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changes in biodiversity Flashcards

1
Q

geological time scale?

A

the events that occurred on Earth from its formation to the present.

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2
Q

how is the geological time scale constructed?

A

Sedimentary rock sequence
Fossils
Radiometric dating

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3
Q

eon

A

largest time period.

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4
Q

era

A

subdivision of eons.

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5
Q

period

A

subdivision of eras.

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6
Q

epoch

A

subdivision of a period.

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7
Q

The Precambrian Time

A

Period of the earth’s formation.
Not an eon, era, period or epoch

Divided into:
Hadean
Archaean
Proterozoic

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8
Q

The Hadean (~4600-4000 mya)

A

Molten ball with meteors pelting
Cooled and formed a rocky terrain
Clouds formed, producing rain which cooled the crust and formed oceans
Not a geological period as there is no rock that old
Rocks found on the moon are 4.6 billion years old- earth and moon formed at same time by a collision with a mars sized planetoid and early earth, moon debris
Oldest rocks 3.8 billion years
Erosion and plate tectonics are blamed for lack of older rocks
Advent of rock record = archaean eon

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9
Q

Archaean eon (4000-2500 mya)

A

1.5 billion years
atmosphere: methane, ammonia
Bacteria formed early
Oldest fossils are microfossils of bacteria from 3.5 billion years ago- stromatolites became common

Stromatolites: layered rocks that form when prokaryotes bind thin films of sediment together.

Stromatolites decreased during Proterozoic

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10
Q

Proterozoic eon (2500-541.0 mya)

A

Smaller landmasses joined forming continental landmasses
More bacteria
Cyanobacteria make oxygen and by 2 billion years ago oxygen filled atmospheres
Anaerobic organisms go extinct due to oxygen being toxic
Aerobic life began to form
Green algae- 1.4 billion years ago
First animals towards end

The end of the Proterozoic eon: the Ediacaran period (~635-541 mya)
Earliest evidence of diversity of multicellular animals- Ediacaran fauna
Found worldwide
small, soft-bodied sea creatures - sea jellies and segmented worms
Phyla invertebrate animals

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11
Q

theories about how life came about?

A

Organic molecules accumulated to form self replicating life
Organic molecules may have arrived by meteorite
But how did the organic molecules come to be?

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12
Q

primordial soup theory

A

Amino acids formed as result of gases in atmosphere and molecules in oceans being energised and changed by lightening and UV
Miller-Urey experiment replicated this and produced organic compounds
Significance of experiment- organic molecules can be formed from inorganic molecules

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13
Q

theory that life evolved near hydrothermal vents

A

In depths of oceans with no light
Single-celled organisms must source energy from organic molecules down there
Modern Archaea survive like this- ancient may have too
High heat and high pressure can combine chemicals to form organic molecules (similar in volcanos)

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14
Q

RNA world theory

A

All living cells have:
Proteins
DNA
RNA

Catalytic RNA (ribozyme)
RNA was first molecule able to stop info, replicate and catalyse
DNA may have evolved due to instability of RNA

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15
Q

Life began in the seas: evolution of cellular organisms theory

A

Replicating organic molecules became enclosed in vesicles, surrounded by a biological membrane
Provided an internal environment for metabolic processes to develop
Evolved to be more complex- organelles etc.
Endosymbiotic theory- how chloroplasts and mitochondria were engulfed by bacteria

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16
Q

The Palaeozoic Era

A

Gondwana and Laurasia formed
Later combined to form Pangaea
Land movement changed climate of land and sea and therefore evolution

  • Cambrian
  • Ordovician
  • Silurian
  • Denovian
  • Carboniferous
  • Permian
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17
Q

Cambrian period (541-485.4 mya)

A

Increase in complexity of ocean creatures- Cambrian explosion
worms, jellyfish, brachiopods, arthropods (most common trilobite)
Lots of fossils due to exoskeleton

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18
Q

Ordovician period (485.4-443.8 mya)

A

Seas had algae
Trilobites diversities and were abundant
Cephalopods and early corals
First vertebrates- jawless armoured fish
Ice age and second-largest mass extinction of Palaeozoic era

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19
Q

Silurian period (443.8-419.2 mya)

A

Earliest evidence of life on land
First- arthropods
millipedes, centipedes and early arachnids appeared
Oldest land plants later in period- small, spore-bearing, vascular plants
Xylem and phloem
Non-vascular plants such as moss may have been there first- no evidence
Terrestrial fungi

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20
Q

Devonian period (419.2-358.9 mya)

A

Land plants and animals deposited on barren soil promoting colonisation of land
Small plants with spores
‘age of the fishes’- diversification of fishes
Jawed fish and ray or lobe finned fish evolved
One fish developed sturdy fins and could support weight on the edge of water- give rise to first terrestrial vertebrates, the tetrapods
Earliest tetrapods were amphibians

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21
Q

Carboniferous period (358.9-298.9 mya)

A

Coal age
Abundant terrestrial plants
Spored plants with woody stems, roots and leaves developed tree forms
Carbon dioxide was lowest
Coal beds from buried trees
Diversification of animals
Giant insects
Tetrapods lost amphibian like bodies to be more like reptiles- less time in water
Amniotic egg evolved, reproduction on land
Scaly skin evolved to stop dehydration

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22
Q

Permian period (298.9-252.1 mya)

A

Pangea formed- polar ice and desserts
One massive ocean
Mass extinction- 90% lost

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23
Q

The Mesozoic Era: The age of the Dinosaurs

A

Reduced competition due to extinction opening up ecological niches- species had a role
Climate was warm and humid
Diversification

  • triassic
  • jurassic
  • cretaceous
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24
Q

Triassic period (252.1-201.3 mya)

A

Polar ice caps melted and harsh conditions lessened
Seed plants
Herbivores gre in number
Plant size increased
Reptiles were dominant vertebrates- crocodiles and earliest dinosaurs
Mammal-like therapsids gave rise to true mammals late in the period
Early mammals- small, insectivorous, nocturnal, hairy and homeothermic

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25
Jurassic period (201.3-145 mya)
Dinosaurs thrived Sauropod dinosaurs- related to birds and crocodiles Oldest bird- archaeopteryx- bony tail and teeth like a reptile but feathers like birds Bipedal dinosaurs Mammals diversified Gondwana and Laurasia formed from Pangea Northern and southern flora and fauna
26
Cretaceous period (145-66 mya)
Diversity reached peak Gondwana and Laurasia broke up into smaller continents like today Most modern fish towards end Small primitive marsupials and insectivores abundant Dawn of the flowering plant Angiosperms (flowering plants) Diversified rapidly Most diverse terrestrial plant by end of period Co-evolved with pollinating insects Chicxulub asteroid caused an extinction- many dinosaurs gone but some evolved into birds
27
The Cenozoic era: The Rise of Birds and Mammals
More modern life Extinction of large species allowed small species to diversify - Palaeogene - Neogene - Quaternary
28
Palaeogene period (66-23 mya)
Early primates Birds became abundant New plants evolved Continents moved changing currents and climates
29
Neogene period (23-2.58 mya)
Continental movement- Australia separated from Antarctica mammals, birds and flowering plants evolved First hominins (human-like) 6-7 million years old Homo habilis 2.5 mya Megafauna- mammoths, sabre tooth tigers, ground sloths, massive lizards and marsupials
30
Quaternary period (2.58 mya-today)
Pleistocene epoch (2.58 mya-0.01 mya) Holocene epoch (0.01 mya-today) Climates warmed and sea levels rose Holocene- interglacial period of warm conditions Plants and animals survived that were better suited to hot dry conditions Giant marsupials distantly related to geese and ducks roamed Australia Megafauna, kangaroos and emus Ice Age extinction at the end of the Pleistocene epoch Neanderthals, Homo neanderthalenis went extinct During glacial periods, land bridges were exposed for migration Holocene epoch is relatively short and does not have major changes in species but does include significant migration such as the first modern humans
31
palaeontology
study of ancient life represented by fossils.
32
fossil
preserved remains, impressions or traces of organisms found in rocks, amber, coal deposits, ice or soil.
33
what usually fossilises?
Usually hard remains- hard to decompose or destroy- bone, shell, spores, leaves, bone
34
fossil record
total number of fossils that have been discovered, providing evidence for evolution.
35
fossilisation
the preservation of the hardened remains or traces of organisms in rocks.
36
how does fossilisation occur?
Unlikely for soft bodies Leaves and wood have cellulose that does not decay quickly Buried in sediments- reduces decay because of lack of oxygen (for decomposers) and hides from predators Pressure from layers squeezes water out As it deepens, temp increases and sediments become rock Sediments are often in water- many fossils in old bodies of water Fossil record has more fossils from wet environments- limits understanding of past
37
what are the types of fossils?
impression fossils, mineralised fossils, trace fossils, mummified organisms
38
what are impression fossils?
The entire organism decays but the shape or impression of the external or internal surface remains. May be filled with foreign material to form a cast fossil
39
what are mineralised fossils?
Minerals replace the spaces in structures of organisms such as bones. Leaves a replica of original organism Mineralisation or petrification Minerals: opal, pyrite, silica
40
what are trace fossils?
AKA ichnofossils are the preserved evidence of an animal’s activity or behaviour without containing parts of the organism. Foot prints, burrows, coprolites
41
what are mummified fossils?
Those that have been trapped in a substance under conditions that reduce decay so little is changed. Insects in amber, leaf from coal deposits, animals frozen or trapped in a peat bog
42
what are the ways of dating fossils?
relative dating, absolute dating
43
how does relative dating work?
Based on stratigraphy Low- old High- young A fossil age is estimated relative to the known age of rock layers above or below the layer Difficult where erosion has occurred, rocks have buckled, moved, been reburied or alternated in sequence
44
stratigraphy?
the study of relative positions of the rock strata, some of which contain fossils.
45
index fossils?
a commonly found fossil, from similar sites fro which the absolute age has been determined.
46
what is absolute dating? types?
a more precise measurement of age, although it does not mean that it provides an exact date- radiometric dating, thermoluminescence and election spin resonance - radiometric - thermoluminescence - electron spin resonance
47
what is radiometric dating?
Radiometric dating: a quantitative technique used to determine the proportion of a particular radioactive isotope whiten rocks and around fossils or sometimes within a fossil. Radioactive isotopes decay into different forms at constant rates (independent of nature) Half lives are used- time taken for half to decay Carbon 14- 58000-62000 years after which there is little carbon left so readings are inaccurate Potassium 40 argon 40 dating- 1.25 billion years
48
what is thermoluminescence?
Thermoluminescence: date fire-treated tools up to 500 000 years old. Emission of light from a mineral when heated Older = more light Intensity is calibrated to reveal time passed since last heated Dates artefacts of human evolution Sample destroyed
49
what is electron spin resonance?
ESR: dates calcium carbonate in limestone, coral, fossil teeth, molluscs and egg shells. Up to 300 000 years Sample is not destroyed
50
what information can be obtained from fossils?
How they parented How offspring were made- egg, womb Herds or alone Contents of meals
51
what is biogeography?
the distribution of of organisms, and evidence for evolution. - patterns of evolution - continental drift
52
biogeographical regions
each region is recognised as having a unique set of related organisms, suggesting that the patterns are a result of evolution.
53
continental drift
If continents were joined, makes sense that organisms may share a common ancestor Supported by plate tectonics Can calculate how long ago continents were joined and thus when species were split
54
structural morphology
studying the body structures of species.
55
comparative morphology
compare species’ structures.
56
homologous features
Homologous features: features of an organism that are similar based on common ancestry. Often have different functions Provide evidence for a common ancestor Known as divergent evolution
57
what are analogous features?
Analogous features: similar features that are found in different groups of organisms and are not due to common ancestry. Butterflies and birds both have wings Have similar selection pressures
58
what is convergent evolution?
similar features evolve independently in unrelated groups of organisms.
59
what are vestigial structures?
Structures that have little or no function anymore | Remnants of organs
60
what is developmental biology?
Developmental biology: how an organisms changes from a zygote to an adult. Comparative embryology Homologous features are seen in embryos but not in adults Master genes control embryo development Organisms that share a common ancestor often have same master genes Embryos will pass through similar stages of development- shows an evolutionary relationship
61
what are mechanisms of evolution? what are observations of natural selection? what were Darwin's inferences? two populations are separated and evolve differently?
Natural selection is the mechanism of evolution Observations of natural selections: Members of a pop vary Species have more offspring that environment can support and most die Darwin’s inferences: Individuals have favourable traits survive to reproduce Unequal ability to survive leads to an accumulation of those that can survive Two populations are separated and evolve differently- divergent evolution and allopatric speciation
62
what is divergent evolution? what are examples of divergent evolution and types?
Divergent evolution: two different species (or pops) from a common ancestor evolve separately. Overtime they differ Homologous features may become different with differing functions Darwin's finches and adaptive radiation
63
Charles Darwin's finches?
Divergent evolution Galapagos islands Related but distant species 13 species of finch with every island home to a number of them Each has a particular beak, body size, feeding behaviour that are advantageous for the island
64
what is adaptive radiation?
Adaptive radiation: the rapid divergent evolution of a large number of related species from a common ancestor. Evolve different adaptations for environment Occurs following extinction of a competitor, colonisation of a new place with vacant niches Finches with different beaks is an example
65
what is coevolution?
Coevolution: species that interact closely exert selection pressures on each other and both evolve together. Predator-prey relationships
66
what is convergent evolution?
Convergent evolution: evolution through natural selection of similar features in unrelated organisms which form analogous features.
67
what is extinction?
Extinction: species fail to adapt to environmental changes or to compete and die out.
68
what is background extinction?
Background extinction: the average rate of natural loss of species. A species usually lasts a few million years
69
what are mass extinctions?
Mass extinctions: significant large-scale extinctions following disruptive changes to the global climate, or loss of sea or land due to shifting continents. Changes selection pressures drastically Natural selection will act on survivors Surviving pops may be small, thus genetic drift in founding populations will lead to rapid evolution Significant diversification and adaptive radiation often follow 5 mass extinctions- 50% of hard boned gone in each

12 biology (13 decks)

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