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This presentation was given at the Oosting Memorial Symposium on April 17, 2009. The authors were Yi-Hsin Erica Tsai and Paul S. Manos.Abstract:Because species respond individually to climate change, understanding community assembly requires examination of multiple species from a diversity of forest niches. We present the phylogeographic history of an understory, parasitic herb (Epifagus virginiana, beechdrop) that has an obligate and host specific relationship with a common eastern North American forest tree (Fagus grandifolia, American beech). The migration histories of the host and parasite were compared to elucidate potential limits on the parasite’s range and to understand their responses to shared climate change. Two chloroplast DNA regions were sequenced and landscape genetic and coalescent methods were used to reconstruct the post-glacial migration history of the parasite. Epifagus virginiana is shown to have migrated from the southern Appalachians into the Northeast and then westward into the Midwest. The parasite's pattern of expansion parallels the development of beech forests but differs from the routes of initial range expansion of beech. This suggests that host density effects drive the distributional changes in the parasite, which are further confirmed in fine scale studies. The composite migration history of this parasite and its host shows how two diverse components of a forest community colonized the landscape separately -- even as aspects of the host's distribution greatly influenced the path of the parasite -- before reassembling into their present day co-distributed range.The animations from the powerpoint were partly converted using code from Neil Mitchell's Haskell Blog, http://neilmitchell.blogspot.com/2007/11/creating-pdf-from-powerpoint-with.html.
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Global change, parasites, and community assembly:
How a parasite expanded its range in the shadow of its host
Yi-Hsin Erica TsaiPaul S. Manos Department of BiologyDuke University
Climate change and a species’ response
Climate change and a species’ response
Climate change
Climate change and a species’ response
Climate change
Climate change and a species’ response
Climate change
Climate change and a species’ response
Climate change
?
Climate change and a community’s response
Climate change and a community’s response
Climate change and a community’s response
Climate change
Climate change and a community’s response
Climate change
Climate change and a community’s response
Climate change
?
How do host and parasite migration patterns compare?
What host life history characters act as constraints?
How do host and parasite migration patterns compare?
What host life history characters act as constraints?
Host = American beech, Fagus grandifoliaParasite = Beechdrop, Epifagus virginiana
Host density effects
The parasite: Epifagus virginiana
DL Nickrent
Obligate parasite
Non-photosynthetic
Host specific to Fagus grandifolia
Annual
Selfer
EA Saulys
Two host migration scenarios
13 kybp
9 kybp
6 kybp
Host fossil pollenDavis 1983, Bennett 1985, Delcourt and Delcourt 1987,Williams et al. 2004
Two host migration scenarios
Host cpDNA McLachlan et al. 2005
13 kybp
9 kybp
6 kybp
PP
PrairiePeninsula
Two host migration scenarios
Host fossil pollenDavis 1983, Bennett 1985, Delcourt and Delcourt 1987,Williams et al. 2004
Host cpDNA McLachlan et al. 2005
PP
13 kybp
9 kybp
6 kybp
Two host migration scenarios
Host fossil pollen
Host cpDNA
PP
13 kybp
9 kybp
6 kybp
High density forest development
Initial range expansion
What limits parasite colonization of a new area?
Host fossil pollen= host density
Host cpDNA = host disperal
PP
13 kybp
9 kybp
6 kybp
Methods: Building a parasite dataset
1064 specimens
95 populations
1016 cpDNA bp
557 bp clpP1 intron
459 bp rbcL pseudogene
47 substitutions
41 haplotypes
4 haplotype groups
Parasite haplotype distributions
PP
13 kybp
9 kybp
6 kybp
Many genetic breaks in the South
Monmonier’s analysis:Manni et al. 2004, Miller 2005, Jombart 2008
Many genetic breaks in the South
- Supported by cross validation analysis
Migration into the MidwestP
roba
bilit
y
Migration rate
0.005
0.015
0.025
1 1000.01
PPPP
13 kybp
9 kybp
6 kybp13 kybp
9 kybp
Hey and Nielsen 2007
Broad-scale story
XHost density matters
But where are the actual migration corridors?
Further work:
Establish directionality - Microsatellite markers
Threshold density of host? - Fine scale plots
Extract migration corridors - spatial models
But where are the actual migration corridors?
Locating migration corridors
Landscape connectivity - McRae et al. 2008
Spatial models with all datasets
Parasite cpDNA ~ Host pollen age+Host cpDNA
Climate change and a community’s response
Climate change
?
Climate change and a community’s response
Climate change
?
AcknowledgementsSpecimen collectors:Yi-Show TsaiRoss McCauley Chuck WilliamsFritz GerhardtGelyn KlineJason McLachlanJohn FreudensteinMaggie WhitsonPaul ManosMark FishbeinDan NickrentHeather NickrentPhilip HyattRobyn BurnhamSally GerhardtSasa StefanovicAlison ColwellErin TrippJordan MetzgarJackson Fox
Funding sources:NSF, Sigma Xi, Duke Grad School, Duke Dept. of Biology, ASPT, Mellon Foundation, AWIS, GWIS, Deep Time, Google, NESCent
Lab/Theory help:Billy SchnackelAmos Little Jason McLachlanSang-Hun OhNorm DouglasDylan O. BurgeErin TrippTaina PriceDudu MeirelesJames BeckChristy HenzlerLisa PokornyMichelle HershSara Chun
Advisor: Paul Manos
