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
