Darwins VoyageOf the HMS Beagle and Finches

The HMS BeagleSet sail in 1831 on a voyage around the worldMission: Chart the poorly known South American coastlineCharles Darwin was the ships naturalistHe collected thousands of specimens of South American plants & animalsHe also observed different land forms and fossilsMaintained extensive journals of his travels

The Route

The Three PatternsDarwin observed three patterns on his journey as he studied the biodiversity and fossils of the world:Species Vary GloballySpecies Vary LocallySpecies Vary Over Time

Species Vary GloballyDarwin noticed that distantly related species living in similar habitats in different part of the world looked similar and had acted in similar ways. E.g. Large flightless birds in different grasslands: Rhea (SA), Ostrich (AF) and Emu (AUS)

Species Vary GloballyHe noticed that some places had unique organisms not found anywhere else. E.g. Marsupials in Australia

Species Vary GloballyHe also noticed that South American plants and animals were very different from species from Africa and Europe. E.g. A tropical SA lizard was more like a SA desert lizard than an African tropical lizard.

Species Vary LocallyDarwin noticed that related animal species that occupied different habitats within a local environment had different features. Especially on Islands E.g: Galapagos ArchipelagoTortoises on Isabella vs. EspaolaMany different Finch species even though they look like they are from bird different familiesMost of the unique species were similar to a mainland species. Therefore, Darwin inferred that the mainland species had changed after colonizing this new environment

Species Vary LocallyDarwin noticed that related animal species that occupied different habitats within a local environment had different features. Especially on Islands E.g: Galapagos ArchipelagoTortoises on Isabella vs. EspaolaMany different Finch species even though they look like they are from bird different familiesMost of the unique species were similar to a mainland species. Therefore, Darwin inferred that the mainland species had changed after colonizing this new environment

Species Very Over TimeDarwin noticed that the fossils he found in SA were very different from those discovered by other naturalists elsewhere.They were uniquely South AmericanThis supported the idea that species living in SA were descended from ancestral species on that continentE.g. Armadillo vs Glyptodon fossils

Geological ChangeDarwin was reading Lyells Principles of Geology on his tripHe experienced an earthquake in the Andes and observed underwater land move above the water level. He had also collected fossils of marine organisms in the mountainsHe reasoned that earthquakes had gradually lifted the rock containing those marine fossils from the sea floor based on Lyells ideas

The road to Darwins TheoryIn 1838, Darwin read an essay on human population by Thomas Malthus who said that much of human suffering was due to human populations potential to grow faster than the rate at which resourced to support that population can be produced.Darwin recognized that these ideas applied to all species and this concept helped him propose a mechanism of evolutionary change

Resemblance to Other AnimalsHow closely do we resemble some animals?

Fish?

Frog?

Alligator?

Eagle?

Wolf?

Monkey?

Chimps?

The race to PublishIn 1844, Darwin wrote a 200-page essay that outlined his idea of evolution but didnt release it to public.Instead he tried to accumulate more evidence to support his idea. But his friend wanted him to publish his work before someone else didIn 1858, Alfred Wallace (Brit) came to the same conclusion and sent Darwin a letter about itWithin a month, both writings were jointly presented to the public.Darwin published The Origin of Species a year later

The Origin of SpeciesDarwin made two main points in this book:All species of organisms living on earth today are descended from ancestral species i.e. species evolve over timeThe mechanism that causes them to change over time is called Natural Selection

Descent with ModificationDarwin proposed that the descendents of the earliest organisms spread into various habitats over a geological time scaleIn these habitats they accumulated different modifications, or adaptations, to diverse ways of lifeHe called this process descent with modificationHe never used the term EvolutionE.g. Jackrabbit vs Snowshoe hare