lecture 4 Flashcards
is branching tree a good metaphor for evolution?
kind of
why branching tree is good?
- No central trunk
- No directionality
- branches not uniforme equal
how are determined the relationship in a phylogenetic tree?
Classification based on common evolutionary descent
can organism share a character and yet not ne evolutionary related?
yes
Two types of shared characters?
- Homology
- Homoplasy
homology
character similarity resulting from common
ancestry
Homoplasy
non-homologous similarities that may be
found in various organisms (evolved separately)
goal of systematics
infer the evolutionary tree (phylogeny) that relates
all extant and extinct species
what is systematics exactly?
grouping organisms based on a set of rules (or system).
how is it accomplished?
by comparing characters
which Characters?
morphological,chromosomal,molecular
can behavioural and ecological featyres also used?
yes
Analysis of ancestral and derived characters used to
construct a
cladogram
Phylogenetic tree
branching diagram showing the inferred
evolutionary relationships among various biological species
Cladogram:
diagram used in cladistics to show evolutionary
relationships between organisms
Clade
unit of evolutionary common descent that includes ancestral
lineage and all descendents
Character:
organismal feature that varies between species
Ancestral character
character state present in the common
ancestor
Derived character
all other variant forms of the character that arose
later within the group
types of clade
- Monophyletic clade
- Paraphyletic clade
- Polyphyletic clade
Monophyletic clade
includes the most
recent common ancestor and all descendants
of that ancestor
paraphyletic clade:
includes the most recent
common ancestor and some but not all
descendants of that ancestor
polyphyletic clade:
does not include the most
recent common ancestor of all members of a
group. i.e. the group has at least two separate
evoutionary origins
what’s the big problem of that analogy?
aren’t considering sexual reproduction ( no paternal line)
old version of the three of life
hierarchical system of classification based on linnaean taxonomy
what is it the old version?
life-domain-kingdom-phylum-class-order-family-Genus-Species
a trick to remember?
Do kangoroos prefer cake or frosting generally speaking?
are intermediate taxas also possible?
yes, but they are not shown
each specie is classified according to?
nested rank of taxa
Taxonomy
Study of the principles of scientific classification;
systematic ordering and naming of organisms.
Who governs taxonomy?
nobody
how do we classify organisms?
lots of ways
fundamental way that we classify
organisms is
based on evolutionary relationships
Linneaus is?
the father of taxonomy
First unified system for naming all plants and animals is?
Systema Naturae
the systema naturae was based on?
shared characters among organisms
what doesn’t it consider the systema naturae?
Doesn’t consider evolution (predates evolutionary biology)
what is the primary focus of this class ?
phylum level
major divisions of life: Three domains
bacteria,archea,eukaryota
what are the kingdoms?
- Animalia(Metazoa)
- Plantae
- Fungi
- Protista
- Bacteria
- Archea
Which kingdoms are also domains?
Bacteria-Archea
problems with modern taxonomy ?
- not governed by any international boy
- Skewed towards pedagogical convenience rather than a true reflection of phylogeny
- Hierarchical ranks are difficult and outdated
why outdated?
- Eukaryotes are over-represented
- if we strictly followed phylogeny we would have an unpalatable number of kingdoms
Systematics
Science of classification of organisms based on
common evolutionary descent (or phylogenetics
cladistics
One approach to systematics ( une des branches de systematics)
cladistics is a way?
of arranging taxa by analysis of evolutionary derived
characteristics so that the arrangement reflects phylogenetic
relationships
Phylogeny:
The evolutionary history of the origin and
diversification of any taxon, usually presented in the form of a
dendrogram. The one true tree of life.
