5.2 Natural Selection Flashcards
ICE AGE mnemonic for natural selection
Inherited variation exists within the population
Competition results from an overproduction of offspring
Environmental pressures lead to differential reproduction
Adaptations which benefit survival are selected for
Genotype frequency changes across generations
Evolution occurs within the population
Gene pool
all the genes and their different alleles present in an interbreeding population
Meiosis and variation
Meiosis promotes variation by creating new gene combinations via either crossing over or independent assortment
Sexual reproduction and variation
The fusion of two haploid gametes results in the formation of a diploid zygote
As meiosis results in genetically distinct gametes, random fertilisation by egg and sperm will always generate different zygotes
Mutations and variation
A gene mutation is a change in the nucleotide sequence of a section of DNA coding for a specific trait
New alleles are formed by mutation
Inheritance patterns and variation
different alleles combine to produce unique phenotypes
Survival of the fittest
as species tend to produce more offspring than the environment can support there is competition, hence any trait that is beneficial will be more likely to be passed on to offspring
Adaptations definition
characteristics that make an individual suited to its environment and way of life
Structural adaptations
physical differences in biological structure
Behavioural adaptations
differences in patterns of activity
Physiological adaptations
variations in detection and response by vital organs
Biochemical adaptations
differences in molecular composition of cells and enzyme functions
Developmental adaptations
variable changes that occur across the life span of an organism
Adaptive advantage
individuals that are better adapted tend to survive and produce offspring while those who are less well adapted ten to die or produce fewer offspring
