Welcome to the 31st IUBS General Assembly and Conference on ...

Swedish Museum of Natural His<strong>to</strong>ry, S<strong>to</strong>ckholm, Sweden. Email:
christian.pott@nrm.se
Plants with cycad‐like leaves (cycadophytes) played a key
role in <strong>the</strong> Mesozoic vegetation prior <strong>to</strong> <strong>the</strong> late Mesozoic
ecological radiation of flowering plants. The Mesozoic,
<strong>the</strong>refore, has sometimes been referred <strong>to</strong> as <strong>the</strong> ‘age of
cycads’, but it has long been clear that <strong>the</strong>se cycadophyte
leaves were produced by at least two groups of seed plants
that were not closely related phylogenetically, i.e.
Cycadales <strong>and</strong> Bennettitales. The Cycadales are a small
group of extant plants that in most phylogenetic
reconstructions are placed as <strong>the</strong> basal branch in <strong>the</strong> seed
plant tree. The Bennettitales are in morphology‐based
analyses usually placed with angiosperms, Gnetales,
extinct Erdtmani<strong>the</strong>cales, <strong>and</strong> Pen<strong>to</strong>xylales in a
monophyletic group (<strong>the</strong> anthophytes). Major problems
with attempts <strong>to</strong> resolve seed plant phylogeny are
extensive extinctions <strong>and</strong> inadequate knowledge of <strong>the</strong>
extinct groups; many fossil taxa included in
morphology‐based analyses are in urgent need of
re‐evaluation using modern techniques <strong>and</strong>
reconstruction <strong>to</strong>ols. Of particular interest is an improved
underst<strong>and</strong>ing of <strong>the</strong> fossil taxa included in <strong>the</strong>
anthophytes <strong>and</strong> o<strong>the</strong>r potentially related fossils. Recent
studies show that <strong>the</strong> cycadophytes were more diverse
than previously accepted <strong>and</strong> that <strong>the</strong> current
classification of <strong>the</strong> group was oversimplified. At least 6
distinguishable groups (fossil <strong>and</strong> modern Cycas‐like
cycads, o<strong>the</strong>r modern cycads, Nilssoniales, Cycadeoidaceae,
Williamsoniaceae, Pen<strong>to</strong>xylales) are generally
incorporated in <strong>the</strong> cycadophytes. These groups
encompass diverse plant architectures, foliage types,
reproductive architectures, <strong>and</strong> ecology, which deserve
more detailed investigations <strong>to</strong> resolve <strong>the</strong>ir phylogenetic
relationships <strong>and</strong> ecological preferences. The talk will
give an overview of <strong>the</strong> status quo <strong>and</strong> analyse <strong>the</strong>
challenges in cycadophyte taxonomy/nomenclature by
means of selected examples.
When <strong>the</strong> world turned ‘brown’: Resource
competition, apparent competition <strong>and</strong> <strong>the</strong>
‘Miocene Transformation’
Yoram AYAL
Ben Gurion University, PO Box 102 Midreshet Ben Gurion, Israel.
Email: ayal@bgu.ac.il
The Miocene was a key epoch during which <strong>the</strong> early
Cenozoic, mostly forested, biomes were transferred <strong>to</strong>
<strong>the</strong> late Cenozoic–Quaternary, open forests <strong>and</strong>
grassl<strong>and</strong>s biomes. Current <strong>the</strong>ories suggest that this
transformation was due mainly <strong>to</strong> abiotic fac<strong>to</strong>rs,
mainly <strong>the</strong> development of cooler <strong>and</strong> more seasonal
climates, <strong>and</strong> <strong>the</strong> decrease in CO 2 levels. Here I suggest
an alternative, ecologically based, hypo<strong>the</strong>sis <strong>to</strong> explain
<strong>the</strong> recorded changes in biomes structure.
During <strong>the</strong> late Oligocene, some browsing mammals
reached body‐size that enabled <strong>the</strong>m <strong>to</strong> minimize
predation pressure on <strong>the</strong>m <strong>and</strong> as a result <strong>the</strong>ir
populations increased <strong>to</strong> a level where <strong>the</strong>y
over‐browsed <strong>the</strong> forest trees <strong>and</strong> control <strong>the</strong>m. Thus,
many forested biomes changed <strong>the</strong>ir state from being
‘green’ (where plants are resource limited) <strong>to</strong> ‘brown’
(where plants are herbivore controlled). The
competition for diminishing browser resources
resulted in <strong>the</strong> evolution of diverse body‐plane of
browsers enabling finer resource partition <strong>and</strong> high
species diversity. The heavy browsing started <strong>to</strong> limit
trees abundance, opening forest gaps <strong>and</strong> as a result,
<strong>the</strong> spread of grassy areas within <strong>the</strong> forested ones. The
spread of open forests selected for <strong>the</strong> evolution of
mix‐feeding habitat generalist Proboscidea, <strong>and</strong>
open‐grassl<strong>and</strong> grazers. Concomitantly, <strong>the</strong> open forest
<strong>and</strong> <strong>the</strong> spreading grassl<strong>and</strong> gave advantage <strong>to</strong> habitat
generalist Carnivora over <strong>the</strong> forest specialists
Creodonta. Thus, at <strong>the</strong> end of <strong>the</strong> Miocene <strong>and</strong> early
Pliocene, habitat specialist titanic perissodactyle
browsers were outcompeted by habitat generalist
Proboscidea, <strong>and</strong> habitat generalist felids <strong>and</strong> canids
replaced <strong>the</strong> forest specialist creodonts. Concomitantly,
apparent competition between (a) medium <strong>to</strong> large,
grassl<strong>and</strong> grazers <strong>and</strong> forest browsers, through habitat
generalist large felids <strong>and</strong> (b) grasses in <strong>the</strong> open forests
<strong>and</strong> grassl<strong>and</strong>s <strong>and</strong> trees in <strong>the</strong> forested habitat through
mix‐feeding Proboscidea, resulted in <strong>the</strong> extinction of
many of <strong>the</strong> forest‐dwelling browsers, <strong>the</strong> decline of <strong>the</strong>
forested biomes <strong>and</strong> <strong>the</strong> spread of grassl<strong>and</strong>s.
Workshop on investigative case­based
learning
Margaret WATERMAN <strong>and</strong> E<strong>the</strong>l STANLEY
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