Exam #2, Speciation

Question 1

Define Species

Answer 1

Species are groups of organisms that share genetic and morphological attributes

Question 2

Define Reproductive Isolation

Answer 2

a state in which two groups can no longer exchange genes

Question 3

True or False: are Species Reproductive Isolated from other groups?

Answer 3

True

Question 4

What is the base unit of taxonomic classification?

Answer 4

Species is the base unit of taxonomic classification.

Question 5

Define Speciation

Answer 5

the process of splitting one population into two populations that are reproductively isolated from one another

Question 6

Species are a result of ___

Answer 6

speciation

Question 7

why do biologists think about species differently

Answer 7

Biologists think about species differently because they ask different questions, which are known as species concepts

Question 8

Define Morphological species concept

Answer 8

Is a construct that assumes that a species comprises individuals that “look-alike” and that those that do not look alike belong to different species

Question 9

Who developed the concept of Morphological Species and the system of binomial nomenclature

Answer 9

Carl Linnaeus

Question 10

In the Morphological species concept, there are Limitations. Define what the term Limitations mean.

Answer 10

Members of the same species do not always look alike

Question 11

In limitations that can be Cryptic Species. Define cryptic Species.

Answer 11

Cryptic species are instances in which two or more species are morphologically indistinguishable but do not interbreed. For example, Hyla versicolor and the Hylya Chrysoscelis.

Question 12

Define: Biological Species Concept

Answer 12

Definition of a species as a group of “actually” or “potentially” interbreeding natural populations that are reproductively isolated from other such groups.

Question 13

Explain what the term “actually” means in the definition of the biological species concept

Answer 13

“actually” implies that the individuals live in the same area and interbreed with one another

Question 14

Explain what the term “potentially” means in the definition of the biological species concept

Answer 14

“Potentially” implies that the individuals do not live in the same area, therefore, do not interbreed, but other information suggests that they would if they were together

Question 15

Does the biological species concept apply to asexually reproducing organisms?

Answer 15

No

Question 16

Define: Lineage Species Concept

Answer 16

Definition of a species as a branch on the tree of life, which has a history that starts at a speciation event and ends either at extinction or at another speciation event

Question 17

Define: lineage

Answer 17

A lineage is a series of populations, species, or genes descended from a single ancestor over evolutionary time

Question 18

Is lineage splitting a gradual or quick process?

Answer 18

Lineage splitting is a gradual process that can take up to thousands of generations to complete.

Question 19

True or False: speciation does not require the interruption of gene flow within a species whose members formerly exchanged genes

Answer 19

False, speciation does require the interruption of gene flow within a species whose members formerly exchanged genes.

Question 20

What is the cause of reproductive isolation in speciation?

Answer 20

Incompatibilities between genes

Question 21

Name the model that describes how reproductive isolation between two physical isolated populations can develop through the accumulation of incompatible genes or chromosomal arrangements

Answer 21

Dobzhansky-Muller Model

Question 22

Explain two events that might occur through the Dobzhansky-Muller Model

Answer 22

1. some combinations of these differentiated genes or chromosomes will not function well together in hybrids
2. genetic incompatibility will develop over time

Question 23

note 1

Question 24

note 2

Question 25

note 3

Question 26

Splitting of the ______ ______ of a species is one way of achieving reproductive isolation

Answer 26

geographic range

Question 27

When does Allopatric Speciation occur?

Answer 27

Allopatric speciation occurs when a physical barrier separates populations

Question 28

What is the dominant mode of speciation in most groups?

Answer 28

Allopatric Speciation

Question 29

We know that in Allopatric Speciation, populations are separated by a physical barrier. Explain how they are physically divided.

Answer 29

A barrier that divides may be a body of water or a mountain range for terrestrial organisms or dry land for aquatic organisms. Moreover, these can form as continents drift, sea level changes, glacier advance and retreat, and climate change.

Question 30

True or False: In Allopatric speciation, the environments in which the isolated populations live are different and, so the populations evolve differently.

Answer 30

True

Question 31

_____ ______ can occur if some individuals cross a barrier to form a new, isolated population

Answer 31

Allopatric Speciation

Question 32

The __ species of finches on the Galapagos (___ ___) arose from a ___ species that colonized the islands from ___ ____

Answer 32

14; Darwins Finches; single; South America

Question 33

Explain why Allopatric Speciation occurred with Darwins finches

Answer 33

The islands have different environments, and are sufficiently far apart for speciation to occur

Question 34

The effectiveness of physical barriers depends on....

Answer 34

the size and mobility of the organisms

Question 35

Does Sympatric Speciation occur with or without physical barriers

Answer 35

without

Question 36

list the two common forms of sympatric speciation

Answer 36

1. Disruptive Selection 2.) Polyploidy

Question 37

Define Disruptive Selection

Answer 37

Disruptive Selection is when individuals with certain genotypes have a preference for distinct microhabitats where mating takes place

Question 38

Define: Polyploidy

Answer 38

the duplication of sets of chromosomes within individuals

Question 39

Polyploidy can arise from two factors. List them.

Answer 39

1.) autopolyploidy 2.) allopolyploidy

Question 40

Define Autopolyploidy

Answer 40

Autopolyploidy occurs from chromosome duplication in a single species

Question 41

Define Allopolyploidy

Answer 41

Allopolyploidy is the combining of the chromosomes of two different species

Question 42

Polyploidy can result in complete reproductive isolation in ___ generations

Answer 42

two

Question 43

What process is an exception to the general rule that speciation is a gradual process

Answer 43

Polyploidy

Question 44

______ is likely to occur when reproductive isolation is incomplete, and these species come back into contact

Answer 44

Hybridization

Question 45

Mechanisms of reproductive incompatibility fall into two categories. Name them.

Answer 45

1.) Prezygotic (before fertilization) isolating mechanisms 2.) Postzygotic isolating mechanisms

Question 46

Define Prezygotic Isolating Mechanisms and the 5 types of isolation mechanisms that can occur

Answer 46

prevent hybridization from occurring 1.) mechanical 2.) Temporal 3.) Behavioral 4.) Habitat 5.) gametic

Question 47

Define: Postzygotic Isolating Mechanisms and the 3 types of isolating mechanisms that can occur

Answer 47

Reduce the fitness of hybrid offspring. 1.) Low hybrid zygote viability 2.) Loy hybrid adult viability 3.) Hybrid infertility

Question 48

Define: Mechanical Isolation

Answer 48

Differences in the size and shape of reproductive organs may prevent the union of gametes from different species.

Question 49

True or False: Reproduction between individuals with mismatched reproductive structures is not physically possible

Answer 49

True

Question 50

Give an example of a Mechanical Isolation

Answer 50

two different species of snails' shells may spiral in opposites directions, thus the genital openings due not align and no mating can occur

Question 51

Define: Temporal Isolation

Answer 51

When mating periods do not overlap

Question 52

When does temporal isolation occur

Answer 52

Many organism have distinct mating seasons and if two closely related species breed at different times of the year (or different times of day), they may never have an opportunity to hybridize

Question 53

Give an example of temporal isolation

Answer 53

breeding seasons of three species of leopard frogs overlap when they are physically separated but do not overlap when they live together

Question 54

Define: Behavioral Isolation

Answer 54

individuals may reject, or tail to recognize, individuals of other species as potential mates

Question 55

Given an example of behavioral isolation

Answer 55

- mating calls of male frogs of related species diverge quickly - Mate choice of one species may be mediated by the behavior of other species 1. Example: pollinators determine pollination

Question 56

Define: Habitat Isolation

Answer 56

when two closely related species evolve preferences for living or mating in different habitats - May never physically come into contact

Question 57

Define: Gametic Isolation

Answer 57

eggs of one species do not have appropriate chemical signals for sperm of another species; or sperm is not able to attach to and penetrate the egg - No zygote formation

Question 58

True or False:Genetic differences that accumulate between two diverging lineages may reduce the survival and reproductive rates of hybrid offspring

Answer 58

True

Question 59

Define Low Hybrid zygote viability

Answer 59

failure of zygotes to mature or develop severe abnormalities

Question 60

Define: Low hybrid adult viability

Answer 60

hybrid offspring may have lower survival rates

Question 61

Define: Hybrid Infertility

Answer 61

hybrids may mature into infertile adults 1. Example: mules produce no descendants

Question 62

Speciation rates are ___ variable across life

Answer 62

highly

Question 63

Speciation rates are influenced by _____ and _______ _______

Answer 63

ecological, behavioral factors

Question 64

Speciation rates are higher in what kind of populations?

Answer 64

Rates are higher in populations of species with specialized diets. For example Herbivory leads to increased speciation

Question 65

Are speciation rates higher in animal-pollinated or wind-pollinated plants?

Answer 65

Speciation rates are higher in animal-pollinated

Question 66

Are speciation rates higher in sexual or asexual selection

Answer 66

sexual selection

Question 67

Define Sexual dimorphic

Answer 67

when male and females of the same species look different) - increase speciation rates

Question 68

Define Polygynous

Answer 68

one male mating with many different females - increase speciation rates

Question 69

True or False: Rapid speciation leads to evolutionary radiation

Answer 69

True

Question 70

Define: evolutionary radiation

Answer 70

is the proliferation of a large number of species from a single ancestor

Question 71

When does evolutionary radiation occur?

Answer 71

Occurs when species colonize new areas that contain no other closely related species

Question 72

define adaptive radiation

Answer 72

If the resulting species from an evolutionary radiation live in a wide array of environments, it is called an adaptive radiation

Question 73

Given and example of a adaptive radiation

Answer 73

Example: Hawaiian silverswords; the plants shown here are more closely related than they appear to be based on their morphology