Ch. 15 Evidence for Evolution Flashcards
What are the 3 evidence for evolution
comparative biocehm, anatomy and fossil
what are the 4 areas of biochem comparison
- DNA
- Junk DNA
- Mitochondrial DNA
- Protein Sequences
what are the 3 areas of anatomical comparison
- Embryology
- Homologues Structures
- Vestigial Organs
What is the fact that all living things have same DNA code provide evidence for
common ancestor
how is speciation evidence for evolution
- Although all species have DNA, sequences very
- Speciation: when it occurs (ancestral species= 2/+ species) new species= similar DNA
o As species changes, accumulate more differences
o Close related species= share greater proportion of DNA
How are genes gained or lost
New genes gained by mutation
Genes lost by natural selection, genetic drift etc.
define junk DNA
Non-coding sequences of bases in DNA, no apparent function
Explain endogenous retrovirus as evidence of evolution
o Viral sequence that has become part of the organism’s genome
o Store genetic info as RNA > enters cell > copies RNA into DNA (reverse transcription) > DNA inserts into one of its hosts cell’s chromosomes
o If inserts into gamete= offspring inherit in same place, same chromosome
o // common ancestor
what has comparing dna strands of different species suggest
- increase genetic distance b/w humans + other primates= indicate all these animals once shared a common ancestor, diverging at different points
what is the rate of mutation of mtDNA show
o Amount of mutation roughly proportional to amount of time has passed
o Scientists use similarity b/w mtDNA of any two individuals to provide estimated closeness of their relationship through maternal ancestors
o // if mtDNA is very different their last common ancestor lived a long time ago
what has comparing mtDNA allowed
o Allowed scientists to track ancestry and trace migration routes of ancient people
o Also been used to demonstrate the evolutionary relationships between humans and closely related species
o Important tool in mapping relationships b/w species
How are degree of similarities show with protein sequences
- Comparing type and sequence of amino acids in protein from different species= degree of similarity can be established
o Animals of same species= identical sequences
Different species= different amino acids or arranged in different order
in terms of protein sequences, what occurs the longer period of time involved
o greater number of amino acids that are different
- Amino acids represented by a three letter code
define ubiquitous proteins
>
One of a group of proteins that appears to be in all species form bacteria to humans
what does all ubiquitous proteins have in common
♣ perform basic but essential tasks that all organisms require for life
♣ Found in all organisms
♣ Completely independent of an organisms specific function or the environment in which it lives
♣ Carry same function no matter where found
what is cytochrome c an example of
ubiquitous protein
what was the human genome project
- 2003 demonstrated that major sequencing projects can generate high quality data // interest in sequencing of genomes of species increased
- By analysing genomic features that have been preserved in a number of species over millions of years, can begin to tease apart subtle differences b/w animal species
- Comparative genomics= revealed
o high number of similarities between closely related organisms
o the diversity of gene composition in different evolutionary lineages
what techniques are used to help compare
bioinformatics and comparative genomics
define embryology
comparing the very early stages of the development of organisms
define homologous structures
organs that are similar in structure but are used in different ways
define vestigial organs
organs that may once have been important but have lost or changed their function
what are 5 common features of embryos
o Gill slits and pouches o Absence of paired appendages o Presence of well-developed tails o Two chambered heart o Similar brain development
why are gill slits important
- vertebrates are views as an evolutionary series that began with fish
o Overtime= evolutionary divergence into amphibians> reptiles> birds > mammals
whats another piece of evidence that supports we came from fish
♣ Humans= one of the embryonic gill slits develops into the Eustachian tube, and tissue surrounding other gill slits develops into the thyroid gland and tonsils
what is embryology evidence for
common ancestry with later evolution along different pathways
whats an example of homologous structures
forelimbs of vertebrares
how does evolutionary mechanisms explain vestigial organs
- They are what remains of organs that were functional in ancestral forms
- Over time + changing environmental conditions= organs no longer essential to survive and were gradually reduced to vestigial remnants
- Not harmful // not been completely eliminated
what is the effect of natural selection of vestige organs
o = waste of organism’s energy and resources to maintain useless structure
o Such organs will probably disappear altogether as no selection pressure to retain them
what are 8 examples of vestigial organs in humans
nicitating membranes muscles that move ears third molars pyramidalis musles tail vertebrae appendix male nipples muscles at base of hairs
explain the vestigial organ of muscles at base of hairs
- In mammals with fur or spines, and birds with feathers, tiny muscles pull the hair or feather upright, creating layer of insulating air to protect against cold
- However, in humans= hair so fine it is not capable of the function and the contraction of the muscles is seen as Goosebumps
define isolated areas
evolved their own distinctive plant and animal populations
define geographical distribution
- the natural arrangement and apportionment of the various forms of animals and plants in the different regions and localities of the earth
what are three examples of geogrpahical distribution
australia galapogs islands and primates
