ap bio chapter 22: Concept 22.1: The biological species concept emphasizes reproductive isolation

What does the word "species" mean in Latin?

“Kind” or “appearance.”

What do biologists compare when grouping organisms into species?

Morphology, physiology, biochemistry, and DNA sequences.

What does the biological species concept define a species as?

A group of populations that can interbreed and produce viable, fertile offspring.

What must offspring be for organisms to be considered the same species?

Viable (can survive) and fertile (can reproduce).

What holds a species together genetically?

Gene flow between populations.

Can similar-looking species be different biological species?

Yes, if they do not interbreed due to behavioral or other differences.

Can members of the same species have high diversity?

Yes, like in humans—large variation, but all can interbreed.

What is reproductive isolation?

Biological barriers that prevent two species from producing viable, fertile offspring.

What is a hybrid?

Offspring from crosses between different species.

What are the two major types of reproductive barriers?

Prezygotic (before fertilization) and postzygotic (after fertilization).

What are prezygotic barriers?

Barriers that prevent fertilization from occurring.

List the five types of prezygotic barriers.

Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, gametic isolation.

What is habitat isolation?

Species live in different habitats and rarely meet.

What is temporal isolation?

Species breed at different times (day, season, year).

What is behavioral isolation?

Unique mating behaviors prevent mating between species.

What is mechanical isolation?

Mating is physically impossible due to incompatible structures.

What is gametic isolation?

Sperm cannot fertilize the egg of another species.

What are postzygotic barriers?

Barriers that occur after fertilization, affecting hybrid viability or fertility.

What are the three types of postzygotic barriers?

Reduced hybrid viability, reduced hybrid fertility, hybrid breakdown.

What is reduced hybrid viability?

The hybrid doesn’t survive or develop properly.

What is reduced hybrid fertility?

The hybrid is sterile and cannot reproduce.

What is hybrid breakdown?

First-generation hybrids are fertile, but later generations are weak or sterile.

Can the biological species concept be used for fossils or asexual organisms?

No.

What is one limitation regarding gene flow?

Gene flow can occur between distinct species (e.g., grizzly and polar bears → grolar bear).

What does the morphological species concept define a species by?

Structural features like shape and appearance.

What is a downside of the morphological species concept?

It's subjective—scientists might disagree on what features matter.

What does the ecological species concept focus on?

The ecological niche and how a species interacts with its environment.

What does the phylogenetic species concept define a species as?

The smallest group that shares a common ancestor on a phylogenetic tree.

What is a challenge with the phylogenetic species concept?

It can be hard to decide how different two groups must be to be separate species.