Natural Selection/Genetics Flashcards
Postulate definition
given truth that assembled together creates a complex understanding
4 mechanisms of evolution
- individuals vary (variation)
- some of the variable traits among individuals are heritable
- there is a struggle for existence, not everyone survives
- individuals with favorable traits survive and reproduce
Darwin’s logic
given enough resources, populations should be able to expand exponentially, yet they dont
this means that there is a struggle for existence
since traits vary and are heritable, the individuals with favorable traits will survive and reproduce
Definition of evolution
inherited change in a group of organisms over time
outcome of evolution by natural selection
a change in allele frequencies in a population over time
fitness
the ability of an individual to produce, surviving offspring relative to that ability in other individuals in the population
adaptation
a heritable trait that increases the fitness of an individual in a particular environment relative to individuals lacking the trait
Common myths of natural selection
- natural selection does not change individuals
- acclimatization is not adaptation (acclimatization is a change of an individual’s phenotype due to natural condition)
- natural select is not goal oriented (mutations are chance, no higher/lower)
- natural select does not lead to perfection since there are trade-offs and vestigial traits
Constraints on traits
genetically constrained
historically constrained (all traits evolve from previous traits)
environmentally constrained
= all 3 cause natural selection not to be perfect
genetic correlation
can cause genetic constraint
a single gene affects multiple traits
How to prevent antibiotic resistance?
Use a high concentration of antibiotics from the beginning and complete the course of antibiotics to prevent adaptations from occurring
What does natural selection lead to?
adaptations
What is more important reproduction or survival?
Both are equally important
Abreu’s natural selection misconceptions
- Individuals do not change
- There is no goal
- There will never be a perfect organism
What did Mendel want to answer?
Why offspring resemble their parents and how transmission of traits occurs
Blending inheritance
The idea that parental traits blend
Offsprings have intermediate traits
Inheritance of acquired characterisitics
Lamarckian understanding
Parental traits are modified and passed down
Scientific name of Mendel’s peas
pisum sativum
Why did Mendel use peas as model organisms?
Easy to grow
Short reproductive cycle
Traits are easily recognizable (discrete)
Produces large numbers of seeds
Matings are easy to control
Model organism
a species that is widely studied because it is easy to maintain and breed in a lab setting
How do peas reproduce?
They can be cross-pollinated or self-pollinated
Phenotype
the observable appearance of a trait
Genotype
the underlying genetic composition that makes up a trait
Pure line
homozygous for a trait
also called true breeding
Particulate inheritance
suggests that hereditary determinants maintain their integrity from generation to generation
genes are independently expressed without the blending of characteristics
Gametes
haploid
contain one allele from either mom or dad
Zygote
diploid
forms when two gametes are fused
contains one allele from both mom and dad
Alleles
different versions of a gene
mendel says that each individual has two alleles
Principle of segregation
two alleles of each gene must segregate into different gamete cells
Ex: Rr splits into R and r
Law of Independent Assortment
the alleles of two or more different genes get sorted into gametes independently
the allele that one gamete receives does not influence the allele that another gamete receives
Adaptations are often…
Compromises
Trade offs occur
How to determine if a dominant phenotype is due to a heterozygous or homozygous dominant phenotype?
Cross with a homozygous recessive plant
This is called a test cross
