Midterm Flashcards
What are the three main questions in evolutionary thinking?
The unity of life, the diversity of life, the adaptation of life
What is a unifying theory?
A theory that is testable, applies to all levels of biology, is model able, is forward thinking, is fundamental, and is applied
Why is the history of biology important?
it is conflicting with many views of creationism
What is the tree of life?
an evolutionary map describing the relationships between all species
Why is the tree of life difficult to create?
Extinctions make for gaps in relations
What are nodes in a phylogenetic tree?
Speciation points
What do hatch marks mean in a phylogenetic tree?
All species to the right of the hatch mark share homologous characteristics
What is homology?
Similarity from common ancestry
What do changes in homologous traits indicate?
descent with modification (ex. cats, humans, whales, bats all have same structure of limbs)
Does homology apply to vestigial traits?
Yes (ex. even snakes have hips)
Does function = homology?
No. Independent evolution of a function often occurs
What is convergent evolution?
Independent solutions to similar challenges (ex. certain desert plants gaining CAM photosynthesis)
How does homology help map evolutionary lineage?
Identifying shared traits can help identify extant or extinct common ancestors
What is molecular homology?
homology of genetics
Why is molecular homology important?
Highly conserved genes can prove universal relationship and solve for early differentiation of life
How did continental drift help solidify evolution?
close relatives on different continents originally seemed to be divine creation. Vicariance can now be seen to be a product of continental drift
What are the 4 testable postulates?
Trait variation
variation in survival/reproduction
covariance between traits and fitness
inheritance of trait variation
What does heritability allow for?
evolution via natural selection
Does artificial selection still function of heritability?
yes
How has the Anthropocene impacted evolution?
Rapid environmental change causes rapid evolution
How do soapberry bugs change after the introduction of different fruits?
Beak lengths change to allow for bugs to specialize on different fruits
What is an individual?
A physiologically integrated individual developed from a zygote
What is a population?
A cohesive group of individuals
What is the gene pool?
the collection of alleles in a population
What is a species?
Individuals that could potentially meet and reproduce
How does phenotype vary within a species?
from allelic recombination, gene flow, and mutation
What is phenomorphism?
Allelic differences
What is continuous phenotypic variation?
Phenotypic variation caused by expression being controlled by multiple loci.
How are variation and loci related?
The more loci there are, the more variation there will be
How does influenza interact with epithelial cells?
It interacts with glycoproteins, resulting in endocytosis
Why is influenza hard to vaccinate for?
It is complex, rapidly evolving, and differentiating
What is a promising method for developing a universal vaccine?
Attacking stem antibody CR9114
What are the reproductive differences between microbial vs multicellular organisms?
Microbial organisms produce rapid generations whereas multicellular organisms have high variance in offspring
Why is it difficult treatment targeting the CR9114 antibody?
CR9114 is highly exclusive and needs a perfect fit
What does inhibiting CR9114 do?
It prevents the fusion of vesicles containing new viral particles to the membrane
What are the two most likely vectors of SARS-COV2?
Pangolins and bats
Why was SARS-COV2 so dangerous?
it differentiated rapidly after 2020
How did the majority of SARS-COV2 variants die out?
Evolution to extinction
How did omicron differentiate?
It came from the trunk of the SARS-COV2 lineage, meaning immunocompromised individuals had harboured early strains, allowing for differentiation
Why do we study evolution?
To explain where we came from and where we’re going
To undestand and protect biotic diversity
To recognize significance of variation between species and within populations
To engineer new products and tools
How is evolution a unifying theory?
Because biology doesn’t make sense without evolution
What evidence is there for evolution?
Historical, experimental, contemporary, fossils, homologies, analogies, vestiges, biogeography, and direct observation (disease, artificial selection, and adaptation).
What is one of the best examples of evolution in agriculture?
Brassica Oleacea. The wild mustard being bred to exhibit specific traits led to broccoli, kale, cabbage, wok choi, brussel sprouts, ets…
Can a phenotype appear outside of the ancestral range in artificial selection?
Yes, when mendelian genetics are more complex.
Can a trait hit an evolutionary max?
Yes, in simpler traits.
What did the corn experiment in illinois show?
The oil content of corn can go far beyond ancestral ranges, showing that multigenic traits can go beyond ancestral ranges, but simple traits can’t
What is phenotypic plasticity?
Adaption to the environment
What is evolution?
Descent with modification
What is descent with modification?
The idea that living species are descendants of ancestral species that were different from the present day ones. The change in genetic composition of a population from gen to gen
Which greek philosopher proposed animals are perfect and permanent?
Aristotle
Who was Carolus Linnaeus?
A Swedish physician and botanist who sought to classify life’s diversity. Developed the binomial system and used a nested classification going from general to specific.
Why are fossils important?
They are traces of organisms from the past found in sedimentary rock, which is formed from compression. This shows the organisms alive at the time that the sediment formed
How did Hutton and Lyell influence Darwin’s thoughts on evolution?
They proposed the idea of large change through gradual processes
What is Lamarck’s hypothesis of evolution?
That there is use and disuse of traits. Some traits become stronger through use, and some disappear. And there Is inheritance of acquired traits. Organisms can pass on the modifications made to their offspring
In. what ways was Lamarck correct and incorrect?
He had the idea of gradual change over time correct, but his mechanism was wrong. Acquired traits are not heritable
What was Cuvier’s observations in regards to strata?
The older the strata, the more dissimilar the life forms were to current life forms. Some species appear, while others disappear. He explained that the disappearance and reappearance of species resulted from extinction events and immigration.
How is evolution supported by drug-resistant bacteria?
The use of antibiotics has allowed for the selection of antibiotic resistant genes. This results in these genes gradually becoming the dominant phenotype.
How do homologous traits support evolution?
They show common ancestry and divergence
Why is evolution only a theory?
Aspects such as speed of evolution are still being criticized. Natural selection isn’t the only aspect involved in speciation.
What is sampling error?
Random bias due to small sample size
What is a Founder Effect?
When a population is founded from a small number of individuals from a different population
What is a population bottleneck?
When a population crashes and regrows, the alleles are not representative of the old population.
What is Genetic Drift?
Individuals make uneven contributions too the next generation, resulting in allele flux. The smaller the population, the more drift there will be.
What is Gene Flow?
The movement of genes between populations. Reduces genetic differentiation. Doesn’t take much to preserve variation.
What is phenotypic selection?
The connection between phenotypic variation and fitness
What is directional selection?
Shifts the overall population makeup by favouring a more extreme variant
What is stabilizing selection?
Removes extreme variants and preserves intermediate variants. Ex. large and small babies die so stabilizing selection has produced more intermediate weights
What is disruptive selection?
Selection that favours extreme variants. Ex. Darwin’s Finches
What would be the genotype in a population without variation in fitness?
HWE
Why is HWE unrealistic?
Sexual selection exists and causes sexual dimorphism
What is ornamentation indicative of?
High genetic quality, high fitness, high access to resources.
What were Darwin’s big ideas?
Variation among individuals in breeding groups
Variation influences survival and reproductive fitness
If variation is heritable then subsequent generations will be better adapted than their forebearers.
How long had Darwin been sitting on the theory when Alfred Russell Wallace wrote to him?
20 years
What was the problem with variance?
Darwin didn’t understand genetics and Mendel only kinda understood genetics
What is HWE
Genotype and Gene Frequencies are constant unless something is changing. p^2+2pq+q^2=1. Requires no mutations, immigrations, selection. Requires large randomly mating population.
What is the modern synthesis?
Darwin+Mendel. microevolution to macroevolution.
How is adaption explained?
Microevolution
What is the driving force of evolution?
Natural selection upon phenotypes
How is environmental stability related to parent offspring similarity?
Stability promotes greater parent offspring similarity
What happened in the drought of 77?
In Daphne Major a drought caused the availability of seeds to change, resulting in more hardy seeds, meaning bigger-beaked birds survived. R^2 between parents and offspring was 0.6
What are plasmodium?
The parasites that cause malaria
When did malaria originate in the human population?
100 000 years ago
What is the relationship between community and Malaria?
Community gives mosquitoes and parasites the perfect opportunity to thrive
What type of organism is plasmodium?
A single-celled eukaryote
How do plasmodium enter humans?
Through mosquito bites
What is the first area of the body that plasmodium target?
The liver. they breed in liver cells and then lyse them, entering the blood as merozoites
What do plasmodium do in the blood?
They breed in RBC, release gametocytes, fertilize an egg which the mosquito sucks in
What do plasmodium do in the mosquito?
A zygote is formed and becomes and oocyte, which then releases sporozoite.
What is microevolution?
Evolutionary change below the species level; change in allele frequencies in a population over generations/
What is genetic variation?
Differences among individuals in the composition of they genes or other DNA segments
How is genetic variation at the whole-gene level quantified?
As the average percentage of loci that are heterozygous.
Why does genetic variation at a molecular level usually not result in phenotypic variation.
Much variation occurs within introns
What is phenotype the product of?
The inherited genotype and many environmental influences.
Can non-genetically determined phenotype have evolutionary consequences?
No
What are the sources of genetic variation?
Formation of new alleles, alterations in gene number or positions, Rapid Reproduction. Sexual Reproduction.
How are new alleles formed?
By mutation
How do harmful mutations persist in diploid organisms?
The remain hidden by a dominant allele, allowing from propogation
What is neutral variation?
Variation with no advantage or disadvantage
In what type of cells can mutations occur that can be passed on to offspring?
In cell lines that produce gametes
How do increases in Gene numbers or positions occur?
Errors in Meiosis
How does rapid reproduction allow for more variation?
Allows mutations to accumulate faster
How does sexual reproduction allow for variation?
Many combinations of alleles exist, along with crossing over and random fertilization
What are the forces of non-equilibrium?
Geme flow, fitness difference, non-random mating, genetic drift
What are thalassemias?
Autosomal recessive disorders affecting both alpha and beta chains of haemoglobin. Point mutations and deletions. Homozygous have anaemia
What is sickle-cell anaemia?
A change from glutamic acid to valine at position 6/146 in haemoglobin leads to sickling
How are anaemias beneficial in areas at risk for malaria?
Heterozygous allows for resistance as the plasmodium cannot complete its lifecycle
What is responsible for the majority of the complexity in organisms?
Sexual reproduction
What is the most complex non-eukaryote?
Bacterial mats
What is the last asexual animal?
bdelloids rotifer
How do bdelloids share genes?
Through membrane
What indicates that sex is ancient and inherent?
Key sexual genes are present in every eukaryote and are basal
What is the only thing more ancient than sex in eukaryotes?
The mitochondria
How does stress drive sexual reproduction?
Through ROS
What does isogamous mean?
Gametes are equal size
What does anisogamous mean?
Gametes are unequal sizes
What are the benefits of small gametes?
Increased motility, increased numbers, higher probability of encounter
What are the benefits of large gametes?
increased probability of survival
What are the detriments of small gametes?
Decreased probability of survival
What are the detriments of large gametes?
Decreased motility decreased numbers
What are the benefits of mating types?
It acts as a check on inbreeding and allows for increased variation
What is problematic about sexual reproduction?
Mitochondria are competitive, very inefficient, low prob. of fertilization, direct conflict and injury in mating, missed opportunities for survival activities, increased predation risk., STDs, competition for mates, antagonistic genes
What are the benefits of sexual reproduction?
Novel genetic combinations, favourable allele combinations
What happens to mitochondria in clonal reproduction?
The best mitochondria prosper
What is selected for in mitochondria in sexual reproduction?
Docility of the mitochondria
What are the two main factors that drive differences in sex due to anisogamy?
Offspring care and energy requirements and the mating system
Why doesn’t ornamentation make sense in natural selection?
It leads to decreased survival, uses increased energy, leads to increased predation
What is intrasexual selection?
same-sex combat
What is intersexual selection?
Mate choice
What was sexual selection critiqued?
Victorians believed in female passivity and that sexual differences were just female inferiority
How does the number of sexual partners impact offspring for males?
increased offspring
How does the number of sexual partners impact offspring for females?
No change in number of offspring
What is Bateman’s principle?
Males have increased variance in the number of mates than females, creating correlation between number of mates and reproductive success
Why are females choosier about mates than males?
They put more energy into gametes and into offspring care
What did Trivers hypothesize?
animal behaviours result from which sex invests more into reproduction (sex that is the limiting resource invests the most offspring into reproduction, and the other sex is more opportunistic)
In what cases are males choosier?
When males invest energy into raising offspring and creating a nest
What is odd about the case of the stickleback?
Males do literally everything
What can be inferred about evolution from sexual selection?
The choosier sex drives evolution
What is a species?
A group of populations who have the potential to breed and produce viable offspring in nature, not just in a lab. Offspring must be fertile?
What is a pre-zygotic barrier?
A barrier to the formation of a zygote
What is a post-zygotic barrier?
A barrier that prevents the viability of offspring
What are the three species concepts?
Morphological, phylogenetic, and ecological
What are the phases of speciation?
Separation, divergence, and reproductive isolation. (mutations diverge, gene flow converges, and drift diverges)
What is allopatric speciation?
A true barrier between poulations
What is sympatric speciation?
Not true separation
What is dispersal?
Founders move away from population
What is vicariance?
Geography evolves to separate
How does sympatric speciation occur?
Specialization based on different resources
How much genetic change is needed for speciation?
Very little. Even one gene change can result in 2 species
What results in rapid speciation?
Meiotic errors
What is fusion?
The collapse of reproductive isolation
What is stability?
Good progeny
What is reinforcement?
Poor viability of progeny
How did life come about?
inorganic->organic->self-replicating organic->aggregates->progenotes
How did the first eukaryote come about?
Progenotes gave rise to LUCA, bacteria arose, archaea arose, archaea encapsulated DNA, genetic separated from the rest of the cell, FECA, protists, endosymbiosis
How did protists evolve into plants, animals, and fungi?
Evolved into opisthokont, which evolved into fungi and metazoa, and evolved into photosynthetic organisms like plants
How any times did plants colonize land?
Only once
What did early plants use for nutrients?
Symbiotic fungi
When did animals colonize land?
After plants, as they were reliant on them for survival
What is the fossil record?
Mineralized and frozen remains of organisms that we can date using C-14 ratio. The ecology is inferred by the contewxt
What percentage of species are extinct?
99%
What is the rate of change of populations with respect to time?
births-deaths/t
How would one determine the number of species alive?
of speciation events - # of extinction events
What did continental vicariance cause?
Rapid speciation, new habitats, extinctions
What are mass extinctions?
Periods of great extinction cause by rapid environmental change
What is the 6th mass extinction being caused by?
Humans
What is adaptive radiation?
A period of rapid evolutionary change where organisms form many new species in order to fill ecological niches
What causes changes in phenotypes?
Differences in gene regulation and expression
How do complex traits evolve?
From multiple genes, independently
Is evolution goal-oriented?
No. Branching is speciation, pruning is extinction
What is taxonomy?
A hierarchal classification
How were early trees constructed?
Appearence
Can an extant species evolve from another extant species?
No
Do primitive species exist?
No
what does monophyletic mean?
All members of group share a common ancestor, and all lineages that share a common ancestor are in that group
What does paraphyletic mean?
All share a common ancestor, but not all lineages are represented
What does polyphyletic mean?
Members don’t necessarily share a recent common ancestor
How are trees built?
From homologous characters
What is the outgroup?
A group used to polarize the others. Least similarity.
How can DNA, RNA, and proteins be used to determine relationships?
Slow mutation rate shows early evolution and divergene
What is parsimony?
Simple is best. The tree that requires the fewest character state changes in the one that most likely happened
What is a cladogram?
A tree that shows a sequence of events
What is a phylogram?
A tree where branch length is proportional to genetic change
What is the molecular clock?
DNA sequences attain mutations at a steady rate, so divergence occurs regularly.
Can hydrophilic signals be dissolved in aqueous fluids?
yes
Can hydrophobic signals be dissolved in aqueous fluids?
No
When can hydrophobic signals be released from cells?
Whenever they get a signal
How do hydrophobic signals travel through plasma?
They require a carrier protein
How do hydrophilic signals interact with a cell?
They bind to an external signal in order to elicit a response
What are hydrophobic signal receptors found?
Inside the cell
How do water soluble signals bring about a response?
By a signal cascade
How do lipid soluble signals bring about a response
By directly influencing trasncri[ption and trasnlation
Are protein factors water soluble?
Yes
What are factors that travel through the blood called?
Hormones
What are the elements ofn endocrine signalling pathway?
Synthesis, secretion, transport, reception, transduction, response
What is synthesis?
The process through which a ligand is synthesized in an endocrine gland
What is secretion?
The process through which a ligand escapes the tissue
What is transport?
The process through which the ligand makes its way to its target tissue
What is reception
The binding of a ligand to its target receptor
What is transduction?
The connection of a receptor to an effector
What is the response?
The ultimate consequence of a signalling cascade
What are the two protein carriers?
Albumin or globulin
What happens to the receptor after binding?
Conformational change that promotes trasnduction. Ex enzyme function or better docking site.
How are receptors specific?
They only bind to things that resemble the natural ligand
How do receptors alter their sensitivity to hormones?
By changing affinity or changing how many of them there are
What are mimetic?
compounds with structural similarities to ligands
What are agonists?
Mimetics that trigger the same response
What are antagonists?
Mimetics that block the natural ligand from binding
What is phytoestrogen?
A mimetic that resembles estrogen in plants. it inhibits or activates estrogen products
What are all receptors comprised of?
Proteins
What are antagonistic hormones?
Hormones tha thave opposite functions
What are tropic hormones?
Hormones that regulate the levels of other hormones
What are exocrine glands?
Glands that secrete their products outside of the body
What are endocrine glands?
Glands that secrete their product within the body
What is the hypothalamus?
A collection of neurons organized into nuclei with dendrites that receive and axons that send
What is the posterior pituitary?
A collection of termini of axons coming from the hypothalamus. Secretions are made in the hypothalamus and capillary beds in pituitary are used to send hormones to the rest of the body
What is the anterior pituitary?
A region of the gland that communicates with the hypothalamus via portal vessels. Tropic hormones from hypothalamus cause the anterior pituitary to release pituitary hormones
What is the adrenal gland?
A gland where the medulla releases catecholamines and the cortec releases steroids
