EEB405 Field Biology Course & BIO220 Events

• EEB405 Temperate Field Biology is accepting applications
• Koffler Scientific Reserve is the location for the field course
• The application deadline is January 31, 2025
• The course dates are from May 18-31, 2025
• Optional events are offered to BIO220 students throughout the course

Beyond BIO Events

• On Tuesday January 14th at 2:10 pm, meet in Room RW 010 in Ramsay Wright for a fun get-together with snacks and trivia for BIO220 social
• On Thursday January 23rd from 11:10 am - 12:00 pm, learn about Toronto's local wildlife, and find out the best spots to see nature in the city in room RW 432 for Birds & Wildlife of Toronto

Human-Agricultural Coevolution

• Study of coevolution between humans and agricultural species addresses general questions
• How humans coevolve with agricultural species
• The imprint such coevolution leaves in genomes
• Humans and their agricultural species instigate reciprocal evolutionary responses through selection
• Evolution driven by natural selection involves genetic and ecological processes
• Ecological factors apply selective pressure
• Genetics supplies the heritable material for subsequent generations
• Ecology encompasses culture alongside other interacting organisms
• Lactase enzyme helps humans digest milk
• Humans utilize lots of milk-derived products
• Lactase production naturally decreases in adulthood
• People of Northern European descent are an exception to typical lactase production decline
• Decline in lactase results in lactose intolerance

Lactase Persistence in Human Populations

• Lactose production persists into adulthood for many humans of European origin, enabling milk digestion
• In European populations, changes in the lactase gene strongly correlate with the ability to digest lactose as an adult
• Substitutions are causal variants and potentially favored by natural selection
• Other human populations with lactase persistence should have similar substitutions or modifications to enzyme production
• Populations reliant on dairy agriculture should exhibit lactase-persistent phenotypes
• Should see genetic evidence of past selection at the lactase gene in the human genome

Lactase Digestion

• African cultures with dairy farming demonstrate unique lactase gene variants
• DNA sequence differences correlate to digest lactose ability
• Molecular variants affect phenotype
• Independent evolution of the same phenotype in different populations is driven by natural selection

Chance versus Determinism

• Single events can be due to chance isolated or to deterministic processes
• Independent evidence confirms deterministic explanations by rejecting chance
• Convergent evolution is an indication and independent evolultion of the same trait indifferent groups
• Selection acts on groups, those groups may be populations or species
• Lactase-persistent evolution studies indicates that Neolithic human remains suggest they could not digest lactose as adults
• Cattle domestication occurred approximately 7,500 - 9,000 B.C.E
• Lactase persistence in Europeans evolved approximately 5,000 - 7,000 B.C.E
• African cultures show mutations in lactase, associated with lactase persistence into adulthood
• Strong evidence replicated association between genotype and phenotype
• Independent derivation is an adult milk digestion is an example of convergent evolution
• Cultural options to genetic adaptations exist.
• Mutations related to lactase persistence have been found in Central Asians 5,000 year-old samples
• Despite presence the mutations were not increased in frequency

Population Genetics and Selection Effects

• Coevolution leaves imprints on genomes, which is understood through principles of genetics of populations
• Selection affects genome fate of mutations
• Mutations change amino acids vs those that do not
• Regions experience genetic variability in regions of the genomes
• More differences between populations at specific sites for the rest of the genome
• Beneficial mutations fix drag along with mutations nearby. This is genetic hitchhiking
• As beneficial mutations fix, genetic variation decreases
• Region size depends on the rate of recombination
• Longer lines indicate regions that are essentially homozygous and also includes causes for evolution of lactase persistence
• Genetic evidence helps identify past selection at the lactase gene

Apply for the EEB405 Temperate Field Biology course at Koffler Scientific Reserve by January 31, 2025. Course dates are May 18-31, 2025. Optional events for BIO220 students include a social on January 14th and a talk on Toronto's wildlife on January 23rd.