LAB CHAPTERS 1-5 Flashcards
How do you understand if a certain trait is an adaptation?
Not always clear, but you can look at phylogeny to understand more about the sequence of traits that evolved
Adaptations for viability
Traits that lead to success in survival and acquisition of food ex. locomotion, predator or parasite avoidance, tolerance of ambient conditions,
Adaptations for Competition for Mates
often leads to evolution of differences between females and males in secondary sexual characteristics (other than testes and ovaries)
Complete Metamorphosis
- very active, ravenously hungry larvae
- egg, larva, pupa, adult
- Coleoptera, Diptera, Lepidoptera, Hymenoptera (beetles, true flies, butterflies/moths, bees/ants/wasps)
Incomplete Metamorphosis
- nymph is a mini adult (only distinguishable by size and presence of wings)
- egg, nymph, adult
phenotypic plasticity
a single genotype can produce different phenotypes in response to its environment
What is an organisms overall phenotype composed of?
Morphology, behaviour, and physiology
Example of trait expressed by single gene
sickle-cell anemia
Continuous phenotypic traits
Result of interaction between multiple genes and often the environment. Ex. height, skin colour
Another word for quantitative traits
Polygenic traits
Polygenic trait
Trait whose phenotype is influenced by more than one gene, display a continuous distribution (each of the genes may have a large or small impact on phenotypic expression)
acclimation
When individuals are able to alter their phenotype in response to environmental variation in a manner than improves fitness (showing phenotypic plasticity)
NOT ADAPTATION
Examples of discrete phenotypic plasticity and continuous phenotypic plasticity
discrete phenotypic plasticity: desert annual plant produces either hard, dormant yellow seeds very quickly when days are long, or soft, green seeds when days are short and development is generally slower.
- yellow or green (dormant or not dormant)
Continuous phenotypic plasticity: number of nitrogen fixing nodules produced by legume plant differ in different soil conditions,. Lower nitrogen levels = more nodules
Reaction norm
Term to describe relationship between the environment and trait in question when the phenotypic plasticity expresses itself in a continuum.
Why aren’t all traits phenotypically plastic?
- insufficient genetic variation exists in the population for the evolution of plasticity to occur
- inherent costs and limitations to the benefits that plasticity may provide (maintaining right sensory and regulatory mechanisms to actually respond to environment accurately)
- linkage between genes might produce a situation whereby genes promoting plasticity might be linked to genes conferring a low fitness for other traits
Limitations to producing new phenotypes
- incorrect assessment of environment possibly producing wrong phenotype
- lag time in producing the phenotypic change (the larger the change the greater the lag time)
What selects for phenotypic plasticity
Heterogenous environments
Another word for stereo microscope
dissecting microscope
Difference between stereo microscope and compound microscope
Stereo
- three dimensional view of object (like how left and right speakers produce stereo sound)
- less magnification
Compound
- 2 dimensional view of slide
- 40 - 1000 x magnification power
- 3 knobs
ocular micrometer
small glass disc inside the ocular on which uniformly spaces lines of unknown distance are etched
- calibrated against a ruler
Calculating magnification
number of mm on stage (visible from ruler) / number of spaces on ocular
Measurement in mm
number of ocular units x length of each ocular unit
phytochrome
photoreceptor that detects shading by other plants
What elicits a response from phytochrome?
when plants are shaded by other plants the ratio of red light to far red light is reduced and phytochrome regulates gene expression by activating a different set of genes
magnification of specimen with compound microscope
equal to magnification of objective lens x magnification of ocular lens (eyepiece)
Devil’s gardens
stands with only one species of tree, ants living on the tree provided a home for the ant and in return the ant injected poison into leaves of other plant species thus reducing competition for resources between plants.
consumer-resource interaction
predator-prey, parasite-host, herbivore-plants
Categories of defensive traits in plants
- timing of flowering or leaf production
- structural defences
- chemical defences
Constitutive defences
Defences that are consistently expressed over time
Induced defence
Traits that are produced or increase with herbivory damage (one chemical is produced in response to damage like jasmonic acid which then triggers production of other defences)
Difference between glandular and non glandular trichomes
Glandular trichomes have a gland on top of the stalk that contains a chemical that is released upon contact.
What affects genetic diversity of populations in the great lakes
size-selective fishing gear, habitat elimination, alteration of prey species, pollution stresses, construction of artificial barriers
What makes populations more homogenous
more gene flow
Decline of the Great lakes fishery
- fish populations greatly reduced
- they look a bunch of sperm and eggs from small number of native fish and reared them until they were sufficient length to be released
- this greatly reduced the genetic diversity of the population (founder effects limit adaptive potential of a species)
Concerns with hatchery raised populations
- founder effects
- introduced diseases and competition that the native species have not had to deal with
allozymes
different forms of the same enzyme (allelic variants)
- differ structurally but not functionally
What causes change in mobility in enzymes
Enzymes of the same size and shape move at a rate determined largely by the ratio of positively-charged to negatively charged amino acids.
monomeric enzyme
produces one polypeptide chain which is a fully functional protein
- in gel electrophoresis you will see different types of bands depending on the individual:
- one thick band for SS slow homozygote closer to origin
- one thick band for FF fast homozygote further from origin
- two thinner bands for an FS individual (because two polypeptide chains were produced)
What is polymorphism and why is it an inadequate descriptor of genetic variation?
The proportion of loci examined that show evidence of more than one allele. Sometimes gene locis are designated as invariant or monomorphic because the most common allele has a frequency greater than 0.95. 0.95 is an arbitrary cutoff and has no real biological basis (could easily be 0.98 and then polymorphism would change)
Dimer
each allele at a gene locus produces a single polypeptide chain which is inactive until it forms a dimer with another chain (three variants)
Whats a better measure of genetic variation—polymorphism or heterozygosity?
Heterozygosity because it is not subjective.
Heterozygosity
average frequency of heterozygous individuals per locus of the population calculated by determining frequency of heterozygotes at each locus then averaging these frequencies over all loci.
Do vertebrates of invertebrates have more genetic variations?
Invertebrates (excepting self fertilizing plants) but humans still have great evolutionary capacity with 7% heterozygosity.
Divergent populations or separate species show I value of… and D value of?
I less than 0.8 and D value greater than 0.2
Most important response to a newly introduced pest
determine species identity of the invader and its geographic origin
Why might populations of zebra mussels vary in their ecological tolerances and response to control methods?
high genetic variability
Differences between Zebra and Quagga mussels
Shell shape, different banding patterns, heterozygosity (zebra has higher H and quagga lower maybe because of lower original H or a small founding population), genetic distance is 1.215 between the pops, quagga have a narrower genetic base for differential response to the environment, must have different life history parameters if they coexist
What demonstrated that Zebra and Quaggas are different species?
No mussels were found with allozyme patterns intermediate between quagga and zebra indicating that hybrids are not readily formed
Systematics
study of the diversity of organisms
Taxonomy
theory and practice of ordering the diversity of life into a classification system
Phylogenetic systematics
Method for reconstructing evolutionary relationships. Implies relationships among groups of organisms that are derived from a common ancestor
What will give you the most informative classification of a group of organisms if you are trying to to determine true evolutionary history
Phylogenetic systematics clusters organisms into groups based on modified characters that are shared by members of the group. A wide character base will be most likely to give you true evolutionary history.
Assumptions of systematic phylogenetics
- evolution occurs
- there is a single phylogeny of life
- characters are passed from generation to generation, modified or unmodified, during evolutionary descent
homoplasy
when a character evolves more than once so that it occurs in more than one species although not in their most recent common ancestor. NOT similarity resulting from common descent.
Examples of homoplasy
Convergent evolution can cause homoplasy (fake homologous structures), and so can character reversals (when a species re-evolves the ancestral character state)
Shared derived characters are used…
to infer evolutionary relationships
What is derived at one level of analysis…
might be ancestral at another level and vice versa (feathers in birds is a shared derived character when comparing them to land vertebrates but it is an ancestral traits when looking at birds and gives no evolutionary relationship)
binary characters
either absent or present (coded 0 or 1)
multistate characters
more than two different states (coded 0, 1, 2, etc)
- usually treated as unordered because we don’t know sequence of evolutionary events
Ordered vs unordered characters
Subset of multistate characters. Ordered characters follow a logical sequence like bird beak size (small to medium to large) whereas disordered characters follow no logical evolutionary sequence (colour change in coral reefs)
outgroup comparison method
used to determine which traits are ancestral
assumptions are:
- any homologous character state found in the ingroup and outgroup is considered ancestral for the ingroup
- character states found in the ingroup but not the outgroup are considered derived
taxon
identifiable category of organisms
How can you identify homoplasies?
Lack of congruence with phylogenetic hypotheses, can really only be identified after the analysis is completed.
Ingroup
group of taxa that is the focus of study (share an ancestral species not shared by any other taxon)
outgroup
More distantly related group of organisms that serves as a reference group when determining the evolutionary relationships of the ingroups. Used to determine which of the two homologous character states may be inferred to be derived. Preferred outgroup is a sister group.
Parsimony
principle which forces one to accept the shortest tree that explains all the character states
Sister group
taxon hypothesized to be the closest relative tp another taxon
