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What do wind-dispersed species tell us about loss of dispersal potential on islands? - Presentation

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What do wind-dispersed species tell us about loss of dispersal potential on islands?

Flightless birds in islands

Flightless insects in islands

Darwin’s wind hypothesis

Reduced of dispersal ability in island plants

Pappus

Cichorieae, Dendroseris Madiinae, Argyroxiphium Cynareae, Centaurodendron Mainland Mainland Mainland Island (Juan Fernández) Island (Hawai) Island (Juan Fernández)

Bidens (Asteraceae) (Carlquist 1966)

Bidens pilosa (American mainland) Pitcairn Islands Society Islands Marquesas Islands

Reduced of dispersal ability in island plants

Dispersal ability in plants

Barbs and hooks Fleshy fruits Plumes and wings Floating diaspores Epizoochory (external animal) Endozoochory (internal animal) Thalassochory (water) Anemochory (wind)

Evolution of dispersability: Anemochory

Small seeds with high surface/volume ratio Allows for testing the evolution of dispersability from a mechanistic point of view Dispersal potential is related to the morphological structures of the diaspore Develop plumes or wings facilitating aerial transport

Achene attached to a feathery plume (pappus) as Predictor of dispersability If selection favours dispersability: >Ratio pappus to achene size , > Wind dispersal

(Sheldon & Burrows 1973)

Efficiency of dispersal: Anemochory

Achene Pappus

Mainland population

Low Medium dispersability High Low Medium dispersabilityHigh

New populations On islands Intermediate age populations on islands Old populations

• n islands

Older island populations show reduced dispersal potential relative to mainland populations or to young island populations (Cody & Overton 1996)

Low Medium dispersability High

Selection

New populations On islands

The loss of dispersal on islands hypothesis

Selection Selection

Low Medium dispersability High

Low

Medium dispersability High

Cody & Overton 1996 Cheptou et al. 2008

Dispersal ability in island populations decreased within a few generations

Mainland vs. island locations Anemochorous species of Asteraceae Fragmented vs. Unfragmented landscape Crepis sancta

Loss of dispersal on islands hypothesis (LDIH)

Rapid evolution towards lower dispersal

Difficulties to support the LDIH

Two Epilobium species Rumex bucephalophorus 27 endemic plants in the Canary Islands

Fresnilo & Ehlers 2007 Talavera et al. 2012 Vazačová and Münzbergová 2014

These species showed higher dispersal ability on islands compared to mainland

Restricted island endemics Relative amount of time

To estimate the loss of dispersability…

Previous studies

Phylogenetical tools

Nowadays

Detailed spatio-temporal population histories

García-Verdugo et al. 2017

Canary Islands Cape Verde

Periploca laevigata

Phylogeographic framework Estimates of dispersal ability

Free falling trials

García-Verdugo et al. 2017

Inverse of seed terminal velocity (Vt)

Classification of lineages as old or young

García-Verdugo et al. 2017

Oldest lineages showed the highest estimates of dispersal ability

Dispersal ability may be favoured, rather than negatively selected for, on islands

Western Canaries

Cape Verde

Mediterranean islands Eastern Canaries

Dating analyses

Canary Islands Cape Verde

García-Verdugo et al. 2017

Islands with higher within-island habitat availability generally have populations with more dispersive seeds

Correlation Haplotypes Islands with higher availability of habitats, had populations with more dispersive seeds Successful dispersal very rare among islands and extensive within islands

García-Verdugo et al. 2018

Periploca Kleinia García-Verdugo et al. 2018

Spatio-temporal Phylogeography

García-Verdugo et al. 2018

Ancestral areas Recent populations

Kleinia and Periploca displayed parallel increases in diaspore dispersability when compared with their respective mainland sister-species

Population age and dispersability

Periploca Kleinia García-Verdugo et al. 2018

Seed size

Increased seed size Decreased seed size

Loss of dispersal potential is not the consequence of selection for larger seeds

General pattern of increased seed size documented on islands (Kavanagh and Burns, 2014) This is linked to loss of dispersability in anemochorous diaspores (Burns, 2018)

The evolutionary potential of dispersal and persistence traits in island adaptative radiations: the subtribe Sonchinae in macaronesian archipelagos. Mairal et al. In prep

Adaptative radiation to study the evolution of dispersal traits Sonchus has shown:

• Morphological variability related to dispersal ability

(dimorfism of pappus)

• Variability in traits related to persistence (longevity,

woodiness, growth habit) We tested dispersal syndromes and persistence traits

• Phylogenetic signal (Pagel´s λ, D statistics)
• Niche conservatism (variance of Ackerly, reversals in Mesquite)
• Dispersal traits were less phylogenetically conserved than

persistence traits.

• Persistence traits (longevity and woodiness)

favour/promote niche conservatism

Main insights

1) LDIH is not common phenomenon to all island taxa 2) Dispersal ability can be favoured on islands: possibly because traits enhancing wind dispersal availability are positively selected when habitat availability is high 3) It is necessary to integrate phylogeography for hypothesis testing: linking phylogeography, plant traits and lineage differentiation. 5) An study on anemochorous plants on islands around the world might elucidate the contribution of dispersal structures vs. seed size 4) Test both phylogenetic signal and the level of niche conservatism to infer the evolution of dispersability

Acknowledgements

Carlos García Verdugo Juli Caujapé Castells Zuzana Münzbergová

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Pho hoto / / Image Credits

• Mycelis muralis. Wall lettuce- www.terrain.net.nz
• Inaccessible Island Rail (Atlantisia rogersi) - Brian Gratwicke
• Solanum nigrum berries – Wikipedia, Vishal Sharma
• Anatalanta aptera – Sub-Antarctic wingless fly- AFBA Project
• Antrops truncipennis - Burton & Croxall, A Field Guide to the Wildlife of South Georgia
• Bidens pilosa – Wikipedia, Wibowo Djatmiko (Wie146)
• Bidens pilosa - Sherwin Carlquist
• Calycopteryx moseleyi- B. Chaubet
• Crepis sancta - KU Leuven
• Dendroseris litoralis- Andrew Masson
• Imagen filogenia - Filogeografía y vertebrados, Capítulo 14, Ella Vázquez Rodríguez
• Epilobium angustifolium - Paul Slichter
• Epilobium hirsutum - Ferran Turmo Gort
• Euphorbia atro - garden.org
• Fleshy fruits - Elmar Robbrecht, Tropical Woody Rubiaceae. Characteristic Features and Progressions. Contributions to a New Subfamilial Classification
• Flightless cormorant (Phalacrocorax harrisi) –Wikipedoa, Charles J Sharp.
• Flightless moth – Pringleophaga marioni. AFBA project webpage
• Habitat fragmentation photo- Ecography Journal.
• Hypochaeris radicata - www.commanster.eu
• Javan cucumber seed (Alsomitra macrocarpa) - Scott Zona
• Kakapo 2 – JIDANCHAOMIAN. Flickr
• Logo phylogeny-fr- www.phylogeny.fr
• Molecular Clock - theconversation blog
• Picea abies seeds with wings – Gmihail, at Serbian Wikipedia
• Rumex bucephalophorus - Jose Quiles
• Schoenophilus pedestris - Kohn 1962
• Stephen island wren - illustration by John Keulemans
• Taraxacum sect. Ruderalia. MHNT-Didier Descouens
• White-throated Rail (Dryolimnas cuvieri). Source: Alamy