Natural Selection and Biodiversity Flashcards
Name Darwin’s major problems:
- No system for generating variation; if entire population acquired the best variant, natural selection cannot happen for that trait again.
- Blending inheritance destroys variation; if red and white flowers made pink ones, all flowers would be pink
Which types of mutation are important for evolution? Small effect or large?
Most selection on mutations of small effect as they result in gradual, slow changes
Give an example of an important macro mutation:
Macro mutations in microbes, used for widespread transfer of genetic material between microbes (e.g antibiotic resistance)
What is Heterozygote advantage and give an example:
When the most fit form is heterozygous
e.g Sickle cell anaemia
Altruism =
a behaviour beneficial to others but costly to oneself (being selfless)
How is altruism compatible with the idea of competitive struggle and individual selection?
- Helping relatives - helping to raise offspring of relations, still passing on family genes
- Give now, receive later
Hamilton’s rule =
total fitness = direct fitness + indirect fitness
(direct: producing and raising offspring
indirect: helping raise relatives’ offspring)
Natural selection works on natural genetic variation, and with constraints. These constraints are:
i) population size limits mutation
ii) poor fitness of intermediate form
iii) best form not genetically pure
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On average, each person carries ___ lethal/deleterious mutations
4
what effect does small populations have on diversity?
genetically simplified population
Which population, small or large, is better prepared for change if it occurs?
Large, as small populations will have a less evolutionary response.
Evolutionary lag =
as soon as a problem is fixed, the problem changes
e.g; when the host evolves to resist the parasite, the parasite will evolve to resist this change
Monogamy =
paired partners raise young together
Polygyny =
alpha males have access to all females
Polyandry =
females attract multiple males
Intersexual =
females choose males based on certain factors
Intrasexual =
males on male competition, males compete for access to females
Which of the following represent traits evolved by intersexual sexual selection?
a) Male crickets supplying gifts of food to their female partners during courtship.
b) Large testes sizes in chimpanzees compared to humans
c) Elaborate courtship in fruit flies
d) Large size of male lions compared to female.
e) Mate guarding, where male damsel flies stay with their female partner until she lays eggs
f) Small wingspan in forest birds
A & C
Mayr’s biological species concept =
a species is a population group that can interbreed with each other and produce fertile offspring
Prezygotic isolation =
barriers that prevent offspring pre-fertilisation
reasons for prezygotic isolation:
- temporal - don’t meet in time
- ecological - don’t meet in space
- behavioural - don’t want to mate
- mechanical - can’t physically mate
- gametic - gametes won’t fuse
Postzygotic isolation =
barriers that prevent offspring after fertilisation
reduced hybrid fertility =
babies are sterile
reduced hybrid viability =
babies are still born (dead)
Allopatric speciation =
Complete geographical isolation resulting in the formation of a species
Vicariance event =
speciation events where a species’ distribution becomes segmented and the separated populations evolve separately
why are phylogenic trees useful?
it tells us particular lifestyles, like living in the sea, evolved repeatedly
it tells us where pathogens emerged from
molecular clock =
looking at the number of nucleotide and amino acid substitutions, more amino acid differences = more time since common ancestor
How can we understand the biology of extinct species?
Trackways of footprints =
movement and running speed
How can we understand the biology of extinct species?
SA/Volume ratio =
heat retained
How can we understand the biology of extinct species?
Dentition =
diet
How can we understand the biology of extinct species?
brain size compared to body size =
cognition (smartness)
aDNA =
ancient DNA
to preserve DNA, conditions must be =
cold and dry
De-extinction:
2 ways…
1.use synthetic biology to recreate whole genomes
2.take important bits from sequence and use
CRISPR-Cas to transfer to extant relative
What happened during the Cambrian Explosion 550 Mya?
•Diversification of multicellular life in the oceans
(first fish and chordates)
•Increased oxygen, allowed for aerobic life in larger organisms
•The Burgess Shale, fossils dating from 540 Mya showed creatures we no longer see today.
525 Mya was the origin of?
Vertebrates
What happened during the origin of life on land 460 Mya?
plants derived from green algae formed spores of Byrophyte (moss like pants)
420 Mya we saw the diversification of fish. What was observed?
jawed fish
cartilaginous fish
ray finned (bony) fish
lobe-finned fish
420 Mya animals lived on land. What animals were these?
terrestrial arthropods living alongside plants
360 Mya amphibia evolved…
Lobe finned fish evolved lungs and bony limbed fins suited to walking along and breathing in stagnant ponds.
fins evolved into tetrapod limbs and with lungs progressed to living on land
310 Mya amphibians –> reptiles…
they had:
- ability to live on land
- sealed amniotic eggs
- scales so skin was water impermeable
225 Mya was the age of ____
dinosaurs
which came first mammals or birds?
mammals came first (220 Mya) and birds came in 160 Mya
