W1 Evolution, Tree Thinking, Human Story

Question 1

What is a Phylogeny?

Answer 1

Phylogeny is the study of relationships among different groups of organisms and their evolutionary development.

Question 2

What is Homology vs Homoplasy?

Answer 2

Homology, is the development of different species of organisms based upon their descent from a common evolutionary ancestor. (Descent)

Homoplasy is shared characteristics between two or more animals that did not arise from a common ancestor. (Convergence)

Question 3

Define biological evolution

Answer 3

Biological evolution is the change in inherited traits over successive generations in populations of organisms.

Question 4

What is the difference between a proximate and an ultimate
explanation for behaviour?

Give examples.

Answer 4

Proximate causes are the mechanisms directly underlying the behaviour. i.e. The underlying hormonal response, which is triggered by separation from the herd.

In contrast, the ultimate causes of social behaviours include their evolutionary or historical origins and the selective processes that have shaped their past and current functions.

i.e. The development of a better defense against predators that results in increased survival of individuals remaining in groups would be an ultimate cause for the tendency to reunite with the herd.

Question 5

So what is an allele?

Answer 5

Different possible

forms of a gene

Question 6

What is Micro-evolution?

Answer 6

Any change in the frequency of alleles within a

gene pool from one generation to the next.

Question 7

What is Genetic drift?

Answer 7

Chance event causes a change in the frequency of

alleles in a population

Question 8

What is the founder effect?

Answer 8

It is a bottleneck that occurs when a

small group colonizes a new location. A form of genetic drift.

Question 9

What is Gene flow?

Answer 9

If a barrier exists between two populations then complete interbreeding is not
possible.
Allele frequencies in each population will vary independently.

Then if a species is mobile in some way: flight, walking, pollen etc. individuals can
enter isolated populations and change the frequency of alleles

Question 10

What is Mutation?

Answer 10

The introduction of variant alleles to a
population via a change in the genetic
material of the reproductive cells.

Question 11

What is selection?

How is a trait naturally selected for?

Answer 11

When an organism reproduces due to a specific trait.

If trait affects the probability of
an organism passing on its genes to the next
generation, it’ll appear more

Question 12

What is Natural Selection?

Answer 12

Natural selection occurs when heritable
differences in organisms lead to differences in
their reproductive output

Question 13

What is Artificial Selection?

Answer 13

When people choose

Question 14

What is Sexual Selection?

Answer 14

Sexual selection occurs when species choose their mates, and may choose based on traits that don’t necessarily infer fitness.

Question 15

Does selection act on species as a whole?

Answer 15

Individuals, not species.

Natural selection acts on individuals, not a whole
species: individuals reproduce or die.

Natural selection not ‘for the good of the species’

Question 16

What are Spandrels?

Answer 16

Features that may look like adaptations but in fact are simply byproducts of design constraints (spandrels).

Question 17

What are Exaptations

Answer 17

Features that may once have been a byproduct or were adaptive for
one function may have changed over time to serve a different
function - exaptations (e.g. feathers).

Question 18

What does “Trees not ladders” mean?

Answer 18

That evolution is not hierarchical, but simply branches.

Question 19

What is Phylogenetics?

Answer 19

(Greek: phyle = tribe, race and genetikos =
relative to birth, from genesis = birth) is the
study of evolutionary relatedness among
various groups of organisms (e.g., species,
populations).

Question 20

How do you read a phylogenetic tree?

Answer 20

Trees show the evolutionary relationships between the species at the tips.

We read a tree as a set of hierarchically nested groups, which we call
clades. DON’T JUST FOCUS ON THE TIPS!

Question 21

What are the parts of the tree?

Answer 21

Root (common ancestor), the root of the tree.

Node, where a species deviates.

Clade, a group of related taxa.

Tip or ”leaf”, a species.

Question 22

What does phylogenetics teach us?

Answer 22

The relationship between all organisms.

When organisms split from one another.

There is no scala naturae (ladder).

How character states have evolved.

Question 23

What are the milestones of Human Evolution?

Answer 23

1: Walking upright (“Lucy” (3.2Mya) Australopithecus)
2: Stone tool manufacture(2.5 Mya )
3: Fire (690-790 Kya)

4: Big game cooperative
hunting (400Kya ) (Spears)

Hafting (200Kya)

5: Symbolic culture (93-110Kya)
Ritual burial, jewellery, cave paintings . Music (400Kya)

Question 24

What happened to the Hominin brain size?

Answer 24

Neocortex expansion.

The high, straight forehead that characterizes modern humans, superceding the
prominent brow ridges of others hominids, is due to the expansion of the cortex,
and especially the prefrontal cortex, in our species.

Question 25

What was the trend of human tools?

Answer 25

Increasingly complex tools, longer cutting edges, more efficient.

Question 26

Describe the human family tree relative to other early hominids.

Answer 26

Our family tree looks very complicated: no linear
progression, DNA work suggests not different species
but isolated populations linked by gene flow.

Not only were we sharing genes, but it seems capacity
for symbolic thought and complex culture may have
existed in other homo species too.

Question 27

What are Tinbergen’s 4 questions?

Answer 27

Ontogeny, Mechanistic, Phylogeny, Adaptive significance

Question 28

What is Ontogeny?

Answer 28

How does the trait develop in individuals?

Question 29

What is Sequence (Diachronic) vs Single form (Synchronic)

Answer 29

Diachronic - throughout time

Synchronic - at one point of time

Question 30

What is mechanism?

Answer 30

What is the structure of the trait?

Question 31

What is phylogeny?

Answer 31

What is the trait’s evolutionary history?

Question 32

What is adaptive significance?

Answer 32

How have trait variations influenced fitness?