3B - POPULATION GENETICS AND NATURAL SELECTION

What is the environmental pressure in Geospiza fortis?

Drought or food scarcity changes which beak types are advantageous

What is the directional selection in Geospiza fortis

The beak size shifts in one direction based on food availability. For example, larger beak sizes during drought

What are the 3 implications of evolution

Does not occur during leaps or saltation. Acts only on heritable characteristics. and Not Ontogeny or individual development.

What is Panicum virgatum all about

It is a type of wetland reed that lives in different environment/have ecotypes

What is about Rangifer Tarandus?

These organisms have cold climate adaptation such as thick fur and hollow hairs for insulation. Moreover, they have seasonal migration in which selected for strong navigation and endurance.

What does genetic variation in alpine fish talks about?

It is the movement of cold adapted aquatic species into the headwaters of glacial valleys that lace the alps created clusters of geographically isolated population.

What are the conditions of Hardy-Weinberg Equilibrium?

Random mating, No mutations, Large population size, No immigration, and equal survival and reproductive rates of all genotypes.

What are the 3 types of natural selection?

Stabilizing selection, Directional selection, and Disruptive selection

This type of selection acts against extreme phenotypes and as a consequence favors the average phenotype.

• Extreme phenotypes have lower rates of reproduction and survival

Stabilizing selection

This type of selection favors an extreme phenotype over other phenotype in the population

• It occurs where one extreme phenotype have an advantage over all other phenotypes

• An exceptional phenotype has higher reproduction and survival

Directional selection

This type of selection favors two or more extreme phenotypes over the average phenotype in a population.

• Average phenotypes have lower reproduction and survival compared to the extremes.

Disruptive Selection

This idea is most effective at changing gene frequencies in small populations such as those that inhabit islands.

Genetic drift

What is the genetic variation in island population?

It shows that genetic variation is lower in isolated and generally small island population

Explain the genetic diversity in butterfly extinctions

Inbreeding contributes to higher extinction rates in small population. It was seen in Glanville fritillary butterflies that populations with highest levels of inbreeding had lowest heterozygosity and had the highest probability of extinction

Selective breeding of domesticated organisms to produce or maintain desirable traits

Artificial selection

Introduction or deletion of genes in domesticated organisms

Genetic engineering

What is the evolutionary consequences of the use of chemicals?

Plants and animal pests may evolve resistance to the chemicals which can result to quick and widespread resistance among pests.