Lecture 1 DA Introduction Flashcards
On a phylogenetic tree, what are nodes?
Points where a species seperates into two, into branches.
What is a species at a node of a phylogenetic tree called?
Inferred species.
What are sister taxa?
Those species more closely related versus the rest of the tree.
What are evidences needed for constructing phylogenetic trees (4)?
Fossil records Traits: -genetic sequences -comparative -architecture/morphology -development
What is an ancestral character? Does it reveal relationships within the group?
Character shared by all taxa in a grouping. Doesn’t reveal relationships.
What is a derived character? Does it reveal relationships within the group?
Character that arose after an ancestor. Does reveal evolutionary relationships.
What is a shared-derived character? Does it reveal relationships within the group?
A synanomorphy, shared by all descendants of an ancestor due to common descent.
What is a synanomorphy?
A character shared by all descendants of an ancestor due to common descent.
How are synanomorphies useful for phylogenetic trees?
Used to define clades/groups.
What is homology?
Similar structure due to a common ancestor.
What is analogy?
Structures that are only superficially similar, and not due to a common ancestor.
How do analogous structures arise?
Via convergent evolution.
What are some ways species can be grouped?
Based on cell orginisation - uni/multicellular
Based on body symmetry
Number of embryonic tissue levels (ecto/endo/meso)
What is a protostome?
The first hole in embryological development becomes the mouth.
What is a deuterostome?
The first hole in embryological development becomes the anus.
What is the problem of using solely deuterostomes and protostomes as a classification in making phylogenetic trees?
Gives conflicting phylogenies.
What is a monophyletic clade?
A grouping including all the descendants of a common ancestor.
What is a paraphyletic clade?
Grouping that doesn’t include all descendants of a common ancestor, will have some from another ancestor as well, but not that ancestor itself.
What is a polyphyletic clade? How do they arise?
Neither a para or monophyletic clade, happens due to convergent evolution.
What are protozoa like?
Eukaryotic, mostly unicellular and some colonial.
Are protozoa motile?
Yes, via flagella and cilia.
What are metazoa like?
Eukaryotic and multicellular
Do metazoa have differentiating cells?
Yes
Which phylum do sponges belong to?
Porifera
Of the three domains of life, which two are more closely related and why?
archaea and eukarya, due to the presence of histones.
What did animals arise from?
Choanoflagellates
Animal and fungi kingdoms came from which protozoa?
Opisthokonta
What are choanoflagellates like?
Loose association of cells, are colonial and genetically identical.
Do choanoflagellates have cell differentiation?
No
Can individual choanoflagellates of a colonial group survive on their own?
Yes
What are choanoflagellate sfunctionally very similar to?
Sponges.
How do choanoflagellates feed?
Filter feed by beating flagella to drive a current through a collar of filtering microfibrils.
What is the simplest metazoan?
Phylum porifera
Do porifera cells have differentiation?
Yes, but only some
Do phylum porifera have any organs?
No