PKA 4

What describes a way for defining species?

A species concept

Two major reasons have been proposed to explain why organisms assemble into different species: 1. Speciation may occur due to abrupt genetic events, which can cause reproductive isolation, or 2. Speciation may arise as a consequence of what?

Adaptation to different ecological niches.

The phenomenon that causes a single ancestral species to evolve into a wide array of descendant species with diverse habitats, forms, or behaviors that occurs often as a result of colonization of a new area is known as ___________ radiation.

Adaptive

Several species of Caribbean Anoline lizards have evolved from a single ancestral species. The species occupy a wide variety of ecological niches, such as tree trunks and the ground, or tree trunks only, or tree trunks and the crown of trees, etc. This type of allopatric speciation is called what?

Adaptive Radiation

When allopatric speciation occurs as a result of a population moving to a new location that is geographically isolated, it can result in the evolution of a variety of new species in the new location in a process called what?

Adaptive Radiation

Speciation that occurs as a result of physical separation of members of a species is known as __________ speciation.

Allopatric

The emergence of a mountain range, fragmentation of a forest, glaciation, and movement of a small number of individuals to a new location during a storm are all examples of circumstances that could lead to ___________ speciation.

Allopatric

__________ speciation results when a population becomes geographically isolated from other populations.

Allopatric

A physical separation of members of populations that causes speciation is known as what?

Allopatric speciation

As shown in the diagram, an ancestral fish population was split into two by the formation of the Isthmus of Panama about 3.5 mya. Due to environmental differences between two sides and natural selection, genetic changes occurred in the two populations. These changes eventually led to the formation of different species. This is an example of what?

Allopatric speciation

Speciation that occurs when populations are physically separated from one another is _________ speciation, whereas ___________ speciation occurs when populations co-occur.

Allopatric; Sympatric

What is Hybrid Inviability?

An egg cell is successfully fertilized by the sperm of a different species, but the resulting zygote fails to develop past the early embryonic stages.

What is Hybrid Breakdown?

An interspecies hybrid is able to produce gametes and reproduce with other hybrids, but subsequent generations harbor detrimental genetic abnormalities.

What is Hybrid Sterility?

An interspecies hybrid zygote develops to maturity, but it is incapable of producing viable gametes.

The different song patterns used by Darwin's finches on the Galapagos Islands are an example of what?

Behavioral Isolation

The __________ species concept defines a species as a group of individuals that is able to interbreed, producing viable and fertile offspring.

Biological

What are examples of Sympatric Speciation?

Divergence of apple maggot flies into separate subspecies depending on whether they prefer apple or hawthorn as host plants Reproductive isolation of Galeopsis tetrahit because it is an allopolyploid as a result of a hybridization event Aggregation of cichlids into distinct populations based on female choice of male coloration

What are examples of circumstances that could potentially lead to allopatric speciation?

Emergence of a mountain range due to plate tectonics A small segment of a large mainland population reaches an isolated island. Movement of a small population to a new location by a storm Fragmentation of a large forest by human development

Adaptive radiation occurs when organisms do what?

Exploit a variety of new environments

True or false: Macroevolution and microevolution proceed independently of one another.

False

True or false: Populations must be completely geographically isolated in order for allopatric speciation to occur.

False

True or false: Reproductive isolating mechanisms occur because members of populations intentionally want to maintain themselves as separate species.

False

What is Gametic Isolation?

Gametes are exchanged, but the egg is not successfully fertilized to produce a zygote.

Speciation most commonly occurs when?

Genetic changes in a particular group deviate from its parent population.

_________ isolation serves as a prezygotic isolating mechanism by preventing members of two species from ever coming into contact with one another because of differences in their habitats.

Habitat

An area where two somewhat isolated populations are able to interbreed is known as what?

Hybrid Zone

How does temporal isolation prevent successful interbreeding among members of different species?

Individuals of different species breed at different times of the day or year, preventing the exchange of gametes.

Evolutionary changes that create new species, impacting the diversity of organisms over long periods of time through the evolution and extinction of many species, best describes which process?

Macroevolution

How does the biological species concept define a species?

Members of a species are able to interbreed in nature and are reproductively isolated from members of other species.

What is Behavioral Isolation?

Members of different species differ in their mating rituals.

What is Geographic Isolation?

Members of two different species never come into contact with one another because they live in different places.

Macroevolution is the product of the accumulation of ______________ changes that occur in single genes.

Microevolutionary

Sympatric speciation can be caused by __________, a genetic change that causes an organism to have more than two sets of chromosomes.

Polyploidy

What statements are TRUE regarding the conditions necessary for allopatric speciation?

Populations cannot be sympatric (living in the same location). Interbreeding among populations must be eliminated or greatly limited.Sympatric speciation can be caused by ______, a genetic change that causes an organism to have more than two sets of chromosomes.

__________ isolating mechanisms prevent the formation of a zygote, whereas ___________ isolating mechanisms come into play after the zygote is formed.

Prezygotic; Postzygotic

The diverse array of honeycreeper birds that are found on the Hawaiian archipelago are the result of the arrival of a single ancestral species and subsequent adaptive ___________.

Radiation

Jeffrey Podos analyzed the songs of Darwin's finches on the Galápagos Islands and concluded that larger beak size, which is an adaptation to cracking open large, hard seeds, constrains vocal performance. This may affect mating song patterns and thereby promote what?The different song patterns used by Darwin's finches on the Galapagos Islands are an example of:

Reproductive Isolation

The formation of new species is a phenomenon known as what?

Speciation

A _______ concept provides an approach for distinguishing one species from another.

Species

A group of related organisms that share a distinct set of attributes, are genetically related, and share an evolutionary history are called a what?

Species

Macroevolution refers to evolutionary changes that create new what?

Species

What is Temporal Isolation?

Species reproduce at different times of the day or year.

What is Mechanical Isolation?

Structural differences between species prevent mating.

Divergence of populations of apple maggots and pea aphids based on their preferred host plant, populations of cichlids based on female choice of male coloration, and immediate reproductive isolation of Galeopsis tetrahit (hemp nettle) because of allopolyploidy are all examples of events leading to __________ speciation.

Sympatric

What is TRUE regarding the relative frequencies of allopatric and sympatric speciation?

Sympatric speciation is thought to be much LESS common than allopatric speciation.

Beetle pollinators of a particular plant are attracted to its flowers' bright orange color. The beetles not only pollinate the flowers, but they mate while inside of the flowers. A mutant version of the plant with red flowers becomes more common with the passage of time. A particular variant of the beetle prefers the red flowers to the orange flowers. Over time, these two beetle variants diverge from each other to such an extent that interbreeding is no longer possible. What kind of speciation has occurred in this example, and what has driven it?

Sympatric speciation, adaptation to local environment

_________ isolation is a prezygotic mechanism that prevents an interspecies hybrid zygote from forming because breeding for two different species occurs at different times of the day or year.

Temporal

What are examples of Adaptive Radiation?

The evolution of 54 different species of honeycreeper from the European rosefinch after arrival in Hawaii 1,000 different species of Drosophila (fruit fly) inhabiting Hawaii in different ecological niches

The difference between allopatric and sympatric speciation depends on whether what?

The populations undergoing speciation live in the same geographic area

What is TRUE regarding relatedness of members of the same species?

They are MORE genetically similar to one another than they are to members of a different species.

Why do reproductive isolating mechanisms occur?

They are by-product of genetic divergence. As population adapts to environment, its unique traits may prevent interbreeding with other species.