2.1 Evolutionary History of Organisms Flashcards
What is biodiversity?
A measure of the number of species on the planet.
What is a species?
A group of organisms that can interbreed under natural conditions and produce fertile offspring.
How does the number of species per square kilometer change as one moves from the poles to the tropics?
It increases
Where are the most diverse habitats on the planet?
Tropical rain forests and coral reefs.
What do the fossil records tell us about life on earth?
Most species are now extinct.
How has biodiversity changed during the past?
Mass extinctions cause ‘bottlenecks’ in biodiversity, where there are not many species on the planet.
These are followed by radiations of new species.
Where are the least diverse habitats on the planet?
The bottom of the ocean and polar regions.
What process drives the evolution of new species?
Natural selection (Darwin)
Give an example of adaptive radiation.
Darwin’s Galapagos finches.
Each island has a unique climate and food source.
The birds on different islands had different mutations causing variations in beak size and shape.
Some beaks were better suited to survival on that specific island.
Those finches with the mutated gene would survive longer. They would breed and pass on the beneficial gene to their offspring.
What is the classification of organisms based on?
Their evolutionary relationships.
What is the simple phylogenetic tree?
A classification concept
What is the heirarchical system of classification?
Kingdom, phylum, class, order, family, genus, species
What are the 5 kingdoms?
Animalia, Plantae, Fungi, Prokaryota, Protoctista
What are the main characteristics of the Animalia kingdom?
Nervous coordination
Cells lacking cell walls
Multicellular
Heterotrophic nutrition (they eat)
What are the main characteristics of the Plantae kingdom?
Cellulose cell walls
Chloroplast for photosynthesis / autotrophic (make their own food)
multicellular
What are the main characteristics of the Prokaryota kingdom?
No nuclear membrane / prokaryotic
Cell wall (variable chemistry but never made of cellulose)
No membrane-bound organelles
Unicellular
What are the main characteristics of the Fungi kingdom?
Cell wall made of chitin Herterotrophic Eukaryotic Rigid cell walls made of chitin Reproduce with spores
What are the main characteristics of the Protoctista kingdom?
No tissue differentiation
Mostly unicellular
Eukaryotic
What phyla is the Animalia kingdom split into?
Annelids
Arthropods
Chordates
What are the main characteristics of the Annelida phylum?
eg earthworms, leeches
Segmented worms - segments have specialised functions Closed circulatory system - blood enclosed by blood vessels Hydrostatic skeleton - thin, moist, permeable skin
What are the main characteristics of the Arthropoda phylum?
eg spiders, beetles, crabs, millipedes
Exoskeleton, jointed limbs
Open circulatory system, fluid-filled body cavity.
What are the main characteristics of the Class insecta?
in the phylum Arthropoda
3 pairs of legs
3 segments to their body
- head, thorax, abdomen
2 pairs of wings when sexually mature (there are exceptions eg fleas)
What are the main characteristics of the phylum Chordata?
Spinal column / vertebrae
Well developed CNS. Brain enclosed in a cranium
Closed circulatory system
Internal skeleton
What 5 classes within the phylum Chordata do you need to know?
Pisces Amphibia Reptilia Aves Mammalia
What are the main characteristics of the class Pisces?
gills
scales
live in water
What are the main characteristics of the class Amphibia?
Live on land or in water
Must return to water to reproduce
Thin, moist skin
Juveniles have gills, adults have simple lungs
What are the main characteristics of the class Reptilia?
Waterproof, dry scales
Lungs
Soft, leathery-shelled eggs
Land based
What are the main characteristics of the class Aves?
Front limbs modified to wings Feathers Hard-shelled eggs Lungs Endothermic (warm blooded)
What are the main characteristics of the class Mammilia?
Hairs covering the body Birth live young Mamary glands - milk Endothermic Sweat glands Double circulatory system
What are analogous structures?
They serve the same function but show no evolutionary link (eg bird wings and insect wings)
What are homologous structures?
Same basic structure, even if they have become modified as a result of evolution to different functions.
They do show evolutionary connections
(eg pentadactyl limbs = bird wings, human hands, bat wings, horse legs)
How can we reduce the mistakes made in classification due to convergent evolution?
Biochemical methods measure the proportion of genes or proteins shared between species to estimate relatedness.
Proteins are usually displayed as bands on an electrophoresis gel.
