Lectures 25-30 Flashcards
What does Diversity mean?
The number of species or higher taxa
What is disparity
The diversity of traits or overall complexity
What has the most diversity and disparity?
Animals
What is phylogenetics?
The reconstruction of evolutionary relationships
What is homology?
the same organ in different animals under every variety of form and function
- inherited from common ancestor
- like the limbs of humans and the fins of whales or wings of bats
- pentadactyl limbs
Sir Richard Owen in 1843
What is a taxon or taxa?
Taxon
- rank-less identifier for a species or group of related species
- TAXA = plural
What do branches represent on phylogenetic trees?
The evolutionary history of all animals closely related to tip than the next tip
- connected by node=common ancestor of 2 tips
What is a paraphyletic group
A grade
What are sister taxa?
Two tips who share a common ancestor
What is phylogenetic taxonomy?
1990s - alternative to Linnaean classification - only monophyletic clades are recognised as valid taxa - no hierarchical ranking system -
What are the two types of defined taxa in phylogenetic taxonomy?
- Node-based - taxa, common ancestor and all descendants
- crown groups are node-based taxa where the two primary branches each contain at least one living species - Stem-based
- more closely related to a crown group than another crown group - only extinct taxa represented by fossils are these forms
3ish - crown and stem together is total clade
What is historical homology?
Genetic, physiological or behavioural traits within different organisms inherited from a common ancestor
What is deep homology?
The sharing of the genetic regulatory apparatus that is used to build morphological and phylogenetically disparate animal features
