Chapter 24: Speciation

In regard to allopatric speciation what is vicariance?

The division of a large population into two sister species due to the development of new geographic barriers

What is allopatric speciation?

The formation of new species in populations that are geographically isolated from one another

In regard to allopatric speciation what is colonization (dispersal)?

The movement of a few members of a species to a new geographical area, resulting in differentiation of the original group into new varieties or species

True or False? The Biological Species Concept (BSC) is most applicable for this course.

True

Evaluate this statement: Gene flow increases the genetic divergence of populations. a) This statement is true. b) This statement is false. Gene flow reduces the divergence of populations. c) This statement is false. Gene flow is not able to influence the genetic divergence of populations. d) This statement is false. Gene flow increases the number of genes in populations.

b) This statement is false. Gene flow reduces the divergence of populations.

What are some external events that would lead to sympatric speciation?

1. Female mate choice 2. Environmental errors

What are the two things speciation results from?

1. Genetic isolation 2. Genetic divergence

What are the two types of reproductive isolation?

1. Prezygotic 2. Postzygotic

What are some limitations of the BSC?

1. Reproductive isolation cannot be studied in fossils or species that reproduce asexually 2. The concept is difficult to apply to closely related populations that do not overlap geographically 3. Reproductive isolation can sometimes be a complex gradient rather than an all or nothing scenario (e.g. prizzly bears)

What are some internal events that would lead to sympatric speciation?

1. Some type of nondisjunction in mitosis or meiosis 2. Autopolyploid - an individual that has more than two chromosome sets that are all derived from a single species (reproduction via self-fertilization) 3. Allopolyploid - a species with multiple sets of chromosomes derived from different species

How does the BSC define a species?

A population or group of individuals who have the potential to interbreed in nature that must produce viable and fertile offspring and they must not produce viable fertile offspring with other such groups

How is a species defined?

An evolutionarily independent population or group of populations

What is the phylogenetic species concept (PSC)?

Identifies species based on the evolutionary history of populations - concept that we all are related by common ancestry - one big tree of life

What is postzygotic isolation?

Hybrid offspring of mating's between members of different species either do not survive or do not reproduce

What is genetic isolation?

Some barrier to gene flow isolates two populations within a species

What is prezygotic isolation?

Prevents individuals of different species from mating successfully

What is the morphological species concept (MSC)?

Researchers identify evolutionary independent lineages by differences in size, shape, or other morphological features - distinguishing features are most likely to arise if populations are isolated from gene flow and independent

What is the Biological Species Concept (BSC)?

The biological species concept attributes the main criterion for identifying species to reproductive isolation - no gene flow between populations that are reproductively isolated - reproductive isolation offers clear evidence of evolutionary independence

What is niche partitioning?

The process by which natural selection drives competing species into different patterns of resource use or different niches so both species are able to exist

What is sympatric speciation?

The process through which new species evolve from a single ancestral species while inhabiting the same geographic region

What is the major flaw of the MSC and the PSC?

They have degrees of subjectiveness for determining species

What is the ecological species concept (ESC)?

Two or more species cannot inhabit the same niche - only one organism can exist in each niche - based on the idea of niche partitioning

What is genetic divergence?

When mutation, natural selection, and genetic drift occur in each of the isolated populations which begin to evolve independently of one another

What is reproductive isolation?

When the members of two populations cannot interbreed and produce fertile offspring

What distinguishes a morphospecies? a) It has distinctive characteristics, such as size, shape, or coloration. b) It is a fossil from a distinct time in Earth's history. c) It is reproductively isolated from other species. d) It represents a distinct branch in a phylogeny of populations.

a) It has distinctive characteristics, such as size, shape, or coloration.

If asked to join a science panel to speak to Congress, could you explain how this fragmentation process could lead to extinction? Select the three correct statements. a) Species can dwindle to extinction due to inbreeding. b) Species can dwindle to extinction due to catastrophes. c) Species can dwindle to extinction due to loss of genetic variation. d) Species can dwindle to extinction because people can eliminate them. e) Species can dwindle to extinction because the amount of a group wouldn't be enough to survive.

a) Species can dwindle to extinction due to inbreeding. b) Species can dwindle to extinction due to catastrophes. c) Species can dwindle to extinction due to loss of genetic variation.

Which species concept would be most useful to a team of biology students conducting a biodiversity survey on their campus? a) The morphospecies concept b) The biological species concept c) All species concepts would be equally useful. d) The phylogenetic species concept

a) The morphospecies concept The most common method for distinguishing species is on the basis of their appearance

Why are Northeast Pacific populations of transient and resident killer whales thought to represent different ecotypes rather than different species? a) Transient killer whales prey on marine mammals, while resident killer whales prey on Chinook salmon. b) Transient and resident killer whales differ in feeding culture but can mate and produce viable offspring in captivity. c) Transient and resident killer whales have different patterns of communication. d) Transient and resident killer whales learn specific methods of hunting from older whales in their pods.

b) Transient and resident killer whales differ in feeding culture but can mate and produce viable offspring in captivity.

Which of the following groups could be identified using the biological species concept? a) bacteria living today b) sunflower species living today c) extinct dinosaurs d) lizard species living today

b) sunflower species living today d) lizard species living today

The common edible frog of Europe is a hybrid between two species, Rana lessonae and Rana ridibunda. The hybrids were first described in 1758 and have a wide distribution, from France across central Europe to Russia. Both male and female hybrids exist, but when the hybrids mate with other hybrids or with adults of either species, they are rarely successful in producing offspring. What can you infer from this information? a) The hybrids form a separate species under the biological species concept. b) Prezygotic isolation exists between the two frog species. c) Postzygotic isolation exists between the two frog species. d) These two species are likely in the process of fusing back into one species.

c) Postzygotic isolation exists between the two frog species.

Which description of reinforcement is correct? a) Reinforcement is the loss of genetic differences between two populations due to gene flow. b) Reinforcement is the genetic divergence of populations in different environments. c) Reinforcement is due to natural selection against interbreeding and production of hybrid offspring. d) Reinforcement leads to development of a hybrid zone.

c) Reinforcement is due to natural selection against interbreeding and production of hybrid offspring.

Which of the following describes the most likely order of events in allopatric speciation? a) divergence, genetic isolation, and genetic drift b) genetic isolation, divergence, and genetic drift c) genetic isolation, genetic drift, and divergence d) genetic drift, genetic isolation, and divergence e) divergence, genetic drift, and genetic isolation

c) genetic isolation, genetic drift, and divergence

Which statement is correct? a) A monophyletic group may include an ancestral population and some, but not all, of its descendants. b) A monophyletic group consists of all of the descendants of an ancestral population. c) A monophyletic group is a theoretical idea that does not exist in the real world. d) A monophyletic group consists of an ancestral population, all of its descendants, and only those descendants.

d) A monophyletic group consists of an ancestral population, all of its descendants, and only those descendants.

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent? a) gametic isolation b) temporal isolation c) habitat isolation d) behavioral isolation

d) behavioral isolation

A researcher notices that in a certain moth species, some females prefer to feed and lay eggs on domesticated solanaceous plants like potatoes and tomatoes. Other females prefer to feed and lay eggs on wild solanaceous plants such as Datura. Both male and female moths primarily use scent to find these plants from afar. Females tend to mate where they feed, and the researcher finds a genetic basis for scent preference in these moths. Based on the above information, what might be occurring in this moth species? a) divergence due to habitat fragmentation b) postzygotic isolation c) polyploidization d) divergence in sympatry

d) divergence in sympatry