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Animal Biology > 1. Radiations and Extinctions > Flashcards

1. Radiations and Extinctions Flashcards

1
Q

What were ancient tetrapod like?

A

Fish-like creatures with four limbs that lived in shallow water and were primarily aquatic. They had gills, lungs, and legs, but were not fully adapted to life on land.

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2
Q

What were some major extinction and expansion events in amphibians ?

A

Cretaceous - Paleogene (K-Pg extinction) extinction event creating mass extinction // climate warming and selective extinction reduced competition and allowed new species to emerge (number of frogs increased drastically) //

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3
Q

What is the meaning of amniotes?

A

animals with an amniote membrane // Membrane surrounding the foetus , allowing eggs to be laid on land// Tetrapod’s which have evolved to inhabit terrestrial habitats

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4
Q

What are anamniotes’?

A

fishes and amphibians

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5
Q

What is the key difference between amniotes and anamniotes ?

A

key difference is amniotes can lay their eggs on land ( reptiles , birds and mammals ) //anamniotes lay eggs in water (fish)

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6
Q

What are some characteristics of Cecilians?

A

Fossorial, legless, dermal
scales, blunt head for digging,
retractable sensory tentacles,
vestigial eyes, internal fertilisation
with copulatory organ (phallodeum),
’blind snakes’, internal or external
development

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7
Q

What are some characteristic’s of Caudata ?

A

reduced skulls, well
developed tails, cylindrical bodies,
internal (via spermatophore) and
external fertilisation, indirect and
direct development, some species
are lungless// e.g. salamander

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8
Q

What are some characteristics of Anura ?

A

short, no tail (as adult),
long muscular hind limns,
shortened vertebral column, mostly
external fertilisation, indirect and
direct development E.G FROG

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9
Q

What is meant by key innovations? Give an example.

A

An adaptive breakthrough or key adaption of a novel phenotypic trait allowing radiation to occur // Reproductive strategies or release of toxins(can be anti-predator defence) by amphibians

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10
Q

What are some examples of variation in reproductive strategies in amphibians?

A

DARWIN FROG- young incubated in males vocal sacs// RHEOBATRACHUS SP- young found in mouth / gastric brooding of frogs// BROOK BREEDING - fewer eggs attach to each plant to reduce loss

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11
Q

What are the defining characteristics of mammals?

A

Sweat glands/ hair / three middle ear bones/ single jaw bone/ red blood cells do not possess nucleus/ neocortex (bridge within the brain)

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12
Q

What is the origin of mammals and mammals traits?

A

Latin word mamma = breasts // same ancestors of modern reptiles // can be classified by number of openings in the brain ( anasida - none// synapisa- one// diasida- two)// LACTATUION - defining characteristic of modern mammals

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13
Q

What are the 3 groups of modern mammals?

A

MONTRENATA - egg laying, no placenta (platypus) // METATHERIA - internal embryonic development, chorio-vitelline (yolk) placenta (kangaroo) // EUTHERIA - most common, chorio-allantoic placenta (humans)

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14
Q

Give some diversification patterns linked to the P/Tr and the K/Pg extinction events.

A

After P/Tr most mammals were small burrowing insects, through competition with dinosaurs niches were created. After k/Pg event competition reduced and populations grew drastically

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15
Q

What are cleidoic eggs ? What are the two main forms of them?

A

Terrestrially adapted eggs, have evolved into placental structures// can either be laid as eggs (oviparous) or carried by the female (viviparous)

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16
Q

What are the main components of the extraembryonic membrane?

A

AMNION- contains amniotic fluid// CHORION - protects the amnion/ VITELLUS- contains nutrients (yolk)// ALLANTOSIS - pocket used for waste management and gas exchange

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17
Q

What are the two types of placenta found in mammals?

A

CHORIO-ALLANTOPIC PLACENTA -> fusion of chorion and allantois with the uterus (e.g. humans) // CHORIO-VITELLINE PLACENTA -> yolk sac forms the placenta (not allantois) offspring are usually underdeveloped and therefore live in a marsupium (pouch) after (e.g. marsupial mammals- wombat)

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18
Q

What does speed of speciation depend on?

A

Time // geography (selection pressure , allopatric or sympatric conditions) // Linerage effects // mutations// number of competitors // ecological selection// gene flow// reproductive isolation.

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19
Q

What is adaptive radiation, what are some examples?

A

Diversification of a group of organisms into forms filling different niches often driven by ecological evolution / e.g. Finches beaks // African child fish and crater lake cichild, have different lip structures for feeding purposes.

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20
Q

What is required for adaptive radiation?

A

single common ancestor / phenotype-environment correlation/ trait utility / rapid speciation / outcome of competition

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21
Q

What is prezygotic and postzygotic reproductive isolation? include examples.

A

prezygotic= before fertilization (habitat isolation/ behavioural isolation/ mechanical isolation.) // post-zygotic = after fertilization (hybrid sterilization / hybrid inviability (dies before birth.)

*prezygotic reproductive isolation arises more quickly than postzygotic

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22
Q

What were the main patterns of extinction across geological time?

A

Cretaceous-tertiary (Paleogene)-> most likely an asteroid event

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23
Q

What causes species to go extinct?

A

Interbreeding -> slow and multigeneration loss in reproductive fitness // Habitat attenuation -> habitat gets smaller until it disappears / Intra and interspecies competition // natural disasters and events

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24
Q

What is the role of extinction in adaptive radiation?

A
  1. Rapid diversification of organisms to exploit distinct available ecological niches// 2. Competition between different forms exploiting ecological niches leading to specialization // 3. Specialization results in trade-offs and means that intermediate phenotypes might be selected against- reproduction isolation and speciation results
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25
What is adaptive radiation?
the diversification of a group of organisms into forms filling different ecological niches.
26
What is phylogenetics ?
The study of evolutionary relationships among species
27
What are some 'trade-offs' associated with becoming multicellular?
28
What is the role of the homeobox gene?
a highly conserved gene which acts as a transcription factor, controlling gene expression// its concentration around the body determines body structure e.g. more hox genes at the shoulder where the arm extends.
29
What was the Cambrian explosion?
An explosion in animal diveristy(490-550million years ago) // expansion of shallow seas due to the breaking of Pangea // end of the recent ice age // increased atmospheric oxygen/
30
What is meant by entropy?
A measure of how randomly energy is distributed in a system
31
What are some synapomorphies of animalia?
Diploid/ Multicellular/ eggs develop from one of the four daughter meiosis II/ Possess true epithelia / conserved genes for body plan
32
What is the different epithelia tissue types?
MESODERM - muscles and organs between digestive tract // ENDODERM-> digestive system and organs in liver and lungs // ECTODERM-> give rise to CNS and Skin
33
What does the halobiont concept refer to?
Each animal is a complex community , containing different bacteria and microorganisms
34
How do body plans influence evolutionary outcomes?
dictating an organism's basic structural design, which in turn shapes its potential adaptations to different environments, allowing certain species to thrive in specific ecological niches while limiting others
35
What are modules ?
A subunit of a system // part of a system which works together and are ususally independently
36
What is dog evolution shown on and why?
A star phylon - as everything occurred so fast and the impact of random breeding pattern it is difficult to understand relationships between species.
37
What did drake and Klingberege investigate?
tested for the modularity of dog skulls and found that mainly dogs changes snout and haw length independently of changing entire skull shape// highlighting genetic changes does not involve trade-offs between jaw length and brain size (intelligence)
38
What is the role of the BMP3 gene?
bone morphological protein which has a role in craniofacial development // an example of a toolkit gene - a gene which has the same function in many species , making it good for investigating// mutations in dogs = short-faced dogs alike pugs
39
What is the role of a morpholino ?
A gene which is designed to block the activity of a specific gene.
40
What is meant by modularity?
idea of breaking a system down into separate parts// identifies independent phenotypic traits // helps to prevent trade-offs
41
What is speciation?
the process by which new species are created through evolution// evolution of reproductive isolation within ancestral species resulting in two or more descendent species
42
What are the different geographic modes of speciation?
Allopatric (vicant an peripatric) // Parapatric or sympatric
43
What are genetic and causal modes of speciation?
Causal - factors of the environment which results in speciation e.g. ecological speciation // Genetic- genes which contribute to reproductive isolation involves cytoplasmic or genetic incompatibility
44
What is allopatric speciation?
Geographic barrier creates no gene flow in a large population, natural selection occurs and speciation occurs e.g. water level rises causing two new islands to be formed.
45
What is peripatric speciation?
A type of allopatric speciation where by a small colony is isolated , small population means no gene flow has a greater impact //
46
What is parapatric speciation?
2 species in the same location have different environments therefore different selective pressures, there is still gene flow e.g. tennesse cave salamander found both on surface of cave and inside
47
What is sympatric speciation?
No geographic barrier or environmental differences - gene flow occurs and reproductive isolation occurs e.g. crater lakes cichlids
48
What is a polyploid?
Animal containing extra chromosomes
49
What are the 5 mass extinction events ?
1. END ORDOVICIAN - 85% if all marine animals // 2.LATE DEVONIAN// 3. END-PERMIAN- closest multi-cellular life has ever got to complete extinction// 4. END -TRIASSIC - conodonts disappear and dinos dominate // 5.CRETACEOUS PALEOGENE- dinos go extinct / most famous 1= OLDEREST -> 5= MOST RECENT
50
What causes mass extinction?
a combination of natural and human-caused environmental changes. e.g. volcanic activity/ change in climate / atmospheric changes / ocean acidity changes
51
What are the consequences of mass extinction?
loss of biodiversity, the disturbance of the natural order, and the loss of ecosystem services.
52
What can we learn from previous mass extinctions?
understand under what conditions different species thrived// allows us to understand the current extinction crisis and respond to it
53
What is a conodonts ?
An organism which we use to base our understanding of time periods // distinctive fossils due to highly specific shapes, they are well preserved and have cosmopolitan distributions-- only first understood in 1983
54
What is used to measure conditions back in time? (geological tool box)
fossil series // shale colours // plate tectonics // flood basalts // stable isotype ratio // modelling of past climate
55
What is the brief origin of birds?
Decedents of reptiles-> Jurassic birds (Hinge like ankle + bipedal posture + simple feathers) ->Archaeopteryx (wings + wish bone) -> Vorona (keeled sternum)
56
What are the two evolutionary theories of flight?
1.CUROSIAL ORIGIN - flight evolved from ground dwelling cursorial dino, birds ran after prey and wings were initially used for stabilising before flight// 2. ARBEREAL - feathers used for aerodynamic use, birds jumped and developed flight
57
Give some characteristics of a birds
Hollow bones/ chambered heart / feathers/ wishbone / endotherm(generates its own heat)
58
What are some animals and the characteristics which are associated with birds ?
ARCHEOPTERYX (had long boxy axis + power of flight + long tail + feathers-> DIEINONYCHUS ANTIRRHOPUS (small body + claws) -> BAMBIRAOR FEINBERGI (no feathers in fossil , latge optic lobe and well adapted to living on the ground
59
What are some advantages of flight?
Escape from predators , exploit new resources / search for mates / migrate rapidly / migrate cheaply
60
What is some requirements for flight?
Low weight / high power / high surface
61
What are some adaptations for flight?
Thin sheets and tubes for bones/ air sacs / no teeth and heavy jaw/ little fat accumulation
62
What are some positives and negatives of living in a group?
POSITIVE ->More competition in groups // defence in against predation / protection of young / food acquisition// NEGATIVES -> disease transmission / visibility to predators / resource competition
63
what is Hamilton's law?
r(relatedness ) B (benefits to recipient ) > C (cost of altruist) // an altruistic act is more favoured by natural selection when the individuals are more genetically related
64
What is meant by kin selection?
type of natural selection where individuals will sacrifice their own lives in an effort to save closely related organisms
65
What is the two types of inclusive fitness?
1.DIRECT FITNESS - fitness you gain from your offspring possessing your genes// 2.INDIRECT FITNESS- benefit of allele and genes related closely to you

Animal Biology (4 decks)

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