BIOL 104 - Unit 4 Flashcards
How does biodiversity change?
Define community.
A group of interacting species in the same place @ same time
What is community disturbance?
any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resource availability/physical environment
what is succession?
repeatable/sequential change in community composition over time after a disruption
primary succession and example
succession with new parent material. mt. saint helen
secondary succession and example
when plants/animals re-establish after a disturbance (ex: australian bushfires)
draw a graph of succession with axis of frequency of disturbance and intensity of disturbance
how does succession work? (4)
- colonizers arrive after disturbance (opportunistic species: r-selected)
- other species arrive, possibly community development
- theoretically reach “climax community” under stable environment
- disturbance resets succession
what are some examples of plants throughout succession
annual, perennial plants/grass, shrubs, softwood trees (pines), hardwood trees
differentiate between “r” and “K” selected species
r: exponential, density independent, high mortality for offspring, unstable enviro (jellyfish)
K: logistic growth, density-dependenet, low mortality for offspring, stable enviro
Name 3 different mechanisms for succession
- Tolerance
- Inhibition
- Facilitation
Tolerance
No critical interactions between early and late succession. Success of a species is limited by its tolerance to a specific limited factor (like Nitrogen). Early-successional species have no impact on establishment of later successional species. later successional species have better tolerance
inhibition
early succession makes it harder for later succession to survive. later succession are prevented until early dies and opens us space for late to grow (environmental stress/consumers)
facilitation
early successional species change environment so enviro is more hospitable for later successional species to invade
primary succession is always governed by ______ model
facilitation
secondary succession is governed by _____ models
facilitation, inhibition, and tolerance!
Under the inhibition model, what stage of succession plants can colonize a site after disturbance?
any stage, but usually late-stage wins over long term because they die less frequently
In the tolerance model, what effect do early succession species have on late succession?
No effect. Late succession species tolerate early succession species and late do better because they are better competitors for resources and light.
autogenic vs allogenic processes
autogenic: internal processes within closed community
allogenic: external processes ensure systems are never in equilibrium (immigration of new species, seasonal changes in weather/sunlight)
Describe intermediate disturbance hypothesis
species diversity is highest when disturbance freqency and intensity are intermediate
Define resilience
ability of a community to return back to its original state after a disturbance
resistance
ability of a community to withstand a disturbance
return time
time required to return to equilibrium after a disturbance
What is the relationship between recovery time and resilience?
shorter recovery time = higher resilience
What happens when the threshold of a distrubed system state is passed?
The environment adapts an alternate stable state. (think coral reefs to bleached reefs)
Defining difference between primary and secondary succession?
secondary: build from existing material
primary: start from ground zero, new substrate
adaptive radiation
process in which organisms diversify rapdily from an ancestral species into multitude of new forms
single lineage produces descendants w/ wide variety of adaptive forms
characterized by rapid diversification
what does adaptive radiation require
ecological opportunity
Define ecological opportunity
reduced competition for resources that allows species to quickly diversify and fill different niches previously occupied by another species
Why do we only see humans and not other hominins?
Homo sapiens are the only survivor of an adaptive radiation of hominins that occured in africa over the last 4-5/7 million years
What are hominids?
Great Apes (great apes and humans including orangutans, gorillas, chimps, bonobos)
What are hominins
humans (all species of modern humans and early humans after split from chimps)
List morphological innovations seen in hominins (what and when)
A. 7-6 MYA: evidence of bipedalism (2 legs) and elongated hind limbs
B. 3.3 MYA: tool making and specialized stones
C. 2-1.8 MYA: increase in brain case size
D. 1 MYA: evidence of controlled fire use
What is a morphological innovation
adaptive breakthrough (trait that makes it possible to exploit resources)
What was the African continent like 8 MYA and change over time?
8 MYA: lush forests everywhere
7 MYA: climate change cooled planet = dry conditions
forests>woodlands>deserts
Who was Lucy and why is she important?
Mostly complete fossil (40%)
at time of discovery was earliest hominin fossil discovered
ominovrous diet and semi-arboreal (living in trees) lifestyle
When did our ancestors become carnivores?
1.8 MYA: evidence that they caught and ate animals
How did our ancestors becoming carnivores change their ecology?
carnivores have to roam more broadly to find food
T/F: all hominins are hominids, but not all hominids are hominins
True! hominins: great apes and humans
hominids: our earliest ancestors and humans
what facilitates adapative radiation?
ecological opportunity, extinction
Arrrange following innovations in order from oldest to most recent:
-bipedalism
- carnivory
- larger brain cases
- social structure
- tool use
social structure (hominids)
bipedalism (hominins)
tool use (australopithecines)
larger brain cases (homo genus)
carnivory (homo genus)
Improved hunting efficiency enabled reduced mastication musculature to evolve.
true
What is the Out-of-Africa hypothesis?
- Homo sapiens evolved in Africa and moved into Europe and Asia in second dispersal event.
- genetic evidence show humans show common ancestor from 200,000 years ago
- Original hominid population did not interbreed with H sapiens during secondary contact.
what pattern of diversity would you expect to see to support out-of-africa hypothesis?
diversity would be greatest in africa and decrease outward (think founder effect)
from a phylogenic tree, what would support the out-of-africa hypothesis
oldest originated in africa, then spread to europe, asia, and outward
what group has the greatest proportion of neanderthal DNA?
Eurasians!
what would it look like if there is evidence for any gene flow between neanderthals and H. sapiens?
euro/asian gene sequence more similar to neanderthal than to african gene flow
In what ways did early human civilizations impact local and global biodiversity?
- Agriculture: gathering food, use of fire, cultivation of plants
- Urbanization
- Megafaunal (big animals) extinction due to hunting (humans are predators)
speciation
formation of new and distinct species in course of evolution
extinction
species having no living members, no longer in existence
how is the survival of individuals, populations, and species connected?
loss of individuals results in smaller population sizes that has following impacts:
- decreased population size causes disruption of survival and reproduction
- small pop at risk for loss due to chance events: genetic drift
- small populations have reduced genetic diversity (less ability to adapt)
extinction vortex
positive feedback loop:
small population = inbreeding + random genetic drift = loss of gene variability = reduction in individual fitness and pop. adapatability = lower reproduction+higher mortality = smaller population
what is a secondary extinction
another species goes extinct because the primary species it depends on went extinct
Define a mass extinction:
-extinction rate > speciation rate
- 60%+ of all species go extinct within short geologic time (<3 million years)
how many mass extinctions to date?
5
What do the 5 mass extinctions have in common?
result of major change to planetary conditions (temprature, atmospheric compositoin or both)
How does climate change impact biodiversity?
- Direct effects: climate affects species
- thermal tolerance
- environmental changes - Indirect effects: climate affects species interactions
- disease vulnerability
- predation/competition dynamics
define climate
long-term averages and variations in weather measured over period of several decades
why do CO2 concentrations fluctuate annually in the northern hemisphere?
CO2 concentrations fluctuate annually because plants perform more photosynthesis in spring/summer but lose leaves in winter and respire
Define ecological footprint and impact on climate change
ecological footprint: how dependent humans are on natural resources
What proportion of NPP is used by Humans?
~30%
How can organisms respond to climate change?
- Acclimate: change physiology, behavior, or morphology
- Adapt
- Move
- Go extinct
Phenotypic plasticity
acclimation. the ability of an organism to change in response to stimuli/inputs from enviro. in one organism’s lifestime
What evidence is there of extinction due to climate change
Loss of habitat
- sea level rise
- melting ice
Change to reproduction
-sex ratio… more F:M
What does the current extinction rate look like compared to the fossil record?
current extinction rates are 1000 times higher
What is conservation biology?
Applied science focusing on protecting Earth’s biodiversity and maintaining natural ecosystems
What are the 3 goals of conservation biology?
- Document full range of biological diversity on Earth
- Investigate human impact on genetic variation, species, and ecosystems
- Develop aproaches that prevent species extinction, maintain genetic diversity, and protect/restore biological communities
What makes conservation biology a normative discipline?
- embraces certain values
- applies scientific methods to achieve those values
What are the roots and ethics of conservation biology?
- preservationist ethic: natural areas have intrinsic value that is superior to tangible material gain from exploitation
- resource conservation ethic: use of natural resources is whateverw will further greatest good for greatest number of people for longest time
- land/ecosystem ethic: consider ecosyste as a whole and include humans
Ethical principles of conservation biology
- Biodiversity has intrinsic value.
- Prevent untimely extinction of populations and species.
- Preserve species diversity and community complexity
- Science plays a critical role in our understanding of ecosystems.
- Collaboration among scientists, managers, policymakers, and the public is important and necessary
Why is involving multiple stakeholders in conservation effort important?
- species successfully preserved
- mechanism of preservation identified
- human productivity maintained
- local investment in preservation increased
How is successful conservation bio measured?
- was extinction prevented
- has genetic diversity been maintained/increased?
- are biological communities and associated functions persisting through time?
