Evolution - Module 1: Evidence for Evolution

BYS-464 Final Study Set - Module 1

What is evolution?

The change in inherited traits (or allele frequencies) of a population across successive generations due to processes that create and filter variation.

What is microevolution?

Small-scale evolutionary change within a population, occurring over short time spans. It includes natural selection, mutation, gene flow, and genetic drift.

What is macroevolution?

Large-scale evolutionary patterns and processes occurring over long periods, including speciation, extinction, and the appearance of novel body forms.

What is speciation?

The evolutionary process by which populations diverge genetically to the point that they can no longer interbreed, forming new species.

What is a vestigial trait?

A reduced or functionless structure that is homologous to a functioning trait in a related species. Can be structural or developmental.

What is a transitional form?

A fossil or species with traits intermediate between major groups, demonstrating evolutionary transitions (e.g., Tiktaalik).

What is homology?

Similarity between species due to shared ancestry; can be structural, molecular, or developmental.

What is analogy?

Similar traits that evolved independently in different lineages due to similar selective pressures, not shared ancestry.

What is a pseudogene?

A nonfunctional gene formed when mRNA is reverse-transcribed and inserted into the genome; accumulates mutations over time and indicates common ancestry.

What is "descent with modification"?

The idea that species change over time, give rise to new species, and share common ancestors.

What are Darwin's five predictions of evolution?

1) Species change through time; 2) Lineages split and diverge; 3) New forms arise from earlier forms; 4) All species share common ancestry; 5) Earth and life are old.

Example of microevolution: soapberry bugs

Soapberry bugs evolved different beak lengths to feed on invasive balloon vines.

Example of microevolution: Darwin's finches

Darwin's finches changed beak size in response to shifts in seed availability during droughts.

How does selective breeding support microevolution?

It demonstrates that heritable traits respond to selection, causing rapid evolutionary change in controlled environments.

What is the law of succession?

Fossil species in a region resemble the present-day species in that region, showing continuity and gradual change over time.

Examples of succession pairs

Glyptodonts → armadillos; Diprotodon → wombats.

Why is Tiktaalik important?

It has both fish traits (gills, fins, scales) and tetrapod traits (limb bones, ribs, mobile neck), confirming predicted transitional features.

What is the speciation continuum?

The set of intermediate stages between fully interbreeding populations and fully separate species, often visible in natural populations.

Example of sympatric speciation

Midas cichlid fish in Nicaraguan crater lakes.

What do phylogenetic trees represent?

Hypotheses of evolutionary relationships showing how species are connected through common ancestry.

Why are homologous traits evidence of common ancestry?

Closely related species share more homologous traits because they inherited them from a recent common ancestor.

What pattern do homologies form across species?

A nested hierarchy: groups within groups based on shared derived traits.

Why do pseudogenes support common ancestry?

Shared pseudogenes with identical mutations indicate inheritance from the same ancestor, not independent evolution.

Why is evolution important for biomedical research?

Many pathways and structures are homologous across species, allowing scientists to study human diseases using model organisms.

How does evolution help explain drug responses and psychiatric conditions?

Conserved molecular pathways and neural mechanisms across species reveal shared biological origins.