Lecture 15? Flashcards
Why can’t we be more accurate about how many species there are?
. Lack of morphological variation in some taxa (bacteria and a lot of insects- a lot of diversity in insects you can’t just see be picking them up they are mainly behavioural
. Function of effort in looking (birds (view casually- we know roughly how many species there are) vs nematodes- have to put a lot of effort into finding them). Organisms in rainforests are fairly well categorised and those in the sea are not (e.g. marine mysids in Japan/ S. China sea)
. Sampling- rich habitats (rainforest). Large (more spread out so harder to sample)- inaccessible habitats (e.g. oceans)
Why should we care about biodiversity?
. A number of ecosystem services
. The more biodiversity in an ecosystem the more robust it is
. Before pesticides we didn’t used to get outbreaks of pests (no predators) like we do now because there was more biodiversity
What provisions does biodiversity provide?
Renewable resources- food, fibres, disease resistance, pest control, vegetation defends against avalanches, flood, soil erosion.
The more biodiversity the more resources you have
Give an example of a provision biodiversity provides
Amazonian babassu palm (tree of life) Uses: . highest yield of vegetable oil from fruit (5 times more than coffee in Brazil)- biofuels . Livestock feed . Thatching . House timbers (wood) . Charcoal (wood)
How does biodiversity provide food security?
Genetic diversity for crop yield, quality, stress tolerance, pest/ disease resistance (if wild types are lost the genes for resistance are lost as well), reduce use of chemicals
Give 2 examples of biodiversity giving food security
- Wild potato varieties
. Blight resistance (if these species go extinct then the genes are blight resistance disappear with them)
. Andean potatoes
. Hungarian purple potatoes - White flies- pests of tomatoes don’t like wild tomatoes
Explain how biodiversity is important in medicines
> 20,000 listed medicinal plants ($50 billion/ year £ 80% people in developing countries depend.
Every time one goes extinct the potential for some medicine disappear with them
Give examples of when biodiversity is used in medicine
Madagascar (13,000 plant species, 80% endemic), Rosy periwinkle. Uses: diabetes, childhood leukaemia (cancer drugs).
Conus (snail species) spp. Venom. Use: pain killer- 1,000 times more powerful than morphine. Nerve Chanel blocker: used following heart bypass/ head injury/ stroke & pain management
Cultural- Aesthetic, educational, recreational (mental health as well)
Each time one of these goes extinct the potential to develop medicine from them goes extinct as well
Why should we classify organisms?
. To group organisms to reflect similarities and proposed relationships
. To organise a universal and recognised way of naming organisms
What is Aristotle’s legacy (384-322BC)?
. Founder of science
. Began first program to catalogue biodiversity
. Observation, description and seductive reasoning (if A, B and C is correct then D must be correct)
. Interested in marine animals
How did Theophrastus name plants?
On the basis of sexual parts of flowers (very variable)
What binomial nomenclature called?
Innaeus
What is the hierarchical classification of two organisms known as?
Linnaeus (Gross categories (with a lot of different species in them) which become more refined- kingdom, phylum etc.)
What are species inventories and how many species are in them?
. Catalogue of life
. 84% of species known to science tracked
(Relationships and distribution)
What will a species inventory tell us?
. Proportion of endangered flora/ fauna (e.g. estimated loss from deforestation ~0.2-0.3% forest species)
. How much/ little we know of life on Earth (e.g. current knowledge of biological processes/ patterns based on relatively few species- have all these species together, can be searched. Example- Loriciferans discovered in 1983- vital to ocean environment)
Describe the structure prokaryotes (bacteria)
. Unicellular
. Small cells
. DNA not in nucleus (floats about in the cell body e.g. plasmids in bacteria)
What are the two groups of prokaryotes?
. Eubacteria e.g. Cyanobacteria
. Archaebacteria e.g. S reducers
Describe the structure of the kingdom Protocista
Eukaryotes- larger than prokaryotes, DNA in nucleus, organelles from prokaryote symbiosis
e.g. Amoebae, green algae, brown algae, slime moulds
How were mitochondria originally formed?
By the symbiosis of a bacteria and a eukaryote cell
What does heterotrophic mean?
Don’t produce own food/ have to eat
Describe the metabolism of prokaryotes
Essential decomposers, altered earths atmosphere making it suitable for life. Autotrophic (self feeding) e.g. Cyanobacteria, O2 evolution- aerobic atmosphere, some fix N2.
Heterotrophic- diverse sources of C/ energy, S reduction. Some inhabit extreme environments
Describe the metabolism of protocists
Autotrophic using CO2- photosynthesis e.g. algae
Heterotrophic various means e.g. Paramecium (found in stomach wall)!
Describe the metabolism of plants
Autotrophic- photosynthesis
Describe the metabolism of animals
Heterotrophic- ingest food
When was the earth formed?
4.5 billion years ago
What was happening on Earth 3800my ago?
No life on Earth.
Condensation and cooling- oceans
Volcanoes expel H2O, CO2, N, CO plus energy from lightening
Sun (energy from the sun striking the sea) form organic molecules- NO, O2
What was happening on Earth 3500 my ago?
First prokaryotic cells (Cyanobacteria)
Simple ecosystems
Photosynthesis releases O2 and changes atmosphere
What are the oldest fossils and when did they exist? Describe them
. 3.5 billion y.a. (Found in rock this old)- first prokaryotic cells
. Cyanobacteria (blue-green algae. Eubacteria)- they started to produce O2 and this allowed more diverse and more complex life forms to evolve)
. Similar physiology to plants and algae
. Photosynthesis- most important evolutionary innovation on earth
What happened on Earth 2000-1800 mya?
O2 in atmosphere reaches critical level
Anaerobes limited to deep water
Some prokaryotes aerobic metabolism in surface waters
Formation of the ozone layer (by production of O2) -UV protection
What happened on Earth 1800mya?
First single-celled eukaryotes
What happened on Earth 1400 mya?
First multi-cellular green algae
What happened on Earth 1100 mya?
Major radiation of eukaryotes- fossils show cyst-like structures- sexual reproduction
Cyst-like structure suggests reproduction by budding off cells
What happened on Earth 600mya?
First animal fossils, soft-bodied metazoans. Simple ecosystem
Ediacaran gains are the fossils from this period- not many different types e.g. Dickinsonia costata, Australian fossil
What happened on Earth 530mya?
Burgess Shale
Start of fossil record if biodiversity (Cambrian explosion)
Most of the phyla we have today came about here. ‘Evolutionary experiments’ in this period- things you just don’t see anymore. Mostly soft-bodied (they are fossilised in fossil beds)- most soft bodied organisms don’t fossilise
What happened on Earth 440mya?
First complex arthropods (hard skeletons from CaCO3, segmented body, jointed limbs) most diverse of groups
microclimates and niches= first complex ecosystems
What happened on Earth 330mya?
Large vascular plants, conifer relatives, forests- complex ecosystems (light, shade, humid). Marine equivalent- coral reefs
Egg laying vertebrates
Synapsid line- mammals: reptiles-birds
Insects
Have trophic structure by this period: (first primary producers -> primary consumers -> secondary consumers etc.)- food webs
330mya when complex ecosystems developed. How did they increase in complexity?
Complex food webs
Increased physical complexity of ecosystems:
- variation, new niches for subsequent diversification
- light and shade- temperature- water
What are millipedes?
Oldest known land animal
What was happening on Earth 500mya?
Land ecosystems- mat of fungi, bacteria, algae on soil surface
What was happening on Earth 350mya?
First insect-like fossils. Evolved on land, few have invaded sea. First true insect fossils (large-winged species) about 300mya
What was happening on Earth 420-400 mya?
First vascular plants (water conducting tissue) e.g. Phynia- cuticle prevents water loss
What was happening on Earth 170mya?
Reptiles on Earth
First birds
What was happening on Earth 145-65mya?
Flowering plants
Extinction of dinosaurs at K/T boundary
What happened on Earth <65mya (to the modern day)?
Rise of birds and placental animals
What happened on Earth 1.8mya?
Modern mammals, origin of humans
What is the long-term average for the extinction rate of mammals in the distant past (fossil records)? What is it now?
For every 1000 mammal species <1 went extinct for every millennium (similar in marine species).
Now we have between 10 and 100 of every 1000 species going extinct every millennium in mammals, birds and amphibians.
So, the extinction rate is currently up to 1000 times higher than in the fossil record.
Which are the species most at threat from extinction?
. Small populations and/ or small geographical range. Exacerbated by habitat fragmentation (small population is less robust than larger ones- so splitting e.g. train line= fragmentation)
. Species tied to habitats favoured by humans
. Large organisms
. Species higher in the food chain. Extinction usually from a combination of factors e.g. red squirrel biological competition habitat fragmentation, disease (paradox virus)
