BIO Ch 10

humans descended from apes

humans descended from apes

false

individuals can evolve during their lifetime

false

evolution always takes thousands of years to cause change

false

evolution directs change towards a predetermined outcome (it is forward looking)

false

you are related to some degree, to plants

true

population

growth of individuals of same species that is separated by geography from other populations

evolution

change in characteristics of a population that typically occurs over a course of generations

microevolution

• the same species but there are changes that lead to different traits in a population over time

• ex: evolution of pesticide resistance, body size, color

macroevolution

• changes that lead to new species over time

• ex: different types of dinosaurs

theory of common descent

• all species on Earth are descendants of a single common ancestor and species represent the product of millions of years of evolutionary changes

• all living things are related to each other

• species that are more closely related share a more recent common ancestor

single origin of life evidence

theory of evolution

homologies

similarity in characteristics due to common ancestry

anatomical homologies

• arrangement of placement of bones

• ex: forearm in humans & apes are homologous

less obvious anatomical homolgies

• functional traits in one organism are non-functional/greatly reduced in another organism

• vestigial traits are indicators of common ancestry

vestigial traits

• remainder of biological heritage

• ostrich wings, the appendix

arrector pili

tiny muscles at base of hairs

5 lines of evidence for evolution

• developmental homologies

• molecular homologies

• convergent evolution & homoplasy

• biogeography

• fossil record

homoplasy

we look alike because we have a similar lifestyle, not because of the common ancestor

developmental homologies

• many organisms display shared developmental pathways because of the common ancestor in the past

• very different species look very similar in early developmental stages

• ex: all chordates have pharyngeal slits & tails that they eventually lose during development

molecular homologies

• shared genes = shared characteristics

• closely related species that share a recent common ancestor share many genes

convergent evolution & homoplasy

• evolution of similar structure in unrelated organisms due to a similar lifestyle

• resulting in homoplasy

biogeography

• distribution of species on Earth

• closely related species cluster in the same geographic region because they descended from the same common ancestor that lived there

• ex: marsupials in Australia

fossil record

• provide a record of change of organisms over time

• many fossil series show progression from ancient forms to modern forms

transitional forms

fossils or organisms that show intermediate states between ancestral form & descendant form

4 evolutionary forces

• natural selection

• genetic drift

• migration

• mutation

natural selection

• differential survival & reproduction of individuals in a population

• causes populations to adapt to their changing environment