LAB 1 - Systematics and Classification Laboratory: Building Phylogenetic Trees Using Caminalcules

Define Systematics

the science of organizing living things into similar, presumably related categories

the science of organizing living things into similar, presumably related categories is…

systematics

Define Systematics

the science of organizing living things into similar, presumably related categories

the science of organizing living things into similar, presumably related categories is…

systematics

Most biologists believe that all species…

evolve from one or a few ancestor species over vast periods of time

the belief that all species evolve from one or a few ancestor species over vast periods of time is believed by…

most biologists

Goal for systematics

create a monophyletic group where all species are thought to have a common ancestor

define monphyletic group

species which are thought to have a common ancestor and doesn’t include those that do not have the common ancestor

systematics wants to avoid these two groups…

polphyletic and paraphyletic

polyphyletic group

members do not all share the same ancestor

paraphyletic group

do not include all the species descended from the common ancestor

Modern Systematics uses these sources of information:

Morphology, Fossils, Biogeographic ranges, genetic information

lab focuses on…

morphology and fossil evidence

caminocules

a hypothetical experimental organism Invented by Joseph Camin (1960s) and has phylogeny (line of descent)

Methods are…

phyletics, phenetics, caldistics

phyletics or…

evolutionary taxonomy

phyletics or evolutionary taxomony focuses on…

Using heavy reasoning power and evolutionary assumptions of the systematist

Making judgements on what the ancestor must’ve been like

Making an educated guess on the sequence of changes

Arranges the tree accordingly

tree in phyletics must show…

hypothetical changes overtime

length of branches in phyletics =

degree of change

phyletics was criticized because…

it’s based on subjective opinion systematist and may involve circular reasoning

phenetics aka…

numerical taxonomy

phenetics or numerical taxonomy

·      Make no initial assumptions and consider as many characters as possible

·      Lists as many characters as possible then counts how many differences there are between each species pair

·      Pair most similar is grouped together first, next is the most similar pair, etc.

result of phenetics

phenogram or cluster diagram

farthest species in phenetics =

more distantly related

assumption of phenetics

we don’t know beforehand what the branching pattern was, and any guesses made will make bias as a result

rule of phenetics

1.        Make a table of all the characters they can measure on the species (list state of each character + assign a value to each)

2.        Rates each of the animals according to each of the characteristics

3.        Make a table of distances (euclidean distance + UPGMA – Unweighted Pair Group Method with Arithmetic Mean)

4.        Looping process

phenetics was criticized because…

it Ignores what everyone knows is the true evolutionary history of living things because…

• it weights all characters equally

• logic is backward

• ignores issues such as convergent evolution

 

cladistics

·      process of determining descent by means of synapomorphies (shared, derived characteristics

·      usually done by examine fossils or closely related groups

·      simplest tree = most likely to be correct

Outgroup

the group of organisms having certain characteristics which forms the base of the cladogram

maximum parsimon =

cladogram which involves the least number of changes would be accepted as the most likely cladogram, since the simplest explanation is considered most likely to be ture

ancestral characteristics

characteristics that a species has which its immediate ancestor species also had

autamorphy

a derived characteristic not held in common with any other species

cladogram

a phylogenetic diagram based on synapomorphies

derived characteristic

characteristic held by one or more species but not held by its immediate ancestor species

monophyletic group

a group composed of an ancestory species and all of its descendants, but with no other species

paraphyletic group

group composed of an ancestor species and some but not all of its descendants

phenogram

a phylogenetic diagram which is based up clustering. many characteristics of the species to be diagrammed are measure, then the species are placed in clusters int he phenogram based on how similar they are to one another. all features are usually given equal weight.

phyletic diagram

a phylogenetic diagram showing lines of descent based upon the subjective judgement of the systematist

phylogenetic diagram

a diagram attempting to portray the evolutionary hisotry and relatedness of a group of species

polyphyletic groups

a group of species in which some of the species are from a different line of descent than other species are from

polyphyletic group

a group of species in which some the species are from a different line of descent than other species are from

synapomorphy

a derived characteristic shared by two or more species. cladistics is based entirely on synapomorphies

symplesiomorphy

an ancestral characteristic shared by two or ore species. have no significance in determining relatedness in cladistics