lab 5

Question 1

what is convergent evolution

Answer 1

two distantly related species which share same evolved traits

Question 2

what is phylogeny?

Answer 2

phylogeny is used to classify organisms into natural groups and can also be used to classify zoonotic disease transmission

Question 3

what are systematics?

Answer 3

study of organism diversity

Question 4

how are systematics and taxonomy related?

Answer 4

both attempt to arrange groups according to evolutionary relationships

Question 5

what are phylogenetic systematics?

Answer 5

reconstructs and implies relationships among groups of organisms that are derived from a common ancestor
evolutionary relationships are inferred from characters which are observable

clusters organisms into groups based on modified characters to produce a hypothesis of evolutionary relationships and classification of the relationships

Question 6

how can phylogentic systematics be made more reliable?

Answer 6

classifications which use many characters are more informative in determining true evolutionary relationships

Question 7

why are phylogenetic systematics good for studying things?

Answer 7

the system is quantitative, producible, testable by scientific method

Question 8

what do phylogenetic systematics assume?

Answer 8

evolution occurs and that there is a single phylogeny of life which everything descended from
characters are passed from gen to gen both modified and not during evolution descent

Question 9

what does descent w/ modification mean and how can it be observed?

Answer 9

descent w/ modification means a genaology (ancestor and descendants) go through a change in characterisitcs or attribute

this relationship can’t be directly observed, but characteristics which stem from it can be observed and so phylogenetic trees are used to present hypothesis for these relationships via observing characters

Question 10

how do characters change over time and what does this mean?

Answer 10

not all characters change at the same rate so organisms will be a combination of ancestral (unmodified) and derived (modified)

Question 11

what are unique derived characters?

Answer 11

character possesed by only one taxa

Question 12

what are shared derived characters and why are they important?

Answer 12

shared derived character states are the ones used to reconstruct evolutionary relationships, the phylogeny of taxa and are used to construct phylogenetic trees

Question 13

what are the steps to constructing a phylogenetic tree?

Answer 13

1. identify homologous characters
2. code characters as ancestral or derived + constructed
3. group shared derived characters to created a phylogenetic hypothesis

Question 14

what is a character?

Answer 14

an observable trait of an organisms can be morphological, molecular, developmental, physiological, behavioural, ecological

Question 15

what are homologous characters?

Answer 15

haracters in 2+ species which are dervied from the same structure in a common ancestor

Question 16

w/o contrary evidence how are common characteristics assumed to arise?

Answer 16

not all resemblances come from a common ancestry (convergent evolution), however, in absence of contrary evidence shared characters are always assumed

Question 17

what is homoplasy?

Answer 17

homoplasy is when characters evolve more than once, which means the character occurs in 2+ species but not in the most recent common ancestor

Question 18

what is character reversal?

Answer 18

character reversal is when species reevolves ancestral character state

Question 19

how are characters coded on a phylogeny tree?

Answer 19

binary which are coded 0, 1 or multistate which are coded 0, 1, 2 etc. this doesn’t mean a sequence of changed but that there’s multiple derived states

Question 20

what are the two types of multisate characters and which is the default?

Answer 20

the multistate characters can also be ordered which follow logical evolutionary paths (small beak→ medium beak → big beak) or unordered which doesn’t follow a logical progression (colours of coral reef fish which all evolve independently from each other/dont follow a precise sequence)

usually multistate characters are assumed unordered since their evolutionary transformation are generally unkown

Question 21

what are caldograms?

Answer 21

caldograms are another name for phylogenetic tree

Question 22

what is a character transformation?

Answer 22

character transformation is modification of a character state

Question 23

what is a character state?

Answer 23

character state is 1+ alternative forms of the same character

Question 24

what is an outgroup?

Answer 24

outgroup is a taxon which is usually a sister group of studied group and is used to determine which two homologous character states maybe be derived

Question 25

what is outgroup comparison?

Answer 25

outgroup comparison is the method to determine which of two homologous character state is ancestral or derived

Question 26

how can ancestral and derived traits be differentiated?

Answer 26

characters found in both outgroup and ingroup are ancestral, those found in only ingroup are derived

Question 27

what is parsimony?

Answer 27

parsimony is the principle in phylogenetics which forces the shortest tree which explains all character sates to be accepted

Question 28

what is principle of parsimony?

Answer 28

principle of parsimony is used to determine which tree bests fits data during phylogenetic analysis as its possible to build more than one tree for one set of character
shortest tree to a trait is always best

Question 29

what is the optimal tree?

Answer 29

optimal tree minimizes number of homoplasious character/required least number of character state transoformation and is known as the shortest tree