G20

Question 1

How can you test the isolation by distance effect?

Answer 1

mantel test
look for relationships between two matrices by regression
greater R^2 = better correlation of FST with distance method (IBD/by cost)

Question 2

How can bottlenecks be identified

Answer 2

using bottleneck software
recent bottlenecks leave a signiture in composition of genetic variation different to that of expected mutation-drift balance; leads to an excess heterozygosity for the no. of alleles observed
heterozygosity increases initially after bottleneck can look for this

Question 3

what are the two models for mutation

Answer 3

infinite alleles model: each mutation/marker form is unique (no back mutation)
stepwise mutation model: eg. microsatellite where length is scored, eg. increases/decrease by one - allows for back mutation.

Question 4

what is landscape genetics

Answer 4

looks at effect of environmental variation, such as altitude, topography, type of ground cover on the gene flow, genetic stricutre, and connectivity of populations. models including landcape variable may be better than IBD (pire euclidean where the crow flies) in examining how FST varies among populations.

Question 5

Describe the case study of the Gulo gulo

Answer 5

wolverine - largest member of the weasel family. has large range, 12 pops sample at 12 microsattelite loci.
found in broeal forests of sub artic and artic tundra, - greatst no. in canada and alasak.
numbers reduced by hunting and climate change.
IBD = unrealistic habitat needs to be taken to account a more realistic cost of travel between populations
use GIDS - geographic info systems to produce raster mpa
for each land varaible cost specified a priori and different cost model evaluated.>1 = facilitates migration

Question 6

what are the problems with the least cost pathway

Answer 6

does single best route and does not account for multiple pathways for gene flow

Question 7

describe the isolation by resistance model

Answer 7

based on circuit theory
- individuals are like the current in a circuit
conductive surface = increased flow on larger swathes of habitat
increased flow between habitats with 2 corridors than 1
mutliple pathways reduce resitance to gene flow
more paths for gene flow, less resistance

Question 8

what did the isolation by resistance show for wolverines

Answer 8

accounting for mutliple pathways and wider habitat swathes connecting populations increases R^2 ie. better explains the genetic varaince among populations and thus the pattern of gene flow

Question 9

what did Isolation resistance show in second wolverine study

Answer 9

between 2 mountain ranges = linear habitat band

found LCP performed better than IBR so IBR could be better suited to populations with non linear habitats.