Study guide- Evolution Flashcards
microevolution
changes within a species
micro vs macro evolution
micro: changes within a species
macro: speciation and extinction
How does the environment play a role in evolution?
each species adapts to their specific environment so traits that best serve that specific environment survive
key elements of microevolution
- & how can we apply these elements to traits?
-Genetic changes in a population/groups of living things over generations
-Need optimal fitness to adapt to their environment and reproduce offspring that also reproduce
-Evolution has No specific goal
-Selection operates on variation (alleles)
A: traits are selected for by the use of these elements like how selection operates on variation to give us a range of skin pigmentation which evolved because of the specific climate they are in
Skin pigmentation
- UV light catalyzes synthesis of Vit D precursor in the skin from dehydrocholesterol
- used for bone development and calcium metabolism
- less sun = need to absorb more UV light = less pigment = lighter skin tone
- excessive UV exposure causes photolysis of folate and it’s deficiency
- more melanin = darker skin = more protection from UV rays so protects from folate depletion
- folate and Vit D hypothesis explains the evolution of skin pigmentation
What is adaptation and are all traits adaptations? How else might traits be shaped?
adaptation: a trait that promotes fitness and has a specific function which is driven by natural selection
No, traits can also evolve from exaptation, genetic drift like fixed mutations, and sexual selection
lactose tolerance evolution & pastoralism
-Due to pastoralism diary is introduced to the diet post weening of children so the mutation that allows us to consume dairy is advantageous
-Evolutionary Convergence
5 Evolutionary Constraints
- limits on physical processes
- evolution incrementally works over a long period of time
- mismatch b/w environment and rate of evolution
- selection operates on phenotype
- exaptation &/or chance results can occur
co-evolutionary ideas
-No species lives in isolation from others
- 2 species have a reciprocal relationship because of selective pressures that affect both
-This can lead to an arms race where both species continually evolve to stay fit
-Ex: human immune system and bacteria
4 forces of evolution
selection
variation
population genetics
culture
selection
-3 types
artificial: outside forces operate on it to change it like in dogs who were domesticated by selecting for specific traits
natural: selection of traits based on which is most advantageous to a specific environment like skin pigmentation
sexual: different sexual success rates that select for certain traits like peacocks long colorful tail feathers or male mortality
4 effects of natural selection
- positive (bigger) or negative (smaller): like giraffe neck length increasing is + (decreases variation)
- stabilizing (birth weight)- decreases variation
- Balancing (ex: sickle cell anemia) - increases variation
- disruptive (Darwin’s finches)- increases variation
Levels of selection and the extended phenotype
* On the group
* On the individual
artificial selection: makes the group more alike in a specific aspect and the individual’s phenotype more advantageous to survival
natural selection: makes the group and individual phenotype shift towards what is good for the specific environment so reducing diversity
sexual selection: makes the group and individual phenotype shift towards what is sexually preferred so reduced diversity
variation
- 4 types
mutation: alteration of nucleotide base, #1 mechanism to increase variation
independent assortment: on chromosomes & increases variation (Mendel’s pea plants)
random fertilization: of oocyte by sperm
recombination: during meiosis so swapping of genetic material to create variation
variation example: skin pigmentation
Population genetics
migration: certain ethnicities/demographics are prone to certain diseases due to genetics (decrease variation)
genetic flow: ppl carry alleles in their genome as they move geographically (increase variation)
genetic drift: allele changes occur due to a random chance event (decrease variation)
bottleneck: : large gene pool but an event occurs so only a few from the OG population survive and reproduce to make a new population like bison or potato famine in Ireland (decrease variation)
founder effect: a population moves to a new area but the gene pool becomes limited like the Dutch settlers moving to Africa (decrease variation)
culture and lactose tolerance
- culture creates selective pressures (gene culture evolution) like lactase persistence
- culture is rapid and influences our biological evolution
-Due to pastoralism diary is introduced to the diet post weening of children so the mutation that allows us to consume dairy is advantageous
3 types of Adaptations
- Anatomical - bipedalism
- physiological - body actions or composition change like shivering when cold
- behavioral - child more dependent on mother so monogamy and parental care
exaptation
a specific trait is selected for a specific purpose but now that trait is used for a new purpose(not OG one). Like feathers are originally for heat but used for flying later
environment changes and adaptations
adaptations occur in response to a change in the environment like we evolved to be bipedal after our environment became less wooded and more open
macroevolution and adaptation
macroevolution: is the process of how species diverged throughout time adaptation: occurs over many lifetimes where organisms adapt to their environment
So adaptations are a mechanism by which the process of macroevolution can occur
How do we define species? Problems associated with this
Biological species concept: interbreeding individuals that are reproductively isolated from other such groups
- Isn’t easily applicable to bacteria because most bacteria divide by fission not sexual reproduction, so genetics and morphology are better to use
- example: ligers
Example of Biological species concept
Ligers can be artificially bred in captivity but don’t produce fertile offspring and are isolated from each other in their natural habitats, so they are 2 diff species because they are reproductively isolated
what is taxonomy
study of how organisms are classified and Classify species based on their characteristics, Carl Linnaeus
Homologous
common evolutionary history with similar structure but different function
- ex: lizards, birds, humans, whales have similar arm structures but diff functions
Analogous
different structures with similar adaptation/function with NO common evolutionary history
-convergent evolution like lactose tolerance
