Evolution & Populations 24funBMS Student PDF

Populations & Evolution Fundamentals BMS  Aims Definitions Applications Classical examples Problems Why it is important to BMS.  What is... Evolution Inheritable change......over time Evolution explains - – history and divers...

Populations & Evolution Fundamentals BMS  Aims Definitions Applications Classical examples Problems Why it is important to BMS.  What is... Evolution Inheritable change......over time Evolution explains - – history and diversity of life  Forms of evolution Micro Evolution Macro Evolution evolution within evolution at species populations level (adaptive or neutral) & fossil history  Evolution needs... A mutable heritable base (DNA) – Heritable variation – Genetically determined differences that passes from one generation to the next Time  Evolution Neutral - changes at DNA level with no phenotypic advantage - do not add to fitness* Genetic drift - Random changes in allelic frequency due to chance Heritable variation - DNA changes that can be passed to next generation  Mutable? Variation? DNA passes from Generation to generation SEX! Meiosis I & II Changes at DNA level (mutations) Mutations - make no difference to αa(neutral) αa change without phenotypic change(neutral) positive difference negative difference  What drives evolution? Selective pressure Environmental changes ❖ Temperature change? ❖ HIV? ❖ Ebola? Corvid19 ❖ Wheat? ❖ Alcohol? ❖ Milk?  Evolution Adaptive evolution – Change driven by outcome increasing fitness*. – Selection from random DNA changes Natural selection – Survival of the fittest – DNA - phenotype - best survival rate Sex selection - DNA give phenotype most attractive to mate  Fitness Measure of relative reproductive success Parent to offspring or Parent to grandchild ? At the level of the individual/ the species/ the population/ the gene  Fitness Energy in = energy out = Fit Critique this for humans Energy in ≥ energy out = Very fit in response to food availability & contraception Energy in ≤ energy out = Not fit  Why important to BMS? Biomedical Science humans + associated species (?) affect environment at micro & macro level affect genes directly without SEX You are changing history eg people live & reproduce who would have died remove some genes introduce some genes alter competing species  What is a species? Species - organisms that could share grandchildren Anatomically similar Phenotypically similar Genetically similar Is there such a thing as a species?  Phylogenetic Tree Of humans - global species Genus name species name Homo sapiens Written in italics Phylogenetic Tree  How is this determined? Anatomical similarity Physiological similarity Behavioural similarity Immunological (serological ) similarity Amino acid homology (proteomics) Genetic homology (genomics)...& bacteria? 70% genetic similarity = a species https://www.ncbi.nlm.nih.gov/pmc/articles/P MC1693353/  Population Genetics study of frequency of alleles in a population * mutation selection inbreeding assortative mating gene flow drift Usually based on detectable phenotype  Population? Group Hardy (Weinberg) – sufficient /infinite size – random mating  Variations in Population Height (Line up) Now by gender  Plasticity Non - inheritable changes to a population WWI Officers 7cm taller than other ranks Now Officers 0.5cm tall than other ranks Why? Seven yr old privileged girl taller than eleven yr old workhouse boy. Height - genetically determined? discuss.....  Plasticity Skulls.. Consequence of feeding methods - no forks! Not genetic Modern: overbite Medieval: end on occlusion...but! Under bite called Hapsburg jaw & it is single recessive gene! Genetics of Hapsburg Jaw 10,000yr old population genetics Lactose  Population Genetics Population 1 Population 2 Dairy non-dairy High incidence of lactose High incidence lactose tolerance intolerance (adults) LL common ll common Single autosomal recessive gene LL Ll ll  Population genetics Population 1 Population 2 Malaria No Malaria High incidence sickle cell No sickle cell anaemia anaemia High incidence sickle cell trait SS & SA AA Single co-dominant autosomal gene SS SA AA Calculating allelic frequency. Hardy-Weinberg 2 (p+q) =1  Worked example Lactose intolerance Devon Lactose intolerance Japan 1344 adults not lactose 750,000 adults not lactose intolerant (LL or Ll) intolerant (LL or Ll) 40 adults lactose 250,320 adults lactose intolerant (3%) (ll) intolerant (25%) (ll) 0.8 L 0.2 l 0.5L 0.5l 0.8*0.8 +2*0.8*0.2 + 0.5*0.5+2*0.5*0.5*+ 0.2*0.2 = 1 0.5*0.5 0.64 + 0.32 +.04 =1 0.25 +0.5 + 0.25 = 1  https://ghr.nlm.nih.gov/condition/lactose-into lerance#inheritance  Pop Genetics Why have allelic forms? Blood groups Bacterial protection.... Syphilis No-syphilis  Why maintain high level pathological allele? Typhoid No typhoid Cystic Fib No Cystic fib  BMS & Population genetics Allow people to stay well reproduce more increase "bad" genes into population  Population change Birth rate number of births in a yr/ number in population mid year Death rate number of deaths in a yr/ number in population mid year not only way of calculating BMS & population genetics - you change things Remove genes from the population Genetic screening/counselling (Tay Sacs) Pre- natal Genetic Screening PID (Pre-implantation diagnoses)  Gene therapy somatic  Altering DNA Layla’s Story (Christmas 2015-16)  Layla Acute Lymphoblastic Leukaemia (ALL) No bone marrow donor available Added CAR19 to own bone marrow cells Promotes own T-cells to attack ALL cells Does not alter germ line Remove genes from the population Gene therapy germ line Antibiotic use Cause evolution amongst competing organisms MRSA: Methicillin-Resistant Staph. Aureus VRE: Vancomycin Resistant Enterococcus FQRP: FluoroQuinolone-Resistant Pseudomonas  Red Queen Hypothesis Evolutionary arms race Predator: prey perpetual evolutionary catch up Bacteria v.rapid replication time Humans can use epigenetics  Summary Change is a Constant  Summary What is evolution Types of variation Types of selection pressures Human evolution Human gene variation What is a population Assessing allelic frequency (Hardy-Weinberg) Why have heterozygous How do BMS influence evolution Change without evolution (plasticity)