Ecology And Evolution (core) Flashcards
Habitat
The environment in which a species normally lives
Species
A group of organisms that can interbreed and produce fertile offspring
Population
A group of organisms of the same species who live in the same area at the same time
Community
A group of populations living and interacting with each other in an area
Ecosystem
A community and it’s abiotic environment
Ecology
The study of relationships between living organisms and between these organisms and their environment
Autotroph
Synthesizes its organic molecules from simple inorganic substances
Heterotroph
Obtains organic molecules from other organisms
Consumers
Ingest organic matter that is living or has recently been killed
Detritivores
Ingest non-living organic matter
Saprotrophs
Live in or on non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion
Food chain
Sequence of trophic relationships, where each member of the sequence feeds on the previous one
3 examples of food chains
1) rainforest: passionflower -> Heliconius butterfly -> tegu lizard -> jaguar
2) European grassland and the air above:
carrot plant -> carrot fly -> flycatcher -> sparrow hawk -> goshawk
3) ocean: phytoplankton -> zooplankton -> sardine fish -> tuna fish
Role of saprotrophic bacteria and fungi in nutrient recycling
Digestive enzymes secreted onto dead organic matter gradually break down this organic matter and release nutrients locked up in complex organic compounds
-> without them, nutrients will remain permanently locked up in dead organic matter
Historical records of carbon dioxide
Concentration measured in bubbles of air trapped in the Arctic ice at different times
From 2 000 years before 1800 - co2 concentration fairly constant at 270ppm
From 1800 onwards - the concentration rose
‘Modern’ records of carbon dioxide concentration
Since 1958 monitored at Mauna Loa, Hawaii
General trend: upwards (more than 100 ppm higher than in 1800 and rising - 290 ppm)
+ there’s an annual fluctuation (lower in spring, higher in winter)
Greenhouse gases (5)
Carbon dioxide Methane Oxides of nitrogen Sulfur dioxide Water vapor
Greenhouse effect
Heat retention by gases in the atmosphere (natural process):
sun emits short wavelength light, which can mostly pass through the atmosphere -> sunlight warms up the surface of the earth! which emit long wave radiation -> GHGs trap some of the long wave radiation -> earth surface is much warmer that it would be if the radiation escaped
ENHANCED by increased production of greenhouse gases due to human activity
Sigmoid curve of population growth (phases)
- Exponential phase
- Transitional phase
- Plateau phase
Carrying capacity
The maximum population size that can be supported by the environment
Evolution
Cumulative change in the heritable characteristics of a population
Evidence for evolution (3)
1) homologous anatomical structures (e.g. pentadactyl limb in vertebrates)
2) fossil records (e.g. Acanthostega - has 4 legs, like most aphibians, reptiles, and mammals, but also gills and fish-like tail - lived in water - missing link)
3) selective breeding of domesticated animals (dogs)
How sexual reproduction promotes variation?
1) meiosis allows a huge variety of different gametes to be produced by each individual
2) fertilization allows alleles from 2 different individuals to be combined in 1 new individual
Variation
- mutation is the original source of new genes or alleles
- variation is promoted by sexual reproduction
- prokaryotes don’t reproduce sexually - have other ways to promote variation by exchanging genes
- some species reproduce only asexually: mutation still produces some variation, but their capacity for evolution is much lower
