Module 6- Patterns of inheritance Flashcards
what are some environmental causes of variation in plants?
-chlorosis (yellowing leaves)
-etiolation (long thin growth)
what are some genetic causes of variation?
-gene mutations
-chromosome mutations
-meiosis/sexual reproduction
-inherited combination of alleles
what is discontinuous variation?
what is continuous variation?
what are the genetic explanations for discontinuous variations?
what is monogenic inheritance?
Characteristics which are controlled by the expression of a single gene
what will the ratio of phenotypes if both parents are heterozygous at both gene loci?
9:3:3:1 (unless epistasis occurs)
what is evolution?
changes in the frequency of different alleles in a polulation
what factors can affect the evolution of a
species?
stabilising selection and directional
selection, genetic drift, genetic bottleneck and founder effect
what is stabilising selection?
-normally occurs when an environment remains unchanged
-favours intermediate (mean) phenotypes
-increase in allele frequency at the mean and a decrease at the extreme
what is directional selection?
-typically associated with a change in environment
-positive selection one side of an extreme phenotype
what is a species?
group of organisms with similar morphology and physiology, which can (theoretically or actually) interbreed with one another to produce fertile offspring
this is the biological species concept
what is speciation?
formation of a new species through evolution
what is allopatric speciation?
occurs when some members of a population are separated from the rest of a group by a physical barrier- geographical isolation
what is sympatric speciation?
speciation that occurs when two populations live in the same location.
