Evolution of major groups of organisms Flashcards
What did the modern plant body plant evolve in response to?
Maximising light via foliage
Maximising water and nutrient capture via roots
And roots providing anchorage
Also extremes of climate, water conservation and physical defence against herbivores
What is the current dominant plant group?
Angiosperms
How did angiosperms become dominant (what advantageous traits do they have)?
‘Biochemical shield’ to defend against herbivores
Faster growing
Efficient pollination systems
What is a body plan?
The way in which the body cavity, organs, appendages, supporting structures and nervous systems are organised
What did arthropods evolve from?
An annelid-like ancestor
Describe arthropods.
Rigid, tubular exoskeleton
Highly diverse
In most habitats
What is the Cambrian explosion?
Sudden appearance in fossil records of complex animals
What has been argued to have played a key role in the Cambrian explosion?
Evolution of eyes
Describe compound eyes.
Repeating units of ommatidia , each of which functions as a separate visual receptor
Form a mosaic image
Provide wide visual range, sometimes full 360 degrees
What is silk and what is it used for?
Ductile protein fibre
Secreted by organs e.g. spinnerets in spiders
Used mainly in prey capture by spiders and as protection by insects
What is winglessness in insects usually an adaptation to?
A parasitic lifestyle
What is the benefit of the pupal stage in insects?
Enabled larval and adult stages to occupy different niches and avoid competition between larvae and adults
Describe the development of molluscs.
Appearance of molluscs
Coincided with trebling of calcium levels in seawater due to tectonic/ volcanic activity
Shell= exoskeleton
Muscular foot for locomotion or prey capture
Shell eventually reduced or lost in some
What is the mollusc radula?
An array of horney protuberances (teeth) used to rasp day at algae, etc
Absent in bivalves (oysters, clams, etc)
Worn/ broken teeth are replaced by new ones
Describe echinoderms.
Spiny-skinned animals like sea urchin and starfish
Radial symmetry
What are vertebrates?
Animals with internal backbone that encloses dorsal, hollow nerve cord
What did teeth in fish develop from?
Armour of early fishes was made of dentine tubercles
Tubercules became more pronounced around and in the mouth to become teeth
Dentine= calcified tissue
Why was the development of bones and their associated musculature in fish useful?
Major advance for positional control
Whole body movements not always required
Enables massive diversification in body shape
What does the swim bladder do?
Internal gas filled organ that contributes to the ability of many bony fish to control buoyancy, can maintain water depth without having to swim (saves energy)
What is the lateral line system in bony fish?
Sensory system that detects movement and vibrations (and electrical impulses in some fish)
Used to avoid collision, predation, detect prey and enable orientation
What did colonisation of the land by vertebrates require?
Advances in mechanical support (bony skeleton) and respiratory gas exchange (lungs)
What was the benefit of colonising the land for vertebrates?
Plenty to eat at that time
Plenty of new niches to occupy
Which bony fishes led to land tetrapods?
Panderichthyids most likely Really ugly marine fish Flattened head Long tail 4 lobed fins
What is limb loss in some amphibians associated with?
Burrowing and swimming
What intrinsic factors led to the success of reptiles?
Insemination/ fertilisation became internal
Development of amnion: membrane enclosing embryo in liquid. Less dependent on aquatic habitats for reproduction
Scaly skin
What extrinsic factors led to reptile success and diversification?
Global warming: fragmentation of tropical rainforests isolates populations. Speciation time boissss
Climate-caused demise of amphibians. No more competition ayyyyy
What would port-wings have possible been used for in birds?
Enable lift, glide for short durations, low altitude leaps when running
Possibly assist prey capture/ evade predators
What happened as a result of the K-T event?
Around 66% of all mammal species go extinct
Surviving mammals radiate greatly
Within 25M years, massive bodied species had evolved
Mammals released from competition with dinosaurs
More above ground and day time activity
What are the differences between apes and man?
Skeleton specialised for sustained upright walking
Large brain coupled with high intelligence and modified cranium
Rounded dental arch with canines reduced to same length as other teeth
When did our ancestral lineage and chimpanzee lineage split?
Before 5 mya
What it the benefit of the Epicanthic fold?
Thought to protect eyes from excessive UV, strong winds an cold
e.g. conditions prevalent in Central Asian Steppes and Arctic
What is Steatopgyia?
Extreme development of the buttocks
Ability to store large amounts of fat is important in very seasonal environments
Once widespread in Africa, confined to a few populations now
