Bio TEST 1, Evolution, Evidence, and Speciation: Key Concepts for Biology

Evolution

Descent with modification. When the genetic composition of a population changes from generation to generation. When organisms accumulate difference from their ancestors as they adapt to different environments over time.

Natural Selection

The overall process by which individuals with certain heritable traits survive and reproduce at higher rates because of those traits.

Selective pressure

A specific environmental factor that causes certain traits to be favored over others, leading to changes in the frequency of those traits.

Direct Observations of Evolution

When we have directly observed evolutionary change in a species in a scientific study.

Homology

When differing species have characteristics with underlying similarities resulting from a common ancestor.

Homologous structures

When anatomical structures in species represent variations on a structural theme that was present in their common ancestor.

Vestigial Structures

Remnants of features that served a function in the organism's ancestors.

Convergent Evolution

When similar features evolve independently in different lineages.

Fossil Evidence

The fossil record documents the pattern of evolution, showing how organisms have changed, gone extinct, and become more complex.

Biogeography

The scientific study of the geographical distributions of species. If lineage branching coincides with continental separation, this provides evidence for evolution.

Species (Biological)

A group of populations whose members can interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such groups.

Reproductive Isolation

The existence of biological factors which prevent members of two species from interbreeding in nature and producing viable, fertile, offspring.

Prezygotic barriers

Barriers that contribute to reproductive isolation by preventing fertilization from occurring. These include habitat, temporal, behavioral, mechanical, and gametic barriers.

Postzygotic barriers

Barriers that contribute to reproductive isolation after fertilization, leading to hybrid inviability or hybrid sterility.

Allopatric Speciation

When speciation is caused by geographic barriers preventing gene flow between populations.

Sympatric Speciation

When speciation occurs in populations that live in the geographic area. Causes could include polyploidy, sexual selection, and habitat differentiation.

Hybrid Zone

A region where members of different species meet and mate, producing offspring of mixed ancenstry.

What is evolution?

The process of descent by modification where organisms face selective pressures that favor certain traits, leading to higher survival and reproduction rates.

What are homologous structures?

Similarities in structure among different organisms that provide evidence of common descent.

What is direct observation in the context of evolution?

Hands-on observations, such as the development of penicillin resistance in bacteria due to natural selection.

How does molecular biology provide evidence for evolution?

By studying DNA sequences, similarities among different organisms can be identified.

What role do fossils play in demonstrating evolution?

Fossils help illustrate the evolution of species over time and provide a timeline for how species have developed.

What is biogeography?

The study of the distribution of species across continents, which can reveal similarities among species in different geographic locations.

What defines a species?

A species is an organism that can reproduce and breed with others of the same type.

What is allopatric speciation?

Speciation that occurs when a geographic barrier prevents interbreeding and sharing of a gene pool.

What is sympatric speciation?

Speciation that occurs in the same area but involves isolation due to prezygotic or postzygotic barriers.

What are prezygotic barriers?

Barriers that prevent fertilization from occurring before a zygote is formed, such as temporal, habitat, mechanical, and gametic isolation.

What are postzygotic barriers?

Barriers that occur after fertilization, such as the inability of offspring to reproduce.

What is peripatric speciation?

A form of allopatric speciation where one group is smaller than the other.

What is parapatric speciation?

Speciation that occurs when a species is spread over a large area, leading to mating primarily with nearby individuals.

Polyploidy

Extra sets of chromosomes, can also occur when two different species interbreed and produce hybrid offspring

Autopolyploid

An individual that has more than two chromosome sets that are all derived from a single species

Allopolyploid

When various mechanisms can change a sterile hybrid into a fertile