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Health Sciences
HSCI 216
Pablo Nepomnaschy

HSCI216: Lecture XII Environment, Development & Health  What constitutes the baby’s first environment?  the womb o Will have the most strongest effect o Relationship with mothers and unborn offspring is complex  Relationship marked by constraints in the quality of the environment the mother faces which necessarily translate into the quality of the fetus’s environment  External constraints  internal effects o Prenatal constraints can affect postnatal phenotypes  Phenotype  what we perceive of the person (outgoing etc. we cant see their hormones)  Survival will depend on the nature and intensity of the constrain, in certain cases (IUGR) survival is possible but it comes at a cost.. o Debate on the resulting phenotypes represent  Unavoidable results of prenatal constraints (ie: not enough food therefore, energy for you to grow in impoverished community)  Cost of prenatal adaptions to those prenatal constraints (ie: changes in the fetus for it trying to survive in the womb, they are small because their metabolism changed for them to be able to fight challenge in the womb)  Adaptive phenotypic changes that will aid the individual in dealing with (expected) postnatal constraints (fetus perceives there is little food in the outside world, therefore born small (phenotype) to be able to survive with little food because requires less energy intake)  *understand these 3 different hypothesis!! o Developmental adaptation results of developmental plasticity  Phenotypic changes are considered to take place in order to survive wither prenatal challenges or expected post-natal constraints  Unavoidable costs  don’t have associated benefits to them (other than allowing for immediate survival)  Plasticity is hypothesized to be an evolved trait  External constraint can lead to internal conflicts o The conflicts of interests with the players involved o Players = mom, dad and fetus o Genes of mom and dad aren’t the same thing  Intra-genomic conflict hypothesis o Meiotic drive  There are some alleles over represented in the egg  Therefore your expression of gene will either reflect mothers or fathers more o phenotype = genotype + environment  genes can become part of other genes environment o maternal-offspring conflict  maternal genes  if you are a maternal allele what would you want the fetus to do?  Maximize inclusive fitness of the mother (fitness of anyone related to mom)  Investment depends on quality of the offspring  Sensitive to tradeoffs between offspring quantity to quality  Sensitive to tradeoffs between current and future offspring  Paternal genes  if you are a paternal allele what would you want the fetus to do?  Survive at (almost) all costs  Take as much from mom as possible (despite costs to siblings)  Can a species mating system affect maternal fetal conflict? o Yes, the dog example where all dogs mate together and all the fetus’s compete, however with humans it is one-on-one creating less competition for resources o You also don’t want the mother to be depleted  Genomic imprinting conflict** o Demand-suppressing genes maternally expressed (increase in demand from paternal)  Mother will try to make it work to lessen her depletion, paternal will oppose o Demand-increasing genes paternally expressed (increase in demand from
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