Evolutionary Patterns

evolutionary biology

historical science because it is figuring out what has happened over millions of years

two ways of reconstructing evolutionary history

phylogenetics and the fossil record (can get lots of info with these two together)

phylogenetics

living species and how they are related to each other to figure out evolution

fossil record

looking at past life

phylogenetic tree

diagram that describes phylogeny

phylogeny

geneology on broadest possible scale of living things

why is the phylogenetic a hypothesis

still constantly collecting data to find the evolutionary relationships among various species

parts of phylogenetic tree

branches and nodes

branches

represent populations

nodes

hypothetical ancestors that gave rise to two species

two axes of phylogenetic tree

time and some kind of change

what does a phylogenetic tree show

speciation events and normal events of isolation and divergence

what do nodes represent

a speciation event; the common ancestor from which the species diverged

sister groups

share a common ancestor not shared by any other group; on either side of a node

monophyletic group

common ancestor and all of its descendants

paraphyletic group

common ancestor and some, but not all, of its descendants

polyphyletic group

does not include a common ancestor; just have similar characteristics

taxonomy

hierarchal system involving successive levels

taxon

group at each level of hierarchal system of taxonomy

domain

most inclusive group of taxonomy, all of life belongs to one of three domains

domains

bacteria, archae, eukarya

classification

phylogenies reflect the hierarchial taxonomic system of Linneaus; all species grouped into single phylum

homology

similarity due to common descent

analogy

superficial similarity, often due to convergent evolution

building a phylogenetic tree

comparing homologous characters by scoring character states

convergent evolution

evolution on two different species that look similar to survive in their environment

character states

what does a character look like in different groups of origins

apomorphy

derived character state

synapomorphy

shared derived character state; taxa that have synapomorphies are related by common descent

apomorphy vs synapomorphy

apomorphy is an evolutionary novelty and a synapomorphy is an apomorphy shared by two or more groups

out group

taxon that derived prior to lineage of taxa of interest

character matrix

compare homologous characteristics to put in tree

determining the best fit of possible phylogenetic trees

the best tree is the most parsimonious one/one with the fewest changes in it because it has had the least amount of evolutionary events

occams razor

simplest explanation

benefits of using molecular data to build a phylogenetic tree

vast amounts of data

fossils

only record of extinct forms

using fossils to create phylogenies

• allow us to calibrate phylogenies in terms of time

• provide a record of extinct species

• place evolutionary events in context with Earth’s history

evolutionary events and fossils

appearance of features can be correlated with geological features

what rocks do fossils typically form in

sedimentary rocks

what makes the fossil record biased

1) common things

2) hard parts

3) aquatic

4) more recent

5) more widespread

do we have a fossil record of everything that has ever lived

no because it is not easy to fossilize

trace/molecular fossils

not body parts

• evidence of animal activity (footprints, burrows, etc)

• molecular seen if look closely at chemical of rocks because there are traces of biochem that is only through living things

burgess shale

some of the earliest animal fossils preserved in Canadian Rockies (early evidence of life)

• soft parts preserved

messel shale

german fossils

• rare

• impressions

hadean era

earth on fire

archean era

first evidence of life

proterozoic era

oxygen present in earth

phanerozoic era

visible life appears

radioactive decay

computes how many half lives have passed in rock

pangea

super continent that existed 250 million years ago

what caused pangea to break up and what happened when it did

extreme environmental conditions and it led to mass extinction

mass extinction

• 5 large mass extinctions

• boundaries between geological time periods are often based on the events

• rapid extinction of species