UNIT 1: EVOLUTION AND PHYLOGENETICS (18&20) Flashcards
Evolution
- The gradual change over time; happens in all kinds of things
- Organisms are static and do not change
Theory
- The way an organism uses anatomical traits is based on the demands of their environment. Based on this use or disuses, their offspring will be born with modified traits that can better deal with those demands (this theory is wrong)
- Inheritance for acquired traits
- Jean-Baptiste Lamarck (1809)
Natural selection
1) Traits are passed from parent to offspring
2) More offspring are produced than can survive
This is due to limited resources such as food, space, mates, etc.
3) Offspring vary in their traits
- Offspring will compete for these limited resources the better competitors survive, and the survivors’ traits are passed on (survival of the fittest)
- If you die; traits font get passed on
- If you survive; your traits get passed on
Species
- A group of individual organisms that interbreed and produce viable, fertile offspring
- Natural selection explains difference between species
- Darwin observed patterns in species based on his travels
Speciation
- Occurs when a group within a species separates from other members of its species and develops its own unique characteristics
Reproductive Isolation
- Enough differences accumulate that they cannot/will not interbreed if reintroduced (separate groups of a population so they can mate which leads to differences so eventually those differences are so different so then they can’t breed together again)
Biological Species Concept
- When two different organisms can reproduce with one another, but are reproductively isolated from other organisms (tiger + lions = ligers)
Phylogenetic Species Concept
- An evolutionary divergent lineage (branch), one that has maintained its hereditary integrity through time and space
Evolutionary Species Concept
- Organism which maintains their morphological (morpho means form) identity from other organisms through time and over space
Types of Speciation
1) Allopatric Speciation
2) Sympatric Speciation
Allopatric Speciation
- Speciation by geographic isolation
- Geographic separation of a population from a parent population
- They have different homes which is why they’re different
Dispersal
- When a few members of a species move to a new geographical area
Vicariance
- Change in the environment to physically divide organisms (seperated due to mountain range or river)
Adaptive Radiation
- An evolutionary process that produces new species from a single, rapidly diversifying lineage
Sympatric Speciation
- The evolution of a new species from a surviving ancestral species while both continue to inhabit the same geographic region
- There are no physical barriers needed
Reproductive Isolation
- The inability of two populations to interbreed and produce offspring
Prezygotic Barrier
- A mechanisms that blocks the gametes from ever meeting
Postzygotic Barrier
- Barriers that occur after a zygote has formed and reduce the viability of the hybrid zygotes or offspring
Gamete Barrier
- Differences in gamete cells (eggs and sperm) prevent fertilization from taking place
Habitat isolation
- Populations that moved to a new habitat that no longer overlaps with the same species’ other populations
Behavioral isolation
- Occurs when the presence or absence of a specific behavior prevents reproduction
Phylogenetics
- The study of evolutionary relationships among biological entities – often species, individuals or genes
- The Taxonomic Hierarchy
Phylogenetics Order
- Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species
Phylogentic Trees
- First created by darwin
- Explained the realtionship between species
- A phylogeny is a fancy way of saying family tree
- A diagram used to reflect evolutionary relationships of a organisms or groups of organism
Branch Point
- A point at which two evolutionary lineages split from a common ancestor
Basal Taxon
- A lineage that evolved early from the root that remains unbranched
Sister Taxa
- Two lineages stemming from the same branch point
Polytomy
- A branch with two or more than two lineages
- More than 2 is a polytomy
- Not accurate
Homologous
- Structures that share a similar embryonic origin (humerus bone analogy in different animals) (use this to define trees)
Analogous
- Structures that have a similar function (wings used to fly) (don’t use this to define trees)
The phylogenetic tree concept
- A single trunk representing a common ancestor
- Branches representing the divergence of species from this ancestor
- Classification of organisms into classes based on the last common ancestor
What determines a tree?
- Morphology
- DNA
- Computer Algorithms
Maximum Parsimony
- The more similar the more closely related they are
Horizontal Gene Transfer
- The introduction of genetic material from one species to another species
- Other than by vertical transmission (parent to offspring)
- Swapping genes with someone from same generation
- No new generation is made
- The transfer of genes between unrelated organisms
Horizontal Gene Transfer Methods
1) Transformation- bacteria makes up naked DNA
2) Transduction- a virus transfers the genes
3) Conjugation- a hollow tube transfers gene between organisms (swap some DNA with each other)
Monophyly
- Includes recent common ancestor and all descendants
Paraphyly
- Includes recent common ancestor but not all descendants
Polyphyly
- Does not include recent common ancestor or all descendants
