Speciation and Reproductive Isolation

These flashcards cover key concepts discussed in the lecture on speciation, reproductive barriers, and examples of mechanisms driving these processes.

What is the key behavior of the jewel wasp when it targets its victim?

The jewel wasp approaches its victim (a cockroach), stings its first thoracic ganglion causing paralysis, then stings the roach's brain to make it behave like a zombie.

What is a prezygotic barrier in speciation?

A barrier that prevents mating or fertilization between species before a zygote can form.

What type of reproductive barrier occurs when two species breed at different times of the year?

Temporal isolation, which is a prezygotic barrier.

What does reinforcement in speciation refer to?

The process where natural selection favors traits that prevent hybridization when two populations come into contact.

What is the significance of pollinator isolation in flowering plants?

Different flowers attract different pollinators, preventing cross-pollination between species and leading to reproductive isolation.

What is the difference between intrinsic and extrinsic postzygotic isolation?

Intrinsic postzygotic isolation involves genetic incompatibilities that affect hybrid fitness regardless of environment, while extrinsic postzygotic isolation involves environmental factors that affect hybrid success.

How can behavioral isolation occur in animal mating?

It can occur when individuals have differing mating signals or behaviors that prevent them from recognizing each other as potential mates.

What is ecological speciation?

A mechanism of speciation where reproductive isolation evolves due to divergent natural selection as populations adapt to different ecological niches.

What is an example of a postzygotic barrier to reproduction?

Reduced fertility in hybrids, such as mules produced from a horse and donkey.

What are magic traits in the context of speciation?

Traits under selection that are also involved in assortative mating, facilitating divergence and reproductive isolation.

What is the role of genetic drift in speciation?

Genetic drift can lead to the fixation of non-beneficial traits in isolated populations, potentially leading to reproductive isolation when populations come into contact.

Why is allopatric speciation considered to be a straightforward process?

Because geographic isolation minimizes gene flow, allowing populations to diverge and evolve reproductive barriers more easily.

What is the importance of geographical barriers in speciation?

Geographical barriers can lead to the formation of distinct species by preventing gene flow between populations.

What happens to species when they experience secondary contact after a period of isolation?

They may either merge into one species, maintain separate identities, or experience reinforcement if hybridization produces unfit offspring.

In what situations is it most likely for speciation to occur?

Speciation is most likely to occur when populations are geographically isolated, minimizing gene flow and allowing for the development of reproductive barriers.

What is the difference between sympatric and allopatric speciation?

Sympatric speciation occurs without geographic isolation, whereas allopatric speciation occurs with geographic isolation.

How did the Isthmus of Panama influence allopatric speciation in marine organisms?

It created a barrier that separated marine life in the Caribbean from those in the Pacific, leading to divergent evolution of species on either side.

What role do hybrid fitness and their environments play in postzygotic isolation?

Hybrid fitness can be affected by environmental factors, leading to extrinsic postzygotic isolation if hybrids are ill-suited to their habitats.

What is the key behavior of the jewel wasp when it targets its victim?

The jewel wasp approaches its victim (a cockroach), stings its first thoracic ganglion causing paralysis, then stings the roach's brain to make it behave like a zombie.

What is a prezygotic barrier in speciation?

A barrier that prevents mating or fertilization between species before a zygote can form.

What type of reproductive barrier occurs when two species breed at different times of the year?

Temporal isolation, which is a prezygotic barrier.

What does reinforcement in speciation refer to?

The process where natural selection favors traits that prevent hybridization when two populations come into contact.

What is the significance of pollinator isolation in flowering plants?

Different flowers attract different pollinators, preventing cross-pollination between species and leading to reproductive isolation.

What is the difference between intrinsic and extrinsic postzygotic isolation?

Intrinsic postzygotic isolation involves genetic incompatibilities that affect hybrid fitness regardless of environment, while extrinsic postzygotic isolation involves environmental factors that affect hybrid success.

How can behavioral isolation occur in animal mating?

It can occur when individuals have differing mating signals or behaviors that prevent them from recognizing each other as potential mates.

What is ecological speciation?

A mechanism of speciation where reproductive isolation evolves due to divergent natural selection as populations adapt to different ecological niches.

What is an example of a postzygotic barrier to reproduction?

Reduced fertility in hybrids, such as mules produced from a horse and donkey.

What are magic traits in the context of speciation?

Traits under selection that are also involved in assortative mating, facilitating divergence and reproductive isolation.

What is the role of genetic drift in speciation?

Genetic drift can lead to the fixation of non-beneficial traits in isolated populations, potentially leading to reproductive isolation when populations come into contact.

Why is allopatric speciation considered to be a straightforward process?

Because geographic isolation minimizes gene flow, allowing populations to diverge and evolve reproductive barriers more easily.

What is the importance of geographical barriers in speciation?

Geographical barriers can lead to the formation of distinct species by preventing gene flow between populations.

What happens to species when they experience secondary contact after a period of isolation?

They may either merge into one species, maintain separate identities, or experience reinforcement if hybridization produces unfit offspring.

In what situations is it most likely for speciation to occur?

Speciation is most likely to occur when populations are geographically isolated, minimizing gene flow and allowing for the development of reproductive barriers.

What is the difference between sympatric and allopatric speciation?

Sympatric speciation occurs without geographic isolation, whereas allopatric speciation occurs with geographic isolation.

How did the Isthmus of Panama influence allopatric speciation in marine organisms?

It created a barrier that separated marine life in the Caribbean from those in the Pacific, leading to divergent evolution of species on either side.

What role do hybrid fitness and their environments play in postzygotic isolation?

Hybrid fitness can be affected by environmental factors, leading to extrinsic postzygotic isolation if hybrids are ill-suited to their habitats.

What is speciation?

The evolutionary process by which new biological species arise from existing species.

What is habitat isolation?

A prezygotic barrier where two species that occupy different habitats within the same geographic area rarely encounter each other.

What is mechanical isolation?

A prezygotic barrier where mating is attempted, but morphological differences prevent its successful completion (e.g., incompatible reproductive structures).

What is gametic isolation?

A prezygotic barrier where the sperm of one species may not be able to fertilize the eggs of another species, or vice versa.

What is reduced hybrid viability?

A postzygotic barrier where the genes of different parent species interact and impair the hybrid's development or survival in its environment.

What is hybrid breakdown?

A postzygotic barrier where first-generation hybrids are fertile, but when they mate with one another or with either parent species, the next generation is feeble or sterile.

How can polyploidy lead to sympatric speciation?

Polyploidy, the presence of extra sets of chromosomes, can result in reproductive isolation in a single generation by preventing mating between polyploid and diploid individuals, commonly observed

What is the key behavior of the jewel wasp when it targets its victim?

The jewel wasp approaches its victim (a cockroach), stings its first thoracic ganglion causing paralysis, then stings the roach's brain to make it behave like a zombie.

What is a prezygotic barrier in speciation?

A barrier that prevents mating or fertilization between species before a zygote can form.

What type of reproductive barrier occurs when two species breed at different times of the year?

Temporal isolation, which is a prezygotic barrier.

What does reinforcement in speciation refer to?

The process where natural selection favors traits that prevent hybridization when two populations come into contact.

What is the significance of pollinator isolation in flowering plants?

Different flowers attract different pollinators, preventing cross-pollination between species and leading to reproductive isolation.

What is the difference between intrinsic and extrinsic postzygotic isolation?

Intrinsic postzygotic isolation involves genetic incompatibilities that affect hybrid fitness regardless of environment, while extrinsic postzygotic isolation involves environmental factors that affect hybrid success.

How can behavioral isolation occur in animal mating?

It can occur when individuals have differing mating signals or behaviors that prevent them from recognizing each other as potential mates.

What is ecological speciation?

A mechanism of speciation where reproductive isolation evolves due to divergent natural selection as populations adapt to different ecological niches.

What is an example of a postzygotic barrier to reproduction?

Reduced fertility in hybrids, such as mules produced from a horse and donkey.

What are magic traits in the context of speciation?

Traits under selection that are also involved in assortative mating, facilitating divergence and reproductive isolation.

What is the role of genetic drift in speciation?

Genetic drift can lead to the fixation of non-beneficial traits in isolated populations, potentially leading to reproductive isolation when populations come into contact.

Why is allopatric speciation considered to be a straightforward process?

Because geographic isolation minimizes gene flow, allowing populations to diverge and evolve reproductive barriers more easily.

What is the importance of geographical barriers in speciation?

Geographical barriers can lead to the formation of distinct species by preventing gene flow between populations.

What happens to species when they experience secondary contact after a period of isolation?

They may either merge into one species, maintain separate identities, or experience reinforcement if hybridization produces unfit offspring.

In what situations is it most likely for speciation to occur?

Speciation is most likely to occur when populations are geographically isolated, minimizing gene flow and allowing for the development of reproductive barriers.

What is the difference between sympatric and allopatric speciation?

Sympatric speciation occurs without geographic isolation, whereas allopatric speciation occurs with geographic isolation.

How did the Isthmus of Panama influence allopatric speciation in marine organisms?

It created a barrier that separated marine life in the Caribbean from those in the Pacific, leading to divergent evolution of species on either side.

What role do hybrid fitness and their environments play in postzygotic isolation?

Hybrid fitness can be affected by environmental factors, leading to extrinsic postzygotic isolation if hybrids are ill-suited to their habitats.

What is speciation?

The evolutionary process by which new biological species arise from existing species.

What is habitat isolation?

A prezygotic barrier where two species that occupy different habitats within the same geographic area rarely encounter each other.

What is mechanical isolation?

A prezygotic barrier where mating is attempted, but morphological differences prevent its successful completion (e.g., incompatible reproductive structures).

What is gametic isolation?

A prezygotic barrier where the sperm of one species may not be able to fertilize the eggs of another species, or vice versa.

What is reduced hybrid viability?

A postzygotic barrier where the genes of different parent species interact and impair the hybrid's development or survival in its environment.

What is hybrid breakdown?

A postzygotic barrier where first-generation hybrids are fertile, but when they mate with one another or with either parent species, the next generation is feeble or sterile.

How can polyploidy lead to sympatric speciation?

Polyploidy, the presence of extra sets of chromosomes, can result in reproductive isolation in a single generation by preventing mating between polyploid and diploid individuals, commonly observed

What is the biological species concept?

A species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not produce viable, fertile offspring with members of other such groups.

How does natural selection contribute to speciation?

Natural selection can drive speciation by favoring different traits in isolated populations adapting to distinct environments (divergent selection), or by reinforcing reproductive barriers against unfit hybrids.

Besides polyploidy, what is another mechanism that can lead to sympatric speciation?

Habitat differentiation, where a subpopulation exploits a habitat or resource not used by the parent population, leading to reproductive isolation.