4. Biodiversity and natural
resources
4.a Biodiversity
Biodiversity
Key terms
● Biodiversity - variety of organisms in an area
● Species diversity - richness and evenness of species
● Species richness - number of different species in an area
● Species evenness - abundance of each species in the area
● Genetic diversity - variation of alleles within the gene pool of a species
● Gene pool - complete set of alleles in a species
● Endemism - when a species is unique to a single place
● Natural selection - adaptation leading to evolution
● Conservation - the protection of a species or habitat to help maintain biodiversity
● Niche - role of an organism within its habitat
Genetic diversity
● You can measure species diversity by looking at genetic diversity. Individuals of the
same species vary because they have different alleles, the greater the variety of
alleles, the greater the genetic diversity.
● To measure the genetic diversity of a species you can look at the phenotypes or the
genotypes:
1. Phenotypes
● The phenotype describes the observable characteristics of an
organism. By looking at the phenotypes in a population, you can get
an idea of the diversity of alleles in that population.
● E.g humans have different eye colours due to different alleles.
Humans in northern europe show a variety of blue, grey, green or
brown eyes. Outside this area, eye colour shows little variety - they
are usually brown. So there’s a greater genetic diversity in eye colour
in northern europe.
2. Genotypes
● The sequence of an organism's alleles that determines the physical
characteristics.
● By sequencing the DNA of individuals of the same species you can
see similarities and differences in the alleles within the species.
● You can measure the number of different alleles.
● You can measure the genetic diversity within a species using the heterozygosity
index, a higher proportion of heterozygotes indicates a higher genetic diversity
-
, 4. Biodiversity and natural
resources
● Species diversity can be measured using the index of diversity, the higher the
index, the greater the diversity
-
Adaptations and evolution
Types of adaptations
1. Behavioural
● Actions an organism takes
● E.g. mating rituals, hunting in packs
2. Physiological
● Internal processes
● E.g. thermoregulation, production of venom
3. Anatomical
● Structural/physical features
● E.g. thick blubber, camouflage
Natural selection and evolution
1. Random mutation will occur introducing new alleles and creating variation
2. Selection pressures and changes to environments can cause these new alleles to be
advantageous
3. Individuals with advantageous allele are more likely to survive and outcompete, this
is natural selection
4. Individuals then reproduce and the allele is inherited/becomes more frequent in
population
5. This continuous over generations leading to evolution
→ GENIE
(genetic variation, environment, natural selection, inheritance, evolution)
Darwin’s peppered moths
Evidence for natural selection.
1. Before the 1800s, there were more light moths than dark moths
2. During the 1800s and industrial revolution, pollution blackened trees
3. Dark coloured moths were then better adapted
4. The light coloured moths were more susceptible to predation so were less likely to
survive
5. Dark alleles reproduced and passes on alleles
6. Over time the frequency of alleles for dark moths increased
resources
4.a Biodiversity
Biodiversity
Key terms
● Biodiversity - variety of organisms in an area
● Species diversity - richness and evenness of species
● Species richness - number of different species in an area
● Species evenness - abundance of each species in the area
● Genetic diversity - variation of alleles within the gene pool of a species
● Gene pool - complete set of alleles in a species
● Endemism - when a species is unique to a single place
● Natural selection - adaptation leading to evolution
● Conservation - the protection of a species or habitat to help maintain biodiversity
● Niche - role of an organism within its habitat
Genetic diversity
● You can measure species diversity by looking at genetic diversity. Individuals of the
same species vary because they have different alleles, the greater the variety of
alleles, the greater the genetic diversity.
● To measure the genetic diversity of a species you can look at the phenotypes or the
genotypes:
1. Phenotypes
● The phenotype describes the observable characteristics of an
organism. By looking at the phenotypes in a population, you can get
an idea of the diversity of alleles in that population.
● E.g humans have different eye colours due to different alleles.
Humans in northern europe show a variety of blue, grey, green or
brown eyes. Outside this area, eye colour shows little variety - they
are usually brown. So there’s a greater genetic diversity in eye colour
in northern europe.
2. Genotypes
● The sequence of an organism's alleles that determines the physical
characteristics.
● By sequencing the DNA of individuals of the same species you can
see similarities and differences in the alleles within the species.
● You can measure the number of different alleles.
● You can measure the genetic diversity within a species using the heterozygosity
index, a higher proportion of heterozygotes indicates a higher genetic diversity
-
, 4. Biodiversity and natural
resources
● Species diversity can be measured using the index of diversity, the higher the
index, the greater the diversity
-
Adaptations and evolution
Types of adaptations
1. Behavioural
● Actions an organism takes
● E.g. mating rituals, hunting in packs
2. Physiological
● Internal processes
● E.g. thermoregulation, production of venom
3. Anatomical
● Structural/physical features
● E.g. thick blubber, camouflage
Natural selection and evolution
1. Random mutation will occur introducing new alleles and creating variation
2. Selection pressures and changes to environments can cause these new alleles to be
advantageous
3. Individuals with advantageous allele are more likely to survive and outcompete, this
is natural selection
4. Individuals then reproduce and the allele is inherited/becomes more frequent in
population
5. This continuous over generations leading to evolution
→ GENIE
(genetic variation, environment, natural selection, inheritance, evolution)
Darwin’s peppered moths
Evidence for natural selection.
1. Before the 1800s, there were more light moths than dark moths
2. During the 1800s and industrial revolution, pollution blackened trees
3. Dark coloured moths were then better adapted
4. The light coloured moths were more susceptible to predation so were less likely to
survive
5. Dark alleles reproduced and passes on alleles
6. Over time the frequency of alleles for dark moths increased
