Chapter 5 & 10 Applications & Interpretations Flashcards
Causes & effects of polyploidy –> speciation
- organism has MORE than 2 sets of chromosomes
- abnormalities in mitosis/meiosis
- fertilization by more than one sperm
- leads to SYMPATRIC SPECIATION –> coexisting in same area but not interbreeding (spontaneous development)
- diploid gamete + haploid gamete = infertile triploid zygote
What are the uses of ployploidy?
- e.g. Allium genus is tetraploid & fertile
- allelic diversity - having many copies of same gene reduces risk of recessive mutations having bad effects
- novel phenotypes can be generated (better aroma, flavour, yield, pest-resistance)
- hybrid vigour
What is hybrid vigour?
the tendency of cross-bred individuals to show superior characteristics to those of their parents
Examples of directional, stabilising, & disruptive selection.
- directional –> changing of the peppered moths during the Industrial Revolution
- stabilising –> robins lay 4 eggs - larger clutches = malnourished chicks, smaller chicks = no viable offspring
- disruptive –> both dark-colored oysters & light-oysters have camouflage advantages
What is punctuated equilibrium
long periods w/ no appreciable change & short periods of rapid evolution
evidence for punctuated equilibrium
- FOSSILS (relatively unchanged for long times BUT changed abruptly at other times)
- sudden MASS EXTINCTIONS
- e.g. cataclysmic events like volcanic eruptions, meteor strikes
How is human height influenced by environmental factors?
- polygenic inheritance
- dif genes can have same effect on phenotype & have additive effect
What are test crosses used for?
- to determine unknown genotypes + recombinant phenotypes
- individual is crossed w/ homozygous recessive individual
What is genetic drift?
change in composition of gene pool due to chance/random events
Morgan’s discovert of non-Mendelian ratios in Drosophilia
- Morgan identified non-Mendelian ratios in Srosophila melanogaster (fruit flies)
- all female offspring of a red-eyed male were red-eyed
- all male offspring of a white-eyed female were also white-eyed - SEX-LINKED GENES
- gene linkage –> no independent assortment
- crossing over (recombination) –> new phenotypic ratios
- more distant alleles = more like to be separated via recombination
Comparison of allele frequencies of geographically isolated population
- POPULATION BOTTLENECKS: occurs when an event reduces large populations size by ~ 50% (e.g. due to overhunting)
- FOUNDER EFFECT: occurs when a small group breaks away from a larger population to colonise a new territory (but original population remains largely intact)
Pentadactyl limb
- pentadactyl limb - 5-digit limb
- e.g. hands = tool manipulation, wings = flying, hooves = galloping, fins = swimming
- despite differences in appearance/function, the structure is repeated
- thus all these animals must have evolved from a common ancestor (ADAPTIVE RADIATION)
Development of melanistic insects in polluted areas
- variation exists within peppered moth population (some have alleles for melanism some don’t)
- industrial areas = lichen killed = tree bark is darker = more melanistic moths survive + reproduce
- over time, is a gradual increase in frequency of melanistic moths
Changes in beaks of finches on Daphne Major
- severe drought = large seeds increase
- finches w/ large beaks increase
- severe storm = small beaks increase
- finches w/ small beaks increase
Evolution of antibiotic resistance in bacteria
- antibtioic resistance arises by random mutation
- a bacterial infection is treated w/ antibiotic (selection pressure), killing most non-resistant strains
- resistant survive (binary fission) + pass on mutation to next generation
- antibiotic resistance increases in frequency in the population
Scientists use the binomial system to identify a species rather than the many different local names
- 1st = Genus, 2nd = species
- enables scientists to communicate clearly w/ each other about living organisms (the same species)
- shows how closely linked organisms are (evolutionary links)
- easier to collect, sort, & group info about organisms based on recognised traits
Classification of one animal species from domain
to species level
WOLF:
Domain: Eukaryote
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: lupus
Classification of one plant species from domain
to species level
CHINESE HIBISCUS
Domain: Eukaryote
Kingdom: Plantae
Phylum: Angiospermae
Class: Dicotyledonae
Order: Malvales
Family: Malvaceae
Genus: Hibiscus
Species: rosa-sinensis
Reclassification of the figwort family using evidence from
cladistics
- originally grouped organisms based on observed traits (e.g tube-shaped flower structure)
- modern cladistics uses DNA/RNA nucleotide base sequences / amino acids
- DNA mutation occurs at relatively constant rate –> allows estimation of when species diverged
- shared/common derived characteristic places organism in same clade
- the # of changes in sequences indicates distance from common ancestor
- the new figwort family is less than half its original size
- originally had 16 genera - later expanded to 275
Analysis of cladograms to deduce evolutionary relationships
cladograms can show evolutionary relationships + demonstrate how recently 2 groups diverged
- root: initial ancestor
- nodes: hypothetical common ancestor that speciated to give rise to 2 or more daughter taxa
- outgroup: most distantly related species in cladogram (point of comparison/reference group)
- clades: common ancestor & all of its descendants
