Unit 1:part 2 (lesson 5+)

Question 1

speciation

Answer 1

the process by which one species splits into two or more species

• responsible for the diversity of life
• explains differences and similarities between species

Question 2

microevolution

Answer 2

changes over time in allele frequencies in a population

Question 3

macroevolution

Answer 3

broad pattern of evolution above the species level

Question 4

biological species concept

Answer 4

says that a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring-but do not produce such offspring with other species

Question 5

reproductive isolation

Answer 5

the existence of biological factors that impede members of two species from interbreeding and producing viable, fertile offspring

• block gene flow between species
• limit hybrids
• types: prezygotic and postzygotic

Question 6

hybrids

Answer 6

offspring that results from the mating of two individuals from different species

Question 7

prezygotic barriers

Answer 7

block fertilization from occurring

types: habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation

Question 8

postzygotic barriers

Answer 8

prevent a hybrid zygote from developing into viable, fertile adult
types: reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

Question 9

habitat isolation

Answer 9

• prezygotic barrier

- two species that occupy different habitats in the same area may encounter each other rarely

Question 10

temporal isolation

Answer 10

• prezygotic barrier

- species breed at different times of day, different seasons, or different years

Question 11

behavioral isolation

Answer 11

• prezygotic barrier

- courtship rituals that attract mates and other behaviors unique to a species may cause isolation

Question 12

mechanical isolation

Answer 12

• prezygotic barrier

- mating is attempted but morphological differences prevent its successful completion

Question 13

gametic isolation

Answer 13

• prezygotic barrier

- sperm of one species may not be able to fertilize the eggs of another species

Question 14

reduced hybrid viability

Answer 14

• postzygotic barrier
• genes of different parent species may interact in ways that impair the hybrid’s development or survival in its environment.

Question 15

reduced hybrid fertility

Answer 15

• postzygotic barrier

- hybrids are sterile

Question 16

hybrid breakdown

Answer 16

-postzygotic barrier

some first generation hybrids are viable and fertile but their offspring are feeble and sterile.

Question 17

limitations of the biological species concept

Answer 17

• can be applied only to a limited number of species
  - does not apply to organisms that reproduce asexually
• cannot evaluate fossils
• some species are morphologically and ecologically distinct but have gene flow

Question 18

morphological species concept

Answer 18

characterizes a species by body shape and structural features
-distinguishes most species but can be subjective

Question 19

ecological species concept

Answer 19

views species in terms of its ecological niche; the sum of how members interact with nonliving and living parts of their environment

Question 20

phylogenetic species concept

Answer 20

defines a species as the smallest groups of individuals that share a common ancestor, forming one branch of the tree of life
-compares separate species

Question 21

allopatric (other country) speciation

Answer 21

gene flow is interrupted when a population is divided into geographically isolated sub- populations
-once separation has occurred, different mutations arise and natural selection and genetic drift may alter allele frequencies

Question 22

Evidence for allopatric speciation

Answer 22

• regions that are isolated or heavily subdivided typically have more species
• reproductive isolation between two populations generally increases as the distance between them increases

Question 23

Sympatric (Same Country) Speciation

Answer 23

• speciation that occurs in populations that live in the same geographic area
• can result from polyploidy, habitat differentiation, or sexual selection

Question 24

polyploidy

Answer 24

an accident during cell division that results in an extra set of chromosomes;
may allow a new species to originate
-most common in plants
-can result from non-disjunction

Question 25

autopolyploid

Answer 25

an individual that has more than two chromosomes sets that are all derived from a single species

Question 26

allopolyploid

Answer 26

has 2 or more chromosome sets as a result of 2 different species interbreeding -can mate with each other but not parent species

Question 27

habitat differentiation

Answer 27

genetic factors enable a sub-population to exploit a habitat or resource not used by the parent population

Question 28

non-disjunction

Answer 28

when homologous chromosomes do not separate during meiosis, sex cell will contain too few or too many chromosomes

Question 29

hybrid zone

Answer 29

a region in which members of different species meet and mate, producing at least some offspring of mixed ancestry -form when 2 species lacking complete barriers to reproduction come into contact

Question 30

reinforcement

Answer 30

strengthening of reproductive barriers | -can occur when hybrids are less fit than parent species

Question 31

fusion

Answer 31

weakening reproductive barriers -much gene flow occurs between two species, gene pools become increasingly alike and eventually fuse into a single species

Question 32

Stability

Answer 32

continued formation of hybrid individuals - sometimes hybrids are fitter - sometimes hybrids are at disadvantage but a small hybrid zone with migration might occur

Question 33

punctuated equilibria

Answer 33

In the fossil record, long periods of apparent stasis in which species undergo little or no morphological change interrupted by relatively brief periods of rapid speciation

Question 34

Speciation Rates

Answer 34

- experiments and observations suggests that once the process of speciation begins, it can be completed rapidly - on average, millions of years may pass before a newly formed species will give rise to another species

Question 35

plate tectonics

Answer 35

continents are part of great plates on Earth's crusts that essentially float on the mantle -plates move over time

Question 36

Consequences of Continental Drift

Answer 36

- alters habitats in which organisms live - causes climate changes as continents shift location: organisms adapt, move, or become extinct - promotes allopatric speciation (continents break apart) - helps explain geographic distribution of extinct organisms.

Question 37

Pangaea

Answer 37

supercontinent formed about 250 million years ago - destroyed shallow water habitats, interior cold and dry - caused extinction, new opportunities for surviving species

Question 38

Mass Extinction

Answer 38

time in which large numbers of species became extinct

Question 39

Permian Mass Extinction

Answer 39

- between paleozoic and mesozoic eras - claimed 96% of marine species and many insect species - enormous volcanic eruptions in Serbia 251 million years ago - warmed atmosphere, oxygen levels dropped

Question 40

Cretaceous mass extinction

Answer 40

- between Mesozoic and Cenozoic eras - about 65.5. million years ago - 50% of marine species and many terrestrial plants and animals extinguished - hypothesized to have been caused by an asteroid striking the earth

Question 41

Consequences of Mass Extinctions-

Answer 41

- reduces diversity of life - changes types of organisms found in ecological communities - can end lineages with highly advantageous features - paves way for adaptive radiations

Question 42

Adaptive Radiations

Answer 42

periods of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities - often occur after mass extinctions - organisms increase in diversity as they play new roles in the environment - organisms that arise can serve as new food source

Question 43

taxonomy

Answer 43

the scientific discipline of naming and classifying organisms

Question 44

binomial nomenclature

Answer 44

names organisms using two part name | -genus name+ specific epithet

Question 45

Hierarchical Classification

Answer 45

``` Domain Kingdom Phyla Class Order Family Genus Species ```

Question 46

phylogenetic tree

Answer 46

a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms 1. Intended to show pattern of descent, not phenotypic similarity 2. Sequence of branching in a tree does not necessarily indicate the actual age of a species 3. Do not assume that a taxon evolved from a taxon next to it

Question 47

PhyloCode

Answer 47

a system of classification that only names groups that include a common ancestor and all of its descendents

Question 48

rooted

Answer 48

describes a phylogenetic tree that has a branch point that represents the most recent common ancestor of all taxa

Question 49

polytomy

Answer 49

a branch point from which more than 2 descendent groups emerge -signifies evolutionary relationships among taxa not yet clear

Question 50

homoplasies

Answer 50

analogous structures that arose independently

Question 51

molecular systematics

Answer 51

the discipline that uses data from DNA and other molecules to determine evolutionary relationships

Question 52

cladistics

Answer 52

an approach to systematics that uses common ancestry as the primary criterion to classify organisms

Question 53

clades

Answer 53

groups that include an ancestral species and all of its descendents

Question 54

monophyletic

Answer 54

a group that consists of an ancestral species and all of its descendants

Question 55

paraphyletic

Answer 55

consists of ancestral species and some of its descendents

Question 56

polyphyletic

Answer 56

includes new taxa with different ancestors

Question 57

shared ancestral characters

Answer 57

a character that originated in an ancestor of the taxon

Question 58

shared derived characters

Answer 58

an evolutionary novelty unique to a clade

Question 59

outgroup

Answer 59

a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the group we are studying

Question 60

maximum parsimony

Answer 60

the principle that systematists should first investigate the simplest explanation that is consistent with all of the facts - requires fewest evolutionary events, or fewest DNA base changes

Question 61

maximum likelihood

Answer 61

given certain probability rules about how DNA sequences change over time, a tree can be found that reflects the most likely sequence of evolutionary events