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Biological Sciences 1 > MBIOL161: Mark's Lectures + a bit of Mairi > Flashcards

MBIOL161: Mark's Lectures + a bit of Mairi Flashcards

1
Q

Why does sex exist?

A

Meiosis: The production of gametes (isogamy or anisogamy) which will then combine by fertilisation to form a zygote (new individual).

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2
Q

Differentiate between sexual and asexual reproduction

A

Sexual: occurs when the sperm from the male parent fertilizes an egg from the female parent, producing offspring that is genetically different from both parents.

Asexual: a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes, producing genetically identical offspring (same as parent).

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3
Q

Name 4 ways asexual reproduction can occur

A
  • Binary fission
  • Budding e.g. yeast (which grows a copy of themselves)
  • Vegetative reproduction
  • Spores (asexual version)
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4
Q

What is the 2-fold cost of sex?

A
  1. Asexual reproduction produces more daughter cells than sexual reproduction.
  2. Asexual population grows 2x the rate of sexual reproduction, hence there is a much greater potential for population growth in an asexual population.
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5
Q

Why is sex common then?

A

In the long term, sexual lineages seem to outcompete asexual lineages, if there is some form of competition, leading to the extinction of the asexual lineage.

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6
Q

What are the advantages of sex? Name 3

A
  • Unique combination of alleles (recombination of alleles) while asexuals do not have this mixing opportunity!
  • Harmful mutations are removed easily and quickly.
  • Production of super-beneficial organisms
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7
Q

What is Muller’s Ratchet?

A

Muller’s ratchet describes the accumulation of mutations in asexual individuals. In asexual individuals, mutations occur and they have no way of getting rid of them as when they reproduce all of the offspring will have that mutation.

If you are sexually reproducing some offspring will have the mutation and some won’t.

Asexual organisms are therefore continually obtaining mutations.

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8
Q

Give differences between asexual and sexual reproduction

A

Asexual reproduction
* Requires less energy
* No costly non-reproducing sex
* Quicker
* Offspring are clones of the parents

Sexual reproduction
* Requires more time and energy
* Two-fold cost of producing males
* Offspring are genetically diverse
* Mutations are more easily purged
* Beneficial mutations can combine more easily

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9
Q

Name 3 ways we can define sex

A

Sexual dimorphism, Difference in gametes and mitochondrial inheritance from parent

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10
Q

What is the most consistent definition of sex?

A

The most consistent definition we have is that the ‘parent’ whose mtDNA is retained at fertilisation is female and the ‘male’ is the ‘parent’ whose mtDNA is excluded.

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11
Q

What is sexual selection?

A

A mode of natural selection in which members of one biological sex choose mates of the other sex to mate with, and compete with members of the same sex for access to members of the opposite sex.

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12
Q

Explain why sexual selection exists

A

Females have a greater investment in gametes (limited number of gametes throughout their lifetime so their reproductive success is limited) and need to select the best males.

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13
Q

What is intra-sexual selection?

A

Competition between males (male-male combat)

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14
Q

What is inter-sexual selection?

A

Choice of mates by females

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15
Q

Name the 5 types of ways sexual selection could have evolved from

A

Direct phenotypic benefit
Sensory bias
Fisherian Runaway Theory
Sexy Son Theory
Indicator Traits

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16
Q

What is Bateman’s Principle?

A

FEMALES: Higher reproductive success with one continuous mate + fitness is limited by offspring quality = being more selective as a result.

MALES: Higher reproductive success with multiple & different mates + fitness limited by the number of mates willing to mate.

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17
Q

What is the Lek?

A

A system which is common amongst birds.

When males gather in groups to display their traits and the females come along and select the best males. Leks occur when males are unable to defend females or resources. In these cases, one or two males are very successful in reproducing and other males have no reproductive success.

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18
Q

What is the Lek Paradox?

A

Strong show in male reproductive success; few generations of mating should eliminate genetic variation, yet females remain selective!

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19
Q

What is anisogamy?

A

It describes a form of sexual reproduction wherein males and females produce sex cells, or gametes, of different sizes.

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20
Q

What is an adaptation?

A

A trait that enables an organism to survive and reproduce better than if it lacked the trait.

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21
Q

What is fitness?

A

A measure of individual success in evolutionary terms (or in reproductive success).

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22
Q

How are birds adapted for flight?

A
  • Forelimbs adapted to produce lift and thrust
  • Light weight skeleton with hollow bones
  • Feathers are shaped like aerofoil to increase lift
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23
Q

What is the most popular theory of adaptation?

A

Natural Selection

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24
Q

What is Co-Adaptation?

A

the correlation of structural or behavioral characteristics in two or more interacting organisms in a community or organs in an organism resulting from progressive accommodation by natural selection.

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25
Q

How many steps are usually involved for an adaptation to occur?

A

2,000 steps, different parts can evolve independently in small steps.

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26
Q

What is a Pre-adaptation?

A

a large change in function accomplished with little or no change in structure

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27
Q

What is an Exaptation?

A

A character trait that performs on a different function to the reason it evolved.

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28
Q

What are spandrels? Give an example

A

Side effects of adaptations, for example, larger brain size was an adaptation to a complex social environment but the ability to do business and other things are side effects of having a large brain size.

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29
Q

What are the 4 reasons that stop natural selection from creating perfect organisms?

A

Time Lags, Historical Factors, Genetic Factors and Development

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30
Q

What are the constraints on selection?

A

time lags, historical constraints, constraints due to available genetic variation, tradeoffs, imperfection due to selection operating at different levels, and constraints due to environmental unpredictability

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31
Q

What is speciation?

A

A process within evolution that leads to the formation of new, distinct species that are reproductively isolated from one another.

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32
Q

What is natural selection?

A

A process where organisms that are better adapted to an environment will survive and reproduce

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33
Q

How can we define species?

A

Biological Species Concept

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34
Q

Define the Biological Species Concept

A

A group of interbreeding populations that is reproductively isolated from other such groups.

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35
Q

What are examples of other species concepts?

A
  • Recognition Species concept
  • Ecological Species concept
  • Phenetic species concept
  • Phylogenetic species concept
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36
Q

Name 3 types of speciation

A

Allopatric, Sympatric and Parapatric

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37
Q

What is Allopatric Speciation?

A
  1. Over time part of the ancestral population splits off.
  2. Mutations, different selective pressures and maybe unequal genetic drift lead to the creation of a species different from its ancestral population.
  3. Population cannot interbreed with ancestors and is considered as a new species.
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38
Q

What is a Ring Species?

A

A situation in which 2 populations which do not interbreed living in the same region and are connected by a geographic ring of populations that can interbreed

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39
Q

What is needed for Allopatric Speciation to happen?

A

A geographical/physical barrier

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40
Q

What is Reinforcement?

A

Things that can reinforce these conditions for allopatric speciation – compounding its effect.

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41
Q

What is a Hybrid Zone?

A

regions where genetically distinct populations meet, mate, and produce at least some offspring of mixed ancestry

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42
Q

Name 3 instances where Allopatric Speciation is most likely to happen

A

Subdivision
Peripheral Isolation
Founder effects

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43
Q

Describe each of these instances of hybrid zones?

A

Subdivision = The equal halving of the population

Peripheral Isolation = A small population at the edge of the species range is isolated

Founder effects = the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

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44
Q

What is Parapatric Speciation?

A

two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes.

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45
Q

What is Sympatric Speciation?

A

New species forms in the geographical range of ancestor; no barrier; no geographical range; only reinforcement. For example, Lacewings and Cichlids in Lake Victoria.

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46
Q

How natural selection and sexual selection lead to evolution?

A

Lead to the production of adaptations = introduction of new species.

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47
Q

What are 2 alternative views that argue the development of the fossil record?

A

Punctuated equilibrium and Phyletic gradualism

48
Q

Describe the Punctuated Equilibrium Theory

A

Most of the time, there is little to no microevolution happening but when evolution does occur, it punctuates the lineage (new, radical theory).

49
Q

Describe the Phyletic Gradualism Theory

A

Constantly on the move and changing all the time. Constant creation of new species (traditional view).

50
Q

What is the main condition for Punctuated Equilibrium to occur?

A

When the majority of speciation is allopatric and there is a peripheral isolation (a small gene pool).

51
Q

Which theory is correct?

A
  • Both are extreme views
  • Evidence? Bryozoans – show punctuated equilibrium
  • While phyletic gradualism was seen in trilobites.
    *Evolution is most likely a mix of both!
52
Q

TRUE or FALSE: Evolution is directed towards a goal.

A

False. Although similar structures can evolve in different species, evolution is not directed towards a ‘goal’

53
Q

What are fossils?

A

The geologically altered remains of a once-living organism and/or its behaviour

54
Q

How are fossils formed?

A

Through a series of unlikely events:

a. The body needs to survive long enough for fossilisation;
b. Bodies must also remain buried in the sediment at the bottom of the water column.
c. Permineralisation
d. Exposure – for example, by tectonic processes etc.

55
Q

What does the quality of the fossils depend on?

A

The quality of the fossil depends on the state of the body at the start of the process and geological factors – pressure, minerals

56
Q

How can we date fossils? Name 3 methods

A
  1. Radio carbon testing
  2. Volcanic ash
  3. Paleomagnetic dating
57
Q

Are fossils still useful?

A

Evidence of evolution but they can only tell us functional morphology. However, the Fossil Record has helped us characterise the geological period into several categories e.g. the Cambrian, Ordovician, Silurian, Devonian etc.

58
Q

What are the key life events?

A

Cambrian - 0.5 billion years ago
Origin of Life - 3.5 billion years ago
Formation of Earth - 4.57 billion years ago
Big Bang - 13.7 billion years ago

59
Q

What was Miller-Urey’s experiment in 1953 trying to prove?

A

That organic molecules in the atmosphere (Methane, ammonia, hydrogen peroxide, carbon dioxide, phosphorus ) could produce amino acids if provided sufficient energy, proving that they were the first sign of ‘life’.

60
Q

Why was the experiment criticised?

A

-The wrong mix of gases
-Required unrealistically high energy input

61
Q

What was the first self-replicating molecule?

A

RNA

62
Q

Name 3 ways complex polymers may have formed

A
  1. Bubble Hypothesis
  2. Clay Hypothesis
  3. Extra-terrestrial Hypothesis
63
Q

Describe the Bubble Hypothesis

A

Bubbles entrap monomers inside membranes + exposing them to UV light = formation of organic polymers.

64
Q

Describe the Clay Hypothesis

A

Organic monomers attracted to silicate crystals + replication was exaptation. Monomers copy this + become independent of clay. Flat sheets in suspension trap other silicate structures – when it gets big, it splits off.

65
Q

What are the two hypothesises of the Extra-terrestrial Hypothesis?

A

Comet and Mars hypothesises

66
Q

What is the Comet Hypothesis?

A

Exogenesis; organic compounds common in space; no heat to evaporate = intro of complex organic polymers.

67
Q

What is the Mars Hypothesis?

A

Life formed too quick = no time for crust cool; crust is small = life formed 1st + asteroids brought organic complex polymers to earth.

68
Q

How were the first cells formed?

A

*Self-replication is more efficient when they are closer to enzymes.
*Proto-cell (scaffold with small pits)
*Thought to have happened in the sea (in a hydrothermal vent)
*Replication more efficient when catalysed by enzymes
*Selection would favour molecules that concentrate enzymes
*Enclosure in a membrane
*Phospholipids spontaneously form enclosed membranes

69
Q

How was the first Eukarya cell formed?

A

Co-evolution (symbiosis)
*Exchange of metabolites between Asgard archaeal cell and alpha proteobacterium – leading to the evolution of eukarytoic cells.

70
Q

What was the origin of Animals?

A

*Formation of colonial flagellate protest (to avoid predation)
*Bigger size (move around more efficiently) – not all cells in the sphere need flagella so they lose it.
*Some become reproductive cells – selective advantage.
*Concentration of food in the digestive cavity so some cells become specialised for digestion.

71
Q

What are the 2 morphological hypothesises?

A

Protosts: spiral cleavage
Deutero: radial cleavage.

72
Q

Describe the Phylum Chordata

A

notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

73
Q

What are Gnathostomes?

A

Vertebrates with jaws

74
Q

What are tetrapods?

A

gnathostomes that have limbs

75
Q

What are amniotes?

A

Tetrapods that have a terrestrially adapted egg

76
Q

What are mammals?

A

amniotes that have hair and produce milk

77
Q

What are primates?

A

Eutherians with hands and feet adapted for grasping, no claws, large brains, short jaws, and stereo vision

78
Q

What are anthropoids?

A

Primates with somewhat opposable thumbs

79
Q

What are hominoids?

A

Anthropoids with a fully opposable thumb- apes and humans

80
Q

What are hominins?

A

Hominoids more closely related to modern humans than modern chimpanzees, gorillas or orangutans

81
Q

Name the 3 other groups of hominoidea

A

Paninins - chimpanzees
Gorillins - gorillas
Pongins - orangutans

82
Q

How many extant species are in each group?

A

Pongins – orangutans (3 extant species)
Gorillins – gorillas (2 extant species)
Panins – chimpanzees (2 extant species)
Hominins – homo sapiens (1 extant species)

83
Q

Name the 3 earliest hominins

A

S. tschadensis, O. tugenensis, A. kadabba, & A. ramidus, three Canididate groups of fossils

84
Q

What was A. Aferensis?

A

Based on a famous chimpanzee-like fossil nicknamed Lucy, discovered in 1974 in Ethiopia from 4.0-4.5 Million years ago

85
Q

What is Bipedal Locomotion?

A

Walking on two feet. Walking on two legs is the single most distinctive feature of the hominins. Anthropoids ancestors were arboreal (30-35 million years ago)

86
Q

What are the 2 theories that explain the evolution of Bipedal Locomotion?

A

Savannah Theory and Aquatic Theory

87
Q

Explain the Savannah Theory

A

It was once thought bipedalism originated as an attempt to deal with the challenges confronted in the open land
-Later discovered was evolved in thickly forest woods

88
Q

Explain the Aquatic Theory

A

Our prehuman ancestors spent a lot of time in and around water so they learned how to hold their breath, stand on 2 legs, and developed a prominent nose with downward facing nostrils

89
Q

What was H.rudolfensis?

A

2.4-1.8 mya sturdier form of H. habilis, 600-800cc brainsize, bigger wider, flatter face, large chewing muscles

90
Q

What was Homo habilis?

A

2.4 mya, Olduvai gorge, Tanzania. Controversial; may be an australopith

91
Q

What was Homo ergaster?

A

First fully bipedal, large-brained hominid, slender, gracile, low sexual dimorphism

92
Q

What was Homo erectus?

A

Extinct species of primitive hominid with upright stature but small brain, may be direct ancestor of modern humans, first migrate our of Africa 1,5 mya

93
Q

Who were the Homo Neanderthalensis?

A

The species before us homo sapiens; lived form 30,000 to 300,000 years ago; they were stronger and had bigger brains, evidence of interbreeding with early H. sapiens in Europe

94
Q

Who were the Homo Sapiens?

A

Oldest fossils 195-160,000 years old in Ethiopia, lack heavy brow ridges, only extant hominin

95
Q

What was the Candelabra Theory?

A

Multiregional Evolution, there was initially one major branch of humans, dispersed to three major continents, evolved in a parallel fashion to each other into modern humans

95
Q

What are the 2 theories that explain the evolution of modern Homo sapiens?

A

Candelabra and Out of Africa theory

96
Q

What was the Out of Africa theory?

A

The hypothesis that modern humans (Homo sapiens) evolved in Africa and spread to other continents, replacing other Homo species without interbreeding with them.

97
Q

When was the Pleistocene?

A

1.8 million years ago to 11,000 years ago. The Last Ice Age.

98
Q

Who were the H. bodoensis?

A

Africa 600,00-126,000, Direct ancestor of H. sapiens

99
Q

Who were the H. daliensis?

A

China 100,000, Sister species of H. sapiens

100
Q

Name the 2 extreme views of life

A
  1. Cone of increasing diversity
  2. Decimation and diversification
101
Q

What do they both show?

A

Adaptive radiation and extinction

102
Q

How is diversity determined?

A

Diversity is determined by the rate of adaptive radiation and extinction

103
Q

What is Adaptive Radiation?

A

the diversification of a group of organisms into forms filling different ecological niches.

104
Q

Under what conditions does Adaptive Radiation occur?

A

-Colonisation of a new area free from competitors
-Adaptive breakthrough
-Extinction of competitors
-Replacement of competitors

105
Q

Give 2 examples of evidence of extinction

A

Steller’s Sea Cow:
-Natives harvested food that sea cows ate
-Discovery by European sailors led to the trade and hunting of blubber from sea cows, driving extinction at fast rates.

Dodo:
-Introduction of species to Mauritius (predators attacked Dodo eggs).

106
Q

What are the 2 scales of extinction?

A

Small scale extinction and mass extinction

107
Q

What are the causes of small scale extinction?

A

-biotic (e.g. when one party loses an arms race)
-physical (climate change)
-developmental constraints (prevent adaptations)

108
Q

Which factors affect the chance of extinction?

A

-Population size
-Longevity (longer living may adapt eventually in their lifetime)
-Rate of increase
-Environment stability

109
Q

How did the K-T mass extinction benefit mammals?

A

Mammals exploited the leftover niches from the death of dinosaurs (passive replacement).

110
Q

What is Sensory bias?

A

female mating preferences are by-products of natural selection on sensory systems.

111
Q

What is Fisherian Runaway Theory?

A

the evolution of the peacock tail is made possible if peahens have a preference to mate with peacocks that possess a longer and more colourful tail.

112
Q

What is the Sexy Son Theory?

A

a female animal’s optimal choice among potential mates is a male whose genes will produce male offspring with the best chance of reproductive success.

113
Q

What are Indicator Traits?

A

traits percieved as attractive

114
Q

What is Permineralization?

A

a type of fossilization that happens when minerals transported by water fill in all the open spaces of an organism or organic tissue (most dino bones)

Biological Sciences 1 (10 decks)

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