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0:00
Hello, my name's Ryan Garrick.
I'm at the University
of Mississippi and
today I'm going to talk about
two of my favorite topics,
phylogeography and
landscape genetics,
which are actually quite
closely related to one another.
I'll try and point out some of,
not only the similarities
but also the differences
between them.
0:25
I'll start with phylogeography.
This is a sub-discipline
that takes a view of
a relatively deeper
timescale and
broader geographic scale
than landscape genetics.
It makes sense to start
with the big picture.
0:43
This is a table
summarizing some of the features
of the sub-discipline of
phylogeography as
initially defined
by Avise and colleagues
many years ago.
I think that some of these
characteristics are really
useful when we make a comparison
between phylogeography
and landscape genetics.
I'll just highlight
a few of them.
First of all, the main goal
of phylogeography is
typically to understand and
reconstruct long-term
population history.
Often the timescale of
interests can be quite deep,
certainly, plus the same
age, perhaps earlier,
such that we're
reconstructing events
that are unobservable to humans.
So we're using inferences to
determine what happens to
generate the present-day
patterns that we see.
The spatial scale of analysis is
often range-wide for
the focal species.
Some of the common
types of interests in
phylogeographic studies
include understanding
past events,
whether they be range expansion,
contraction, lineage
splitting, or fusion events
that impacted the present-day
distribution of genetic diversity,
but also understanding
recurrence population processes,
such as gene flow, for example.
The primary data type that
is used for
phylogeographic analyses
really includes geo-referenced
DNA-sequence haplotype data.
I've noted here that recently
single nucleotide
polymorphism data
are also increasingly
being used,
but for the purposes today,
I'll just assume that
the underlying data are
the haplotype data.
There are non-genetic data that
can complement
phylogeographic analyses.
These include data
geological events,
perhaps dated fossils and
certainly, paleoclimatic
or ecological
niche modeling projected
back into the past.
The questions
addressed are often
those of basic research.
Evolutionary questions
about how species arise,
and what kinds of
events have shaped
the spatial distribution of
genetic diversity
within species today.