Chapter 5 - Reconstructing and Using Phylogenies (Exam 1)

Phylogenetic Trees

how to make traits used in reconstructing phylogenies

A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms.

Uses of phylogenetic trees

Organizing knowledge of biological diversity

Allowing structured classification of organisms

Providing insight into evolutionary events

Demonstrate that living species are the result of

their evolutionary history

Show that all living species are contemporaries-

each organism is the product of parents that

successfully gave rise to offspring for the last >3

billion years

How traits evolved

biogeographic patterns

age of divergence

bioactive chemical searches

Phylogeny

history of the descent of a group of organisms from their common ancestor

Phylogenetic / Evolutionary Tree

shows order or pattern of when different species or groups of species evolved

When species evolve via "descent with modification" the

closer the species are together the more characteristics should be (mores common characters the closer related)

Systematics uses

fossil, molecular, and genetic data to infer evolutionary relationships

(living organism)

How are phylogenetic trees constructed?

trees constructed with analysis of characters or traits

Characters can be

morphological, molecular, or behavioral

Apomorphic

Derived characters (those possessed by some taxa on the tree but not all and not the common ancestor)

Plesiomorphic

Ancestorial characteristic (ancestors had this trait and descendants have it as well)

Homologus

similar due to common ancestor (good)

Analogus

misleading due to convergence (bad)

Homologous Characteristics

inherited from a common ancestor, hence due to common ancestry (sometimes has different functions though)

Bird vs. Insect Wing

analogous

Bird vs. Bat Wings

Homologous

Analogus Characters

NOT due to inheritance but similar due to convergence/ parallel evolution

Adaption for a similar function

Analogus

Vultures same or different?

New World - from storks

Old World - from raptors

Convergence doesn't come from same species but look similar because adapted to same environment

ex. Sharks, Dolphin, Ichthyosaur

Divergent Evolution

evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions

Divergent evolution may make homologues traits appear different

ex. vertebrate limbs (common origin, but vastly different)

Tenants

Species change over time

species are related by common ancestor

Morphological evolution

Whales and Hippos

What traits are used to reconstruct phylogenies

nucleic acid sequences and molecular data

When did humans and apes slit

7 - 10 mya

Parsimony

simplest explanation of evolution is the best explanation (fewest evolution characters)

Bayesian analysis

to revise and update initial assessments of the event probabilities generated by the alternative solutions. (makes more readable)

maximum likelihood analysis

likelihood is the probability of the data given a tree, its branch lengths and a model of evolution

Embryo development evolution

human embryos go through all former common ancestors (tail, gills, notochord, Chordata, etc.) before final form

Phenetics (numerical taxonomy)

uses both apomorphines and pleomorphisms (groups based on overall similarity)

Evolutionary phylogenetics

uses apomorphines, but recognizes monophyletic and non-monophyletic groups in classification

Cladistics

uses only apomorphias, but recognizes only monophyletic groups in classification

Classification systems

improve ability to explain organism relationships (reflects evolutionary history, memory aid, and unique universally used names)

Monophyletic tax tonic groupings

should be used in our classification systems

monophyletic group

a common ancestor and all of its descendants (reflect evolutionary history in classification)

Molecular clocks

the average rate at which a species' genome accumulates mutations, used to measure their evolutionary divergence and in other calculations.

Phylogenetic trees help with

classification, disease control, crop development, conservation

Polyphyletic

pertaining to a group of taxa that includes distantly related organisms but does not include their most recent common ancestor

paraphyletic

Pertaining to a group of taxa that consists of a common ancestor and some, but not all, of its descendants.