Flashcards in Chapter 3 Deck (31)
Flashback to Ch3. List the 4 types of keystone species
modifier of physical environment
continuous food providers
Where are the two most diverse ecosystems one earth (that the book picked)
tropical rain forest
What two variation styles are theorized to result in diversity patterns on earth?
variation in climate/environment
variation in topography, geological age, and habitat size.
Describe the rain forests
occupy 7% of land area
contain over half of the world's species
based mainly on samping of arthropods
reasonable estimates range from 5-10 million species
maybe up to 30 million
40% of plants are found in rainforests (275k sp total)
30% of birds are found here. (of about 2600 species)
What physical aspect of the rainforest lends itself to diversity?
the layering of foliage and communities within the canopy
Trends in rainforest availability
around the equator is the most dense, but in general we just have been killing it.
Describe coral reefs
marine equivalent to tropical rain forests in species richness and complexity
-sunlight penetrates deeply through the clear water
How do cruise boats and resorts hurt coral reefs?
pollution. Clear water is essential to coral reef functioning/productivity
Facts about the great barrier reef
349000 square km (0.1% of ocean surface)
400 species of coral
1500 species of fishes (8% of world's fish species)
4000 species of mollusks
6 spcies of turtles
What are the differences between tropical rain forests and coral reefs
very few reef species have narrow distributions like rain forests
widely dispersed during juvenile phase.
only isolated islands like Hawaii have endemic species
Most biodiversity is found ONLY in the oceans.
(Diversity is spread over broad range of phyla and classes)
Diversity is spread over broad range of phyla and classes. Give some specific stats.
32 of 34 extant animal phyla are found in marine systems
13 of these exist only in marine environment (not fresh water or land)
1 phylum is found exclusively in terrestrial environments.
0 phyla are found exclusively in freshwater environments.
Patterns of diversity that vary in climate and environment show that species richness increases with what 3 factors mainly?
3 main factors:
-decreasing elevation (mts vs valleys)
-increasing solar radiation (equator)
What factors cause species diversity to increase with variation in topography, geological age, and habitat size? Why?
-complexity of topography (diff habitat types)
-greater geological age
--coral sp. richness is greater in indian and west pacific ocean vs Atlantic which is younger
Why: It allows genetic isolation, local adaptation, and speciation.
What correlations exist among types of organisms in distribution of species richness?
The amount of diversity among these groups is correlated.
Amphibians, birds, mammals, and plants in South America:
-most in western amazon
-secondary concentration in highlands of NE South America.
Birds, amphibians, and mammals in africa.
areas of species diversity that are very important to conserve.
Why are there so many species in the tropics? (5 reasons)
receive more solar energy
have had longer periods of stability
have warm temperatures and high humidities
more predictable environments
larger geographical areas
What groups of organisms have more species diversity toward the tropics?
almost all groups.
birds, trees, mammals, mollusks
exceptions: marine algae (20-40 degrees latitude) and small groups like bees, penguins, salamanders, waterfowl
Marine species also increase toward tropics
-great barrier reef northern end has more sp than southern end
-tunicates (sea squirts) have 6x the sp diversity toward tropics
How many tree species are in a hectare of the amazon compared to a US/European forest?
>>300 spcs, compared to less than 30 in american termpate forest
"maybe not on test"
More solar energy in the tropics results in..
more abundant rainfall
higher rate of productivity
greater resource base can support wider range of species
why have the tropics had longer periods of stability
allowed uninterrupted evolution and speciation
has allowed greater evolutionary specialization and local adaptations in tropical areas
How do warm temps and high humidity help species diversity in the tropics
favorable conditions for growth and survival for most species
do not need to evolve mechanisms to cope with cold/freezing conditions
entire communities can develop in tree canopies
How do predictable environments help with species diversity in the tropics?
species interactions are more intense
leading to greater competition among species
leads to more speciation via niche specialization
How does a large geographic area help develop sp. diversity in the tropics?
leading to greater rates of sp. and lower rates of extinction
tropicsl areas north and south of equator are next to one another
temparate areas are divided by tropics
therefore, more overall connected space.
How many sp. worldwide?
about 1.5 million have been described
300,000 fossil species
at least 2-3x remain undescribed
(estimated 5-10 million total)
20k sp discovered each year.
(1-2% increase per year for insects, spiders, mites, nematodes, fungi)
Name a few recently discovered communities
tropical tree canopies
earth's crust (bacterial communities 2.8 km deep, 1000 million cells/g rock)
interior of leaves of tropical trees
-1000s of sp of undescribed fungi
-symbioses: exclusion of harmful bacteria/fungi for carbs
deep sea floor
-almost entirely unexplored; unique geothermal vents; deep sediments
-10 mill bacterial cells/cube cm
-182 species on arms of 6 people
-expect similar levels of microbial abundance on other animals
How do we collect/count species?
requires large institutions
team of scientsts
-we collect, sort. classify, and describe them.
(lots of beetles collected in Indonesia, identified about 3000 new species with this one adventure of 1million beetle collection)
ex. flora of N Am project; missouri botanical garden
ex. Flora Malesiana; Netherlands
What is a way to estimate the number of species?
Extrapolation of ratios of organisms
ex. insects in the rainforest
fungi in britain
Recently discovered underrepresented species
rare species like lithophragma maxima
recently evolved on Sam Clemente Island
What is a living fossil?
-Wollemi pine: genus thought to be extinct for 60 mya
found in a gorge in Wollemi National Park, Australia.
-40 Individuals alive.
-thought to be extinct 65 mya
-possible ancestor of first land vertebrate
-population of 200 found in underwater caves near Grand Comoro Island