Conditions and Interactions

Conditions may affect The availability of a resource

• Coleophora alticolella

Development of disease• Grasshoppers• Corn fungus

Outcome of competition• Salmon – temp • Tribolium beetles – temp and humidity• Barnacles – susceptibility to desiccation

Conditions May Affect Species Interactions

Coleophora alticolella

Conditions and Interactions

Conditions may affect The availability of a resource

• Coleophora alticolella

Development of disease• Grasshoppers and fungus• Corn and fungus

Outcome of competition• Salmon• Tribolium beetles (lab)• Barnacles (later with competition)

Camnula pellucida

Killed by Entomophaga grylli

Conditions and Interactions

Conditions may affect The availability of a resource

• Coleophora alticolella

Development of disease• Grasshoppers• Corn fungus

Outcome of competition• Salmon• Tribolium beetles• Barnacles

Corn Leaf Blight

Development of Disease

Conditions and Interactions

Conditions may affect The availability of a resource

• Coleophora alticolella

Development of disease• Grasshoppers• Corn fungus

Outcome of competition• Salmon• Tribolium beetles• Barnacles

Salvelinus malmaDolly Varden

Salvelinus leucomaenisWhitespotted Char

Temperature Changes Outcome of Competition

Effects on Competition

Thomas Park (University of Chicago, late 1940s and 1950s)

Flour beetles: Tribolium confusum and T. castaneum Many experiments

• A major finding was that environmental conditions can influence the outcome of competition.

• Mechanism: exploitative and interference (cannibalism and predation: larvae eat eggs and pupae; adults eat eggs, pupae, and each other)

Joseph Connell – barnacles Outcome of competition determined by both biotic and

abiotic factors

Competition among barnacles

• Rocky intertidal zone• Adult barnacles

immobile on rocks• Planktonic larvae

settle on rocks at all levels

• Environment prevents competitive exclusion– Realized niches

• Joseph Connell (1961) Ecology 42:710-723

Distributions of Balanus & Chthamalus

Balanus

Adults Larvae

Chthalamus

Adults Larvaelowest low tide

highest high tide

Balanus

Chthamalus

ROCK

Responses to Global Warming Pitcher plant mosquito Wyeomyia

smithii Compared larvae collected in the

field in 1972 and 1996, Found that more recent mosquitoes

require 14 fewer minutes of light exposure to exit diapause. Wake up earlier and breed earlier.

That suggests that the mosquitoes have adapted to spring weather that is arriving earlier than in the past.

Read PNAS article

Responses to Global Warming

Red Squirrels in Canada Increasing spring

temperatures and food supply

Squirrels have advanced the timing of breeding by 18 days over the last 10 years — six days for each generation.

Responses to Global Warming

These are Evolutionary changes - adaptations

Other examples Birds migrating north earlier Plants leafing out & flowering earlier in spring

What might be a drawback to these trends?

Limiting Factors

Limiting factor - the “slowest” factor process depends on several different factors speed of process determined by slowest factor can be too little or too much of factor e.g. photosynthesis limited by too little light in early

morning and too much heat in afternoon

Liebig’s Law of the Minimum

Factors can interact: compensation; synergism

Synergistic Factors

Two factors; both depend on elevation Tidal flooding Soil salinity

Observed Lower in marsh, periodic tidal flooding is important

abiotic factor• Plants must be able to tolerate inundation

Higher in marsh, get increasing salinity• Plants must be able to tolerate high salt levels

Normal Pattern: Plant biomass highest in intermediate elevations; Salicornia grows lower in marsh than Anthrocnemum

Synergistic Factors

SalicorniaGlasswort

AnthrocnemumPickleweed

Synergistic Factors

Salicornia and Anthrocnemum Both plants do best at intermediate elevation

where levels of tidal flooding and salinity were moderate

Anthrocnemum avoids hypersaline areas of upper elevations and flooded regions of lower regions of the coastal marsh

Salicornia tolerates flooding but may lose out at the intermediate zones due to competition from Anthrocnemum

Synergistic(combined) Factors Pennings and Callaway Common Garden

Experiment Transplanted both species throughout saltmarsh at

all elevations Where did plants do best? See graph

• Salicornia grows lower than Anthrocnemum, can tolerate flooding

• Both species performed best in intermediate regions where flooding and salinity were moderate

• Anthrocnemum avoids hypersaline areas of upper marsh and flooded regions low in the marsh

• Salicornia is probably excluded from intermediate regions by Anthrocnemum

Factors can interact: ex: water and salinity

reciprocal transplant experiment with Salicornia and Anthrocnemum

Adaptation

Over time, natural selection can result in adaptation to environmental stress. Individuals with traits that make them best

able to cope with stress are favored. Over time, these unique, genetically-based

solutions become more frequent in the population.

Adaptation

Adaptation is similar to acclimatization/ acclimation but it is the long-term, genetic response of a population to environmental stress that increases its survival and reproductive success.

Acclimation and Acclimitization are shorter term responses

Where does this fit on your table of responses to environmental variation?

Adaptation

Populations with adaptations to unique environments are called ecotypes.

Ecotypes can eventually become separate species as populations diverge and eventually become reproductively isolated.

Animals Orcinus orca – Killer Whale Tritema stick insects Asellus aquatic benthic invertebrate

Orcinus orca

Fish eating ecotype Resident

Marine mammal eating ecotypes Transient “Offshore” Transient

The traits examined depicted on representative specimens of each host ecotype

Nosil P, Crespi B J PNAS 2006;103:9090-9095

©2006 by National Academy of Sciences

Why do Organisms Live Where They Do?

Environmental Variation