Chp 24 Origin of Species/Macroevolution

These flashcards cover key concepts from the lecture notes on biological diversity, focusing on the origin of species and mechanisms of speciation.

What are the various definitions of species and their limitations?

Species can be defined by morphological traits, ability to interbreed, phylogenetic relationships, and ecological characteristics, but these definitions can be limited and may not apply to all organisms.

Why is reproductive isolation necessary for divergence in populations?

Reproductive isolation prevents interbreeding between different populations, allowing them to evolve independently and potentially form new species.

What are the eight mechanisms of reproductive isolation?

The eight mechanisms include habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation, reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

How can sympatric speciation occur?

Sympatric speciation can occur through habitat differentiation, polyploidy, and sexual selection, without geographic barriers.

What is allopatric speciation?

Allopatric speciation is the most common way new species arise, occurring when some members of a species become geographically separated.

Define speciation.

Speciation is the evolutionary process by which new biological species arise.

Define reproductive isolation.

Reproductive isolation is the set of mechanisms preventing different species from interbreeding and producing viable offspring.

What is the biological species concept?

The biological species concept defines a species as a group of organisms that can interbreed and produce viable, fertile offspring.

What is polyploidy?

Polyploidy is a condition in which an organism has more than two complete sets of chromosomes, often leading to speciation in plants.

What is an example of a prezygotic barrier?

Behavioral isolation, where unique courtship rituals prevent different species from mating.

What happens during hybrid inviability?

In hybrid inviability, fertilized eggs do not develop past the early embryo stage.

What is hybrid sterility?

Hybrid sterility occurs when interspecies hybrids are viable but sterile, such as mules derived from a horse and a donkey.

What is adaptive radiation?

Adaptive radiation is the process by which a single ancestral species evolves into a variety of forms to adapt to different environments.

What is the role of gene flow in speciation?

Gene flow between populations must be interrupted for speciation to occur, allowing populations to diverge genetically.

What are postzygotic barriers?

Postzygotic barriers occur after fertilization and include reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

What is meant by hybrid breakdown?

Hybrid breakdown occurs when hybrids are viable and fertile, but their offspring have decreased viability or fertility.

What is the significance of the fossil record in determining species?

The fossil record can provide information on the morphological traits of extinct species, helping to define them based on phylogenetic relationships.

How does ecological characteristics distinguish species?

Species might be distinguished based on their ecological characteristics, such as responses to environmental factors like antibiotics or food sources.

What factors contribute to microevolution?

Microevolutionary processes include natural selection, genetic drift, non-random mating, and migration.

What is the relationship between microevolution and macroevolution?

Microevolution and macroevolution are connected; macroevolution involves cumulative changes in population genetics that lead to new species over time.