Wild Sheep Flashcards
Which sheep species does this study look at?
Soay sheep (from st kilda, scotland)
Who carried out this study?
Gratten et al. (2008)
In Soay sheep, … coat colour is associated with … …, which is … and positively correlated with fitness, yet the frequency of … … has decreased over the past 20 years
dark, large size, heritable, dark sheep
This unexpected microevolutionary trend is explained by … … between the causal mutation underlying … polymorphism and … trait loci with … effects on size and fitness
genetic linkage, colour, quantitative, antagonistic
As a consequence, … dark sheep are large but have … fitness relative to phenotypically indistinguishable dark … and … sheep
homozygous, reduced, heterozygotes, light
In these sheep, variation in coat colour is controlled by a single … locus, and the … allele is dominant to the … allele. The light phenotype is determined by … of a single recessive amino acid
autosomal, dark, light, homozygosity
Dark sheep are … than light sheep and body size is positively correlated with … and … …
larger, survival, reproductive success
Selection cannot favour light sheep on the basis of crypsis, as…
predators have never existed on St Kilda
… selection does not favour light sheep as there is no evidence of … mating
Sexual, assortative
The failure of dark sheep to increase in frequency may be due to microevolutionary constraints imposed by other genetic factors in the vicinity of TYRP1
yes
There was no evidence for selection on coat colour itself (as heterozygous black sheep showed no difference in fitness to homozygous recessive white sheep - it was the homozygous dominant black sheep that displayed the fitness costs)
just read
This suggests there is linkage with a deleterious … allele to the dominant TYRP1 allele for coat colour (as well as linkage with an allele for … … …)
recessive, large body size
This all constrains … of these sheep
microevolution
