Lecture one wed

Lecture Two  

Wed, may 8th 2024 

Dr. Eve  

 
Genetics and Processes of Evolution/Bio Anthropology  

 

Housekeeping 

  •  No office hours today  

  • Homework and lab will be relapsed tomorrow morning  

  • In persons labs begin next week 

  • Accessability accommodation letters- quizzes?  

 

 

Jean Baptist Lemark  

  • Not right compared to the natural selection of the griffafe long nexgk  

 

Adaption  

  • Adaptive radtion: The eolvtion of mutiple divergent specices from a single less specialized ancestral species  

  • Niche: the role of a species within its enviomrent.  

  • Adaptive radtions interlines with niche.  

 

 

Six tenants of natural selection  

  • Variation exists and is heritable  

  • Some variants are better adpated to their enviomrent then others 

  • If let unchecked, organisms will produce more offspring than can survive 

  • Offspring will have the adaptions of their parents  

  • Overtime, pop will change ,  

  • Over very long time period 

 

 

Todays lecture  

Forces of evolution  

  • 1. Selection  

  • Natural selection, artificial selection  

  • Sexual selection (non random mating) 

  • 2. Genetic drift 

  • (genetic drift, random inheritance, founder effect, population bottleneck.  

  • Mutation  

  • Gene flow  

 

 

Artificial selection  

  • Selected by humans fro particular characteristics that are considered good, i.e chicken, cow.  

  • Breeding the chicken that has the best meat.  

  • Dog breeds, as well, from a wolves similar to a grey wolf, all dogs are all the same specicies but are just different breeds of the species.  

 

Sexual selection 

  • Charles Darwin (1809-82)  

  • Selection on features or behaviours associated with mating.  

  • Takes two forms 

  • Male-male completion (bighorn sheep headbutting)/ behavior adpation i.e bower birds building decorative bowers to impress females.  

  • Female choice: of choosing their mates with Bower birds  

  • This leads to secondary sexual characteristics in males i.e weaponry, body size, ornamentation.  

Lead to sexual dimorphism   

  • Different appearances between makes and females, e.g size, colour, morphology,  

  • Not always good for survival i.e peacocks.  

  • Bio Goal: Maximize reproductive success 

  • Reproductive success: Number of infants that survive until adulthood 

  • Reproductive output (quantity)  and Parental Investment (quality)  

  • Female Mammals have do deal with a lot of parental investment, they have to deal with producing milk, dealing with the gestation period,  females have a cap, whereas males don’t  

  • Conception investments: Sperm Cheap, eggs costly 

  • Sexual selection in humans? 

  • Selection based on cultural factors i.e race, religion, wealth can lead to non random mating  

  • I.e Charles II of Spain, ex of effects of inbreeding.  

 

Mutation  

  • A change in dna can refer to changes in dana bases as well as changes in in chromosomes numbers/strucutre 

  • Only important to evolution if they occur in sex cells  

  • The ultimate source of all variations  

Sickle Cell anemia  

  • Results of a point mutation  

  • A point mutation occurs in a single base in a condon  

 

 
Genetic drift  

  • Evolutionary changes as a result of random processes 

  • Particularly significant in small populations  

 

Random Inheritiance 

  • Changes in genetic material passed on to the next generation just as random of chance in which variants get passed on  

 

Founder effect  

  • Difffernce in frequency of variants in a population as a result of random chance in which members start a new population.  

  • Founder effects can be increased in the relative frequency of a rare type, eg. Rare but non fatal disease  

  • I.e Ariaatje and Grettit Jansz, carriers of the gene of porphyria, 30,000people can trace it back to this couple.  

 

Bottleneck effects 

  • A restriction in genetic variability with a decrease in pop sizes due to random factors, like natural disasters 

  • I.e cheetahs  

  • Variability is good.  

  • Fall of the dinosaurs, K-Pg extinctions  

 

Gene flow 

  • Exchange of genes between populations  

  • Has the effects of making pop more similar   

 

Timescale of Evolution  

  • Micro evolution 

  • Changes in allele frequencies within breeding pop, (Small changes in a single species) 

  • I.e Industrial Melanism: peppered Moth light and dark variants.  

  • Can occurring in an observable timeframe  

  • Macro evolution 

  • Changes prpducted only after many generations  

  • Events at a higher level, such as speciation  

  • Seen with horses, moving from a small generalized herbrivore and becoming a large specialized for speed and eating grass.  Began loosing toes as they progressed through time.  

 

Terms 

  • Microevoluton  

  • Small changes occurring within a species,  

  • Can occur in an observable timeframe  

Macroevolution  

  • Changes produced only after many generations  

  • Events at a higher level, such as speciation.  

 

Early genetic ideas  

  • Gregor Mendel (1822-1884) 

  • Father of genetics  

  • Monk who worked in the Czech Republic  

  • Three conclusions  

  • 1. Pea plants passes two alleles from the parents, purple was dominant and white was reccessive. 

  • Law of segeration: Getting alleles from dad/mom is completely random.  

  • Blending or particular inheritiance: What happens if you mate a plant that consistently produces smooth peas with one that consistently produces wrinkled peas. 

  • Blending inheritance: Somewhat Wrinkled peas, in several generations would look more and more intermediate.  

  • Particular inheritance 

  • Smooth and wrinkled peas, in several generations, there will be both types of peas in predicatbale proportions.  

  • Results  support Particulate inheritance, stastiistal results indicated that each trait is controlled by two factors per individual.  

  • Alleles: alternate forms of a gene. Codes from the same trait but a different phenotypes,  

  • We get one allele from each parents, so we have to alleles for each gene. 

  • The same allele from each parent, (homozygous, e.g SS or ss)  possessing two of the same allele 

  • Different alleles from each parent (Hetoerzygous: Eg. Ss.  Possessing two different alleles.  

  • Genes: A sequence of DNA bases that specifies the order of amino acids in an entire protein, portion of a protein, or any functional product.  

  • Dominat allele: that allele that is expressed in a hetoerzygote (Ss)  

  • Recessive allele: the allele that is not expressed in a hetero zygote. 

 

Evolution: A change in allele frequencies in a population over time. 

I.e  a change in the frequency of the different forms of a gene.  

 

Why do some features appear to blend in offspring (i.e skin colour) 

  • Monogenetic: A characteristic coded dead for by one gene î.e one set of alleles; Mendelian traits  

  • Polygenic: a characteristic coded for by one mor than gene,  

  • The complex interaction of mutiple genes can produce the appearance of blending  

  • Some alleles are co-dominat which can also produce the appearance of blending  

  • I.e for sickle cell anemia have approximately 40% deformed cells and 60% healthy cells.  (Codomiance)  

 

DNA and protein synthesis 

  • James Watson (1928-) Francis Crick (1916-2004) , and Francis Crick, described the structure of DNA molecules in 1953  

  • Structure of DNA  

  • Nitrogenous bases  

  • A= adenine  

  • T= thymine  

  • G= Guanine 

  • C=cytosine  

  • A ALWAYS bonds with T 

  • C ALWAYS bonds with G 

 

The cell  

  • Nucleus: Control centre of the cell, contains nuclear DNA, which you get from both parents (50% from mother, 50% from father) 

  • Ribosomes:  Protein manufacturing centre of the cell 

  • Mitochondrion: energy producing part of the cell, contains mitocondrial dna, which you geto from your mother.  

 

Karytope  

  • 23 Paris of chromosomes= 46 total  

  • 22 pairs are autosomes  

  • 1 pair are the sex chromosomes  

Gene: a sequence of DNA bases that specifies the order of amino acids in an entire protein, portion of a protein, or any functional product.  

 

In the nucleus’s  

  • Transcription: A sequence of DNA base pairs is coped onto a molecule of messenger RNA (mRNA)  

  • Transcribe: mRNA transcribes into the MRNA codons—> then delivers to the ribosome.  

  • Translation: in the ribosome the tRNA uses the information from the MRNA to build a protein out a amino acids.  

  • Translate:  Transaltes MRNA codons into amino acids which build a protein.  

  • Codon: a set of three bases in MRNA that codes for a particular amino acid 

  • Anticodon: Corresponding set of threee bases on the transfer RNA (tRNA)