Exam 4 Lecture 23

Associated with this warming, there has been:

1. Widespread retreat of mountain glaciers 2. Thinning of the polar ice caps 3. Melting permafrost Rate of sea level rise greater than any in the past 3,000 years

Which of the following statements about global climate change is incorrect? 1. the general warming trend has led to the rising sea levels 2. the global warming trend has been consistent across all ecosystems 3. the general warming trend has led to changes in precipitation around the world including more frequent extreme weather events 4. the general warming trend has led to the melting of polar glaciers

2. the global warming trend has been consistent across all ecosystems

Which of the following is least likely to increase the likelihood of extinction? 1. endemism 2. wide geographic range 3. habitat specificity 4. very small population

2. wide geographic range

the diversity-stability theory

A long-standing idea in ecology is that species richness is positively related to community stability

competitive displacement

A process in which the best competitor uses limiting resources that the weaker competitor requires ultimately causing a decline in the weaker competitor's population growth to the point of extinction.

dynamic equilibrium model

An elaboration of the intermediate disturbance hypothesis combines disturbance frequency and rate of competitive displacement to determine species diversity - proposes that species diversity is maximized when the level of disturbance and the rate of competitive displacement are roughly equivalent.

complementarity hypothesis

As species richness increases, there will be a linear increase in community function. Each species added has a unique and equally incremental effect.

True or False: Introduction of non-native species is always detrimental to the existing ecosystem

False

Broad resource spectrum

In this community, the resource spectrum is broad, making more kinds of resources available to support more species -species are generalists -don't compete fiercely but there is more competition

idiosyncratic hypothesis

Strength of ecological function varies greatly. Some species have a large effect, some species have a minimal effect. -Addition of dominant species will have a large effect on community function, producing a curve with an idiosyncratic shape

competitive exclusion

Strong competition can lead to local elimination of one of the species. (not realistic- disturbance and stress cause changed conditions that effect species)

resource partitioning

The division of environmental resources by coexisting species such that the niche of each species differs by one or more significant factors from the niches of all coexisting species -We can think of each type of resource as varying along a "resource spectrum," representing different nutrients, prey sizes, habitat types, etc.

redundancy hypothesis

The functional contribution of additional species reaches a threshold. As more species are added, there is overlap in their function, or redundancy among species. This model best fits the results of Tillman et al

community stability

The tendency of a community to remain the same in structure and function, or to return after a disturbance. They found that plots with higher species richness were better able to withstand drought than plots with lower species richness. Plant biomass decreased less in species-rich plots during the drought.

greenhouse effect

The warming of Earth by atmospheric absorption and reradiation of infrared radiation emitted by Earth's surface due to greenhouse gasses in the atmosphere --water vapor, carbon dioxide and certain other gases

True or False: One of the focuses of conservation biology is ecosystem services

True

True or False: Shifts in climate may cause latitudinal shifts for whole communities

True

hypotheses explaining the relationship between species diversity and community function & the 2 variables in each of them

Two variables in all the hypotheses: 1. Degree of overlap in ecological function of species 2. Variation in strength of the ecological functions of species A. complementarity hypothesis B. redundancy hypothesis C.Idiosyncratic hypothesis

climate change

a directional change to the global climate that lasts for three decades or more • Earth is currently experiencing significant climate change - Average global surface temperature increased 0.8 degrees C between 1880 and 2012

Competing species are more likely to _____________ if they partition resources

coexist

variable conditions allow species to __________ because ______________ competitors can thrive

coexist; thrive Darwin was the first to consider disturbance as a mechanism to maintain species diversity

competitive exclusion is dependent on _______________ conditions

constant

variable conditions

disturbance, stress, or predation keeps the dominant competitor from reaching carrying capacity -competitive exclusion cannot occur, and coexistence will be maintained. -Positive interactions may also facilitate coexistence

narrow resource spectrum

entire community of specialist organisms -less overlap

Atmospheric concentrations of CO2 , CH4 , and N2O are increasing substantially, primarily as a result of ______________________________ and __________________________.

fossil fuel combustion; land use change

The ____________ the overlap of resource use, the more competition between species. The ________ overlap, the more specialized species have become, and the less strongly they compete

greater; less More species can be "packed" into a community if overlap is small. Or, if the resource spectrum is broad, a diversity of resources would be available for use by a wide variety of species.

Precipitation in the high latitudes of the Northern Hemisphere has ______________, but weather has been _________ in the subtropics and tropics

increased; drier There is also a trend of increasing frequency of extreme weather events such as hurricanes and heat waves.

If species have a high degree of specialization, it can result in _______ competition and _________ species richness

less; high

climate

long term description of weather, including average conditions and the full range of variation

At _________ levels of disturbance, competition regulates diversity. At _________ disturbance levels, many species cannot survive

low; high

The warming trend has not been consistent around the globe. Some regions have seen greater warming, especially ____________________ latitudes in the _______________ Hemisphere

mid-to-high; Northern

ecosystem services

natural processes that sustain life, such as water purification, soil formation, pollination of crops, climate regulation, and flood control These functions depend on the integrity of natural communities and ecosystems

climate variation

occurs at multiple time scales, from daily and seasonal to decadal.

constant change prevents any one species from _____________ the other species to ______________

outcompeting; extinction

____________ interactions are more common under relatively high levels of disturbance, stress, or predation.

positive

Hacker and Gaines (1997) incorporated ____________ ______________ into the intermediate disturbance hypothesis.

positive interactions At low levels of disturbance, competition reduces diversity. • At intermediate levels, species involved in positive interactions are released from competition and can increase diversity. • At high levels, positive interactions are common and help to increase diversity

resource ratio hypothesis

species coexist by using resources in different proportions plants: high nitrogen and high water coexist

intermediate disturbance hypothesis

species diversity will be greatest at intermediate levels of disturbance

weather

the current state of the atmosphere at any given time

conservation biology

the scientific study of biodiversity, how human activities impact it, and how to maintain it and prevent its loss • Protecting biodiversity is critically important on many levels. • People rely on biodiversity. We use hundreds of domesticated and wild species for food, fuel, fiber, medicines, building materials, spices, and decorative items

resource partitioning: warblers

warblers partition resources by feeding in different parts of the same trees. The shaded areas in each tree diagram represent the parts of trees where each warbler species fed most often. -shaded area is where they feed

_________ _________contributes the most to greenhouse warming

water vapor concentration varies regionally, and changes in average concentration have been small.