • In US: • ~20% genotypes are T. ramosissima homozygotes (blue-blue) • ~20% genotypes are T. chinensis homozygotes (red-red) • ~20% genotypes are T. ramosissima -T. chinensis hybrids (red-blue) • Also get novel genotypes plus hybrids with other Tamarix species • Complicates biological control efforts in US

  30. What makes a species invasive? • c) Micro-evolutionary change hypothesis • SUMMARY: Micro-evolutionary change hypothesis • Likely that most (if not all) invasive species go through founder events, experience genetic bottlenecks & drift, and undergo selection • In other words micro-evolutionary changes • Good evidence for hybridization being beneficial

  31. What makes a species invasive? • c) Micro-evolutionary change hypothesis • SUMMARY: Micro-evolutionary change hypothesis • Likely that most (if not all) invasive species go through micro-evolutionary changes • Good evidence for hybridization being beneficial • But • Have evidence of micro-evolutionary changes for only a limited number of species • For only a subset of these, have evidence that micro-evolutionary changes have been beneficial • A species that undergoes micro- (or even macro-) evolutionary changes does not automatically become invasive

More Related