Phylogeny and evolution

Phylogeny

the evolutionary history and relationships among species or groups of organisms.

cladogram

a diagram based on shared characteristics.

monophyletic

describing a group of organisms that includes an ancestor and all its descendants, forming a clade.

Paraphyletic

describing a group of organisms that includes an ancestor but not all of its descendants, resulting in an incomplete clade.

polyphyletic

diagram that represents evolutionary relationships among organisms. Phylogenetic trees are hypotheses, not definitive facts. A group of organisms that does not include the most recent common ancestor of the members, typically formed from multiple clades.

nodes on a phylogenetic tree

They tell use the age of the most recent or less recent common ancestor.

branch on a phylogenetic tree

refers to the line representing the evolutionary pathway between two nodes, showing the relationship between different lineages.

root on a phylogenetic tree

the common ancestor of all organisms in the tree, serving as the starting point for the evolutionary relationships depicted.

Taxonomy

the science of classifying organisms into groups based on their evolutionary relationships and characteristics.

What tells you how closely related two species are

two species are more related if they have a more recent common ancestor and less related if they have a less recent common ancestor.

polytomy

a branch point in a phylogenetic tree where three or more descendant groups emerge, indicating uncertain relationships.

what can phylogenetic trees not tell us

we organize species into nested groups based on shared derived traits (traits different from those of the group's ancestor).it does not tell us the exact timing of evolutionary events or speciation.

derived traits

traits that evolved within a group and differ from the ancestral trait.

In terms of DNA of relatedness

• A larger number of differences corresponds to less related species

• A smaller number of differences corresponds to more related species

Genomic changes

Changes in DNA and Cell divison and environmental disruptions

Continous change in fossil records

Transition fossils can show the evolutionary changes as one groups evolve into another

Resistance to various chemicals

Resistance can show evolutionary changes in terms of new mutations

Fitness

The ability of an organism to reproduce

Pathogens

infectious agent that produce dieases, evolves, can become chemically compatible with its host, and can change phenotypes.

Viruses

They evolve rapidly

Virus Recombination

two different viruses swap genetic material (DNA or RNA) when they have hosted the same cell to create a new viral strain, potentially leading to new characteristics or abilities.

Random mutation

A change in DNA sequence

Evidence for common ancestry in Eukaryotic

linear chromosomes, membrane bound organelles, and Genes that contain introns

Membrane bound organelles

Shown in Mitochondria and chloroplasts; have double membrane, endosymbiotic theory, and have ribosomes.

endosymbiotic theory

the hypothesis that eukaryotic cells evolved through a symbiotic relationship between different species of prokaryotes, leading to the formation of organelles like mitochondria and chloroplasts.

Linear Chromosomes

Found in all Eukaryotes. It differs from prokaryotic genomes (circular chromosomes ).

What is an Introns

non-coding sequences of DNA within a gene that are removed during RNA splicing.

Intron for common ancestry

Found in all eukaryotes.

Macroevolution

large scale evidence for evolution: anatomy, embryology, molecular biology, biogeography, and fossils.

homologous

variation in a structure that was present in a common ancestor

analogous

structures that evolved independently in different species due to similar environmental conditions/selective pressures

evidence 1- molecular biology

DNA sequence comparisons can show how different species are related.

evidence 2- biogeography

These patterns provide clues about how species, both alive and extinct, are related to each other

evidence 3- fossils

are preserved remains, impression, or trace of once living organisms from the past, it tells us age/geographical data

evidence 4 - anatomy/embryology

Anatomical features shared between organisms (including ones that are visible only during embryonic development) can indicate a shared evolutionary ancestry

vestigial structure

A reduced feature that serves little to no purpose for the organism; for example; the human tailbone

Biochemical evidence

A comparison of DNA nucleotide sequences and/or protein amino acid sequences provides evidence for evolution and common ancestry

True or False: Analogous features is convergent evolution

True

reduction of isotope - like carbon 14

is a method used in radiometric dating to determine the age of organic materials by measuring the decay of carbon-14 isotopes.