where is biodiversity ? Flashcards
Lecture 3 - John Spicer (27 cards)
species-area relationship
principle pattern
as size of geographical area increases so to does the number of species
practical use - predict that as area is reduced, tend to lose species
habitat loss / fragmentation
major determinant of modern extinctions
sea/land phyla
all animal phyla ( approx 34 ) occur in the sea (one exception - velvet worms (onychophora))
two thirds ( 20 ) almost exclusively marine
marine phyla
98 % live in/on the sea floor ( = BENTHIC )
2 % live floating or swimming in the sea ( = PELAGIC )
only 15% of named species are marine
photosynthesis - sea/land comparason
sea : very few, large photosynthetic organisms - mainly short lived, microscopic algae
land : dominated by persistant long lived ‘large’ flowering plants
herbivoress - sea/land comparason
sea : dominant herbivores - micro (copepods) majority of large animals carnivorous
land : dominant herbivores can be large
grazing - sea/land comparason
sea : grazing - ingestion of entire autotroph
land : grazing - rarely removes significant amounts of communities ( indigestible e.g wood )
autotroph
an organism that can produce its own food using light, water, carbon dioxide, or other chemicals
food chain - sea/land comparason
sea : food chain average 5 links
land : food chain average 3 links
abyssal
depths od ocean between 4000-6000m deep
bathyal
relating to the zone of the sea between the continental shelf and the abyssal zone (depths 1000 - 4000m)
hadal
relating to the zone of the sea greater than 6000 m in depth chiefly oceanic trenches
littoral
area of shoreline where land is subject to wave action
sublittoral
living, growing, or accumulating near to or just below the shore
endemic species
plants and animals that exist only in one geographic region
Alexander Von humboldt
latitude - 1799 onwards
Venezuela - Mexico : species identity differs with latitude
Alfred Russel Wallace
number os species increases as you go from temperate to tropical regions
planktonic diversity
- all 3 domains of life
- overall decline in diversity towards the poles ( saame pattern as on land )
- driven by decresing water temperatures
species richness
the number of species within a defined region
shallow water - species richness
- coastal marine fish/bacteria - increase in species richness towards the equator
- coral reef fish - no pattern
- amphipods/isopods/bivalves - highest before reach the equator
deep sea - species richness
- increase in richness towards the equator for number of taxa of bivalves, gastropods and isopods
- forminiferans - highest before reach the equator ( single celled protists - very simple microorganisms )
pelagic - species richness
- increase in richness towards the equator - ostracods, euphausiids (krill), shrimp, fish (N. hemisphere), bacteria,
elevation
Von Humboldt - number and type of plant species changed as ascended volcano
species richness decreases with increasing elevation
life below Earth’s surface
endemic cave communities
- chemosynthetic ecosytem (chemosynthesis is the process by which certain microbes create energy by mediating chemical reactions)