Biological and Phylogenetic Species Concepts in Speciation(Week 3 Slides)

What defines a species according to the Biological Species Concept (BSC)?

Members of the same species must be reproductively compatible and produce fertile offspring.

What is a key limitation of the Biological Species Concept?

It does not apply to asexual species, extinct species, or requires extensive study of reproduction.

What does the Morphospecies Concept state about species?

Members of the same species usually look alike, but this can be misleading.

What is the basis of the Ecological Species Concept (ESC)?

It is based on the idea that there is a one-to-one correspondence between a species and its ecological role or niche.

Which species concept is most useful for determining if two insect populations that can interbreed but occupy different ecological niches should be considered separate species?

Ecological Species Concept.

What does the Phylogenetic Species Concept (PSC) emphasize?

All members of a species have descended from a common ancestor and share a common fate.

What type of reproductive isolation occurs before fertilization?

Pre-zygotic reproductive isolation.

What are the five types of pre-zygotic reproductive isolating mechanisms?

1. Geographical/Ecological isolation, 2. Temporal isolation, 3. Behavioral isolation, 4. Gametic isolation, 5. Mechanical isolation.

What are the two types of post-zygotic reproductive isolating mechanisms?

1. Hybrid inviability, 2. Hybrid sterility.

What is an example of temporal isolation?

American Toad breeds in early summer while Fowler's Toad breeds in late summer.

What is allopatric speciation?

Speciation that occurs when populations become physically separated.

What are the two ways populations can become allopatric?

1. Dispersal, where individuals colonize a new area; 2. Vicariance, where a geographic barrier arises.

What is sympatric speciation?

Speciation that occurs without physical separation of populations.

How can hybridization lead to speciation?

Hybrids can have different chromosome numbers, leading to reproductive isolation from parent species.

What is the significance of genetic drift in speciation?

Speciation can occur with or without natural selection, and genetic drift can drive divergence.

What is the role of natural selection in speciation?

Natural selection does not always lead to speciation; it can occur through genetic drift.

What is an example of allopatric speciation by vicariance?

The separation of antelope ground squirrels by the formation of the Grand Canyon.

What is the importance of recognizing a species' specific call before mating?

It serves as a pre-zygotic isolating mechanism.

What is hybrid inviability?

A condition where a zygote fails to develop after fertilization.

What is hybrid sterility?

A condition where offspring are produced but are sterile.

What is an example of behavioral isolation?

Individuals only mate with others based on specific behaviors.

What is the challenge of identifying species using the Morphospecies Concept?

Superficially similar species may have significant genetic differences.

What is the significance of reproductive isolation in the Biological Species Concept?

Populations must be reproductively isolated to be considered separate species.

What does the term 'dispersal' refer to in the context of allopatric speciation?

The process where individuals colonize a new area, leading to population separation.

What is the role of disruptive selection in sympatric speciation?

It can drive reproductive isolation in the absence of physical separation.

Which species concept is most appropriate for determining whether two fossil forms represent different species?

Morphospecies Concept.