evolution
descent with modification, proposing that Earth's many species are descendants of ancestral species that were very different from those alive today.
change in the genetic composition of a population over time.
pattern and a process
pattern
revealed in observations about the natural world.
process
consists of the mechanisms that have produced the diversity and unity of living things.
fossils
remains or traces of organisms from the past mineralized in sedimentary rocks
strata
layers of rock created when new layers of sediment cover older ones
Paleontology
the study of fossils, was largely developed by the French anatomist Georges Cuvier (1769-1832).
Jean-Baptiste de Lamarck (1744-1829)
explained his observations with two principles: use and disuse of parts and the inheritance of acquired characteristics.
Use and disuse
concept that body parts that are used extensively become larger and stronger, while those that are not used deteriorate.
inheritance of acquired characteristics
modifications acquired during the life of an organism can be passed on to offspring.
The voyage of the Beagle
The primary mission of the five-year voyage of the Beagle was to chart poorly known stretches of the South American coastline
Darwin noted that the plants and animals of South America were very different from those of Europe.
adaptations
characteristics of organisms that enhance their survival and reproduction in specific environments.
Adaptions arise by natural selection
natural selection
a process in which individuals with certain inherited characteristics leave more offspring than individuals with other characteristics.
The Origin of Species
All organisms are related through descent from a common ancestor that lived in the remote past. As a result, organisms share many characteristics, explaining the unity of life.
Over evolutionary time, the descendents of that common ancestor have accumulat
artificial selection
Humans have modified a variety of domesticated plants and animals over many generations by selecting individuals with the desired traits as breeding stock.
two observations of nature
Observation #1: Members of a population vary greatly in their inherited traits.
Observation #2: All species are capable of producing more offspring than the environment can support, and many of these offspring fail to survive and reproduce.
Inference #1:
homology
Similarity in characteristic traits from common ancestry
Descent with modification can explain why certain traits in related species have an underlying similarity even if they have very different functions.
homologous structures
represent variations on the ancestral tetrapod forelimb.
vestigial organs
structures that have marginal, if any, importance to a living organism but that had important functions in the organism's ancestors.
evolutionary tree
reflects evolutionary relationships among groups of organisms.
convergent evolution
the independent evolution of similar features.
biogeography
the geographic distribution of species
Evidence for evolution also comes from the geographic distribution of species
Pangaea
Two hundred fifty million years ago, all of Earth's landmasses joined to form a single large continent
endemic species
species that are found nowhere else on Earth.
Specific to a single geographical location
theory
more comprehensive than a hypothesis, accounting for many observations and much data and attempting to explain and integrate a great variety of phenomena.