A4.1 Evolution and Speciation IB Bio- Evolution

Evolution

A change in the heritable characteristics of a population over time.

Lamarckism

The idea that acquired traits can be passed down to offspring, which is not supported by genetics.

Darwin's Theory of Evolution

Variation exists within a population; nature selects individuals with traits best adapted to survival and reproduction.

Evidence for Evolution

Includes DNA, RNA, and protein sequences showing common ancestry and gradual mutations over time.

Homologous Structures

Structures that are similar in form but have different functions, indicating a common ancestor.

Selective Breeding

Humans choose plants or animals with desirable traits to reproduce offspring with those traits.

Convergent Evolution

The evolution of similar structures in unrelated species due to adaptation to similar environments.

Analogous Structures

Structures that serve a common function but do not share a common structure, resulting from convergent evolution.

Speciation

The formation of a new species through evolution leading to reproductive isolation.

Extinction

The complete loss of a species, resulting in no living members remaining.

Pre-zygotic Isolation

Reproductive isolation that occurs before fertilization.

Post-zygotic Isolation

Reproductive isolation that occurs after fertilization.

Geographical Isolation

Reproductive isolation due to physical barriers like rivers or mountains.

Sympatric Speciation

The formation of new species while inhabiting the same geographic area due to behavioral or temporal isolation.

Behavioral Isolation

Reproductive isolation due to different mating behaviors.

Temporal Isolation

Organisms reproduce at different times, preventing mating.

Allopatric Speciation

The physical separation of populations leading to speciation.

Adaptive Radiation

The evolution of a single ancestral species into several species adapted to different niches.

Hybrids

Offspring resulting from the mating of two different species, often sterile.

Prezygotic Barriers

Barriers that prevent fertilization of eggs and sperm.

Post-zygotic Barriers

Factors preventing hybrid offspring from developing into viable, fertile adults.

Polyploidy

Organisms with more than two sets of chromosomes; can lead to immediate speciation.

Diploid

Organisms that have two sets of chromosomes.

Triploid

Organisms with three sets of chromosomes, often sterile due to uneven chromosome pairing.

Tetraploid

Organisms with four sets of chromosomes, capable of reproducing sexually.