Evolution And Classification Of Organisms Flashcards
Convergent evolution
Process whereby organisms not closely related independently evolve similar traits as a results of having to adapt to similar environments or ecological niches
Adaptive radiation
Event in which a lineage rapidly diversifies and are adapted to specialised modes of life
Monophyletic taxon:
includes the most recent common ancestor and all of its descendants
Paraphyletic taxon
Includes last common ancestor but not all descendants
Polyphyletic
does not include the common ancestor of all members of the taxon
– Usually indicates convergent evolution
Cladistics: Plesiomorphy
An ancestral or primitive character state
Cladistics:
– Symplesiomorphy (subterm of plesiomorphy)
• A character state shared by a number of groups, but inherited from ancestors older than the last common ancestor
Apomorphy
A derived or specialised character state
Automorphy (subterm of apomorphy)
Apomorphy unique to one group
Synapomorphy
• Apomorphy shared by two or more groups which originated in their last common ancestor
• Shared derived character states in two taxonomic groups indicate that they are evolutionarily related
Homoplasies (convergent evolution)
– Similar character states that evolved independently = parallel evolution or convergence
– Could be the result of adaptation to similar ecological niche/environment
Systematics
Catalogue of organisms
When was the publication of Charles Darwins ‘On the origin of species by means of natural selection’?
1859
Darwin’s concept of evolution consists of…
1) Generation of random variation- varied population
2) Natural selection- competition, not all reproduce
3) combination of two- hereditary advantage= better chance to reproduce
The Tree of Life shows that…
All life forms on earth are related
Domains: the basic subdivision
Prokaryotes (w.o. nucleus)= (Eu)Bacteria and Archaea
-Eukaryota
Which domains possibly share a common ancestor?/
Eukaryota and Archaea
Four kingdoms of Eukaryotes
1) Protists
2) Plants
3) Fungi
4) Animals
Supergroups of eukaryotes (SOE):
Archaeplastida (Plantae)
- glaucophytes, red algae green algae, land plants
- united by posession of a plastid derived from primary endosymbiosis
Plastid
double membrane bound organelles found inside plant and some algae. Responsible for activities related to making and storing food.
Endosymbiosis
Process where one cell is taken up by another and retained internally
SOE: Excavata
-free living and symbiotic forms
-e.g parasites for humans
many lack classical mitochondria
-e.g. euglenoids, zooflagellates
SOE: Chromalveolata
e. g. diatoms, brown algae, dinoflagellates
- widespread presence of plastids- derived from secondary endosymbiosis with red algae.
SOE: Rhizaria
e.g. foraminifers, amoebae
SOE: Unikonta
e.g. animals, choanoflagellates, fungi, slime molds, amoebes
Taxonomy
Hierarchical classification system
Phylogeny
Evolutionary relationships between organisms
Evidence for phylogeny
- Comparative morphology – homologous and related structures
- Palaeontology –features in fossils vs similar features in extant species and other fossils – Isotope dating gives time scale
- Molecular biology – DNA and protein sequences
- Developmental Biology -> Evo-devo, embryo development
Homologous
related by common descent
Cladistics
Reconstruction of phylogenetic trees
Clade
Organisms related through a common branch
Why use scientific names?
-Vernacular names lack precision, language barriers, different scripts
Requirements for scientific name…
1) “unknown to science”
2)collected and preserved
3)described- sufficient detail for
future recognition
4)location in Animal Kingdom determined-anatomy and gene sequences (?)
5)suitable name selected
6)type specimen in a museum for future reference
ICZN- International code of zoological nomenclature (1901)
1) only one correct name
2) genus names =unique
3) Latin grammar rules
4) first name is used
5) type specimens must be nominated
Proper use of scientific names
Capital & Italics= genus
Lower Case& italics= species
Brackets= Author
Character states that are informative for the construction of phylogenetic trees…
Synapomorphies
Character states that show similarity as a result of convergent evolution
Homoplasies
A taxonomic group that includes all species derived from a unique, single ancestor is called
Monophyletic
