Unit 2: Species and Speciation

Question 1

What is Species?

Answer 1

group of populations that interbreed and produce fertile offspring

Question 2

What is Speciation?

Answer 2

a splitting event that creates 2 or more distinct species from a single ancestral species

Question 3

What is Species Concept?

Answer 3

a set of criteria used to define and differentiate species

Question 4

What is Morphological Species Concept?

Answer 4

species defined based on differences in size, shape, or other morphological features

Question 5

What are the Pros & Cons of morphological species concept?

Answer 5

Pros:
- typically easy to measure traits
- can be applied to asexual and extinct species (fossils)
Cons:
- which traits, and how different do they need to be?
- species with different morphs (order of colors of birds)
- cryptic species ( 2 different species which look alike)

Question 6

What is Gene Flow?

Answer 6

transfer of alleles from one population to another; makes populations similar

Question 7

What is Reproductive Isolation?

Answer 7

behaviors or processes that prevent gene flow between populations; creates opportunity for divergence

Question 8

What is Biological Species Concept?

Answer 8

species defined based on reproductive isolation:
- species do not interbreed in nature, or if they do, the offspring is not viable/stable

Question 9

What are the Pros & Cons of biological species concept?

Answer 9

Pros:
- based on mechanism (reproductive isolation) low to lead to evolutionary divergence
Cons:
- can not be applied to asexual and extinct species
- what if populations are not sympatric?

Question 10

What is Phylogenetic Species Concept?

Answer 10

species defined based on analysis of a phylogeny

Question 11

What is Phylogeny (Phylogeny Tree)?

Answer 11

(evolutionary tree) representation of the evolutionary relationship among organisms

Question 12

What is criteria of the phylogeny tree?

Answer 12

species are the smallest possible sets of monophyletic groups on a phylogeny tree

Question 13

What is Monophyletic Group/Clade?

Answer 13

a group that consists of one ancestor and all its descendants

Question 14

Phylogenies are nest hierarchy of clades. True of False?

Answer 14

True

Question 15

What are the steps of prating Phylogenies?

Answer 15

1. gather data from multiple population and samples
2. use data to construct phylogeny
3. analyze for monophyletic groups

Question 16

What are the Pros & Cons of phylogenic species concept?

Answer 16

Pros:
- can be applied to asexual and extinct species
- can be used to analyze allopatric populations
Cons:
- production of phylogenies limited by samples
- different data sets may produce different phylogenies

Question 17

What is Allopatry?

Answer 17

(occurring in different geographically areas) is an effective way to hinder gene flow between populations

Question 18

Without gene flow, there is opportunity for populations to _____ and become reproductively isolated.

Answer 18

diverge

Question 19

What is Allopatric Speciation?

Answer 19

speciation that occurs via geographically separation; most common mode of speciation

Question 20

What are 2 routes to allopatry?

Answer 20

1. dispersal to a new habitat
2. vicariance

Question 21

With dispersal, the likelihood of speciation is ______ correlated with connectively between patches

Answer 21

negatively, high connectivity = low chance of speciation

Question 22

What is Vicariance?

Answer 22

the physical splitting of a population into smaller, isolated populations by a physical barrier

Question 23

With vicariance, the likelihood of speciation is _____ correlated with the strength of the barrier.

Answer 23

positively

Question 24

What is Reproductive Isolation?

Answer 24

situation that occurs when a species is reproductively independent from other species

Question 25

What causes reproductive isolation?

Answer 25

- behavior - location - reproductive barriers

Question 26

Isolating mechanisms can be _______ (before zygote formation) or ________ (after zygote formation)

Answer 26

prezygotic, postzygotic

Question 27

What are the types of mechanism that prevent the formation of a zygote?

Answer 27

1. temporal 2. habitat 3. behavioral 4. mechanical 5. gametic

Question 28

What is Temporal Isolation?

Answer 28

differences in breeding schedules that can act as a form of pre zygotic barrier leading to reproductive isolation

Question 29

What is Habitat Isolation?

Answer 29

reproductive isolation resulting when species' populations move or are moved to a new habitat, taking up residence in a place that no longer overlaps with the same species' other populations; may never come into contact during mating periods = no hybridization

Question 30

What is Behavioral Isolation?

Answer 30

type of reproductive isolation that occurs when a specific behavior or lack of one prevents reproduction from taking place (e.g. sound frequencies in mating calls are unattractive)

Question 31

Does behavioral isolation extend to plants?

Answer 31

Yes, pollinators may favor different floral shapes or food (nectar)

Question 32

What is Mechanical Isolation?

Answer 32

differences in size and shape of reproductive organs, making mating impossible (e.g. genital lock & key)

Question 33

What is Gametic Isolation?

Answer 33

prezygotic barrier occurring when closely related individuals of different species mate, but differences in their gamete cells (eggs & sperm) prevent fertilization from happening

Question 34

What are types of mechanisms that prevent zygotes from passing on alleles?

Answer 34

1. Hybrid Inviability 2. Hybrid Biological Sterility 3. Hybrid Ecological Sterility

Question 35

What is Hybrid Inviability?

Answer 35

hybrids do not survive to sexual maturity, instead they die during development or soon after birth

Question 36

What is Hybrid Biological Sterility?

Answer 36

hybrids survive to maturity but do not produce gametes or are not fertile

Question 37

What is Hybrid Ecological Sterility?

Answer 37

hybrids survive to maturity are are fertile, but have an intermediate phenotype that keeps them from reproducing (e.g. don't attract mates or are not adapted to environment)

Question 38

How do these reproductive isolation mechanisms evolve?

Answer 38

allopatry (e.g. natural selection, genetic drift, and mutation)

Question 39

What are the 3 types of changes in hybrid zones?

Answer 39

1. reinforcement 2. fusion 3. stability

Question 40

What is Reinforcement?

Answer 40

continued speciation divergence between 2 species due to low fitness of hybrids between them

Question 41

What is Fusion?

Answer 41

reproductive barriers weaken until the 2 species become 1

Question 42

What is Stability?

Answer 42

fit hybrids continue to be produced

Question 43

What is a Hybrid Zone?

Answer 43

area where 2 closely related species continue to interact and reproduce, forming hybrids; relatively stable over long periods of time

Question 44

In a Hybrid Zone, exchange of alleles is limited and parental species remain distinct. True or False?

Answer 44

True

Question 45

Since producing hybrids decreased fitness, natural selection results in _____

Answer 45

reinforcement