Speciation

Question 1

How do we generally define species?

Answer 1

group similar things together,

Question 2

What are some problems with defining species?

Answer 2

we need to identify species in a way that reflects evolutionary history, variety of different definitions

Question 3

What are the different species concepts?

Answer 3

morphological, ecological, phylogenetic, and biological

Question 4

How does the morphological species concept define species?

Answer 4

using similar physical (morphological) features, look similar to members of the species and different from others,

Question 5

Why do some biologists disagree with the morphological species concept?

Answer 5

sometimes members of the same species look different (humans), convergent evolution can be misleading, the weight of characters or traits

Question 6

How does the biological species concept define species?

Answer 6

members of the same species can interbreed with one another and produce viable offspring (healthy and fertile)

Question 7

What is the most commonly used species concept among biologists?

Answer 7

biological

Question 8

When is the biological species concept not applicable?

Answer 8

extinct species, asexual organisms, organisms with alternative modes of reproduction, hybrids

Question 9

How does the ecological species concept define species?

Answer 9

a species is a group of organisms that are all adapted to a particular type of resources, called a niche

because selection favours certain phenotypes in a niche

Question 10

What is the challenge in the ecological species concept?

Answer 10

identifying the niche

Question 11

How does the phylogenetic species concept define species?

Answer 11

estimate the phylogeny of populations and then identifies the smaller monophyletic groups (most similar DNA)

species have a shared and unique evolutionary history

Question 12

What is an advantage and a challenge for the phylogenetic species concept?

Answer 12

can be applied to any type of organism

because slight differences are found among every group of organisms it can divide them up into to many groups

Question 13

What are some reproductive isolating barriers?

Answer 13

pre-zygotic (makes mating hard) and post-zygotic (zygote doesn’t survive)

Question 14

What are some pre-zygotic isolating mechanisms?

Answer 14

ecological isolation, temporal isolation, behavioural isolation, mechanical isolation, gametic isolation

Question 15

What is ecological isolation?

Answer 15

when two species have different habitats and don’t interact and therefore can’t mate

Question 16

What is temporal isolation?

Answer 16

when two species that live in the same ecological range have different times when they sexually mature/breeding seasons

Question 17

What is behavioural isolation?

Answer 17

different species don’t mate because they have different mating calls, chemical cues, sexual displays, etc

Question 18

What is mechanical isolation?

Answer 18

when two species have a physical difference that makes it hard to mate (size, incorrect flower shape for pollination)

Question 19

What is gametic isolation?

Answer 19

when the sperm and egg of different species have incompatible plasma membrane receptors and cannot make a zygote

Question 20

What are some post-zygotic isolating mechanisms?

Answer 20

hybrid inviability, hybrid sterility, hybrid breakdown

Question 21

What is hybrid inviability?

Answer 21

mating between two individuals creates a hybrid that does not survive past the embryonic stages

Question 22

What is hybrid sterility?

Answer 22

species are closely related enough to produce viable hybrids, but the hybrids are sterile (infertile)

Question 23

What is hybrid breakdown?

Answer 23

two species can make a hybrid that is viable and fertile, but the successive generations decrease in viability and fertility

Question 24

What is speciation?

Answer 24

when a new species is created

Question 25

What is allopatric speciation?

Answer 25

when a new species is created through geographic isolation

Question 26

What is sympatric speciation?

Answer 26

when a new species develops in the same geographic area

Question 27

If a flood seperates two populations, what process would this be?

Answer 27

allopatric speciation

Question 28

Dog breeders isolate the different dog breeds when they are fertile, what isolation is this the most similar to?

Answer 28

ecological isolation

Question 29

What is the most likely order of events in allopatric speciation?

Answer 29

genetic isolation then genetic drift then divergence

Question 30

If two lizard species don’t mate because of differing mating rituals what type of isolation is occuring?

Answer 30

behavioural isolation

Question 31

A mule is an example of what posyzyogtic barrier?

Answer 31

hybrid sterility

Question 32

Local variants of species that interbreed where their distributions overlap are called what?

Answer 32

subspecies

Question 33

When does vicariance occur?

Answer 33

when a population is fragmented into isolated subpopulations

Question 34

How can sympatric speciation occur?

Answer 34

instantaneously through formation of polyploid offspring, disruptive selection

Question 35

What can result in allopatric speciation?

Answer 35

dispersal and vicariance

Question 36

What are some pathways that lead to polyploidy?

Answer 36

autopolyploidy and allopolyploidy

Question 37

What is autopolyploidy?

Answer 37

when an individual has a complete extra set of chromosomes that is derived from a single parental species (usually by self-fertilization)

Question 38

What is allopolyploidy?

Answer 38

occurs when an individual has multiple sets of chromosome sets derived from different species

Question 39

Why do plants speciate from polyploidy more than animals?

Answer 39

the reproductive cells in plants are not seperated early in development, some can self-fertilize, hybridization is more common

Question 40

What is a hybrid zone?

Answer 40

An area where two populations may breed and produce viable, fertile offspring