ch 25 Flashcards
(24 cards)
taxa
a species
polytomy
more than 2 branches from a comm ancestor
ancestral trait
existed in an ancestor
derived trait
modded form of ancestral trait found in descendent
synapomorphy
trait found in 2+ taxa that is present in most recent comm ancestor but missing in more distant ancestors
monophyletic group/clade/lineage
an evolutionary unit that includes an ancestral species and all its descendants, and no others
homoplasy
same form evolves interpedently, not comm ancestry
what/where organisms are most likely to fossilize according to habitat bias?
areas where sediments are deposited:
- beaches
- mudflats
- swamps
burrowing organisms
what organisms are most likely to fossilize according to taxonomic and tissue bias?
organisms with bones are shell bc these decay slowly enough or for things like plants hard exteriors like a tough pollen shell while a flower wouldnt fossilize
what organisms are most likely to fossilize according to temporal bias?
recently extinct rather than looooooooong ago
what organisms are most likely to fossilize according to abundance bias?
organisms that were just extremely bountiful
what was responsible for creating oxygen atmosphere originally?
cyanobacteria ~2 bil years w/o
adaptive radiation
- a single lineage produces many descendants w a wide range of adaptive forms
- species originate and diversify rapidly
why adaptive radiation happens
1) when there is ecological opportunity - availability of more/new resources
2) morphological, physiological, or behavioral innovation - evolution of key trait that might allow descendants to live in new areas, use new foods, or find mates in a new way (ex: flowers, wings)
what is the adaptive radiation of animals called?
the Cambrian explosion
what caused Cambrian explosion possibly (could be any or all of these)?
- higher O2 levels
- rise of eukaryotic photosynthesis
- evolution of predation
- new niches ==> more new niches
- new genes ==> new bodies (Hox genes)
when is it considered a mass extinction?
60%+ of species gone within 1 million years
which extinction wiped out the dinosaurs NOOOOO dinosaurs :(
66 mya, end of cretaceous prd
when does background extinction occur
- normal environmental change
- emerging disease
- predation pressure
- competition w other species
when does mass extinction occur
extraordinary, temporary, sudden environment changes
impact hypothesis
- asteroid killed dinos fr, found evidence of asteroid landing and like large quantities of substance from the asteroid
- this bitch was about the size of mount everest and had the force of several million nuclear bombs
- worldwide catastrophic wildfires
- largest tsunami in 3.5 bil years
- extensive acid rain
- sun blocked for a long time so global cooling and crash in plant productivity
fr hell on earth omg….
why did birds experience an adaptive radiation?
they ate seeds which wouldve been more abundant during the nuclear winter
why did mammals survive?
back then they were small enough to
