Genetic Rewilding : how connectivity can rescue small populations Sarah W. Fitzpatrick Kellogg Biological Station Department of Integrative Biology Michigan State University
Why does connectivity matter? • geographic distribution • range size • population dynamics • evolutionary trajectory of species
Charley Harper
Connectivity shapes biodiversity patterns through gene flow gene flow = genetic connectivity
Connectivity shapes biodiversity patterns through gene flow Dispersal patterns of ancient humans out of Africa
Why does gene flow matter for conservation?
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness fitness = a measure of reproductive success
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness gene flow low high fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness gene flow low high fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness low high fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness gene flow low high fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness low high fitness
Why does gene flow matter for conservation? - Gene flow can decrease fitness - Gene flow can increase fitness • increase genetic variation • facilitate local adaptation • rescue small populations low high fitness
Problems with small populations • risks of inbreeding depression • reduced adaptive potential • little buffer to withstand environmental disturbance Devil’s hole pupfish Cheetah Scrub mint Bighorn sheep
habitat loss severe population declines signs of inbreeding depression • 49 % of male panther’s suffered from cryptorchidism (undescended historical range (green) testes) current range (red) • kinked tail phenotype
Inbreeding exposes deleterious alleles By 1994, only 20-30 adult panthers remained in Florida
1995 8 female panthers from Texas introduced to Florida historical range (green) current range (red)
genetic diversity increased Great. What about population size? Johnson et al 2010 Science
genetic diversity increased population size increased too! Johnson et al 2010 Science
Genetic rescue: increase in population growth by more than the demographic contribution of immigrants genetic diversity increased population size increased Johnson et al 2010 Science
How does connectivity, or lack thereof, affect evolution and persistence of small populations?
How does connectivity, or lack thereof, affect evolution and persistence of small populations?
How does connectivity, or lack thereof, affect evolution and persistence of small populations?
Rest of talk 1. Effects of a rapidly changing landscape on natural patterns of connectivity in a threatened fish
Rest of talk 1. Effects of a rapidly changing landscape on natural patterns of connectivity in a threatened fish 2. Genetic rescue in guppies: a model system for evolution, conservation, and education
Rest of talk 1. Effects of a rapidly changing landscape on natural patterns of connectivity in a threatened fish 2. Genetic rescue in guppies: a model system for evolution, conservation, and education
Characterizing gene flow in an imperiled species Arkansas darter ( Etheostoma cragini )
Characterizing gene flow in an imperiled species Arkansas darter ( Etheostoma cragini )
lives up to its name Big Sandy Creek
COLORADO 2010 Arkansas darter sampling more than 5 darters 5 darters or less Big Sandy Creek B SY 04 R C R 05 H G P08 R C R 06 Rush Creek FT N 01 R C R 07 Fountain Creek FT N 02 FT N 03 A FT 13 A FT 10 A FT 12 Arkansas River Perennial Intermittent A FT 09 A FT 11 0 5 10 20 30 40 miles perennial intermittent
COLORADO 2010 Arkansas darter sampling more than 5 darters 5 darters or less Big Sandy Creek B SY 04 Totals R C R 05 H G P08 • 12 sites R C R 06 Rush Creek • 614 darters FT N 01 R C R 07 Fountain Creek FT N 02 sampled • genotyped at 10 FT N 03 microsatellite loci A FT 13 A FT 10 A FT 12 Arkansas River Perennial Intermittent A FT 09 A FT 11 0 5 10 20 30 40 miles perennial intermittent
COLORADO 2010 Arkansas darter sampling more than 5 darters 5 darters or less Big Sandy Creek B SY 04 Totals R C R 05 H G P08 • 12 sites R C R 06 Rush Creek • 614 darters FT N 01 R C R 07 Fountain Creek FT N 02 sampled • genotyped at 10 FT N 03 microsatellite loci A FT 13 A FT 10 A FT 12 Arkansas River Perennial Intermittent A FT 09 A FT 11 0 5 10 20 30 40 miles perennial intermittent
Low genetic diversity within sites & connectivity among sites Big Sandy Creek B SY 04 R C R 05 H G P08 R C R 06 Rush Creek FT N 01 R C R 07 Fountain Creek FT N 02 FT N 03 A FT 13 A FT 10 A FT 12 Arkansas River Perennial Intermittent A FT 09 A FT 11 0 5 10 20 30 40 miles Fitzpatrick, S.W., H. Crockett, W.C. Funk (2014) Conservation Genetics.
How does the landscape affect connectivity? Mantel’s r: 0.656 p-value: 0.001 0.3 genetic distance 0.2 F st 0.1 0.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 log Stream Distance stream distance (km) overall distance Fitzpatrick, S.W., H. Crockett, W.C. Funk (2014) Conservation Genetics.
Stream distance lowers connectivity Mantel’s r: 0.656 p-value: 0.001 0.3 genetic distance 0.2 F st 0.1 0.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 log Stream Distance stream distance (km) overall distance Fitzpatrick, S.W., H. Crockett, W.C. Funk (2014) Conservation Genetics.
Intermittency acts as a barrier to gene flow Mantel’s r: 0.656 p-value: 0.001 0.3 genetic distance genetic distance 0.2 F st F st 0.1 0.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 log Stream Distance log Stream Distance stream distance (km) % intermittency % intermittency overall distance % intermittency Fitzpatrick, S.W., H. Crockett, W.C. Funk (2014) Conservation Genetics.
Intermittency acts as a barrier to gene flow Mantel’s r: 0.656 p-value: 0.001 0.3 0.2 F st F st F st 0.1 0.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 log Stream Distance log Stream Distance % intermittency overall distance % intermittency Fitzpatrick, S.W., H. Crockett, W.C. Funk (2014) Conservation Genetics.
How should isolated, threatened populations be managed? Big Sandy Creek B SY 04 photo credit: Kurt Fausch R C R 05 H G P08 R C R 06 Rush Creek FT N 01 R C R 07 Fountain Creek FT N 02 FT N 03 A FT 13 A FT 10 A FT 12 e r Perennial a s R i v r k a n s A Intermittent A FT 09 A FT 11 0 5 10 20 30 40 miles
Rest of talk 1. Effects of a rapidly changing landscape on natural patterns of connectivity in a threatened fish 2. Genetic rescue in guppies: a model system for evolution, conservation, and education
“The island of Trinidad formed the natural laboratory for the present work” - Caryl Haskins Venezuela
“The island of Trinidad formed the natural laboratory for the present work” - Caryl Haskins Venezuela
“The island of Trinidad formed High Low the natural laboratory for the present work” - Caryl Haskins High Low Mid Venezuela
Low predation • small headwater populations • isolated from gene flow • good proxy for threatened species
low predation high predation
12 microsatellite loci Initial divergence between native and source populations N e = 3 N e = 928 N e = 2
12 microsatellite loci Initial divergence between native and source populations N e = 3 N e = 928 N e = 2 male body shape & size traits
- Gene flow can decrease fitness - Gene flow can increase fitness
“Counting fish is like counting trees… except they are invisible and they keep moving.” -John Shepard 2 streams 29 months 9,590 guppies 25,581 captures photo: Andrés Lopez-Sepulcre
catching guppies
lab processing catching guppies
lab processing catching guppies release!
Increase in migration rate
Increase in migration rate and genetic diversity
Changes in population size following gene flow 1200 Caigual number of captures 1000 Taylor 800 600 400 200 0 2009 2010 2011 mark- recapture begins upstream introduction
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