species and taxonomy Flashcards
What is a species
group of organisms that can interbreed and make fertile offspring
Suggest why 2 different species are unable to produce fertile offspring
*different species have different chromosome numbers → offspring may have odd chromosome number
*So homologous pairs cannot form → meiosis cannot occur to produce gametes
Explain why courtship behaviour is a necessary precursor to successful
mating
● Allows recognition of members of same species → so fertile offspring produced
● Allows attraction of opposite sex
● Stimulates release of gametes
● Indicates sexual maturity
● Establishes a pair bond to raise young
Role of courtship in species recognition
*courttship is specific to species and used to classify organisms
*if courtship behaviours are similar in species it shows that theyre closely related
Whats a hierarchy
smaller groups arranged in larger groups with no overlap in between groups
Describe a phylogenetic classification system
*Species arranged into groups, based on their evolutionary origins and relationships
● Uses a hierarchy:
○ Smaller groups are placed within larger groups
○ No overlap between groups
How is each species universally identified and whats an advantage of binomal system?
A binomial consisting of the name of its genus and species.
*advantage-Universal so no confusion as many organisms have more than one common name
Describe two advances that have helped to clarify evolutionary relationships between organisms
*genome sequencing- comparison of DNA base sequences
* differences in DNA base sequences → more distantly related / earlier common ancestor
* As mutations (change in DNA base sequences) build up over time
2. Advances in immunology → allowing comparison of protein tertiary structure
● indicates a similar amino acid sequence and tertiary structure
● So less time for mutations to build up
Two species are closely related if….
they share a RECENT common ancestor
