L4: Taxonomy and phylogeny Flashcards
What is taxonomy?
The classificationof a species.
What is phylogeny?
The study of evolutionary history and relationships among individuals or groups of individuals
What is the general definition of what a species is?
Species reproduce to create viable offspring. Species may transform into another new species.
What form does evolution take?
bifurcated tree
What are the problems faced with phylogenetic analysis of the past?
Too much consideration of the presence and absence of characters
The lines of descent assumed we could identify ancestors by way of one species giving rise to another
Too much reliance on stratigraphic distribution of fossils
What is the cladistics revolution?
Scientists working on insects realised the techniques used to determine evolution were flawed - from this, they generated cladistics
What is cladistics?
an approach to biological classification in which organisms are categorized in groups based on the most recent common ancestor
What is the parsimony method for analysing character distribution?
Look at the simplest way to acquire characters
What is the bayesian method for analysing character distribution?
Uses a likelihood function
What are synapomorphies?
Characteristics present in ancestral species and shared exclusively by evolutionary descendants
What are synplesiomorphies?
Ancestral traits shared by two or more taxa, but also with other taxa in early line
What are autopomorphies?
Distinct features, they are derived traits that are unique to a given taxa
What is homology?
A character shared by a set of species but not present in their common ancestor
What are the 5 steps for constructing a cladogram?
Create a character matrix Analyse character distribution Identify where characters arise - homologus or analogous Establish sister group relationships Illustrate using a cladogram
What is a monophyletic group?
a group of organisms that are classified in the same taxon and share a most common recent ancestor
What is a paraphyletic group?
descended from a common evolutionary ancestor or ancestral group, but not including all the descendant groups
What is a polyphyletic group?
derived from more than one common evolutionary ancestor or ancestral group and therefore not suitable for placing in the same taxon
What is the crown group?
Includes all living animals
What is the stem group?
No living representatives
What is the total group?
Everything from the common ancestors ,alive members and fossils
What are the tetrapods?
A monophyletic group of vertebrates primitively bearing four limbs
From what did tetrapods evolve?
From a fish species that crawled out of the water at the end Devonian, Evolved only once
What are the four classes of tetrapods?
Amphibia
Reptilia
Aves
Mammalia
What two groups do the tetrapods divide into?
The Anamniotes and the amniotes
