Evolution L.A.'S

save me i thought i had my first lecture today but it was the second so im already a whole goddamn lecture behind, literally SOS bithces

Explain the concept of natural selection

Individuals with certain traits (in a species/population) may reproduce at a higher rate (because of those traits), over time as this process is repeated the favourable adaptation become more frequent.

What are the four adaptation categories, explain and identify an adaptation for each classification

• Structural adaptations: Physical features that aid survival, a giraffe’s long neck to be able to reach leaves from high trees to eat them.

• Behavioural adaptations: Things organisms do to survive, phototropism in plants: plants growing towards any light they may sense

• Physiological adaptations: How an organism functions on the inside, a snake having venom

• Coadaptation: Coevolution of advantageous traits, a flower growing in such a shape that only its desired pollinator can access it’s pollen.

Give 4 examples of evidence for evolution

• Direct observation of evolutionary change: The adaptation of certain traits in species with short lifecycles and bacteria developing (multi-)drug resistance

• homology: Similarity in structure (of limbs) resulting from common ancestry,

  • Anatomical homology: the arms of a human and the fins of a whale

  • Molecular homology: Having similarities in genes

  • Analogy is when independent evolution causes similar features to appear in species from different ancestors

• Fossil records: can provide evidence of the extinction of a species, the origin of new groups and changes within groups over time.

• Biogeography: The study of geographic distributions of species

Define and explain the difference between micro- and macroevolution

• Microevolution: Evolution up to a species level, a change in gene frequency within a population. (e.g. different dog breeds)

• Macroevolution: Evolution beyond a species level (e.g. evolving from a unicellular organism into a multicellular one)

Name the five mechanisms behind evolutionary change and give an example for each.

• Natural selection: Green beetles being preyed upon more than the brown beetles in a population, therefore causing the amount of green beetles to diminish.

• Mutation: A beetle population of green beetles mating with one another and producing a baby beetle that is brown because of a mutation.

• Gene drift: Chance events that cause change to a population leading to an allele being disproportionately over- or underrepresented in the next generation, e.g. natural disasters wiping out a part of a population of mixed coloured beetles leading to lots of green beetles dying and more brown ones surviving

• Gene flow/Migration: Individuals from different populations visiting each other and introducing genes into the other population. If they stop visiting the gene will vanish from the population

• Non-random mating(/sexual selection): When individuals with certain characteristics are more likely to acquire mates, therefore causing their genes to be more abundant in a population as others are not (as) desired. Beetles preffering to mate with dark brown beetles over light brown or yellow ones

What is a Hardy-Weinberg equilibrium and what are the conditions a population must have in order to be in one.

A population being in a Hardy-Weinberg equilibrium means that the population is NOT evolving, the allele and genotype frequencies remain constant

• No mutations

• There MUST be random mating. There must be no sexual selection

• No natural selection

• The population must be of an extremely large size

• There must be no gene flow

Describe the concept of biological species and reproductive isolation

• (Biological) Species: A group of population whose members have the potential to interbreed (in nature) and produce viable, fertile offspring.

• Reproductive isolation: The existence of biological factors/barriers that impede two species from producing viable, fertile offspring

Name the two categories of reproductive isolation

• Prezygotic barriers (before gamete fusion)

• Postzygotic barriers (after gamete fusion)

Give all possible prezygotic barriers and state before what “key event” they take place

• Habitat isolation: BEFORE MATING ATTEMPT, Two species encounter each other rarely because of a difference in habitat, despite not being isolated by physical barriers (e.g. flies living on different trees growing in the same area)

• Temporal isolation: BEFORE MATING ATTEMPT, two species cannot mix their gametes because they breed during different times of the day, different seasons or even years.

• Behavioural isolation: BEFORE MATING ATTEMPT, Courtship rituals/mating behaviour unique to a species are a barrier for mating with others.

• Mechanical isolation: BEFORE FERTILIZATION, morphological (shape and structure) differences can prevent successful completion of mating.

• Gametic isolation: BEFORE FERTILIZATION, Sperm of one species may not be able to fertilize eggs of a different one (species)

Give all possible postzygotic barriers and state before what “key event” they take place

• Reduced hybrid viability: BEFORE VIABLE, FERTILE OFFSPRING, Offspring may not be viable, the genes of the different species may interact and impair the hybrid’s development or survival in its environment.

• Reduced hybrid fertility: BEFORE VIABLE, FERTILE OFFSPRING, the offspring may survive, but not be able to reproduce

• Hybrid breakdown: BEFORE VIABLE, FERTILE OFFSPRING, the hybrid may reproduce, but as generations pass the offspring will become more and more short lived and have its survival impacted (so won’t survive to last as a species)

What are two approaches taken to understand how life on earth developed?

• Top-down: Reduce complex systems to derive precursor states

• Bottom-up: Construct increasingly complex systems from fundamental components

explain how life on earth probably developed in 4 steps

• Abiotic synthesis created the first small organic molecules, this likely happened near openings of volcanoes or deep-sea hydrothermal vents.

• The small molecules were joined into macromolecules, small organic molecules like amino acids polymerized on hot surfaces (hot sand, clay or rock)

• The molecules were packed into protocells (Pre-cells)

• These protocells formed the origin of self-replicating molecules as the first form of genetic material present, RNA, can act as enzymes (ribozymes) which catalyze many different reactions, one being making complementary copies of RNA

Explain how eukaryotes were formed in 4 steps

• The nuclear envelope and endoplasmic reticulum (ER) evolved because the plasma membrane folded in on itself, becoming an ancestral prokaryote

• This ancestral prokaryote engulfed an aerobic (proteo)bacterium, now becoming a host cell for it as it developed into a mitochondrion. This became the ancestral eukaryote

• The ancestral eukaryote (heterotroph) engulfed a photosynthetic cyanobacterium

• The photosynthetic bacterium developed into a plastid an the whole became the ancestral photosynthetic eukaryote

Interpret and construct simple phylogenetic trees from molecular data:

Give for each number the correct term

1. Branch point

2. Most recent common ancestor

3. Sister taxa

4. Basal taxon

Interpret and construct simple phylogenetic trees from molecular data:

Give the correct name and description for each present, numbered group

1. Monophyletic group: The selected taxa all derive from the same common ancestor and are ALL the derived taxa from this common ancestor.

2. Paraphyletic group: The selected taxa all derive from the same common ancestor, but NOT ALL taxa FROM this common ancestor are shown

3. Polyphyletic group: The selected taxa derive from multiple ancestors (they are in separate clades

Interpret and construct simple phylogenetic trees from molecular data:

Define the next terms:

• Outgroup

• Plesiomorphy

• Apomorphy

• Maximum Parsimony

• Maximum Likelihood

• Molecular clock

• The taxon in a phylogenetic tree that is (presumably) less related

• An ancestral characteristic (a characteristic a distant ancestor had????)

• A derived characteristic (unique to a taxon?)

• The phylogenetic tree that requires the fewest evolutionary events

• The tree with the most likely sequence of evolutionary events

• The approach for measuring the absolute time of evolutionary change, with the assumption that there is an approximately constant rate of mutation (HOEVEELHEID MUTATIES IS RECHT EVENREDIG MET DE TIJD SINCE DIVERGENCE)

Interpret and construct simple phylogenetic trees from molecular data:

Name the right term for each description:

• The taxon in a phylogenetic tree that is (presumably) less related

• An ancestral characteristic (a characteristic a distant ancestor had????)

• A derived characteristic (unique to a taxon?)

• The phylogenetic tree that requires the fewest evolutionary events

• The tree with the most likely sequence of evolutionary events

• The approach for measuring the absolute time of evolutionary change, with the assumption that there is an approximately constant rate of mutation (HOEVEELHEID MUTATIES IS RECHT EVENREDIG MET DE TIJD SINCE DIVERGENCE)

• Outgroup

• Plesiomorphy

• Apomorphy

• Maximum Parsimony

• Maximum Likelihood

• Molecular clock