topic 6 - co-evolution conflict

Molecular clock

Character change in molecular phylogeny can occur in a clock like fashion that enables us to put time stamps on evolutionary events

Cladogram

Branching diagram (tree-like) that represent hypotheses about how species are related based on shared derived characteristics

Each branch point (node) represents a common ancestor from which descendant groups diverged

Phylogeny

The study of the evolutionary history and relationships among organisms or groups of organisms

Shows how species or higher taxa (like genera or families) are related through common ancestry

Looks like a cladogram but usually includes branch lengths to represent evolutionary time or the amount of genetic change

Can be constructed using different kinds of evidence:

• Morphological traits (physical characteristics)

• Molecular data (DNA, RNA, protein sequences)

• Fossil records

Parsimony

Requiring the fewest assumptions or evolutionary changes - is not likely to be correct

Used in phylogenetic to infer evolutionary relationships

Favours the tree that explains the data with the least number of evolutionary steps (like mutations or trait changes)

List three factors we need to know to construct a parsimony

Character data: these are the traits or features you’re comparing across species; can be morphological (eg number of limbs, presence of feathers), molecular (eg DNA or protein sequences)

Character states: describe the form or version of each trait in each species (eg presence of a backbone)

Adaptive phenotype

Set of observable traits (morphological, physiological, behavioural) that increases an organism’s fitness - meaning it improves the individual’s ability to survive and reproduce in its specific environment

Phenotype

Any observable characteristic, such as body size, colouration, metabolism or behaviour that results from the interaction of genes and enviornment

Adaptive

The trait provides a selective advantage in the current environment (eg camouflage reduces predation, thicker fur in cold climates, antibiotic resistance in bacteria)

Natural selection

Favours adaptive phenotypes because individuals with these traits tend to leave more offspring, spreading the advantageous genes through the population.

Reproductively isolated

Can be prezygotic or postzygotic, not able to reproduce an offspring

Population structure

Arises when the demographic processes produce systematic differences in allele frequencies between subsets of a larger population

Isolation or some other factor that causes non-random mating

Eg. Western and Eastern deer separated by mountain range. No gene flow can happen. Relatively recent opening of the pass allows gene flow