SU Genome Complexity in salamanders 15/10

Question 1

Abstract

Answer 1

This presentation explores the genomic architecture of complex eukaryotes, with a focus on two organisms: the critically endangered pygmy hog (Porcula salvania) and Triturus newts. The first part delves into the implications of inbreeding in the pygmy hog, including the loss of genetic diversity and the presence of regions of homozygosity (ROH), which highlights the challenges for conservation. The second part introduces the enigmatic genome of Triturus newts, emphasizing the “balanced lethal system” (BLS) and its reproductive consequences. This system reduces the survival rate of offspring due to lethal alleles on certain chromosomes. The lecture highlights how genomic architecture, rather than natural selection, may contribute to these unusual genetic phenomena.

Question 2

Regions of homozygosity (ROH)

Answer 2

are used to measure the extent of inbreeding, and longer ROHs indicate more recent inbreeding

In species like the pygmy hog, inbreeding reduces genetic diversity and increases the risk of inbreeding depression due to the accumulation of harmful alleles.

Question 3

Balanced lethal system (BLS)

Answer 3

is a genetic system in which two lethal alleles are maintained in a population because heterozygous individuals (carrying one copy of each lethal allele) are viable, but homozygous individuals (carrying two copies of the same lethal allele) are inviable or die early in development. This system leads to a situation where only heterozygous individuals survive and reproduce, thereby perpetuating the lethal alleles in the population.

Question 4

Supergene

Answer 4

Is gene cluster that stays together during meiosis as they perform an important role together

is a group of neighboring genes located on a chromosome that are inherited together because they are tightly linked and typically do not recombine. These genes often work together to control a complex trait, such as mating behavior, color patterns, or ecological adaptations. Supergenes are particularly important in maintaining combinations of advantageous traits that might otherwise be broken apart by recombination during meiosis.

Question 5

Linkage mapping

Answer 5

(also known as genetic mapping) is a technique used to determine the relative positions of genes or genetic markers on a chromosome based on how frequently they are inherited together. The principle behind linkage mapping is that genes located close to each other on a chromosome are less likely to be separated by recombination (or crossover) during meiosis and thus are more likely to be inherited together. By analyzing the frequency of recombination between different genetic markers, researchers can estimate the distances between them and create a map of their relative positions on the chromosome.