4.5 SPECIES AND TAXONOMY

SUGGEST WHY TWO DIFFERENT SPECIES ARE UNABLE TO PRODUCE FERTILE OFFSPRING?

• Different species have different chromosome numbers→ offspring may have odd chromosome numbers.

• So homologous pairs cannot form → meiosis cannot occur to produce gametes.

WHY IS COURTSHIP NECESSARY FOR SUCCESSFUL MATING?

• Allows recognition of members of same species → so fertile offspring produced.

• Allows recognition / attraction of opposite sex.

• Stimulates /synchronises mating / production / release of gametes.

• Indicates sexual maturity / fertility.

• Establishes a pair bond to raise young.

HOW IS COURTSHIP BEHAVIOUR DETERMINED?

• Innate; genetically determined.

• Same species.

DESCRIBE A PHYLOGENIC CLASSIFICATION SYSTEM?

• Species arranged into groups, called taxa, based on their evolutionary origins (common ancestors) and relationships.

• Uses a hierarchy.

HEIRACHY?

• Smaller groups within larger groups.

• With no overlap.

WHAT IS THE TERM USED TO DESCRIBE THIS METHOD OF NAMING ORGANISMS

ADVANTAGE OF BINOMIAL NAMING?

Universal so no confusion as many organisms have more than one common name.

DESCRIBE ADVANCES THAT HAVE HELPED TO CLARIFY EVOLUTIONARY RELATIONSHIPS BETWEEN ORGANISMS?

1. Advances in genome sequencing →allowing comparison of DNA base sequences.

   1. More differences in DNA base sequences → more distantly related/ earlier common ancestor.

   2. As mutations build up over time.

2. Advances in immunology → allowing comparison of protein tertiary structure (eg. albumin).

   1. Higher amount of protein from one species binds to antibody against the same protein from another species → more closely related/ more recent common ancestor.

   2. As indicates a similar amino acid sequence and tertiary structure.

   3. So less time for mutations to build up

IF ORGANISMS HAVE THE SAME GENUS THIS MEAN?

Same evolutionary origin / common ancestor.

SIX KINGDOMS:

1. Bacteria.

2. Archaea.

3. Protoctista.

4. Fungi.

5. Plants.

6. Animals.

OTHER THAN HUNTING, SUGGEST TWO REASONS WHY POPULATIONS MIGHT SHOW VERY LOW LEVELS OF GENETIC DIVERSITY?

• Population might have been very small / genetic bottleneck.

• Population might have started with small number of individuals / by one pregnant female / founder effect.

• Inbreeding.