Molecular data and evolutionary biology

Question 1

How is molecular data used in evolutionary biology?

Answer 1

Phylogenetics assesses the relatedness of organisms by comparing their genes.

Question 2

Animals with similar base sequences are closely related. True or false?

Answer 2

True.

Question 3

What kind of events can eventually cause speciation? Give 3 examples.

Answer 3

1. SNPs
2. Gene duplications
3. Polyploidisation

Question 4

What is the basic principle of speciation?

Answer 4

A mutation that gives an organism a selective advantage that eventually leads to it becoming reproductively isolated from members of its original species.

Question 5

What kind of events can give misleading information about relatedness? Give 2 examples.

Answer 5

1. Horizontal gene transfer

2. Introgressive hybridization

Question 6

Define introgressive hybridisation.

Answer 6

Whereby the gene of one species enters the gene pool of another species via the repeated backcrossing of interspecific hybrids.

Question 7

What does ‘backcrossing of interspecific hybrids’ mean?

Answer 7

Whereby a hybrid is created between two species, and this hybrid is then bred to either one of its parent species.

Question 8

Define orthologous genes or ‘orthologues’.

Answer 8

Homologous genes that are descended from the same ancestral sequence.

Question 9

Define homologous.

Answer 9

The same in evolutionary origin but not necessarily in form or function.

Question 10

Some genetic markers can be used to trace a lineage. Give an example.

Answer 10

mtDNA can trace female migration.

Question 11

Give 4 reasons why mtDNA is so useful in evolutionary genetics.

Answer 11

1. It does not recombine
2. Maternal inheritance allows a direct phylogeny to be constructed
3. It evolves 10 times fater than nuclear DNA
4. It has a high copy number

Question 12

Define DNA barcoding.

Answer 12

A DNA barcode is a short sequence from a standard, agreed-upon position in the genome. The DNA barcodes of different species are unique, like a barcode on something in a shop.

Question 13

Some regions of the genome are highly conserved between organisms, although there are still sequence differences between species. This means we can use universal primers in experiments. True or false?

Answer 13

True.

Question 14

Give an example of a DNA barcoding gene in animals.

Answer 14

Cytochrome C oxidase 1.

Question 15

What is a BLAST search?

Answer 15

An algorithm that searches for similarities in a database of DNA sequences.

Question 16

What is one problem with using universal DNA barcodes?

Answer 16

They are often still the same in very recently separated taxa. Need to look at more rapidly evolving markers like SNPs.

Question 17

Why is DNA taxonomy important to conservation?

Answer 17

We like to catalogue the species that exist on our planet.