test 3 Flashcards
sexual selection
selection associated with reproduction
what does sexual selection do?
explains extreme traits of males and females
who came up with sexual selection?
darwin
strategy
a behavior (or physiology) that can be different from another
optimality approach (or argument)
identify the strategy with the highest reproductive success
differences between males and females
females make larger gametes that males
sexual chromosomes are not universal
gamete hypothesis
behavior depends on investment in gametes
(aka: sperm takes less energy to make compared to eggs)
sex table (all other things being equal)
gamete size
relative energy per gamete
reproductive success is limited by
care in offspring
total investment
usual sex role
gamete size: eggs large; sperm small
relative energy per gamete: eggs high; sperm low
reproductive success is limited by: number of eggs/young for female; number of mates for male
care in offspring: higher (more often) in females; lower (more often) in males
total investment: usually higher in females; usually lower in males
usual sex role: females are choosers; males are courters
sex table shows that
sexes have different priorities
parental investment
resources parents devote to reproduction
what do parents invest in during parental investment
gametes
care/protection of mates
parental care (caring for eggs/offspring)
what do the sexes’ different priorities depend on?
on the relative investment of resources to producing successful offspring
choosers
select among prospective mates
courters
try to persuade another to be its mate
___________ should be individuals that have lowest parental investment
courters
courters should try to court individuals (of the opposite sex) with the ____________ parental investment
highest
____________ should be the individuals that have the highest parental investment
choosers
when do sex roles reverse?
where males invest more/investment is higher
2 types of sexual selection
male-male competition and female choice
(sexual selection) male-male competition
males compete directly for mates/fertilization
(sexual selection) female choice
females choose among potential mates
(sexual selection) what does female choice lead to?
more elaborate males –> male ornamentation and display
hermaphrodite
produces both eggs and sperm
when mating, it’s better for a hermaphrodite to be _______ since they invest ______ and can invest into _____________ more
male; less; reproducing
hermaphrodite compromise
when hermaphrodites are both male and female at once, they both can mate at the same time by working out truce
self-fertilization
lowers genetic diversity and gives advantage when moved to a new environment since they don’t need other plants to reproduce
optimal strategies for males
keep females from mating with other males
convince (or force) more females to mate with you
remove/kill the sperm of other males that have already mated with a female you are mating with
sperm competition
(optimal strategies for males –> keep females from mating with other males)
strategies
guard her until she has her offspring/lay her eggs
plug her up after mating
injure/poison her or shorten her lifespan
infanticide
killing of babies when left alone unprotected
when does sperm competition evolve?
when females are promiscuous (mate with more than one male)
monogamous
one-lifetime/one at a time mating partner
promiscuous
high number of mating partners
alternative mating strategies (when primary ones don’t work)
sneaky copulator strategy
satellite male strategy
sneaky copulator strategy
males team up to court females
satellite male strategy
males that hang around males that are calling and when the woman comes to call, first male will jump on and mate with them
what is the goal of satellite male strategy
to breed and not let her reach other males
optimal strategies for females
female choice favors evolution of “honest signals” of male quality
mate with male with the best genes
get males to fight over access to you
mate with males other females prefer mating with
mate with males that give you more resources
mate with several males
keep males from giving resources to other females
good-genes theory
mate with the male carrying the best genes
how to tell which males have the best genes
have immune system alleles that differ from hers
have fewer parasites
have bigger/showier ornaments
provide resources to the female
beat other males in fights
waste their resources
mate copying
prefer males they see mating, even if less colorful
why does mate copying happen?
mating with other females –> male sexy –> sexy sons –> more grandchildren
nuptial gift
resources given to females at mating
spermatophore
packet of energy-rich ejaculate
sexual cannibalism
female eats male if they don’t cooperate
male choice
males choose among potential (courting) mates
female-female competition
females compete for male
what is an example of equal investment?
monogamy
T or F: true monogamy is rare
true
T or F: female-female pairs are not common
false; they are common
extra-pair copulation
both sexes sneak off to mate
naturalistic fallacy
“If it doesn’t happen in nature, it must be immoral” and “if it happens in nature, it must be morally defensible” –> It does happen in nature and nature isn’t defensible/doesn’t have to relate to humans
intelligent design’s assertion
some traits are too complicated to have arisen naturally, so some intelligent being must have created them
arguments for intelligent design’s assertion
some traits are really, really complicated (scientific assertion)
if you take any parts away, they won’t work (irreducibly complex)
scientists haven’t been able to explain how they evolve –> so they couldn’t have –> must have been designed and created
simple transformation series
observed series of (+/- gradual) stages from ancestral to present-day forms
(trait’s function stays the same)
plausibility argument (when fossil record is incomplete)
series of (+/- gradual) stages from ancestral to present-day forms
(trait’s function stays the same; more data –> more plausible)
(plausibility argument) what if early/intermediate stages are non-functional?
early stages can have a different function
functional shift
function changes as a trait evolves
(functional shift) Darwin’s idea
numerous cases have the same organ performing at the same time wholly distinct functions –> organ that completes 2 functions
2 distinct organs sometimes perform the same function in the same individual
(functional shift –> Darwin’s idea) what does natural selection do when an organ is performing 2 different functions?
might easily specialize a part or organ which had performed 2 functions before –> one function
(functional shift –> Darwin’s idea) what happens when 2 distinct organs perform the same function in the same individual?
one of the organs might be modified and performed so it can only perform the task alone, then the other organ might be modified for some other functions or die
did life originate in some ‘primordial soup’ of chemical building blocks and lightning strikes?
no
age of earth
~6.4 billion years old
oldest bit of crust (zircon crystals)
~4.37 billion years old
oldest rocks
~4.2 billion years old
oldest fossil
3.456 billion years old
around when did life originate
between first candidates and oldest fossil periods
what is present day algae?
cyanobacteria
when did cyanobacteria evolve sophisticated photosynthesis?
2.7 billion years ago
when did the atmosphere reach high O2 concentration?
2.4 billion years ago
T or F: free oxygen (O2) is toxic in cells
true
what happens when proteins and many other molecules react with oxygen (O2)?
they oxidize and become denatured
present day earth and O2
high environmental O2 concentration
“oxidizing environment” –> widespread O2 available to bind
prebiotic earth and O2
low O2 environmental concentration
“reducing environment” –> O2 unavailable to bind
energy sources before sunlight
deep sea vents
deep sea vents were sources of “building blocks” for _____________, ___________, and ___________ _________
nucleotides; lipids; amino acids
what leads to faster reactions?
warm (not hot) temperatures
when the pH is low, what is high?
concentration
what does LUCA stand for?
last universal common ancestor
LUCA must have had
DNA
RNA with genetic code
proteins with 20 amino acids
plasma (cell) membrane
cell cycle (mitosis, cell division, etc)
biochemistry of complex metabolism (glycolysis, Krebs cycle, etc)
most viruses don’t have …
DNA
what is the hereditary material in viruses?
RNA
what does RNA do in viruses?
catalyzes reactions
carries hereditary material
ribosomes and tRNAs –> protein synthesis
what is a “small-subunit” ribosome made of?
2900 bases (A, U, C, G)
(protein synthesis) what is a layered structure?
stable 220-base core
does protein synthesis (poorly)
core duplicated –> 110-base fragment
(protein synthesis) tRNA
5-base RNA can do first step (bind to amino acids)
transcription –> done by protein synthesis (RNA polymerase)
can RNA copying evolve?
yes; it can copy itself as well
self catalyze
when small RNA’s copy RNA
how many bases is the smallest RNA?
40 bases
(artificial selective experiment) self-copying RNA will evolve to be more _________ in virtually all tubes, but _____ ___ in some tubes than others
efficient; more so
(artificial selective experiment) what happens to self-copying RNA after 10 cycles?
longer length
copying more efficient
differently in each replicate
(artificial selective experiment) what happens to self-copying RNA after 16 cycles?
shorter length
copying more efficient
differently in each replicate
original RNA fragment lost –> “irreducibly complex” –> evolved by selection
RNA world hypothesis
pre-DNA period where RNA created hereditary material
natural selection began as soon as RNA …..
began to self-catalyze
why do some RNA molecules copy themselves better than others?
because of their nucleotide sequences
T or F: nucleotide sequences differences are inherited
true
(before RNA world –> plasma membrane) impermeable
contents don’t diffuse away
(before RNA world –> plasma membrane) permeable
nutrients in and waste out
(before RNA world) diverse channel protein job
allow nutrients in and waste out
each channel protein does different things – specific jobs for each
why are membranes sophisticated systems?
they have to be permeable and impermeable at the same time
what do you need to ideally build the building blocks?
low-energy reactions (environment not too extreme)
what are big players in building building blocks?
H2O and HCN (hydrogen cyanide)
what is formed when H2O and HCN are combined?
NH2CHO (formamide)
what does formamide do?
combine to make bases (A, U, C, G)
with catalyst: formaldehyde (sugars)
with common mineral catalysts: amino acids and simple proteins
once you have nucleotides, RNA assembly is …
easy with mineral catalysts
where do nucleotides come from?
some self-assemble easily
where did metabolism come from?
nutrients in –> energy extracted and used –> wastes out
organisms need metabolism because it
acquires energy and nutrients
converts them to building blocks
assembles complex molecules
eliminates waste products
outside membrane has ______ concentration and inside membrane has ______ concentration
low; high
membranes _______ flow in and out of cell
block
what controls the flow of nutrients in and out of the cell?
proteins
astrobiologists
people that study the origin of life
family hominidae –> ___________ –> great apes
hominids
subfamily homininae –> _________ –> bipedal hominids
hominins
evolutionary tree of the hominins
Sahrleanthropus → ardipithecus → australopithecus → homo
when did Sahelanthropus evole?
~ 7 mya
when did Ardipithecus evolve?
~5 mya
bipedalism
opposable toes
T or F: human-chimp ancestors looked like chimps
false
when did bipedalism form?
during ardipithecus
features of australopithecus
flat, human-like foot
everything besides external features are well known based on reconstruction
what was Lucy?
an australopithecus
when did austrolpithecus garnhi evolve?
~2.6 mya
when did homo evolve?
~2 mya
what was so special about homo?
they were the first to have a large brain –> large brain size evolves
large brains become possible when …
meat becomes a bigger part of diet
what percentage of adult metabolism supports the brain?
25%
what independently evolved from australopithecus?
homo nadeli; homo floresiensis; homo luzonensis
what do homo nadeli, homo floresiensis, and homo luzonensis have in common?
smaller brains
different foot structure –> flat feet
when did homo nadeli evolve?
~350-250k years ago
what evolved in the last 800k years?
homo sapiens, homo neandethalensis ( → denisovans and neanderthals), homo altai
neanderthals
Eastern (AS) /western (EU) neanderthals (Switzerland)
Lived from ~400k-35k years ago
DNA based phylogeny
Had pale skin and red hair
denisovans
Known from only a few teeth and small bones
DNA reveals alleles for dark skin
lived in ~400k-70k years ago
From cave called Denisova
DNA sequences of humans, neanderthals and denisovans show
ancient human species interbred
modern human chromosomes carry small pieces of other species’ DNA
introgression
leakage of genes of one species into another
how many cases were there of interbreeding in early humans?
at least 6
T or F: there are NO pure humans
true
effect neanderthals had on modern humans
east and central asians and europeans come from neanderthals
~1.5-3% neanderthal DNA in europeans
what do the introgressed alleles in neanderthals do?
deleterious –> risks increase for: heart disease, skin cancer, depression
beneficial: pathogen resistance; more expected
effects denisovans had on modern humans
East and central Asians, Europeans, Australians and New Guineans → denisovans
~1.5-6% denisovan DNA in diverse humans
what do the introgressed alleles in denisovans do?
beneficial: protects against hypoxia (low O2) in high Himalayans; speculation about possible deleterious alleles
what is the maximum number of human species that coexisted on Earth?
at least 7
mitochondria
have their own DNA
inherited from mother via egg
what is the name of mitochondria DNA?
mtDNA
Y chromosomes
inherited via father only
there is a ______ diversity of human mtDNA in Europe and Asia
high
where could patterns from different groups of mtDNA on different continents come from?
natural selection (likely but not confirmed)
genetic drift
mutation
gene flow
where did the first ancestors of all modern humans live?
africa
mitochondrial Eve
woman who carried common ancestor of all humans’ mtDNA
mitochondrial eve had ____ daughters; one of them carried a ___________
2; mutation
______ diversity of Y-chromosomes in Europe and Asia
huge
where did Y chromosome variants start?
Africa; then spread to rest of world
Y-chromosome Adam
man who carried common ancestor of all living mens’ Y chromosome
Y-chromosome Adam had __ sons; one of them carried a __________
2; mutation
difference between mitochondrial Eve and Y-chromosome Adam are not so ____________ _____________
statistically different
T or F: mitochondrial Eve and Y-chromosome Adam could have easily lived at different times in different places
true
is “evolution is just a theory, so it may or may nor be true” a common misunderstanding?
yes
scientist to scientist theory definition
1) a mathematical analysis of the logic that underlies a complex explanation
2) a set of explanations that is supported by logic and fully tested by observations and experiments
if there are holes in a theory, then the theory is
incomplete
T or F: there has never been an observation in biology that is inconsistent with evolutionary theory
true
