Chapter 27 Evolution of Life

Evolution

Change in heritable traits of populations over generations.

Natural selection

Process where organisms with favorable traits survive/reproduce more successfully.

Adaptation

An inherited trait that helps an organism survive and reproduce in its environment

Descent with modification

The idea that modern species descended from ancestral species and changed over time

Artificial selection

Humans selectively breed organisms for desired traits.

Lamarck’s inheritance of acquired characteristics

The incorrect idea that traits acquired during an organism’s lifetime can be inherited.

Homologous structures

Similar structures inherited from a common ancestor.

Analogous structures

Similar-function structures that evolved independently and do not indicate close common ancestry

Vestigial structures

Reduced structures that have little or no current function.

Fossil

Remains, traces, or other evidence of past life.

Transitional fossil

Fossil showing characteristics of both ancestral and descendant groups.

Relative dating

Determines whether a fossil is older or younger than another fossil.

Absolute dating

Determines the actual approximate age of a fossil or rock.

Half-life

Time required for half of a radioactive isotope to decay.

Mass extinction

Event in which many species become extinct in a relatively short period

Gene pool

All the alleles present in a population.

Allele frequency

Proportion of a specific allele in a population.

Prokaryotyes arose

3.5billion years ago

Eukaryotes arose

2.1 billion years ago

Multicellularity arose

700million years ago