Transcript Co-evolution, starring ferns

Co-Evolution
Starring Ferns
Fern-Environment Interactions
• How do ferns interact
with animals?
• With other plants?
• With the soil around
them?
Ferns: Kickin’ it Old School
• Herbivore deterrents.
• Fierce competitors.
• Ancient Warriors trained in the school of hardknocks.
Toxin Accumulation
• Ferns are known for their ability to
uptake toxins, particularily arsenic.
• Chinese Brake Fern (Pteris Vittata),
a hyper-accumulator of arsenic can
even absorb arsenic through its
foliage (Bondada, 61-70)
• Arsenic is stored in the form of
arsenate, the most oxidized and
most toxic structure of arsenic.
Null Hypothesis:
• Ferns do not exhibit any of the coevolutionary trends seen in the angiosperms.
Such As:
• Seed (spore) dispersal by herbivores.
• Symbiotic relationships with bacteria and
fungi.
• Pollination by external agents (birds, bees,
etc.)
Things may not be as simple as they
seem….
• Numerous case studies of ferns have found
many such plant-environment interactions
such as:
– Bacterial and fungal symbiotic relationships.
– Spore consumption by herbivores.
– Mutually beneficial insect interactions.
Spore Consumption
• First reported case of fern spore consumption by a
small mammal (Arosa, 115).
• Spores of Culcita macrocarpa eaten by woodmouse in
Northwest Spain.
• Fertile fronds purposefully targeted.
• Spore disporsal through droppings is a possibility,
though most spores are ingested.
Methods:
• Two separate populations studied, Eume and Capelanda.
• 90 individuals selected, one fertile frond per plant marked
at random.
• Sterile and fertile pinnae for each frond were recorded, as
well as any marks of consumption.
• Marked leaves were observed every 15 days for 3.5
months.
• Droppings were collected from feeding sites.
• DNA analysis of droppings determined herbivore identity.
• Possible herbivores were captured at the sites and brought
to the lab to see if they exhibited the same consumption
patterns.
Results:
• Fern consumption found exclusively on fertile
fronds.
• Max consumption rates occurred in December
and was practically finished by mid-February.
Results cont.
• Consumer identified as the woodmouse.
• Droppings placed in petri dishes showed
germination in 2 of 14 dishes.
• Between 14% and 69% of spores remained
unbroken by digestion.
Azolla-Cyanobacteria
• Symbiotic relationship between the floating
water fern Azolla and nitrogen-fixing
cyanobacteria.
• Recent studies show that the cyanobiont in Azolla
ferns is neither Anabaena nor Nostic yet cannot
be classified as a distinct genera (Baker, 43)
• Signifies evolution of the cyanobacteria within
Azolla.
• Phylogenetic relationship was determined using
genomic sequencing of the 16S ribosomal RNA
gene.
Mycorrhizae
• Ferns have them too!
• Arbuscular mycorrhizae increase the arsenic
uptake in Pteris vittata (Trotta, 74).
• More on this from Tim and others.
Epiphytism
• Little fossil evidence of epiphytes.
• Numerous rapid radiations could coincide with
the establishment and diversification of tropical
forests.
– Humus collection (Bird’s Nest Fern)
– Ant Mutualism (Lecanopteris sp.
– Water entrapment (Staghorn fern)
• New evidence from Schuettpelz suggests
development of major living epiphyte groups in
Tertiary not Carboniferous.
• New evidence shows that fern epiphyte
diversification may have been linked to the
development of the flowering plants.
What’s it all mean?
• Ferns do not exist as an entity separate from
their surroundings.
• The evolution of ferns is in a direct
relationship with the evolution of their
surroundings.
• All evolution occurs as such, they dynamic
interplay of the sum of all parts.
• Even non-biological factors have a role to play
in evolution.
Where does that put us?
Works Cited
•
•
Baker J.A., Entsch B., McKay D.B. The cyanobiont in an Azolla fern is
neither Anabaena nor Nostoc (2003) FEMS Microbiology
Letters, 229 (1), pp. 43-47.
Dubuisson J.-Y., Schneider H., Hennequin S. Epiphytism in ferns: diversity
and history (2009) Comptes Rendus - Biologies, 332 (2-3), pp. 120-128.
• Arosa, M.L., J.A. Ramos, L.G. Quintanilla, and D. Brown. "First report of
fern (Culcita macrocarpa) spore sonsumption by a small mammal
(Apodemus sylvaticus)." Mammalian Biology 75.2 (2010): 115-121. Web.
25 Apr 2010.
•
Bondada B.R., Tu S., Ma L.Q. Absorption of foliar-applied arsenic by the
arsenic hyperaccumulating fern (Pteris vittata L.) (2004) Science of the
Total Environment, 332 (1-3), pp. 61-70.