Download What do Ecologists Study?

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Population Growth Curves
Exponential vs. Logistic Growth
Predator-Prey Population Cycles
Fig. 38.4
Figures 38.3
and 38.5
What do Ecologists Study?
• Ecosystem: all interactions between living things
(community) and physical factors in a given area
– Biotic (living) vs. abiotic (non-living) factors (ex., floods, droughts)
• Habitat: place where organism lives; can be general or
specific (biomes are major climatic zones)
• Niche: organism’s way of life; multi-dimensional; in theory,
only one species can occupy a niche (ecological
species concept)
• Energy Flow: producers, autotrophs, phytoplankton;
consumers, heterotrophs, zooplankton, herbivores,
carnivores, omnivores, detritivores, decomposers
– Food Chains: ~90% energy loss each trophic step
– Food Webs: more realistic; note importance of krill in Southern
Ocean food web (shared resource, not necessarily limited)
– Food Pyramids: less biomass (and abundance) at higher levels;
decomposers act on all trophic levels
• Biogeochemical Cycles: hydrologic, carbon, nitrogen cycles
– Carbon cycle: related to global warming theory
Fig. 37.4
Fig. 38.1
Fig. 38.13
Fig. 38.14
Fig. 38.15
What Relationships Exist Between
Organisms in Ecosystems?
• Predation and Anti-predation
– Diet Specialists/Generalists: specialists can have morphological, behavioral,
and physiological adaptations for capturing/assimilating prey; scarcity of
prey can lead to extinction of diet specialists
– Anti-predation: cryptic and warning colorations, mobbing, displays
• Competition: assumes a limited (not just shared) resource; removal
experiments used to test for effects on fitness
– Intraspecific: between members of same species; most intense is between
males for access to females
– Interspecific: between separate species; can lead to competitive exclusion
– Scramble: rare in nature; all may get less than needed
– Contest: mechanisms; ex. harems vs. sneakers (ex., wrasse, marine iguana)
• Symbiosis: evolved life-relationship between two or more species
– Mutualism: both species benefit (ex. anemone and clownfish)
– Parasitism: one benefits, other is harmed; endo- and ectoparasites
– Commensalism: one benefits, other with no effect; least common,
examples often debated (exs. whale shark with pilotfish; reef shark with
remora? – debatable, since remora may cause hydrodynamic drag)
• Facilitation: organism indirectly benefits others (ex., earthworms aerate
soil, nightly excretion of ammonium by blacksmith benefits algae)
Fig. 38.10
Why is Biodiversity Important?
• Biodiversity: variation among living organisms
– Species diversity: number of species in an ecosystem; increases
with stability/uninterrupted evolution (ex., deep sea, tropical rain
forests), and available niches; decreases with isolation
– Genetic diversity: variation within a species
• If low, more vulnerable to catastrophic changes/extinction
• Importance of Biodiversity
– Ecosystem stability: keystone species are those with influence
disproportionate to their abundance (ex. sea otter in Alaska)
– Genetic reserves; esp. regarding agriculture; endemic species are
unique to particular habitat (ex. marine iguana in Galapagos Is.)
– Practical uses (ex. medicine, future foods)
– Aesthetic and ethical value: biophilia, Gaia Hypothesis
• Largest Threats to Biodiversity
1. Habitat loss and fragmentation: conservation incl. wildlife corridors
2. Introduced species (especially on islands)
3. Hunting/poaching; illegal trade  international treaty (CITES)
Fig. 38.12
Endemic Species
Document related concepts

Theoretical ecology wikipedia, lookup

Habitat conservation wikipedia, lookup

Bifrenaria wikipedia, lookup

Occupancy–abundance relationship wikipedia, lookup

Island restoration wikipedia, lookup

Habitat wikipedia, lookup

Latitudinal gradients in species diversity wikipedia, lookup

Introduced species wikipedia, lookup

Biodiversity action plan wikipedia, lookup

Ecological fitting wikipedia, lookup

Unified neutral theory of biodiversity wikipedia, lookup

Food web wikipedia, lookup

Reconciliation ecology wikipedia, lookup

Ecology wikipedia, lookup

Lake ecosystem wikipedia, lookup

Biodiversity wikipedia, lookup

Biogeography wikipedia, lookup

Fauna of Africa wikipedia, lookup

Ficus rubiginosa wikipedia, lookup

Extinction wikipedia, lookup