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Biodiversity and the Tree of Life
Brent D. Mishler
Dept. of Integrative Biology
University and Jepson Herbaria
Berkeley Natural History Museums
Summary of talk
• What is biodiversity and why is it
• The importance of the Tree of Life: two
big ideas for students!
• A quick run-through of major branches of
the Tree, with emphasis on plants.
• Introduction to teaching phylogenetic
• A brief introduction to comparative
What is biodiversity? It is the whole tree of life!
A single, magnificent genealogy connecting all organisms alive
today. Two main lessons for students:
1. We are all related -- not just in the John Muir sense of all being
part of the same worldwide ecosystem, but literally genealogically
related !
** This should inform our moral treatment of other living things.
2. We are not all that special -- just one tiny twig on a strange,
gigantic tree that took root on one little planet in an infinite universe.
You are here
What is the value of biodiversity?
• ethical: each lineage is a thread in an heirloom
fabric that we have the responsibility to pass on to
future generations.
• intellectual: we have a basic need to understand the
world, how it came to be, and where we fit in it.
• ecological: biodiversity is needed for proper
function of ecosystems, and as the raw material for
natural selection (future evolutionary potential).
• economic: natural lineages are a potential source for
a myriad of products of direct economic benefit
(medicines, food, esthetics, shelter, etc.).
Valley Life Sciences Building
The Berkeley Natural History Museums is a consortium of six
museums, which together encompass some of the world's most
valuable natural history and anthropology collections. Their unique
synthesis of research, teaching, outreach and collections allows indepth insights into the history and evolution of life.
•University and Jepson Herbaria
•Museum of Vertebrate Zoology
•Essig Museum of Entomology
•Phoebe A. Hearst Museum of Anthropology
•University of California Botanical Garden
•University of California Museum of Paleontology
Courtesy of Sogin Lab -- MBL
Crown Eukaryotes:
Metazoa (animals)
Fungi (mushrooms, molds, yeast)
Green Plants (green algae, land plants)
Rhodophyta (red algae)
Alveolates (dinoflagellates, ciliates)
Stramenopiles (brown algae, diatoms,
oomycetes, chrysophytes)
How can we discover
phylogenetic history?
• You can’t actually see phylogeny, so
how do you make inferences about it?
• Think of a huge oak tree buried in a
sand dune, with only the tips of the
twigs showing -- what would you do?
• The concept of historical markers -characters
• Need to find something that changed its
condition along a lineage, and survived
in recognizable form to the present.
period of
shared history
a marker
changing state
Phylogenetic Reconstruction:
Need to find markers that can be hypothesized to have changed
their state on some shared branch in the past, and to have retained a
recognizable record of the derived state to the present.
Phylogenetics explained:
homology -- a feature shared by two lineages because of
descent from an ancestor that had the feature.
transformation - a heritable change in a homology along a
lineage from a prior state to a posterior state
divergence -- the splitting of one lineage into two lineages
reticulation - the blending of two lineages into one lineage
monophyly -- all and only descendants of a common ancestor