Readings Midterm 2 Flashcards
T/F
species are grouped into distinct species because there is a lot of variation
true
birds = size, shape, colouration, feeding habits, nesting habits
what does interbreeding help do
- the reason we have diversity
- highly variable offspring are produced
what would happen without interbreeding
- it would make all species distinct
- less diversity
- faster divergence between populations
- lack of intermediate forms = sudden evolutionary transitions like wings or limbs
= less of a continuum of forms
List the barriers to interbreeding
Prevent Mating
- geographic isolation
- mechanical isolation
- behavioural isolation
- gametic isolation
- temporal isolation
After Mating
- hybrid inviability
- hybrid sterility
- hybrid breakdown
Explain temporal isolation
different reproductive timings - cannot interbreed
- some flowers germinate in the summer and winter
explain behavioural isolation
animals not having the correct scent, courtship dance, appearance, etc for the female to allow mating
explain mechanical isolation
- before mating
- physical differences in the structure of reproductive organs that prevent mating from happening in the first place
- insects with different genital shapes or sizes can’t physically mate
explain hybrid inviability
- some species can interbreed with each other but the first-generation hybrids often fail to develop - can survive but at very low rates
- the second generation is not affected
- mules - donkeys x horses
T/F
barriers to interbreeding are likely by-products of changes occurring when a population has been geographically separated
true
- when darwins finches were exposed to new locations they = a new population = distinct
what allows new populations to thrive in new locations
- natural selection
- mutation
- genetic drift
they adapt to new environments
explain geographic variation with a human example
humans = numerous racial differences and skin pigmentations which = adaptations to living in different continents of the world - close to the equator = darker
what is migration
when some of the population diverges or remains
what happens to the genes when a population successfully interbreeds with a new population as a long-term effect
genes = homogenized = genetic differences between populations are reduced making them more similar over longer periods of time
T/F
if a species has low mobility it means it has high migration rates
false
low mobility = low migration
high mobility = high migration - can spread genes faster over larger areas
what is an example of a local adaptation
strong NS can make a species adapt to extreme environmental extremes
- plants that grow near mines with metal in the soil are selected very strongly for those who can withstand the metal in the soil
- now these plants thrive in the toxicity = metal tolerant and resistant
- without toxicity, they fail
give an example of gradual changes
- northern mammals (arctic animals) = have large body sizes
- a lower SA/V ratio for those who live in colder climates
- shorter ears
- shorter appendages
:. This conserves heat and it was adapted as species migrated over time
T/F species in different geographic locations experience different pressures
true
different locations = new challenges =
different adaptations = divergence
give an example of a selection pressure take can produce different adaptations to certain locations
humans in africa regions = malaria resistant
what is genetic drift
differences among populations through a random drift without any selective advantage
what’s an example of a genetic difference with no visible phenotypic difference
blood types
type A, B, O shows geographic variation
type b = India
type O = more frequent in some regions
what is gradual divergence
populations at the end of the species range have had a lot of divergence and changes to the point where they cannot interbreed if the intermediate population becomes extinct
- if the intermediate population becomes extinct then the species = distinct
what is a hint of reproductive isolation?
sterility of hybrid males
T/F early signs of speciation are hinted at through geographic isolation
true
- it the beginning of speciation (bc if they were to ever come back to the original location they could potentially reproduce again)
- having reproductive isolation completes divergence
In the situation with M. Lweisii and M. Carinalias, why does NS drive reproductive isolation
these are the same species but with different genus
they have different pollinator behaviours = which significantly contribute to reproductive isolation
- as pollination systems diverge - NS favours reproductive isolation because as each environmental adaptation is overcome it changes the genetic composition of the population
T/F genetic drift spreads variants with a lot of effects on fitness
false
- the variants = little effect
- if this variation is favoured it will not cause any harmful hybridization
= mating incompatibility - overtime interbreeding abilities from the 2 populations deteriorates as the genes diverge from each other
why do genes from different species become dysfunctional when brought together in hybrids?
When two populations diverge, their genes become different, and the result of interaction becomes hybrid sterility—when the offspring can’t reproduce viably.
why do some species have a faster evolutionary rate to speciation
sometimes in cases where the species have different behavioural, colouration and structural differences and align well with their new environments = rapid
- Galapagos finches, laboratory experiments
is it true that some species have lots of structural/behavioural differences but very little differences in their DNA sequences
yes this is true
- gene expression is different in the species causing these phenotypic differences
- mutations
- domestic dogs, Galapagos finches
is it true that some insects look very similar but do not reproduce with each other
yes - distinct species can have similar adaptations that make them look similar if they face the same environmental challenges
- EX: some insects look the same but do not readily mate with each other
T/F there is a perfect relationship between external traits and the strength of reproductive isolation
false - external phenotypic traits do not show the strength of the reproductive isolation
why are fossils not an accurate tool to see sudden evolutionary changes
they take too long to mould in water or soft material = fail to provide proper evidence and see the correct dates for these new changes
- they only track external changes
What is the best way to see if there is a relationship between species
DNA sequencing
what is the melanocortin receptor gene
a hormone receptor gene that is present across humans, chimpanzees, dogs, mice, pigs
- shows evolutionary relation between all these species
explain what silent changes to DNA sequences are
silent changes to genes = do not alter the protein sequence (amino acid codon) but can still = evolutionary divergence if it is beneficial and favoured by NS
- humans and chimpanzees = more silent changes
- a lot of the silent mutations spread through populations like genetic drift
what are replacement changes?
Replacement changes directly alter the amino acid sequence of proteins, which can affect protein function
- Replacement changes are often more significant in adaptive evolution because they produce functional changes that can help populations survive in diverse environments.
how are whole-genome sequences helpful
comparing the whole genome = more efficient = more rapid = better understanding phylogenetic relationships
what are neutral mutations and give an example
- no advantages - they fluctuate randomly in a population
- Because neutral mutations are not weeded out or selected for, they accumulate steadily and randomly in the gene pool
EX: fruitflies = mutation in gene colour variants = if the colour of the fruitflies mattered it would’ve been maintained by genetic drift
What are the 3 ways that most commonly lead to random gene frequency fluctuations
- some parents will choose to have more offspring - adding more of their genes to the gene pool - some will choose to have no offspring = with less gene pool variation
- genetic drift
- eventually, a population will either lose the alleles or become fixed for a trait - smaller populations are more affected - random inheritance and survival rates of individuals will impact what genes get passed on
what is the first and second effect of genetic drift
first: the allele frequency becomes either 100% or 0% - towards fixation or lost entirely
second: increase in genetic differentiation between populations –> might lead to speciation
what does the rate of divergence depend on
- the rate at which new neutral mutations arise (how often a neutral mutation gets passed to offspring)
- the rate at which genetic drift leads to the replacement of one version of a gene by another
- larger pops = more mutations per generation BUT = less genetic drift (these factors cancel each other out so :. the rate of neutral mutations determine the rate of divergence
what is the molecular clock
its a clock that helps to estimate the time divergence between species
To calibrate the clock you need to compare the DNA sequence from species with known divergence dates
why is it harder to compare species that diverge using proteins
protein sequencing doesn’t have all the mutations and all the information like DNA does (ex, silent mutations)
- it is easier to rely on slow evolving proteins like cytochrome C because it evolves steadily and a predictable rate
what is chronology
the order in which things were created
the first 2 divisions = eubacteria and archaebacteria
The next 2 divisions = angiosperms and ascomycete
- animals diverge much later - rodents, primates, carnivores
how do complex adaptions evolve?
- simpler models are refined over the years
- they adapt to work better and better
- minor changes throughout the generations that increase survivability and reproduction
how does evolution prove that proteins have evolved?
AA chains started with short chains with a few AA
- they improved as they evolved
- if there is a small number of changes to the sequence protein it could evolve to form a new function
how did complex enzyme reactions evolve
early organisms had a lot of chemicals in their environment and used them for enzymes to gradually evolve and be used to catalyze reactions
- without the external chemicals in the environment organisms evolved new pathways = evolution of complex pathways
:. simple –> complex
what is comparative anatomy
studying the anatomy of living species can reveal evolutionary relationships and adaptions with other past species
- EX: flying squirrels and bats = developed gliding = convergent evolution = prevents predation and enhances mobility
explain the evolution of complex eyes
- started with a patch of light-sensitive cells in the retina
- transparent cornea
- lens that focuses on light
- muscles that adjust for clear vision
simple vertebrates = can only detect light and dark
simple –> complex
T/F the light-sensitive protein = rhodopsin is also found in bacteria
true
it shows ancient origins that we also have
what is the theory behind the reason why humans age
aging results from the cumulative damage to systems necessary for the survival of the organism - and NS may not be strong enough to counteract this damage
- only the reproductive cells in multicellular organisms regenerate every generation but the rest of the body does not
- **aging evolves because there are selective pressures on traits that enhance early-life survivral
how does NS cause aging
- harmful mutations in early life are selected out for but if they occur later in life they won’t be selected out by NS
- beneficial traits that are good for early life will be favoured even if they have harmful side effects (reproductive hormones = increase fertility but may risk cancer)
why do species with higher mortality rates age faster
because NS doesn’t favour those who have higher rates and can not reproduce
- if a disease occurs later on in life it doesn’t matter because they have already had kids by then
T/F humans have evolved to have faster aging rates than other resembling species like chimps
false - humans now age slower than chimps
because of increased intelligence, social cooperation and reproductive maturity
what is kin selection
close genetic relationships (relatives) allow the reproductive success of relatives to indirectly help and increase the genes of sterile workers (those who can not reproduce)
- helping siblings or other close relationships indirectly helps your fitness of u even if you do not reproduce (they have similar genes to you - they’re fitness = your fitness)
- this is how NS favours those who do not reproduce
what is an example of kin selection
social insects like bees, wasps, and ants forget their reproduction and help their relatives to increase genetic success
- traits that increase the reproductive success of a colony are passed through queens are reproductive males
- overall it helps the survival of the whole group
what are some unsolved problems in evolution
- origin of cells (chemical basis - more complex molecules being made with the rapidly changing earth conditions - but how did we go from chemical to simple protein chains)
- the origin of human consciousness (evolved gradually with communication, self-awareness, language ability, learning from others, genetic mutations affecting speech and language control)
what do we know more about in terms of evolution and the advancements we have in 2024
we now know more such as:
- mechanisms of inheritance
- genetic information
- technology to code for entire genomes
- knowledge of hereditary
- range of behaviour - mental characteristics
T/F Are species done evolving?
false, they are not, species are still evolving from simple to complex
- evolution of aging
- some species are still = reduction of complexity (fish that lose eyesight because not needed in the environment)
is it true that NS can not foresee the future
yes it is true
NS is only favouring those traits that are good in the environment
- evolution is not direct
- evolution affects populations over time, not individuals
what are the 2 main reasons we have a large distribution of species
geography and climate
how is climate change affecting the distribution of species
warmer means species are moving towards the poles as it is colder
- but it is hard to move there because of physical barriers
what are dispersal limitations
barriers that prevent species from moving to new locations - hard for breeding and reproduction
- these barriers are the reason why we have global distribution of animals and plants
- the reason why giraffes are in Africa and not south America
- geographic isolation can also make unique species
the ___ of species is a result of evolutionary isolation and dispersal limitations across these regions
distribution
what are transplant experiments
when you introduce an organism to a new area
- shows whether species could survive in different regions
- if they thrive that means they were there before and their absence is because of dispersal limitations
how have humans impacted the distribution of animals/plants
accident/deliberate
- invasive species - imports/exports, human travellers, hitchhiking on clothes
- some species are introduced to act like a pest
- cane toad was introduced to control beetles but it became a pest itself
T/F there are dangers and benefits to introducing species
yes
what are some positive outcomes of the introduction of a new species
rainbow trout - improved trout fishing
sambar deer
is it true that the success rates of species have increased when more individuals are introduced at once
yes
- more population = more genetic diversity = more chance to overcome challenges and adapt
what are the steps to the invasive process
- transport
- establishment
- spread
- impact
failure at any stage = eliminates the new species or prevents the reproduction of them
what is an example of a situation that prevents the establishment of a species
predators may prevent the establishment
- the common mussel
- mussels are hunted aggressively because of crab and starfish
- the solution is to use mesh cages to protect the mussels
T/F climate is the limiting factor for species distribution but local ecological processes are still fully not known
true
what are trade winds
winds the blow from east to west - they help drive weather patterns
bag of juices
organisms = lots of chemicals
spatial distribution
the area that they can disperse to
is limited for every species because if the conditions are unsuitable = organisms cannot survive
Abiotic Vs Biotic
abiotic = non-living
biotic = living
“the big two”
water availability and temp
what is transect sampling
Sampling along gradient (soil moisture) to observe how species vary along environmental factors
enzyme
biological catalyst
very sensitive to temps
physiological (body) response to environmental challenges
Water = osmotic balance and takes place in almost all chemical reactions
Too much or too little water can = dehydration, dilution, or denaturing of protein
environmental equilibrium
organisms tend to reach their desired temperatures and moisture of their surrounding
- Organisms are vulnerable all the time - cannot control the environment
SA:V influences what in an organism
thermoregulation and osmoregulation
T/F if you have high SA:V you are more susceptible to environmental changes
true
endotherm
Endotherms are animals that produce their own body heat through internal metabolic processes.
stable internal body temperature regardless of the external environment.
*they can have a wide range of temperatures
need to eat more
ectotherms
Ectotherms are animals that rely on external sources (like the sun) to regulate their body temperature
- body temperature fluctuates with the environment
*eat less
Bergmann’s rule
Larger body sizes are more common in colder habitats as they retain heat better due to a lower SA/V ratio
allens rule
Animals in warmer climates tend to have longer appendages (ears, tails, legs)
This is to increase heat loss, maximizing the SA/V ratio
insulation
Using body fat, fur, and feathers for heat insulation - traps air - creates a temperature gradient that reduces heat loss
Feathers and fur can be adjusted in thickness with seasonal shedding - the warmer seasons = more shedding
countercurrent circulation
To retain heat - animals with extremities like whale flippers use this circulation method
arteries = warm blood from core to body
veins = cold blood back to core from body
what are some desert adaptations
- Kangaroo rats - get water from metalizing food - kidneys minimize water loss (ADP)
- Nocturnal habits + burrow use help avoid extreme daytime heat
- Water storage - store water to survive dry periods - developing deep and shallow roots to maximize SA and water uptake in plants
T/F plants desire a large SA for more photosynthesis
true
what is stomata used for
open and close for gas exchange and evaporation
what are the different pathways a plant can have
C3 pathway: common in temperature plants - inefficient in hot conditions because of photorespiration
C4 Pathway: evolved for water efficiency - common in grasses lie maize and sugarcane
CAM Pathway: found in succulents - stomata open at night to conserve water - they store carbon dioxide for use during the day
what is the laminar flow
- Smooth leaf surfaces
Irregular surfaces on leaves = turbulence, enhancing gas exchange (turbulent flow)
xerophytic adaptions
adaptions in dry areas - deserts
cacti = relying on small green stems for photosynthesis
- leaves = modified thorns (water conservation and predation)
- leaves drop in the dry seasons
Sclerophylly Puzzle
Describes plants with small, tough, thick and leathery leaves
Pine needles, leaves on some angiosperms like rosemary
- evolved independently across different habitats
