Genetic 14

What is the difference between r- and K-reproductive strategies?

r-strategists produce many offspring with little parental investment, while K-strategists produce fewer offspring with greater parental investment

What is a haplogroup?

A group of related haplotypes that share a common ancestor

What are the main principles of natural selection proposed by Darwin?

Individuals vary, some variation is heritable, more offspring are produced than can survive, and individuals with advantageous traits have greater reproductive success.

What is stabilizing selection?

Favors intermediate phenotypes and selects against extreme phenotypes

What is directional selection?

Directional selection favors one extreme phenotype, shifting the population toward that phenotype

What is disruptive selection?

Disruptive selection favors both extreme phenotypes over the intermediate phenotype

How is genotype frequency calculated?

The number of individuals with a specific genotype divided by the total number of individuals.

What is allele frequency?

how common a specific allele is in a population.

What is Hardy-Weinberg equilibrium?

A genetic equilibrium in which allele and genotype frequencies remain constant across generations

Why are real human populations not perfectly in Hardy-Weinberg equilibrium?

Because evolutionary forces such as migration, selection, mutation, and genetic drift can change allele frequencies.

What was the aim of the Cavener and Clegg experiments?

To test whether natural selection can change allele frequencies in a population

When can genetic drift strongly affect a large population?

When its effective population size becomes small, for example after a population bottleneck.

What is panmixia?

Panmixia is random mating within a population.

What is the inbreeding coefficient (F)?

The probability that two alleles in an individual are identical by descent from a common ancestor

What is the genetic problem with inbreeding?

Inbreeding increases homozygosity and therefore the risk of harmful recessive alleles being expressed

What is assortative mating?

Non-random mating in which mate choice is based on particular traits

What are HOX genes?

HOX genes are regulatory genes that control the development and position of body structures along the body axis.

What happens if the promoters of two HOX genes are exchanged? Explain why.

Each HOX gene will be active in the body region of the other gene. This can cause body structures to develop in the wrong place, because HOX genes control body development and promoters control where genes are active.

How is the anterior-posterior axis established in Drosophila

Localized maternal bicoid and nanos mRNAs are translated after fertilization and form protein gradients. Bicoid specifies the anterior region and Nanos the posterior region by regulating developmental genes

Why are Y-DNA and mtDNA useful for haplogroup analysis?

Y-DNA follows the paternal line and mtDNA follows the maternal line. Both undergo little or no recombination, making ancestry easy to trace.