Species and taxonomy – AQA A Level Biology Summary Notes
Two organisms belong to the same species if they are able to produce fertile offspring
Species
- The basic unit of classification
- Group of organisms with similar features that can reproduce to create fertile offspring
(Hybrids are not fertile so can NOT be classed as a species)
Courtship behaviour is a necessary precursor to successful mating
CB increases probability of successful mating by:
1. Attracting individuals from the same species
2. Helping recognition of mate from opposite sex
3. Indicating sexual maturity
4. Aiding the formation of a pair bond between two organisms
5. Stimulating release of gametes
CB is SPECIES SPECIFIC; similar species may have similar courtship behaviour, however it will be
distinct
Phylogenetic classification system attempts to arrange species into groups based on their
evolutionary origins and relationships
- This model assumes that all life has originated and diversified from a single common
ancestor SO, the more recently two organisms share a common ancestor the most closely
related they are in evolutionary terms
A phylogenetic group is a group of organisms with a shared evolutionary history
Classification
- Grouping of organisms
Phylogenetic classification systems are hierarchical - smaller groups are placed within larger groups, with
no overlap between groups. Each group us called a taxon (pl. taxa). Groups reflect evolutionary history
Artificial classification – based on physical observations
Phylogenetic classification – based on evolutionary relationships (DNA analysis)
Two organisms belong to the same species if they are able to produce fertile offspring
Species
- The basic unit of classification
- Group of organisms with similar features that can reproduce to create fertile offspring
(Hybrids are not fertile so can NOT be classed as a species)
Courtship behaviour is a necessary precursor to successful mating
CB increases probability of successful mating by:
1. Attracting individuals from the same species
2. Helping recognition of mate from opposite sex
3. Indicating sexual maturity
4. Aiding the formation of a pair bond between two organisms
5. Stimulating release of gametes
CB is SPECIES SPECIFIC; similar species may have similar courtship behaviour, however it will be
distinct
Phylogenetic classification system attempts to arrange species into groups based on their
evolutionary origins and relationships
- This model assumes that all life has originated and diversified from a single common
ancestor SO, the more recently two organisms share a common ancestor the most closely
related they are in evolutionary terms
A phylogenetic group is a group of organisms with a shared evolutionary history
Classification
- Grouping of organisms
Phylogenetic classification systems are hierarchical - smaller groups are placed within larger groups, with
no overlap between groups. Each group us called a taxon (pl. taxa). Groups reflect evolutionary history
Artificial classification – based on physical observations
Phylogenetic classification – based on evolutionary relationships (DNA analysis)
