exam 1 Flashcards
What traits evolve … (according to darwin)
- must be inherited (lamark was wrong)
- must show variation between individuals (inbreeding reduces variation
- environment must exert some pressure on the traits (some variants must provide an advantage or disadvantage)
three types of finches
cactus eater, seed eater, and insect eater (each had varied beak size
Darwin’s evidence came from
homology, embryology, vestigial structures, biogeography, paleontology, comparative anatomy, and selective breeding
structural genes
code for structurally important molecules (hox genes, sonic hedgehog)
regulatory genes
code for structurally important molecules (proteins, fibers, etc.)
epigenetic and inductions
tissue-tissue interactions that have demonstrable effect on morphologies (ex: teeth)
genes encode for instructions of how to make RNA , RNA is read to produce what?
proteins, hormones, etc… the raw materials for tissue , organ, etc production
homeotic gene influence (hox genes) do what?
mediate epigenetic interactions
- also known as pattern formation genes
- segmentation genes for example
- serial homology (similar structure bc common ancestor)
- forelimbs/hindlimbs
___ genes are found in all segmented animals
homeotic
homeobox genes are found in…
arthropods (+annelids), vertebrates (many vertebrate HOX genes are found with drosophila primers)
Genotype
make phenotypes! are defined as simple traits, single genes, or whole chromosomes (sex determination)
two allele- one from the mother and one from the father
phenotype
outward manifestation of the genotype –> physical traits, enzymes, etc… xx female genotype = female phenotype, xy male genotype = male phenotype, 50 percent probability either gender
what are the three types of alleles in the ABO blood system?
recessive, dominant, and co dominant
individuals have two alleles
dominant allele
The allele posssed in a heterozygote
co dominant allele
when both alleles are expressed in a heterozygote
recessive
the allele that is not expressed in a heterozygote
obesity is a …
complex interaction between genes, environment, and phenotype, there are 32 genes associated with obesity
gregor mendel
plant experiments… established the idea of particulate inheritance (no blending) but NOT ALL TRAITS ARE MENDELIAN… discovered dichotomous variation..
mendel’s postulates about inheritance (1)
- hereditary characteristics are controlled by particulate unit factors that exist in pairs in individual organisms
- traits remain discrete (not diluted over time)
- because now we know their genes and the exact sequence of genes is preserved through generations
Mendel’s 2nd postulate
when an individual has two different unit factors responsible for a characteristic, dominant (expressed) recessive (not expressed) —> recall some phenotype traits are influenced by multiple genes
Law of segregation
no bias between maternal and paternal source
law of independent assortment
features are passes onto offspring individual of eachother
linkage
genes found on same chromosome closer = more linkage
crossing over
makes possible the independent assortment of linked genes
point mutation and sickle cell disease
whena single base in a gene is changed
trinucleotide repeat disease
insertion mutation or deletion of several bases in sequence of a gene. EX) huntington disease caused by CAG repeat (code for glutamine) 40-180 tiems on chromosome 4, autosomal dominant disorder
mutations can be
can be bad good or neutral.
bad = reduce ability to function causing mild reduction in fitness with lethal results
neutral = no change in protein form of function or slight changes with no effect on reproduction
good = increase “”
x linked disorders
result from mutations to genes on x chromosome - males more prone because 1 x chromosome… colorblindness, hemophilia, etc…
examples of medelian genetics in humans
widows peak, dimples, earlobes, darwins tubercle, hairy back , ptc
two types of non medelian genetics
qualitative variation: discrete, present/absent, two/four
quantitative variation: continuous, color, size, gradient differences
natural selection is defined as
The primary mechanism of evolution
other types of natural selection include
directional, diversifying, stabalizing
directional selection
selection pressure against one end of the population curve, results in a shift of the bell curve in one direction –> any variable.. size, color, etc
diversifying/disruptitive selection
against the middle of the bell curve, promotes success at either end of the curve
stabalizing selection
selection against both ends resulting in more homogeneous population –> common in generations after speciation events
the modern (evolutionary or genetic) synthesis
meetings to discuss why geneticists believe natural selection was wrong and why random selection was correct
what are some other mechanisms of evolution
gene flow, genetic drift, founder effect, and sexual selection
gene flow
movement of genes between populations
genetic drift
random change in frequency of a populaiton
founder effect
genetic bottleneck
sexual selection
differential reproductive success with one sex of any species
More about gene flow (alleles)
- movement of alleles among a population
- alleles can be transferred through movement of fertile individual gametes (pollen)
gene flow tends to…
- reduce differences between populations over tiem
- is more lilkey than mutation to alter allele frequency –direction
- can decrease the fitness of a population
with genetic drift, the smaller the population…
increased chance of deviation from a predicted result
genetic drift…(alleles)
- describes how allele frequency flucuates unpredictably
- tends to decrease genetic variation
- random change in population, thus unpredictable…so not due to natural selection
founder effect
- occurs when a few individ. become isolated from a bigger population
- allele frequency in the smaller population can be different from those in parent population
- new populations derived from bigger population not representative of original, parent population
bottleneck effect
sudden reduction in population size due to change in environment
resulting gene pool may no longer be reflective of original population gene pool
if population remains small, it may be affected by genetic drift
sexual selection
mate choice is not equally balanced
- typically the less common gender can choose from among many possible mates
- most species maintain 1:1 gender ration under normal conditions
- transiet differnce in sex ratios can have long term effect
- choice of features can result in significant changes in opposite sex (anatomy, behavior, etc.)
sexual dimorphism
typically a result of sexual selection different morphology (anatomy) between two genderes females exhibit choice more often than males resulting in unusual male morphologies
examples of dimorphism in class
peacocks: symmetry, handicap, survival
orangutan: size and facepads (secondary sex characteristic)
elephant seal: size/nose
how is sexual selection affected by social structure
polygamy and monogamy
polygamy
mating is promscious without strong pair/bonds
sexual dimorphism common
promiscuity is hormonally reinforced
monogamy
1 male and 1 female
sexual dimorphism not common
monogamy hormonally reinforced
selected for…
biological species concept: who? and what is it?
ernst mayr
any two or more animals capable of potentially interbreeding to produce fertile offspring and are reproductively isolated from other such group in nature
problems with bio species concept
not typically practicable - observable - in life
no concept of time (not possible to introduce a test if you try)
asexual species
phylogenetic species who and what?
GG Simpson
common ancestry defines the species lineage evolving independently of other species
problems w phylogenetic species
gray - how much difference is enough to warrant species distinction ?
exploitable
genetic species definition + prob
presence of unique alleles in a population
may or may not correspond w phylogenetic species and how many??
ecological species who + what
leigh van valen
niche defines the species (comparative in nature)
a set of organisms adapted to a particular niche in environment
may or may not form monophyletic group
possess discrete phenetic clusters that we recognize as species because ecological and evolutionary pressures
recognition/ mate-recognition species concept
essentially mediated by mating behavior or biology
identified after the fact
morphological species
based on morphological distinctions
may be from molecular or whole anatomy
…most common, paleontological species
reticulate species concept
a species breaks apart and becomes many species and then may re-form into a single species or possibly multiple species
- occurs constantly at all scales of space and time
isolating barriers - two types
geographic: extrinsic properties of landscape that prevent gene flow - allopatric - sympatric - parapatric
reproductive: features of organisms that prevent interbreeding
- barriers effective even in sympatry
- pre/ post-zygotic or pre/post-mating
pre zygotic isolation mechs
ecological, behavioral, temporal, mechanical, (all pre mating) and gametic (post mating)
ecological isolation
tions/ligers do not occur in wild
lion and tigers rangers overlap in india but they use different habitats
behaviorial isolation
blue-footed boobies select mates after elaborate courtship display
will not mate with other boobies
temporal isolation
hybrids can be made experimentally and are fertile
rare in nature because mating seasons differ
mechanical isolation
structure of male and female copulatory organs may be incompatible
- known in plans and animals
- domestic breeds create greater diversity than found in the wild
gametic isolation
external fertilzation. promotes gametic isolation (ex = fish)
surface factors and binding sites may prevent fusion of gamete
post zygotic isolation mechs
intrinsic: hybrid inviability, hybrid sterility, and hybrid breakdown
extrinsic: ecological inviability, behavior inviability
hybrid inviability
weak, malformed, non-function
hybrid sterility
mules! chromosome number problem, acromosomal reaction fails, abnormal reproductive anatomy, dysfunctional gamete
hybrid breakdown
F2’s and later.. multiple causes of reduced viability
ecological inviability
can be easily seen, like a liger in a tiger habitat
behavioral inviability
mating ritual doesn’t work
speciation
the evolution of new species –> diversification
pied flycatcher example
pied flycatcher and collard flycatcher appear very similar where they occur alone
in areas where they are sympatric, differences in color and pattern allow individuals to avoid hybridizing
geography of speciation
species is a two part process:
- initially identical population must diverge
- reproductive isolation must evolve to maintain differences
homogenizing effect of gene flow…
erases differences
speciation more likely in …
geographically isolated populations
three types of speciation
sympatric, parapatric, and allopatric
john maynard
developed first mathematical model for sympatric speciation by assortative mating among ecological morphology.
- one gene per trait model with three genes and three traits
1. ecological perfomance
2.resource choice
3. choice of mating sites
he demonstrated its difficult to create and maintain associations between matcing alleles at three gene loci because re-mixing
rhaogletis example
flies co evolved with plants : apples, etc..
why is sympatric speciation rare? what is needed?
problem is how to avoid intermediate genotype that will function as bridges for gene flow which would eliminate difference.
- need: polymorphism and assortative mating (look alike)
- problem: if these two are not genetically couple, recombination will eliminate the barrier to gene flow
euhadia shairs example
mutation in one gene –> shell spirals in opposite direction
= instant mechanical isolation = 2 species
subspecies
common throughout bio, an identifiable subunit of species (+/- = race.. but politically charged term)
- often geographically based, multiple unique traits, must have at least two
- subspecies are in the “eye of the beholder”
- … may be made-up of multiple populations
Deme
generally a subset of species or subspecies ( = population defined by genetics)
- population density, western hemisphere. note that political boundaries are largely arbitrary
population
generally a subset of species or subspecies that is identifiable based on some quantitative or qualitative criteria
recording human variation in past civilizations
- ancient Egyptian : recognize physical differences
- ancient greeks: Ethiopians = dark-skinned
- ancient roman: very little biological difference among its people
Monogeism-Polygenism Debate (about 18th to 19th century)
monogeism = all people of all races = single creation
polygenism = different races = terms of own evoltuionary history
environment = environment has power to shape anatomy of individual organisms
DARWIN KILLS DEBATE
RACE/RACISM
racism = a prejudicial belief that members of one ethnic group are superior in some way to those of another
Later in the 20th century - Franz Boas
phenotypic plasticity ( growth and sleep) lack of relationship between race and achievement
Biology of Ethnic (Racial) feature-
- skin color
- eye form
- hair color + form
- head shape
population genetics
study of genetic variation within and between groups of organisms
microevolution
study of evolution phenomena that occur within species
polymorphisms
ABO and other blood type systems
- two or phenotypes
maternal-fetal incompatibility
Human leukocyte antigen (HLA) system
A, B, AB, + O
first found during crimean war (1854-1856) British army surgeon kept records of successful blood transfusion
Both A B have
antigens (carbs) , O = no
antigen
stimulates immune response , especially production of antibodies produced by plasma B cells….
Gene flow and morphology
complex genetics of morphological traits makes gene flow studies problematic
- some traits = simply inherited = good for study = tooth shape and form
polymorphism and phylogenetics studies
phylogeny = an evolutionary tree indicating relatedness and divergence of taxonomic groups
- sample quality is critical
- polymorphisms can confound poorly sampled studies
evolution of lactose tolerance
genetics of lactose tolerance:
lactose/lactase
lactose/ malabsorbers
LCT *P
Explanations for lactase polymorphism
cultural historical hypothesis
lactose tolerance is an example of the interaction of biological and cultural factors
balanced polymorphism
sicke cell & other conditions
sickle cell = heterozygous advantage (fights malaria)
OTHERS: tay-sachs disease and cystic fibrosis
acclimization
the process of term changes in physiology that occu in response to changes in environmental changes
adaptability
ability of organism (individuals) to make changes after chronic exposure to stressful environmental and conditions - AKA phenotypic plasticity
parapatric speciation
speciation without complete geographic isolation and no clear isolation mechanism
no geographic barrier… speciation takes place on edges
clinal variation
ring species clinal variants, and sometimes several parapatric speciation events
ex) bears..
ring species
populations at end can no longer interbreed
ex)mountains
cladogenesis
speciation characterized by diversification and increased species number (branching)
anagenesis
essentialy “chronogensis” that results from accumulated change through time in a single lineage
Tempo and Mode..
darwin expected..
gradual divergence of species… lyell’s uniformitarianism influence. (sympatric/allopatry)
selection pressure = low
punctuality equllibrium
(eldridge + gould) is the rapid divergence of species followed by periods of relative stasis
-hopeful monsters analogy
-hox genes
selection pressure = high
direct fitness
number of copies of genome left in the next generation
indirect fitness
total including not immediate fam, nieces, nephews , etc..
inclusive fitness
direct + indirect fitness . explains appearance of group selection, atruisim, etc.
adaptation verb + noun
v: process by which inherited characters evolve in a population resulting in improved performance
n: a trait that has a functional role in life history of an organism and is maintained by natural selection
Enhance evolutionary fitness ( + maybe survival)
mathematical measure of genes contributed to subsequent generation
human adaptations examples
dark skin: in tropics = screens out UV radiation, reduces folate destruction, prevents sunburns, reduces risk of skin cancer
light skin: outside tropic = admits UV radiation, helps synthesize vitamin D, prevents rickets and osteoporosis
adaptationists
every feature is adaptive (now or in past) they’re wrong = spandrels of st. marco
biological spandrel exampels
human pelvis (holes), farm fox experiment (fur = not adaptive), music
adaptive radiationists
closely related species that have evolved from a common ancestor by adapted to different parts of the environment —>occurs = evolutionary innovations // in an environment with few species and many resources
natural selection acts at the level
of individuals.
group selection doesn’t really occur, though it can look like it does
fitness
mathematical calculation of an individual reproductive contribution to the next generation
1 diploid offspring = 0.5 , 2 - 1.0 , etc…
why do we study non human primates
behaviors are universal among modern primates and give us clues to our ancestors’ behavior –> allows the reconstruction of social structure, ecology, and intelligence of early humans.
compare and constrast primate social organization, communication, and intelligence –> interesting and my shed light on human diversity
better understand the environment factors that led to the divergence of the human lineage. —> environment affect behavior, and human culture exhibits diverse behaviors.
conservation of nonhuman primates NHPs
the evolution of behavior (3)
behavior has evolved through natural selection
- brain structure, organization, etc..
individuals act to maximize their own reproductive success - evolutionary success
behavior is the product of complex interactions between genetic and environmental factors - polymorphisms, environmental plasticity, etc..
studying primates
captive study (zoo) semi free ranging (jane goodall, food= affects behavior and time budget) field study (no provisioning) (lose group)
allogrooming (contrast: autogrooming)
reinforces male-female mate bonds
reinforces same sex friendships bonds
measurable physiological effects on both the individual being groomed and the one doing the grooming
Promiximate causes
hormonal or physiological reason to act
ultimate causes
deeper, evolved strategies that have been shpaed over millions of years of natural and sexual selection
two paradigms of studying primate behavior
socioecology and sociobiology
important primate behavior
dominance communication aggression affiliative reproducing and reproductive strategies mothers and infants NHP cultural behaviors (crab eating macacks) primate cognitive abilities
socioecology
relationship between social behavior and natural environment. Favors select for the individuals daily survival.
sociobiology
focuses on the genetic predisposition to behaviors and those behaviors’ enhancement of reproductive success.
evolutionary fitness
a component of sociobio. a quantification of reproductive success (% of genes left in generation)
natural selection acts on behavior…
the same way it acts on physical characteristics
behavior
is a phenotypic expression and genes may code for specific behaviors. directly or indirectly through neurological features.
provides opportunity to show the effects natural selection has had in shaping primate behavior.
Case study (sociobiology)
3 monkeys allogrooming
altruism
an action which increases (or potentially increases) someone else’s fitness while placing one’s own at risk
FAKE
genes… who else has our genes?
what effect does helping them have
inclusive fitnesss
the total effect an individual has proliferating its genes
coefficient of relatedness
the proportion of genes you share with a relative
ex) siblings 50%, cousins 12.5%
kin selection
the behavior associated with being altruistic preferentially toward relatives
socioecology
primatologists consider the following factors:
quality and quantity of different factors
distribution of food sources (relative with other species
activity patterns (diurnal v nocturnal)
relationship with other species
impact of human activities
environmental factors such as resource availability and predation
have strong influence on group size and structure
- multimale/female groups have an advantage when predation pressure is high
- adult males may join forces and chase and attack predators
- savannah baboons have been known to kill domestic dogs and attack leopards or lions
solitary forging may be related to…
diet and distribution of resources or predator avoidance
social behavior and reproductive asymmetry
femae philopatry (committment is longer) male philopatry
male reproductive strategies
dominance
have priority access to food and mating partners
many factors influence dominant status: sex, age, level of aggression, time spent in group, intelligence, motivation, and mother’s social position
female reproductive strategies
dominance
sexual receptivity signals
why are NHP social?
PARADOX OF SOCIALITY
- access to mates
- food
- avoiding predators
CONS = competition and altruism rewarded.
types of NHP societies
solitary monogamy polygamy fision-fusion polygamy (no pair bonding) (baboons at seasonal plant site) polyandry
poly andry
many males one female
primate origins
+/- mya (plesiadapis)
extant taxa
+/- 300 species of nonhuman primates are recognzied
size and form vary greatly
anatomical traits
grasping hands and opposable thumbs and big toes
flattened nails instead of claws
forward facing eyes with stereoscopic vision
generalized body plan
generalized teeth
petrosal bulla (hearing)
life history traits
single offspring
large brains - encephalization and neocortex
extended otegeny - lifecycle
sociality living in grups
behavioral traits
Activity patterns: diurnal, nocturnal, crepuscular (active during dawn and dusk)
sociality
living in groups
highly territorial
synaptomorphies (aka PROMISIANS)
Tooth grooming
grooming (toliet) claw
ansa coli (fermentation)
other : dental formula 2133/3133
lepilemurs
26 sp nocturnal, arboreal, hoppping
lemuridae
24 (+/- sp) diurnal, arboreal/ terrestrial, generalists
indriiae
19 sp VCL 2123/2123
DAUBENTONIIDAE
ONE SP,continuous incisor growth, omnivore, crepuscular, solitary
galagos and bushbabies
nocturnal, ominvore, small family groups or solitary
haplorhines
dry nosed primates
tarsers
dry nosed, lack tooth comb, 2133.1133
elongate tarsals (good jumpers)
phylogenic relationships ambiguous
platyrhines
new worl monkeys
small body size
three pre molar teeth
arboreal, prehensile tail in a few species
catarhines
old world monkeys
ischial callosites
estrus (in some )
bilophodont molars
new world v old world
lateral/flat nostrils v. nostrils point forward
Hominoids
increased encephalization
brachiation
extended ontogeny
increased social complexity
a guide to NHP
apes = gibbons (14 sp. indonesia and asia), orangutans(indonesia), gorillas (2 sp. africa), chimpanzees (2 sp. africa. bonobo (female dom + sexual) and chimps (male dom)), humans (1 sp. world wide)
diet
most herbivores
folivore
langurs and gorillas (leaf eating)
frugivores (+ nectar feeders)
marmosets and tamarins (fruit eater)
gramnivores
seed eaters (some baboons, orangutans, and hominids)
omnivores
galagos, bush babies, lorises, pottos, chimps
dietary and digestive strategy
strategic foraging
primate communities
like communities of other animals , are integral parts of the tropical rainforest ecosystems (Seed dispersal)
