Chapters 20-25 Flashcards
Define polymorphic locus
if one allele has very high frequency then the other alleles are unlikely to be observed, unless the sample size is very large
Define Hardy-Weinberg equilibrium
Proportions of genotypes do not change in a population if
- no mutation takes place
- no genes are transferred to or from other sources random mating is occurring, the population size is very large, no selection occurs
What is the founder principle and bottleneck effect
When a species is nearly hunted to extinction resulting the species having a loss in almost all of its genetic variation an example: would be the near extinction of the northern elephant seal in the 19th century
what is natural selection
the organism that is most fit will survive and pass on its genes to next generation
Define Stabilizing
acts to eliminate both extremes
define Disruptive
acts to eliminate intermediate types
define Directional
acts to eliminate one extreme
give an example of heterozygote advantage
Sickle cell anemia in Africa to protect from malaria
Why did Darwin’s finches have different beaks
Each beak size was better adapt to break certain seeds and accessing flowers
What is industrial melanism
phenomenon in which darker individuals come to predominate over lighter ones (i.e., moths)
Darwin’s finches and industrial Melanism are examples of what
Natural selection/ directional selection
most highly artificially selected crop plant
corn
What links Archaeopteryx to birds and dinosaurs
Possesses some ancestral traits and some traits of present day birds
Define Vestigial structures
structures that have little to no use that are left from evolution. (appendix)
Define Derived characters
Similarity that is inherited from the most recent common ancestor of an entire group
Outgroups in morphological data and in a phylogeny
An organism that is clearly similar but not related to the clade
Define clade
Species that share a common ancestor as indicated by shared characteristics
How much difference there is between human and chimp DNA
.106%
What has happened to some of the OR genes in humans
Loss of gene function, Inactivation best explanation for our reduced sense of smell
60% of human OR genes are pseudogenes Sequences of DNA that are very similar to functional genes but do not produce a functional product Likely explanation is we rely on other senses so selection pressure against loss of OR genes reduced
Define homoplastic structure
Homoplastic (analogues) structures, same or similar functions, arose independently
