A4.1 Evolution and speciation

What is the definition of evolution?

Evolution is the change in the heritable characteristics of a population over time.

What are heritable characteristics?

Traits inherited by offspring from parents.

What is the mechanism of evolution?

Natural selection.

What is another name for evolution by natural selection?

Darwinism.

What are acquired characteristics?

Characteristics that change during an organism's lifetime due to environmental influences.

Give an example of acquired characteristics in trees.

Trees can develop an asymmetric form if exposed to wind.

Why are acquired characteristics not inherited?

No mechanism exists for the environment to cause specific adaptive changes to gene base sequences.

Who was the main proponent of inheritance of acquired characteristics?

Jean-Baptiste Lamarck.

What was the leading theory of evolution before Darwin's publication in 1859?

Lamarckism, based on the inheritance of acquired characteristics.

How can we detect evolution in terms of genetics?

By observing changes in the base sequence of DNA or RNA and in the amino acid sequences of proteins.

What evidence of evolution was observed in the coronavirus that caused the COVID-19 pandemic?

Base sequence changes in its genes led to new variants that spread more successfully.

How does comparing gene base sequences provide evidence for evolution?

Closely related species have fewer differences in their base sequences.

What do similarities in Hox genes across diverse animal groups suggest?

Common ancestry.

What is the function of Hox genes?

They help determine the body plan during development.

What is artificial selection?

The process of humans selectively breeding organisms for desired traits.

What does artificial selection demonstrate about evolution?

It shows that significant evolutionary changes can occur over relatively short periods.

What is an example of artificial selection in animals?

Breeding of egg-laying hens from junglefowl.

What is an example of artificial selection in plants?

Selective breeding of wheat for human consumption.

What did Darwin call similarities in the structure of vertebrate limbs?

Unity of type.

What is a pentadactyl limb?

A limb with five digits (fingers or toes).

Why are pentadactyl limbs considered homologous structures?

They have a similar anatomical position and structure despite different functions.

What is an example of homologous structures in vertebrates?

The forelimbs of humans, bats, and porpoises.

What are vestigial organs?

Reduced structures that no longer serve a function.

Give an example of a vestigial organ in whales.

The small pelvis and thigh bones found in their body walls.

What is convergent evolution?

The process by which unrelated organisms evolve similar traits due to similar environmental pressures.

What are analogous structures?

Structures that are similar in function but have different evolutionary origins.

Give an example of analogous structures.

The wings of birds and insects.

What is speciation?

The formation of a new species by splitting from an existing species.

What are the two key processes required for speciation?

Reproductive isolation of populations and differential selection.

What is a gene pool?

The set of genes in a population.

What is geographical isolation in speciation?

Separation of populations by physical barriers, preventing interbreeding.

What is allopatric speciation?

Speciation that occurs due to geographical separation.

What is sympatric speciation?

Speciation that occurs within the same geographical area.

What does "adaptive radiation" mean?

A pattern of diversification where species from a common ancestor occupy a range of ecological roles.

What is an ecological niche?

A role or position a species has in its environment.

What are interspecific hybrids?

Hybrids produced by cross-breeding members of different species.

Why are interspecific hybrids often sterile?

Chromosomal mismatches prevent successful meiosis.

What is an example of an interspecific hybrid?

A mule (horse × donkey).

What is polyploidy?

A condition where an organism has more than two sets of homologous chromosomes.

What is an autotetraploid?

An organism with four sets of chromosomes from the same species.

What is an allotetraploid?

An organism with four sets of chromosomes from two different species.

How can polyploidy contribute to speciation?

It can lead to the formation of a new species with distinct traits.

What is the difference between homologous and analogous structures?

Homologous structures share common ancestry; analogous structures do not.

What evidence supports that evolution has occurred?

Fossil records, genetic similarities, and observed natural selection events.

How does artificial selection demonstrate evolution?

It shows that selective breeding can cause rapid changes in traits

What does differential selection mean?

Differences in selection pressures cause populations to evolve differently.

What is the role of courtship behavior in preventing hybridization?

It helps individuals identify potential mates of the same species.

What is the significance of vestigial organs in evolution?

They provide evidence of changes in function and adaptation over time.

What causes adaptive radiation?

Access to unexploited ecological niches.

What is the result of natural selection acting differently on two populations?

The populations diverge and may form separate species.

What is reproductive isolation?

The prevention of gene flow between populations.

How does geographical separation lead to speciation?

It isolates populations, preventing interbreeding and mixing of genes.

What are the main factors causing differential selection?

Climate, predation, and competition.

What is an example of speciation due to geographical isolation?

The lava lizards of the Galápagos archipelago.

What is hybrid vigor?

The phenomenon where hybrids show superior traits compared to their parents.

What is the main challenge for meiosis in polyploid organisms?

Mis-pairing of homologous chromosomes.

What is the role of genome duplication in polyploidy?

It allows the formation of new species with distinct traits.

What are cladograms?

Diagrams that show evolutionary relationships between species.

What does sympatric mean?

Same homeland.

What does allopatric mean?

Different homelands.

What is the biological species concept?

A species is a group of organisms that can interbreed and produce fertile offspring.

What causes speciation to reverse?

Mixing of alleles between populations due to migration or human activities.

What is the evolutionary explanation for homologous structures?

They were inherited from a common ancestor.

What is the evolutionary explanation for analogous structures?

They evolved independently due to similar environmental pressures.

What happens if hybrids are fertile and interbreed with parent species?

Speciation may reverse, leading to allele mixing.

Why is sympatric speciation less common than allopatric speciation?

It requires reproductive isolation within the same geographical area.

What is a founder population?

A group of individuals that migrate to a new area and establish a population.

What is an example of convergent evolution?

The similar tails of fish and whales.

What is hybrid swarm?

A population with mixed traits from two species due to hybridization.

Why is hybridization a threat to biodiversity?

It can lead to the extinction of native species.

What is adaptive radiation's role in minimizing competition?

It allows species to exploit different ecological niches.

What is the role of climate in differential selection?

It creates varying selection pressures across regions.

Why are polyploid organisms often considered separate species?

They cannot interbreed with their diploid parent species.

What is a common use of artificial hybridization in agriculture?

To produce new plant varieties with desired traits.

What happens when allotetraploids are formed?

A new species arises with traits from both parent species.

What is the relationship between adaptive radiation and biodiversity?

Adaptive radiation contributes to biodiversity by diversifying species roles.

Why are species-specific courtship behaviors important?

They prevent mating between different species, avoiding sterile hybrids.

How do ecological niches reduce competition among species?

They allow species to specialize in different resources or roles.

What is the significance of homologous structures in evolutionary biology?

They suggest common ancestry and adaptive modification.

How does natural selection drive adaptation?

It favors traits that improve survival and reproduction in a given environment.