Genetic Diversity & Adaptations

Genetic diversity definition

Total number of different alleles in a population

Population definition

Group of individuals of same species living in same area and able to breed

Species definition

Group of organisms that can interbreed to produce fertile offspring

Relationship between species and populations

A species consists of one or more populations

Effect of high genetic diversity

Increases chance of survival if environment changes

Allele definition

Alternative form of a gene

Gene pool definition

All alleles present in a population

Niche definition

Role of a species within its environment

Competition definition

Occurs when species share the same niche

Natural selection definition

Process where better adapted individuals survive and reproduce

Fitter individuals definition

Those better adapted to the environment

Advantageous alleles

Alleles that increase survival or reproduction

Evolution definition

Change in allele frequencies in a population over time

Cause of evolution

Natural selection

Requirement for natural selection

Variation within a population

Phenotype definition

Observable characteristics of an organism

Source of phenotypic variation

Different alleles

Selection pressure definition

Environmental factor affecting survival

First step of natural selection

Variation in phenotypes

Second step of natural selection

Environmental change alters selection pressure

Third step of natural selection

Individuals with advantageous alleles survive

Fourth step of natural selection

Advantageous alleles passed to offspring

Final outcome of natural selection

Change in allele frequencies

Selection definition

Process where better adapted organisms survive and breed

Types of selection

Directional and stabilising

Directional selection definition

Selection favouring one extreme phenotype

Effect of directional selection

Mean phenotype shifts

Cause of directional selection

Environmental change

Example of directional selection

Antibiotic resistance in bacteria

Penicillin resistance mechanism

Production of penicillinase enzyme

Result of antibiotic resistance

Increased frequency of resistance allele

Stabilising selection definition

Selection favouring intermediate phenotypes

Environmental condition for stabilising selection

Stable environment

Effect of stabilising selection

Reduced variation

Phenotypes selected against in stabilising

Extremes

Example of stabilising selection

Human birth weight

Optimal birth weight example

Around 3kg

Adaptation definition

Characteristic increasing survival

Types of adaptation

Anatomical, behavioural, physiological

Anatomical adaptation definition

Physical structural feature

Anatomical example

Long Loop of Henlé in desert mammals

Purpose of long Loop of Henlé

Produces concentrated urine

Behavioural adaptation definition

Change in behaviour improving survival

Behavioural adaptation example

Mating calls

Physiological adaptation definition

Internal body process improving survival

Physiological adaptation example

Regulation of blood flow through skin

Link between niche and selection

Competition leads to survival of better adapted species