BIO120

Evolution and Adaption

Mutation (And its types)

Random errors during gene replication, ultimate source of genetic variation. Can be neutral to fitness, deleterious (severely detrimental), 

1. Point 2. Indels 3. Changes in repeat number 4. Chromosomal rearrangement

Biological Evolution

Individual variation due to heritable traits that leads a change in frequency of inheritable traits across generations

Adaptation

Any trait that makes an organism more “fit” in their environment

Microevolution vs Macroevolution

Microevolution refers to changes to a population within a species, macroevolution refers to changes across species

Phylogeny

Evolutionary history of organisms

Biology/Evolution before Darwin

Before Darwin prominent theories regarding the origins of species included Lamarckism (Traist acquired during lifespan to somatic cells can be passed down to offspring) or static thiestic origins (Great Chain of being, Paley’s watchmaker argument)

Who inspired Darwin?

Darwin was inspired by many sources, most prominently Charles Lyell and his book ‘Principles of Geology” (Uniformitarianism - Gradual, constant forces shape Earth) as well as Thomas Malthus’ book “The Principle of Populations” (A Struggle for survival exists due to lack of resources)

Evidence for Evolution (4 main pieces of evidence)

1. Geology - Fossil records show new fossils are more alike to modern day species compared to older ones, indicating progressive evolution over millenia 2. Homology - Similar characteristics between species that are inherited from the same ancestor (Features seem to be modified, not independently created) 3. Geography - Animals on islands are all great colonizers and areas with a common ancestor relating to many diverse species imply it adaped and speciated to fill the open niches 4. Domestication - Human control over the selection of traits prove that certain traits are heritable and could be chosen over others by a mechanism (Human or natural)

Genotype

Genetic composition of an organism

Phenotype 

Physical and behavioural expression of an organism’s genes 

Genome

The entirety of an organism’s DNA (Including non-coding sections)

Independent Assortment

Form of inheritance in diploid organisms where alleles of genes are randomly separated independently during meiosis causing the ability to create new allele combinations in offspring

Theory of Blending Inheritance 

Traits from parents mix together in offspring, causing the offspring to express a trait that is the average of its parents

Issue With Blending Inheritance

Blending inheritance does not explain how a new mutation could spread rapidly amongst a population and become fixed, because if blending inheritance were to be true new mutations would be “diluted” due to constantly being averaged out with the "wild type.”

Discrete vs Continuous trait

A discrete trait has distinct phenotypical categories where there are few (countable) expressions (Hair colour), it is often linked to few loci/alleles - Mendelian

A continuous trait is influenced by many different alleles and its expression can be mapped onto a continuous graph of distribution (exists on a spectrum) - Quantitative