Speciation and Macroevolution

What is an adaptation?

A trait that helps an organism survive and reproduce.

What causes adaptations?

Natural selection.

What is speciation?

The formation of new species.

Why do species become different from their ancestors?

They adapt to different environments over time.

What is a species?

A group of organisms that can interbreed and produce offspring.

What is the Biological Species Concept?

Species are groups that can interbreed and are reproductively isolated from others.

What is the Morphological Species Concept?

Species are defined by physical appearance.

What is the Ecological Species Concept?

Species are defined by their ecological role.

What is the Phylogenetic Species Concept?

Species share a common evolutionary history.

What is reproductive isolation?

When populations can no longer interbreed.

Why is reproductive isolation important?

It allows speciation to occur.

What is gene flow?

The movement of genes between populations.

What happens when gene flow stops?

Populations can diverge and form new species.

What is genetic divergence?

The buildup of genetic differences between populations.

What is ecological isolation?

Species breed in different habitats or at different times.

What is behavioral isolation?

Different mating behaviors prevent breeding.

What is mechanical isolation?

Physical differences prevent mating.

What is gamete isolation?

Sperm and egg cannot successfully combine.

What is postzygotic isolation?

Barriers that occur after fertilization.

What are three types of postzygotic isolation?

Inviability, infertility, and hybrid breakdown.

Why is a mule sterile?

It is a hybrid affected by postzygotic isolation.

What is allopatric speciation?

Speciation caused by geographic isolation.

Why are islands common sites of allopatric speciation?

Populations become geographically separated.

What is sympatric speciation?

Speciation without geographic separation.

What is polyploidy?

Having extra sets of chromosomes.

How can polyploidy cause speciation?

It can instantly create a new plant species.

What are homologous traits?

Similar traits due to common ancestry.

What are vestigial traits?

Leftover structures from ancestors that no longer serve a major function.

What is an example of a vestigial structure in humans?

The tailbone.

What are analogous traits?

Similar traits that evolved independently

What causes analogous traits?

Convergent evolution.

What is convergent evolution?

Different species evolving similar traits because of similar environments.

What is adaptive radiation?

Rapid formation of many new species from one ancestor.

When does adaptive radiation often occur?

When competition is low or new habitats become available.

What is background extinction?

The normal, low rate of extinction.

What is a mass extinction?

A rapid loss of many species.

What is macroevolution?

Large-scale evolutionary change over long periods.

What are the main types of evidence for evolution?

Fossils, morphology, embryology, DNA, direct observation, and biogeography.

How does the fossil record support evolution?

It shows organisms changing over time.

How does comparative morphology support evolution?

Related organisms share similar structures.

How does comparative embryology support evolution?

Related species have similar embryos.

How does DNA support evolution?

Closely related species share more DNA.

What is artificial selection?

Human-directed evolution.

What is biogeography?

The study of species distributions around the world.

What are homeotic genes?

Genes that control the activity of many other genes.

Why are homeotic genes important?

Small changes in them can cause large physical changes.

Who developed the modern classification system?

Carolus Linnaeus.

What is taxonomy?

The science of classifying organisms.

What are the levels of classification from largest to smallest?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

What is a phylogenetic tree?

A diagram showing evolutionary relationships.

Why are homologous traits important in phylogenetic trees?

They show common ancestry.

Why can analogous traits be misleading?

They result from convergent evolution, not shared ancestry.