biology unit 8

Descent with modification

Passing of genetic traits to offspring across generations; with ancestor and diversity

Artificial selection

Intentionally breeding animals/plants for specific traits leading to genetic changes in those species over generations

Sexual selection

Form of natural selection, individuals with specific traits are more successful at obtaining mates+reproduction

Fossil record

In rock layers, showing fossils with oldest at the bottom

Fossil

Preserved remains of once living organisms

transitional species

An organism with intermediate traits, gap between ancestors and descendants

Homology

Similarities resulting from common ancestry

Structural/anatomical homologies

Physical features shared by different species deriving by a common ancestral

Molecular homologies

Similarities in DNA due to common ancestors

embryonic homolgies

Similarities in the embryos among different species that come from common ancestors

Vestigial structures

Remnants of features that served important functions in the organism’s ancestors

Sources of variation

Genetic (inherited), environmental (non/inherited), combined

Heritable vs non heritable traits

heritable: genetic dna from parent to offspring (eye color, blood type)

non heritable: acquired through organism lifetime by environment (skills, behaviors)

Adaptation

Heritable trait that improves organism chance of survival and reproduction in environments

Darwin’s observations from his voyage

1. tortoise and finches vary by island, adapt to local foods

2. Discovered fossils (connections between extinct + modern species)

Natural selection

Process where organisms better adapted to environment tended to survived + produce more

Conditions of natural selection

Variation, inheritance, survival/reproduction differential, adaptation to environment

takeaways natural selection

1. Populations evolve, individuals do not

2. NS can amplify or diminish genetic traits

3. No goal, doesn’t lead to perfect adaptation