Week 5: Adaptation to Environmental Stress Flashcards
In complex traits, offspring tend to…
Resemble parents but regress towards the population mean
Offspring mean height lies between parental mean height and population mean height because of what 3 factors?
- During meiotic cell division, segregation and recombination break up combinations of genes leading to extreme phenotypes
- Parental phenotype is a result of both genetic and environmental factors
- Offspring phenotype is a result of both genetic and environmental factors
Define heritability
How well genetics can account for differences in one’s phenotypic expression ( a number between 0-1)
E.g. Height: heritability = 0.88 meaning genetic factors dictate this largely although environmental factors have some effect
E.g. Sleep: heritability = ~0.15 meaning it is largely environmental although some genetic effect is present
What is the estimated % of species loss per annum?
~0.25% per year
This is 5000 - 25,000 species a year dependant on how many species actually exist which is definitively unknown
Describe Bergmann’s rule
Larger species are found towards the poles (colder environments) with a decrease is size as one moves towards equatorial regions (warmer regions).
Low latitude organisms are smaller
High latitude organisms are larger
Why is this?
Surface area to volume ratio - larger organisms retain heat better and are thus better equipped cope with colder environments. This is a genetic adaption over time.