Ch 20 part 2 Flashcards
origin of first cells
Earth was hot, mostly ocean with volcanic gases and LOW O2
Earliest evidence of life
oldest cell fossils of prokaryotes in stromatolite formations (layers of rock, specifically cyanobacteria)
What does a new group/taxon begin with
1 ancestral species that arose through speciation, more microevolution, and more speciation/extinction
Adaptive radiation
rapid increase in number of species due to great ecological and morphological diversity and new ecological niches, descend from ONE ancestor species. the ancestor species is isolated, acquires a new adaptation, and expands form there to create many species
Exaptation
an adaptation that performs differently from its original function, ex. hair (insulation) to procupine quills (defense). Change in function, THEN form
function of developmental genes
control development of multicellular organisms
many developmental genes are
regulatory genes, which control the expression of 1+ genes
how do dramatic changes in final form happen
mutation–> affects gene expression –> changes in final form
heterochrony
changes in timing of development results in evolutionary change, also called allometric growth, due to mutation in developmental gene
homeotic genes (hox)
are responsible for the development of body structures. a mutation in a homeotic gene can cause body structures to develop in the wrong area. this can be linked to changes in form
relative dating
compares positions of strata (rock layers) to approximate date/sequence of structures
absolute dating
numerical age of fossils: two types, radiometric dating (decay rate of isotopes) and half time (time for half isotope to decay)
geologic time scale
hadean, arcane, proterozoic
Hadeon Eon
planet formed, molten rock surface, no liquid water
archaean eon
crust cooled, solidified, condensed water formed global ocean, volcanoes created first land, low O2, first life (prokaryotic cells), oxygen revolution, O2 rich atmosphere