Biology 2 Chapter 21 Terms & Concepts

Front 1

taxonomy

Back 1

science of describing, naming, and classifying living organisms

Front 2

systematics

Back 2

study of biological diversity and the evolutionary relationships among organisms

Front 3

extant

Back 3

species still alive

Front 4

extinct

Back 4

no species no longer alive

Front 5

taxonomic group

Back 5

hypotheses regarding evolutionary relationships from systematics

Front 6

taxon

Back 6

each group at any level

Front 7

domain

Back 7

the three domains that ALL life fall under: bacteria, archaea, and eukarya

Front 8

supergroup

Back 8

lies between a domain an kingdom

Front 9

the seven supergroups

Back 9

excavata

land plants and relatives

alveoloata

stramenopila

rhizaria

amoebozoa

opisthokonta (fungi and animalia)

Front 10

the taxonomic hierarchy

Back 10

1. domain

2. supergroup

3. kingdom

4. phylum

5. class

6. order

7. family

8. genus

9. species

Front 11

binomial nomenclature

Back 11

how species are named

genus and species name used, genus is capitalized and species lowercase

Front 12

phylogeny

Back 12

the evolutionary history of a species or a group of species, using systematics

based on morphological or genetic data

always a hypothesis

Front 13

phylogenetic tree

Back 13

hypothesis of evolutionary relationships

Front 14

cladogenesis

Back 14

a species that diverges into 2 or more species

Front 15

clade

Back 15

all species that derive from a common ancestor

Front 16

anagensis

Back 16

one species evolve into a different species

Front 17

extinct and extant species on a phylogenetic tree

Back 17

extinct are at the bottom and middle while extant are always on top

Front 18

monophyletic

Back 18

a group that contains a common ancestor and ALL of its descendants (a clade)

Front 19

paraphyletic group

Back 19

a group that contains a common ancestor but doesn't have all of its descendants

Front 20

polyphyletic group

Back 20

groups species with different common ancestors but may be classified together because they have a similar characteristic that developed convergently

Front 21

what group to taxonomists usually recognize and classify?

Back 21

monophyletic groups

Front 22

systematics based on homolgy

Back 22

similarities song species occur because they are derived from a common ancestor; can be morphological, developmental, or genetic

Front 23

what did the first studies of systematics focus primarily on?

Back 23

morphological features; but this was troublesome because of convergent evolution due to some species not being related at all but having similar characters

Front 24

molecular systematics

Back 24

studies genetic homologies and propose phylogenetic trees

looks at DNA and amino acid sequences

Front 25

reversal

Back 25

when a DNA section is deleted in a species but them reinserted later on in an evolutionary descendent; the character state has been regained

Front 26

cladistics

Back 26

compares homologous traits which exist in two or more states

based on evolutionary relationships

chooses the least complex explanation

Front 27

cladogram

Back 27

a diagram based off cladistics, is the least complex of all the options based on evolutionary relationships

can also be constructed using gene sequences

change in gene = modification in character

Front 28

characters

Back 28

features of a species

Front 29

branch point

Back 29

where two species will differ in shared derived characters

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shared primitive character

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inherited from ancestors older than last common ancestor

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shared derived character

Back 31

originated in most recent common ancestor

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ingroup

Back 32

the group whose evolutionary relationships are being evaluated

Front 33

outgroup

Back 33

a species or group that is assumed to have diverged before the species of the ingroup so they are not being analyzed

Front 34

how to construct a cladogram

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1. determine polarity of character states between primitive and derived

2. group taxa by shared derived characters and they should only appear once unless convergent evolution occurred

3. choose the most likely, simplest option

Front 35

principle of parsimony

Back 35

the preferred hypothesis of a cladogram is the one that is the simplest for all the characters and their states

Front 36

molecular clocks

Back 36

nucleotide differences used to estimate time since divergence

more time since divergence = greater accumulation of mutations

Front 37

linearity of a molecular clock

Back 37

not very linear, due to difference in generation times and variation in mutation rates

Front 38

rapidly evolving genes

Back 38

are useful for studying closely related species

Front 39

slowly evolving genes

Back 39

are useful for studying evolution over long periods

Front 40

vertical evolution

Back 40

hanges in groups due to descent from common ancestor

Front 41

neutral theory of evolution

Back 41

proposes that most genetic variation that exists in populations is due to the accumulation of neutral mutations that are not acted upon by natural selection

Front 42

horizontal gene transfer

Back 42

an organism incorporates genetic material from another organism without begin the offspring of the organism

common in prokaryotes (bacteria and archaea gave rise to chloroplasts and mitochondria)