Bisc 102 final Flashcards
1
Q
Evolution by natural selection in three steps
A
- Variation among individuals
- Heritable variation
- Variation linked to fitness
2
Q
Asexual reproduction
A
Reproduction without fertilization or conjugation; Parent passes on 100% of its genes to all its offspring (produces clones); Can be parthenogenesis, fragmentation, budding, vegetative propagation
3
Q
Sexual reproduction
A
Occurs through fertilization to produce a genetically novel individual; Each parent passes ~50% of its genes to each offspring; Offspring tend to resemble parents; Internal or external fertilization
4
Q
Variation in sexual function
A
Separate sexes; hermaphrodites (simultaneous ex. flowers or sequential ex. some fish that start as female then become male)
5
Q
Karyotype
A
A display of the chromosome pairs of a cell arranged by size and shape- homologous pairs have the same staining pattern and centromere position
46 chromosomes in humans (44 autosomes, 2 sex chromosomes) 2n = 46; 18 in carrots; 32 in cats;
1262 in adder’s fern (why so many: a lot would not be useful!)
6
Q
3 events unique to meiosis
A
- Synapsis and crossing over during prophase 1 (formation of the synaptonemal complex and genetic rearrangement between nonsister chromosomes) 2. Homologous pairs at the metaphase plate, rather than individual chromosomes 3. Separation of homologs instead of separation of chromatids.
7
Q
Sources of genetic variation
A
Crossing-over (= recombination), Independent assortment, Random fertilization
8
Q
Crossing-over
A
Exchange of corresponding segments of DNA by non-sister chromatids in a tetrad during Prophase I, producing new combinations of maternal and paternal alleles
9
Q
Independent assortment
A
Random alignment of each pair of homologous chromosomes at Metaphase I plate ie. each pair of homologs may orient with either its maternal or paternal homolog closer to a given pole, independently of any other pair of homologs (2^23 possibilities= 8.4 million)
10
Q
Random fertilization
A
Which egg of 2^23 possibilities will combine with which sperm of 2^23 possibilities? Any 2 parents will produce a zygote with ~70 trillion (2^23x 2^23) diploid combinations
11
Q
Advantages of sex
A
Introduces new combinations of heritable traits in offspring; Introduces new combinations of heritable traits in offspring; Potentially useful in a variable, dynamic environment
12
Q
Mendelian genetics
A
The scientific study of how traits are passed on from parent to offspring; The study of heredity
13
Q
Mendel’s 1st law of heredity
A
Law of segregation: The two alleles for a heritable trait separate during gamete formation and end up in different gametes
14
Q
Mendel’s 2nd law of heredity
A
Law of independent assortment: Each pair of alleles segregates independently of each other pair of alleles during gamete formation
15
Q
Genotype
A
The genetic makeup or set of alleles of an organism
16
Q
Phenotype
A
The observable physical and physiological traits of an organism which are determined by it’s genetic makeup
17
Q
Incomplete dominance
A
The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele ex. Rr gives pink flower, when RR is red and rr is white
18
Q
Co-dominance
A
The situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways ex. blood types IAIB contains both A and B proteins
19
Q
Sickle cell disease is an example of what kind of phenotypic expression of genotype?
A
Both codominant and incomplete dominance:
RB cells are codominant (A1A1 normal, A1A2 50% sickcle, A2A2 all sickle) while the individual shows nomal or mild or full diseases symptoms
20
Q
Heterozygote advantage
A
Approximately 1/10 African Americans is heterozygous for the sickle-cell allele. This is higher than expected, because sickle cell anemia gives partial protection from malaria
21
Q
Polygenic inheritance
A
Multiple genes determine trait; Polygenic characters have near-normal frequency distribution; ex. Human skin colour
22
Q
Multiplication law
A
Probability of independent events A and B = (Probability of event A) x (Probability of event B)
23
Q
Autosomal recessive pedigree
A
If a condition is recessive (i.e. afflicted individuals have 2 recessive alleles): Homozygous recessive individuals ARE afflicted; ‘Normal’ parents can have afflicted offspring; The condition can appear suddenly or skip generations
24
Q
Autosomal dominant pedigree
A
If a condition is dominant (i.e., afflicted individuals have 1 or 2 dominant alleles): Homozygous recessive individuals ARE NOT afflicted; Afflicted offspring have at least one afflicted parent; The condition cannot skip a generation
25
Autosomal vs sex-linked
In humans:
1 pair of sex chromosomes XX = female XY = male
X is larger and has more genes
If a gene is X-linked, A female has 2 alleles, A male has 1 allele (on X)
26
Natural selection
Process by which the individuals that have the characteristics best suited to the environment survive and reproduce better than other individuals, The main mechanism of evolution
27
Evolution
‘Evolution is a change in allele frequencies of a population over time’
28
Two scales of evolution
Microevolution : Changes within species = change in allele frequencies
Macroevolution : The evolution of new species
29
Allele frequency
The fraction of each allele in a gene pool, ex. 10 A and 10 B, so the frequency of A=0.5, the frequency of B=0.5, and the frequency of A and B= 1
30
How do new alleles originate?
Mutation;
| Horizontal gene transfer
31
Mutation
Random, heritable changes in DNA that introduce new alleles into a gene pool
Point mutation;Gene duplication; Genome duplication
Mutation rates are generally low, can be deleterious, neutral, or beneficial. Only mutations that occur in germ line (generate gametes) are inherited
32
Why would a duplicated gene accumulate mutations more quickly than a non-duplicated gene?
because the mutations can accumulate without an effect, because the unreplicated gene on the homologous chromosome, and can therefore be passed on to the next generation (no fitness consequences)
33
Horizontal gene transfer
Genes passed from one organism to another
Common among bacteria
Likely origin of eukaryotic chloroplasts and mitochondria
34
What affects allele frequency
Genetic drift; Gene flow; Selection
35
Genetic drift
Random (=chance) fluctuations in allele frequencies from one generation to the next; examples are bottleneck effect or founder effect
36
Gene flow
Transfer of alleles from one population to another; Immigration & emigration / accidental movement; Important in mobile organisms
37
Directional selection
favours variants at one extreme of distribution ex. mice, from all colours to favouring dark coloured
38
Disruptive selection
favours variants at both extremes of distribution ex. favouring light or dark mice over intermediate brown coloured mice
39
Stabilising selection
favours intermediate variants and removes extremes of distribution
40
Natural selection in the wild: Coloration of Trinidadian guppies is an example of
directional selection- Above waterfalls, bright coloured for females, Below waterfalls, dull coloured in the presence of Pike-cichlid
41
Natural selection in the wild: Bill size in Darwin’s finches is an example of
Disruptive selection- During a drought, birds with large bills could eat seeds or by bark stripping, birds with smaller bills could eat rotting parts, birds with medium sized bills who ate fruit died
42
Natural selection in the wild: Birth weight in humans is an example of
Stabilising selection- think of the graph: infant mortality is at its lowest when the birth weight is between 6-8, goes up on either side
43
Types of questions: proximate vs. ultimate
```
PROXIMATE = explanations based on immediate cause (stimuli, genetics, hormones, experience)- Ethology / psychology
ULTIMATE = explanations based on survival value or function (evolution)- Behavioural ecology
```
44
Is behaviour heritable?
It is much more complicated than physical traits, but it is partly genetic! There is a lot of evidence for this: artificial selection for mating speed in fruit flies and errors in a maze for mice.
Evolution optimises every trait, including behaviour, through natural selection
45
Blackcap migratory behaviour
Experiment where birds were breeded for migratory behaviour- it took 3 generations for 100% of birds in one population to show migratory restlessness, and 6 generations for all birds to show non-migratory behaviour
46
What is behavioural ecology?
The study of the survival and reproductive value (i.e. the adaptive significance) of behaviour; The ‘ecology’ part is due to the fact that the way in which behaviour contributes to survival and reproduction depends on ecology
47
Behavioural ecologists ask ultimate questions
Why do these behaviours occur? Why have they evolved?
48
Does behaviour influence survival and reproduction?
```
Feeding behaviour:
- How & where to search for food?
- What type of food to eat?
- Forage alone or in a group?
•
Sexual behaviour:
- How to search for a mate?
- Which mate to choose?
- Which mating strategy to use?
•
Territorial behaviour:
- Defend a territory or not?
- How large and where?
```
49
A general theme of BE: Natural selection affects
gene survival and individuals (vehicles for genes) should behave to maximise inclusive fitness
50
What is fitness?
How well an individual (= a gene) does relative to others in the population
Fitness = 0 no representation of allele x in next generation
Fitness = 1 100% allele x in next generation
51
‘to ensure the survival of the species’ is incorrect
Individual advantage is what counts! think of infanticide in lions
52
Evolution of altruistic behaviour
Acting to increase another individual’s lifetime
| number of offspring at a cost to one’s own survival and reproduction
53
Helping in bee eaters is an example of
Inclusive fitness: DNA analysis shows that helpers are related to breeding pair! Altruistic behaviour is therefore genetically selfish!
54
Inclusive fitness
Fitness gained:
directly, through personal reproduction, and
indirectly, by contributing to the survival and reproductive success of relatives
55
Relatedness
r = coefficient of relatedness between two individual
= the probability that a particular allele, present in one individual, is also present in another individual because of their descent from a common ancestor
= the proportion of genotype in 2 individuals that are identical because of their common descent
56
r = Σ 0.5^L
L is the number of generation links between the 2 individuals concerned
ex. parent- offspring = 0.5, siblings = 0.5, grandparent-grandchild= 0.25, cousins= 0.125
57
Kin selection
Process by which characteristics (or alleles) are favoured due to their beneficial effect on the survival or reproduction of relatives
Kin selection should occur if Hamilton’s rule is met
58
Hamilton’s rule
rB – C > 0 (** note the GREATER THAN not greater than or equal to)
where B = benefit to the recipient of the altruistic act
C = cost to the donor
r = coefficient of relatedness between donor
and recipient
59
reciprocal altruism
```
What about altruism towards non-kin?
Whenever Brecipient > Cdonor
AND
help is reciprocated later
then both participants benefit
```
60
Vampire bats regurgitating is an example of
Reciprocal altruism- Vampire bats favour kin, but they also help non-related roost mates
61
THE fundamental difference between males and females
Females produce few, large, energetically expensive gametes; Males produce numerous, small, cheap gametes
62
Bateman’s principle
Male reproductive success is determined by number of mates
| Female reproductive success is not
63
Comparing the reproductive success of each sex
Selection for males to maximise quantity so males compete with each other
Selection for females to maximise quality so females choose their mates carefully
64
On average, the reproductive success of males and females is the same! (everyone has two parents!) What does this mean?
Males have great potential, but are highly variable
| Females have low potential, but low variability as well
65
Sexual selection
Process by which individuals that have traits that increase mating success are favoured over individuals that do not have these traits; competition or mate choice
66
Intrasexual selection
Process favouring the ability to compete directly with member of the same sex (usually males) for access to the opposite sex (Sexually selected traits for fighting)
67
Intersexual selection:
Process favouring the ability to attract members of the opposite sex (mate choice) (Sexually selected traits for seducing)
68
Mating systems determines:
The pattern of mate acquisition by both sexes; Shaped by male/female reproductive potential, parental care, ecology and phylogeny; Major determinant of how strong sexual selection will be
69
Types of mating systems
Monogamy (care of young by both parents; evenly dispersed resources ex. penguins)
Polygyny (care of young by female only; patchy resources ex. gorillas)
Polyandry (Care of young by male only; low male rate of reproduction ex. some bird)
Promiscuity/ polyGAMY (No care of young or care by female only; Evenly distributed resources)
70
Direct benefits of choosing mates carefully
Mate with member of the correct species; Have access to good/safe territory; Get fed lots of food; Get a good parent for offspring; Get a fertile mate
71
Indirect benefits of choosing mates carefully
Good genes: Sexually selected traits advertise genetic quality because they are costly to produce
Sexy sons: Females choosing males with well-developed sexually selected traits produce sons with the same traits
72
Good genes in peacocks
Peacocks provide nothing to females apart from sperm / genes; Females prefer bigger males with bigger eyespots on tail; Females experimentally mated with males with bigger eyespots produced offspring with faster growth rates and higher survival
73
Imprinting
Ex. of female finches preferring males with ornaments because their fathers has ornament feathers
74
Mate choice copying
A behaviour in which individuals in a population copy the mate choice of others
75
Agonistic behaviour
An often ritualized contest that determines which competitor gains access to a resources such as food or mates.ex. male stalk-eyed flies
76
Biological species concept
Groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups
77
Other definitions of species
Morphological species concept: based on similarity of appearance
Ecological species concept: based on similarity of resource and habitat use
Phylogenetic species concept: based on similarity of ancestry
78
Issues with the biological species concept
How do we know if fossil forms were interbreeding?
What about species that are asexual?
What if we don’t observe mating?
-Morphological similarity can be used to indicate interbreeding
-If morphologically similar organisms do not interbreed, consider genetic relatedness
-But threshold genetic difference is not defined
79
Allopatric speciation
Physical separation of two populations = interruption of gene flow ex. ratites, ancestor from Gondwana, species now include emu, ostrich, kiwi, etc. on different continents/islands
80
Sympatric speciation
No physical barriers!
81
Reproductive isolation by
Mutation: Polyploidy- Common in plants
Ecology:
Behaviour:
82
host shift in the apple maggot Rhagoletis is an example of
Sympatric speciation from habitat differentiation
83
cichlids are an example of
Sympatric speciation from sexual selection
84
What happens when divergent populations come into contact?
1. The populations hybridize but hybrids are less fit than the parents= Reinforcement of differences
2. The populations hybridize a fit and hybrids are as fit as parents= Fusion
3. Populations hybridize and hybrids preferentially mate with each other= Stable hybrid zone
85
Speciation is a _____ and NOT an _____
process, event
86
Microevolution
Evolution on a small scale
Changes in allele frequency within a species
Processes: natural selection, drift, mutation
Focus on changes in living species
87
Macroevolution
Evolution on a large scale, as seen through the history of life
Patterns of stasis, change, origin of new lineages, and extinction
Fossil record
88
Adaptive radiation
The sudden and rapid diversification of a phyletic line into several lineages; Occurs when a new set of niches opens up due to
- Evolution of a novel feature
- Opening up of a new habitat
- Extinction of other species or clade
89
Speciation
An evolutionary process in which one species splits into two or more species
90
Explain Adaptive radiation by Galapagos finches
Causes? Archipelago-New habitat-New food sources
| Speciation by ‘island hopping’
91
Hawaiian honeycreepers is an example od
adaptive radiation
92
Explain how bats show adaptive radiation
2nd most diverse order of mammals, radiated ~50 mya
Causes?
Extinction of pterosaurs (a huge niche left open, took it over at night so it was even more empty)-Peak insect diversity (different specialist bats)-Novel features (
93
Tempo of speciation (note: it is highly variable between taxa, ex. 100000 yrs in finches, 17000 yrs in cichlids, 300 million yrs in horseshoe crabs)
Gradualism- (Traditional view, Not supported by fossil record)
Punctuated equilibrium- (Rapid appearance, Slow to no change later)
It is likely in between these two extremes because fossil record is incomplete, so it can't show gradualism, physiological, behavioural changes, etc.)
94
Extinction
| Name the five main mass extinctions
~99% of species that have existed are now extinct; Typical ‘lifetime’ of a species = 1 my
Ordovician, Devonian, Permian, Triassic, Cretaceous
95
Permian extinction (~250 mya)
The ‘Great Dying’
90% + of all species (96% marine species, 70% land species incl. plants, insects, and vertebrates)
Victims include: ammonites, trilobites, blastoidea, and mammal-like reptiles
96
Cretaceous-Tertiary (K/T) extinction (65 mya)
60-80% of animal species extinct
Terrestrial animals hardest hit
Victims: Pterosaurs, Dinosaurs, Many plants & invertebrates
Spared: Mammals, crocodiles, non-North American plants
97
Possible causes for the K/T extinction (65 mya)
Climate change- Sea level changes- Increased volcanic activity
**Meteorite impact (Evidence: global iridium layer at K/T boundary, 180 km diameter crater in Mexico; this would have caused Fires- Tidal waves (as much as 4 km high!)-Dust, darkness, cooling-Water vaporized from ocean & acid rain-Earthquakes and volcanoes-Mass extinction!)
98
Possible causes of the Permian extinction (~250 mya)
Siberian volcanoes (would cause climate change from inceased CO2, y ~6 C. food chain collapse)- Formation of Pangea (Changed ocean circulation patterns and a Drop in sea level)-Reduced oxygen in oceans-Climate change
99
Are we in the middle of a sixth mass extinction?
Recent megafauna extinctions- large terrestrial animals (>44kg); Began in the Late Pleistocene (100,000 to 10,000 years ago)
Africa 14% Europe29% North America 73% South America 79% Australia 96%
Causes: Climate? Hyperdisease? Humans?
100
Primates
```
Mammalian order~ 180 spp
Derived characters:
5 digits
Flat nails
Large brain
Long parental care
Complex social systems
```
101
Anthropoids
| =simians) (Yes! A clade!
```
Primate suborder
Includes monkeys, apes, humans
Derived characters:
Fully opposable thumb
Larger brain
```
102
Hominoids (Yes! A clade!)
```
Anthropoid superfamily
Includes apes and humans
Derived characters:
Tail-less
Arm-swinging
More erect posture
Larger body size
Larger brain
```
103
Hominoid families
Hylobatidae (Gibbons)
Pongidae (Orangutans, gorillas, chimpanzees, bonobo)--paraphyletic group, not used much anymore
Hominidae (all pongidae and humans)
104
The first hominin?
Sahelanthropus tchadensis or Ardipithecus kadabba
105
Sahelanthropus tchadensis
Lived 7-6 mya
Derived traits: reduced canines + flat face
Probably an ape?
106
Ardipithecus kadabba
Lived ~5.5 mya
| Derived traits: reduced canines + signs of bipedalism
107
Australopithecines- Australopithecus afarensis
```
4-3 MYA
‘Small’ brain (~500 cc)
Long arms
Bipedal
*note bipedalism arose much earlier than large brain
```
108
Bipedalism- Clues to modes of locomotion
arm length (shorter), knee joints (allow feet to be positioned close together), attachment of skull to vertebrae (underneath skull), pelvis (shorter, wider)
109
Evolutionary significance of bipedalism
Improved predator detection;Display or warning signal (these do not give reason for timing!)
Freed the hands in order to carry things (careful of putting are function on the ancestors)
More energy-efficient if long travel distances needed and Efficient method of thermoregulation (these two can be explained by a changing climate at the time!)
110
Genus Homo
Derived characters
Significant brain enlargement
Elaboration of material culture
(tools & art)
111
Homo habilis - The handy man
2.4-1.6 MYA
Short jaw, small molars
Larger brain (600-750 cc)
Tool use
112
Tool use
Appears more than 2 MYA
H. habilis and/or A. garhi (450 cc)?
Shift in diet?
Evidence of cognition
113
Homo ergaster – The working man
```
1.9 to 1.5 MYA
Long slender legs
Small teeth
Larger brain (900 cc)
Reduced sexual dimorphism
```
114
Homo erectus – The erect man
1.8 MYA - 200,000 YA
| Out of Africa to Asia
115
Homo neanderthalensis
```
200,000 – 25,000 YA
Europe and the Near East
Cold-adapted (from body shape)
Large brain (1200-1700cc)
Did Neanderthals and humans interbreed?
```
116
Homo sapiens
Oldest fossils 195,000 YA from Ethiopia
| Migrated out of Africa ~115,000 YA
117
Homo sapiens
```
Derived characters
•Abstract thought
•Innovation
•Symbolism
•Goal-directed behaviour
```
118
Male-male competition in humans
ex. love triangle murders, higher rates of infidelity in males
119
Sperm competition
Can occurs from wife sharing, prostitution, pre-marital sex
120
Mate guarding
Strategies to reduce the potential for sperm competition
| Marriage, Guarding by eunuchs, Veiling, Chastity belts
121
How to study mate choice in humans?
Personal ads:
Advantages: not aimed at researchers, Short so only important info appears, Advertisers are truly interested
Disadvantages: People might understate what they truly want, People might overstate what they have to offer
122
Female mate choice
Commitment and resources (Tends to be older men, intelligent men)
If they can't get resources, women look for health, physical appearance, good abilities
Why? Wealthier, or higher skills increases fertility (but not in developed countries)
123
Male mate choice
Looks (younger women, intelligent (sort of), shapely women), low waist-to-hip ratio (lower 0.7 indicates health, pregnancy state, age)
Why? Increased female fertility related to age, fat
124
Tibetan farming villages shows
Polyandry in humans: Farm rice, wheat, pulse, Land is poor and winters are long, Land is divided into family estates
Only first son marries, Younger brothers may marry the same woman, Daughters marry out or do not marry (30%), Younger sons in large families marry out or become monks (30%)
Marriages are arranged
125
Reproductive consequences of polyandry
Polyandrous advantageous for females, and INCLUSIVE fitness roughly equal for monogamous, diandrous, or triandrous males as co-husbands are brothers!
126
Pitcairn Island
Are monogamous societies effectively monogamous?
127
biodiversity
“biological” + “diversity” = “biodiversity”
| variability from genes to ecosystems and beyond…
128
1992 United Nations Earth Summit
"the variability among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems”.
129
Three levels of biodiversity
1. Genetic diversity ex. breeds of dogs
2. Species diversity ex. different species of trees in a forest
3. Ecosystem diversity ex. marine ecosystem can be beach, coral reefs, kelp forests, mangroves, etc
130
Taxonomic distribution of spp diversity
identified insects 55%, other anthropods 9%, mollusks 4%, other invertebrates 5%, chordates 3%, nonvascular plants 5%, vascular plants 18%
131
How many more species? Different calculations
1. Size-diversity relationship (Sir May)
2. Extrapolate from well-known fauna (Kevin Gaston)
3. Extrapolation from tropical beetles (Terry Erwin)
4. Comparing numbers in PCOFGS (Camilo Mora)
132
Size-diversity relationship
We rarely identify new species of large animals, so we can be fairly confident of those numbers. Because of the energy pyramid, it would make sense that there are many more smaller animals- extrapolating a graph of number of species vs. animal size shows the area under the curve that is missing
133
Extrapolate from well-known fauna
The number of insect species in Great Britain is very well known, and number of butterfly species is also fairly certain. Calculating the percent of insects that are butterflies in the UK, and assuming the percent of butterflies to other insects in the world is fairly constant, calculate the expected number of insects in the world (5-6.6 million insect species)
134
Extrapolation from tropical beetles
A bit far-fetched? Find # of beetles in the tree canopy, assume 20% are tree specific, then assuming 40% of insects are beetles, find the number of specialist insects per tree, assume 2/3 of insects live in canopy, find the number of insect spp per tree spp, and from the # of tree spp, calculate the number of insects in tropical forests (30 million spp)
135
By Camilo Mora
log of the number of described groups in phylum, to class, to order, etc.
We are fairly certain about the number up to genus
These give a nice parabolic curve
From that, we can calculate where species is expected to be
136
Patterns in species diversity
Latitudinal gradient–Diversity decreases from equator to poles
Altitudinal gradient–Diversity decreases the higher you go up a mountain
Area gradient–Diversity decreases as island size decreases
137
Why are the tropics so species-rich?
```
Evolutionary history (glaciers have cause temperate and polar communities to repeatedly start over)–Environmental stability–Tropical communities are older–Faster speciation rate from growing season that is five times longer
Climate–High solar energy input–Water availability
```
138
Habitat size and species diversity
Larger areas have a greater diversity of habitats
139
productivity
the potential evapotranspiration- highest when there is large amounts of water and solar energy, which allows greater species diversity (graphs for plants, birds, mammals, reptiles show square root graphs (increasing to a point!)
140
Island biogeography theory
Predicts number of species in an area (e.g. oceanic island, habitat island); Rates of immigration and local extinction predict species richness at equilibrium (think of the graphs)
141
Effect of proximity to mainland, and island size
Number of species on near, large islands are higher because there is more immigration, and large islands are bigger targets
142
What is conservation biology?
A recent discipline concerned with the effects of environmental change on biodiversity
A crisis discipline
Multidisciplinary: ecology, social, economics, policy, ethics
143
The ultimate cause of loss of biodiversity
We have gone around the bend on a series of J curves:
Increasing population size
Increasing use of finite resources
Increasing pollution
144
Consequences of human population explosion
(1) Habitat destruction
(2) Overexploitation- (from changes in technology, short-sighted psychology, economics)
(3) Introduced species
(4) Pollution- (light, noise, contaminants-far reaching long lived effects)
(5) Climate change
145
The 'value' of biodiversity
Intrinsic value-Value independent of utility, Philosophical or religious perspective, Not very effective in policy debates…
Extrinsic (utilitarian) = Ecosystem services (benefits such as food, medicine, wool and services like pest control with birds, pollination, flood control)
Species and habitats have a monetary value = cost of providing a man-made alternative (think of earthworms!)
Estimate of global economic benefits of biodiversity= 11% of total world economy
146
Henslow, FitsRoy, Lyell are associated with
Darwin
147
Darwin's description of evolution
Descent with modification
148
Why is mutations only in gametes not limiting plants and fungi?
Mutations acquired by the parent is more likely to pass this on to offspring because many different cell lines can produce gametes, while most mutations in animals are in somatic cells
149
What are the 4 key points of genetic drift?
1. significant in small populations 2. can causes allele frequencies to change at random 3. can lead to a loss of genetic variation within populations 4. can cause harmful alleles to become fixed (think egg-hatching rate in prairie chickens)
150
The example of difference in taste preference in banana slugs is an example of
how selection acted on coastal snakes to be able to recognize banana slugs as food, and therefore has higher fitness. This also meant that the taste was genetically acquired
151
Prezygotic barriers
1. Habitat isolation 2. Temporal Isolation 3. Behavioural isolation 4. Mechanical isolation 5. Gametic isolation
152
Post zygotic barriers
1. Reduced hybrid viability 2. Reduced hybrid fertility 3. Hybrid breakdown
153
Effects of mass exinction
typically takes about 5-10 million years for the diversity of life to recover o previous levels after a mass extincion, or longer
153
Effects of mass exinction
typically takes about 5-10 million years for the diversity of life to recover o previous levels after a mass extincion, or longer
154
Examples of adaptive radiation that played entirely new ecological roles
photosynthetic prokaryotes, large predators during the Cambrian explosion, the colonization of land by plants, insects, and tetrapods
154
Examples of adaptive radiation that played entirely new ecological roles
photosynthetic prokaryotes, large predators during the Cambrian explosion, the colonization of land by plants, insects, and tetrapods
155
Why is diversity important?
contributes to community stability: more productive and better able to withstand and recover from environmental stresses
155
Why is diversity important?
contributes to community stability: more productive and better able to withstand and recover from environmental stresses
156
MacArthur and Wilson
Came up with the island equilibrium model; this model is good over relatively short periods, and a limited number of cases, but is applied to conservation biology
