Ch. 4 Ecological, Evolutionary, and Biogeographic Implications of Climate Change

Most important abiotic factors that determine an organisms niche

Climate and food

Niche tracking

spps move to stay in their climatic preferances

two types of niches

fundamental and realized

Fundamental niche

space it occupies without spps interaction

Realized niche

space a spps occupies with spps interaction

Niche filling

degree to which a spps occupies its fundamental niche

Complete niche fillilng

fundamental and realized are the same

Incomplete niche filling

spps distribution in the real world is more restricted than its fundamental niche suggests

Niche underfilling

Realized niche - spps is precluded from upper and lower thermal ranges due to competition

If a climate changes and a spps closely fills its niche…

it is more likely to move to track with climate change

Niche may be underfilled in a geographic range due to competition causing the spps to….

move slowly or not move at all due to climate change

Niche filling in terrestrial and marine organisms

Marine organisms tend to fill their thermal niches

Terrestrial organisms tend to underfill their thermal niches in equatorial regions and overfill at higher latitudes

Spps with wide climatic tolerances….

will experience change over only part of their region

Spps with narrow niche breadth…

are more likely to be vulnerable to climate change and may find most of their suitable range affected by climate change

Examples of niche breadth in tropical mountain flanks

Spps tend to be packed into narrow elevational bands with narrow temperatures

Tropical montane species

Live in the tropical mountains and have narrower thermal tolerance and reduced dispersal ability resulting in vulnerability to rapid climate change

T/F Tropics are most sensitive to climate change

True

Woolly mammoths

Woolly mammoths likely went extinct because of a switch from flowery to green-dominated tundra and steppes across the Arctic

Individualistic range movement

species-unique niche tracking in response to climate change

Novel ecosystems

Ecosystems that form in the future that are unlike any that currently exist

Disappearing ecosystems

ecosystems that previously existed but were not found later

Population growth in response to climate change

population growth depends on fitness and fitness depends on temperature

activity is limited by critical thermal values

often at thermal optimum where population growth is highest

Population growth in response to climate - competition

Interspecific and intraspecific competition altered by climate change

Each spps exhibits unique thermal response curves and performance

Ex: reversal in competition due to climate change

Allele effect

relationship between population size and fitness of population

Tradescantia leaf beetle

probability of mating increase as number of males increased

Negative density dependent

population growth is limited by crowding, competition, and predators

Leading edge

occurs at the cooler range boundary in a warming climate (lowest genetic diversity)

Trailing edge

occurs at the warmer range boundary where spps exceed thermal maxima (highest genetic diversity)

Where to expect change in evolutionary responses?

Marine organisms first and most dramatically because they fill their niches tightly

Terrestrial spps tend to tightly fill cooler boundaries but rainfall is important bc increase in temperature means a decrease in water so they will have to compete resulting in extinction

Conservation implications

Mostly focused on mountain slopes in the tropics

Spps are categorized as irreplaceable