Lecture 9/10 Flashcards
are all characteristics developed
yes
what are types of environments
- unconstrained
- patterned
- constrained
What are unconstrained environments
- environment is supportive
- individual achieves full potential
What are patterned/channeled environments
- growth is shaped by environmental pressures leading to developmental adaptations in response to challenges
what are constrained environments
- phenotypic plasticity does not allow for a complete adaptation
- growth is constrained and the full impact of the challenges depend on timing and severity of the insult
What is the baby’s first environment
mother
what marks the relationship between mother and unborn offspring
- constraints in quality of mother’s environment = quality of fetus’ environment
- conflict of interests between players involved
______ and _____ will depend on the ______ and ______ of the constraint
adaption, survival, nature, intensity
True or false: prenatal constraints tend to affect post-natal phenotypes
true
What do post natal phenotypes from constraints may represent?
- unavoidable costs of prenatal constraints
- the costs of prenatal adaptations to those prenatal challenges
- predictive adaptive responses
What does it mean when unavoidable costs have unavoidable results
- no benefits associated - the result of not having enough resources
- ex: small phenotype could be because of scarce energetic resources
What does the costs of prenatal adaptations mean
- surviving in utero require changes in developmental trajectories - trade offs such as lower quality post natal phenotype
- ex: prioritize development of brain rather than body
- (may be mediated by phenotypic plasticity)
What are predictive adaptive responses
- phenotypic changes that do not provide immediate advantages but may aid with predictable future challenges
- (can be mediated by phenotypic plasticity_
What is plasticity ?
change phenotype according to environment
explain Daphnia helmets/water fleas
- grows head and spokes with exposure to pheromones that it is developing near predators
- Less energy in belly, more to the spike = smaller belly
What is the intra-genomic conflict hypothesis
- predicts different replication strategies by individual genes within a genome leading to conflicts that affect the phenotype
- could result from different transmission strategies within parent or competition between genes of different parental origin
What is meiotic drive
- segregation distortion during meiosis - some alleles overrepresented in oocytes
describe segregation distortion
…..
true or false: genes are not part of other genes’ environment… if false explain
FALSE
- the presence of particular alleles on the genome can affect transmission of other alleles
- the presence of particular alleles on the genome can affect expression of other alleles
What would benefit maternal genes
- maximize inclusive fitness of mother
- modulate investment according to offspring quality
- sensitive to tradeoffs between offspring quantity and quality
- sensitive to tradeoffs between current and future offspring
What would benefit paternal genes
- survive at almost all costs
- take as much from mom as possible (despite costs to siblings)
What does a promiscuous mating system lead to
lower genetic relatedness to father in a mother’s brood
Selection in a promiscuous mating system should favour…..
paternal genes that either
1. favour maternal investment
2. silence maternal genes that down regulate maternal investment
selective pressure on maternal genes should favour
- genes that aid in regulation of maternal investment
- genes that silence paternally expressed genes that increase demands on mother
serial monogamy =
polygamy
(divorce)
Homo sapiens is a species with a ______ degree of polygamy
moderate
When are potential times for conflict
- conception
- early survival of embryo
- placentation
- intrauterine growth
- gestational length
- early post partum
- post natal development
How can conflict at conception and early survival of embryo arise
- deteriorating environments ==> mechanisms preventing conception (anovulatory cycles, hostile vaginal environment)
- prevent implantation (change uterine chemical or physical environment)
How is a potential mechanism a mom can assess ability of embryo to develop
by the levels of cytokines or human chorionic gonadotropin (hCG) the embryos produce
(these are the same hormones pregnancy tests measure)
How do fetuses try to gain more blood
- change diameter of maternal spiral arteries and increase blood volume to placenta
What are consequences to the mother by the fetus trying to gain more blood
- vasoconstriction (reduce diameter of blood vessels)
- high BP
What is preeclampsia
- decreased blood flow to placenta = premature brith and LBW
- decreased blood flow to mother’s kidneys, brain, liver, retina
- can lead to eclampsia = maternal cerebral hemorrhage, seizures, death, fetal stillbirths
the risk of pre-eclampsia _______ with changes in sexual partner
increases
What is the role of the male partner in pre-eclampsia
- may be mediated by immunological interaction between male and female tissues
- some men linked to higher risks
true or false - preeclampsia may have had some effect in evolution of human mating system
true
what are health implications of viewing pre-eclampsia as a paternal/fetal strategy
- strengthen maternal counter-adaptations to limit fetal manipulation
- preventing nutritional conditions that trigger it
- develop preventative tests for men with partners who experienced it / women who change partners
What does the placenta releasing human placental lactose do?
increase insulin resistance, keeping blood glucose circulating for a longer time after meal = more glucose for fetus
How do mothers’ bodies counter effects of human placental lactogen
increase insulin secretion
- which can result in gestational diabetes
What are health risks of gestational diabetes
- really large babies
- increased risk of maternal non-gestational diabetes
- newborn problems regulating circulating glucose, increased risk of diabetes and obesity
What can the adrenal glands trigger
parnurtition/pre-mature —> maturation of the lungs
How are babies and tadpoles similar
- adrenal glands signal metamorphosis in tadpoles when environment is not too good
- adrenal glands in baby can trigger premature birth because of environment
What is low birth weight and influenced by?
<2500 g
- influenced by maternal nutrition and disease
What is intrauterine growth retardation
- fetal weight < 10th percentile = smaller than expected for gestational age
- thin, pale, loose, dry skin, thin and dull umbilical cords
What are maternal proximate factors associated with IUGR
- high BP
- chronic kidney disease
- diabetes
- CVD
- malnutrition
- anemia
- infections
- substance use
What are proximate factors involving the uterus and placenta associated with IUGR
- decreased blood flow
- placental abruption (detachment from uterus)
- placenta previa (attaches low in uterus)
What are proximate factors associated with IUGR related to the fetus
- multiple gestations
- chromosomal and birth anomalies
- organ growth limitation
- low fetal heart rate
what conditions linked with IUGR
- still birth
- low Apgar scores (reflex?)
- meconium aspiration (inhaler fecal ish matter)
- hypoglycemia
- body temp regulation problems
- polycythemia
- shouldn’t treat these independently
What are interventions for IUGR
- maternal nutrition (fetal growth?)
- maternal bedrest (circulation to fetus)
- delivery (may be necessary)
What could post partum depression, psychosis, infanticide be?
- evolved mechanisms for maternal investment avoidance?
- contributing factors - lack of support, low self esteem, inadequacy, isolation, financial, life changes
is there one gene for one behaviour
NOOOOOOO
What are factors affecting growth trajectories
- pre and perinatal problems
- nutrition
- high altitude hypoxia
- pollutants
- maternal health conditions
- psychosocial environment
- social and economic status
growth problems in utero/childhood can lead to
fetal programming and chronic diseases in adulthood
- psychosocial consequences
what is growth canalization
a tendency to keep to a narrow and predictable track of growth, usually along a centile line
When is the biggest growth spurt one will ever have
in utero, between 20-30 weeks of gestation fetus grows at rate 120 cm/year
Why are growth spurts a time of increased vulnerability
- If one cell is exposed to a toxicant -> mutation or effects epigenome then the cells will carry that affect - organs and tissues affected, the younger you are and faster you develop the higher the impact of the exposure will be
What is the thrift phenotype hypothesis
poor prenatal nutrition leads to small postnatal phenotypes, a decrease in basal metabolic rates, efficient fat metabolism which ultimately lead to an increased risk for metabolic syndrome
Infant nutrition
- early nutrition crucial for healthy growth
- breast fed infants grow differently from formula fed infants
What is the most vulnerable period for growth and development
- weaning period
What is protein energy malnutrition
- typically when weaning
- thin limbs, enlarged belly
- severe growth faltering
- overall health and mental impairment
PEM + caloric deficiences/dehydration =
increased risk of infections and circulatory disorders like marasmus
how is over nutrition a modern mismatch
- low levels of physical activity
- hyper caloric diet
What are possible causes of the association between SES and height
- nutritional status
- disease load
- access to medical care
- psychosocial stress
What is psychosocial short stature/dwarfism/kaspar houser syndrome
growth failure/delayed development in association w emotional deprivation
Why do low SES and high SES seem more even in Sweden than other countries
- welfare state - social programs and support
are children born in restricted environments doomed?
no! if they are placed in a more advantageous environment they can grow up and catch up with those who enjoyed a more nourishing environment
What is catch up growth
- an unusually rapid height increase, considering age and/or maturity of an individual, following a transient period of growth inhibition
canalization makes it possible to…..
identify a period of catch up growth
what is puberty
onset of reproductive, physical and behavioural changes leading to adulthood
why do sex differences in heigh exist
the timing and pace of transition of puberty are sensitive to …….. factors
internal(development) and external(ecological) factors
The hypothalamus regulates
growth, cardiac function, body temperature, hunger, sleep, reproductive function via the pituitary gland
What does the hypothalamus release by the median eminence
gonadotropin releasing hormone/GnRH to anterior pituitary
What does GnRH stimulate
production and release of the gonadotropins
1. follicle stimulating hormone
2. luteinizing hormone
from anterior pituitary
what do FSH and LH do
stimulate the gonads (testes/ovaries)
What does FSH do in women
stimulate recruitment and development of ovarian follicles (egg) for ovulation
What does the luteinizing hormone do in women
triggers ovulation and formation of corpus luteum
Maturation of follicle triggers…
estrogen - stimulates proliferation of the endometrium
formation of the corpus luteum results in….
an increase in luteal progesterone
- maintains the endometrium
what does LH do for men
stimulate production and release of testosterone
what does FSH do for men
with testosterone, stimulate sperm production
how often is GnRH released
in pulses, once an hour
what is the circhoral rhythm
once an hour - crucial for function of HPGA
What affects GnRH cir choral rhythm of secretion
environment (auditory, olfactory, visual, tactile stimuli, changes in photoperiod)
What are two theories of the maturation of HPGA axis during puberty
- Gonadostat hypothesis
- Hypophysiotropic hypothesis
What is Gonadostat hypothesis
pre puberty GnRH pulse generator highly sensitive to gonadotropin levels and during puberty that decreases, resulting in an increase in gonadal steroids
what is the hypophysiotropic hypothesis
puberty associated with an increase in positive feedback by stimulatory factors
what are the 5 correlates of HPGA maturation
- somatotropin axis
- adrenarche
- insulin sensitivity
- body composition
- skeletal maturation
Somatotropin (GROWTH) axis
- regulated by the hypothalamus via growth hormone releasing hormone and somatostatin
- acts on pituitary to regulate release of growth hormone
- GH stimulates release of insulin like growth factors from liver and other tissues
- GH and IGF1 stimulate skeletal growth and protein anabolism
- increase in somatotropin activity appears to be a consequence of gonadal steroid production
- both estradiol and testosterone affect GH production by augmenting the amplitude of GHRH pulses
adrenarche
- adrenal cortex and medulla
- during adrenarche adrenal cortex develops third layer - zone reticular and begins producing large amounts of adrenal androgens (DHEA and androstenedione) which increase in pre-pubertal children
- changes occur before detectable increases in gonadotropins and gonadal steroids
- suggested WEAK ANDROGENS MAY CONTRIBUTE TO MATURATION OF HPGA
insulin sensitivity
- controls energy metabolism
- produced by islet cells in pancreas
- stimulates cellular uptake of glucose
- insulin and growth hormone up regulate each other
- elevated insulin -> increased IGF1
- more insulin = more gonadal steroid hormone levels
How does insulin relate to puberty
during puberty = a decrease in insulin sensitivity -> insulin resistance -> increase in insulin levels -> increases in gonadal steroid -> pubertal development
body composition
- fatness threshold hypothesis = criticized
- increase in fat mass as a consequence of HPGA maturation and not cause
- skeletal dimensions ???
skeletal maturation hypothesis
timing of puberty is coordinated with attainment of appropriate physical size for reproduction
Why is the HPGA so sensitive to the rhythm hypothalamus releases GnRH pulses
allows us to
- adjust reproductive maturation and function to the quality of environment
- as long as development is not complete, reproduction comes second to growth and survival
What do we need to develop well
- to be wanted
- tranquil parents
- social support group
- clean environment
- appropriate nutrition
- appropriate stimulation
- to be loved
