Climate Effects on Species

Concept 52.4: Interactions between organisms and the environment limit the distribution of species Species distributions are the result of ecological and evolutionary interactions through time Ecological time is the minute-to-minute time frame of interactions between organisms and the environment Evolutionary time spans many generations and captures adaptation through natural selection

Events in ecological time can lead to evolution For example, Galápagos finches with larger breaks were more likely to survive a drought as they could eat the available larger seeds As a result, the average beak size was larger in the next generation This resulted in an evolutionary change

Both biotic and abiotic factors influence species distribution For example, temperature, water availability, and interspecific interactions, affect the distribution of the saguaro cacti

BAJA CALIFORNIA BAJA CALIFORNIA SUR Figure 52.15 ARIZONA CALIFORNIA BAJA CALIFORNIA SONORA BAJA CALIFORNIA SUR GULF OF CALIFORNIA Figure 52.15 Distribution of the saguaro in North America N 100 km Sonoran desert Saguaro cacti observed

Figure 52.15a Figure 52.15a Distribution of the saguaro in North America (part 1: photo)

Ecologists ask questions about where species occur and why species occur where they do

Why is species X absent from an area? Figure 52.16-1 Why is species X absent from an area? Does dispersal limit its distribution? Figure 52.16-1 Flowchart of factors limiting geographic distribution (step 1)

Why is species X absent from an area? Figure 52.16-2 Why is species X absent from an area? Yes Area inaccessible or insufficient time Does dispersal limit its distribution? Does behavior limit its distribution? No Figure 52.16-2 Flowchart of factors limiting geographic distribution (step 2)

Why is species X absent from an area? Figure 52.16-3 Why is species X absent from an area? Yes Area inaccessible or insufficient time Yes Does dispersal limit its distribution? Habitat selection Does behavior limit its distribution? No Do biotic factors (other species) limit its distribution? No Figure 52.16-3 Flowchart of factors limiting geographic distribution (step 3)

Why is species X absent from an area? Figure 52.16-4 Why is species X absent from an area? Yes Area inaccessible or insufficient time Yes Does dispersal limit its distribution? Habitat selection Does behavior limit its distribution? No Do biotic factors (other species) limit its distribution? No Yes No Predation, parasitism, competition, disease Figure 52.16-4 Flowchart of factors limiting geographic distribution (step 4) Do abiotic factors limit its distribution?

Why is species X absent from an area? Figure 52.16-5 Why is species X absent from an area? Yes Area inaccessible or insufficient time Yes Does dispersal limit its distribution? Habitat selection Does behavior limit its distribution? No Do biotic factors (other species) limit its distribution? No Yes No Predation, parasitism, competition, disease Figure 52.16-5 Flowchart of factors limiting geographic distribution (step 5) Chemical factors Water, Oxygen, Salinity, pH, Soil nutrients, etc. Do abiotic factors limit its distribution? Temperature, Light, Soil structure, Fire, Moisture, etc. Physical factors

Dispersal and Distribution Dispersal is the movement of individuals or gametes away from centers of high population density or from their area of origin Dispersal contributes to the global distribution of organisms

Natural Range Expansions and Adaptive Radiation Natural range expansions show the influence of dispersal on distribution For example, cattle egrets arrived in the Americas in the late 1800s and have expanded their distribution In rare cases, long-distance dispersal can lead to adaptive radiation For example, Hawaiian silverswords are a diverse group descended from an ancestral North American tarweed

Figure 52.17 Current 1970 1966 1965 1960 1961 1943 1958 1937 1951 1956 Figure 52.17 Dispersal of the cattle egret in the Americas 1970

Figure 52.17a Figure 52.17a Dispersal of the cattle egret in the Americas (part 1: photo)

Species Transplants Species transplants include organisms that are intentionally or accidentally relocated from their original distribution If a transplant is successful, it indicates that its potential range is larger than its actual range Species transplants can disrupt the communities or ecosystems to which they have been introduced

Behavior and Habitat Selection Some organisms do not occupy all of their potential range Species distribution may be limited by habitat selection behavior

Biotic Factors Biotic factors that affect the distribution of organisms may include Predation Herbivory For example, sea urchins can limit the distribution of seaweeds Competition Mutualism Parasitism

August 1982 February 1983 August 1983 February 1984 Figure 52.18 Sea urchin Limpet 100 Both limpets and urchins removed 80 60 Seaweed cover (%) Only urchins removed Figure 52.18 Inquiry: Does feeding by sea urchins limit seaweed distribution? 40 Only limpets removed 20 Control (both urchins and limpets present) August 1982 February 1983 August 1983 February 1984

Figure 52.18a Sea urchin Figure 52.18a Inquiry: Does feeding by sea urchins limit seaweed distribution? (part 1: sea urchin)

Figure 52.18b Limpet Figure 52.18b Inquiry: Does feeding by sea urchins limit seaweed distribution? (part 2: limpet)

Abiotic Factors Abiotic factors affecting the distribution of organisms include Temperature Water Oxygen Salinity Sunlight Soil Most abiotic factors vary in space and time

Temperature Environmental temperature is an important factor in the distribution of organisms because of its effects on biological processes Cells may freeze and rupture below 0°C, while most proteins denature above 45°C Mammals and birds expend energy to regulate their internal temperature

Water and Oxygen Water availability in habitats is another important factor in species distribution Desert organisms exhibit adaptations for water conservation Water affects oxygen availability as oxygen diffuses slowly in water Oxygen concentrations can be low in deep oceans and deep lakes

Salinity Salt concentration affects the water balance of organisms through osmosis Most aquatic organisms are restricted to either freshwater or saltwater habitats Few terrestrial organisms are adapted to high-salinity habitats Salmon are able to migrate between freshwater and ocean

Sunlight Light intensity and quality (wavelength) affect photosynthesis Shading by leaves makes competition for light intense on the forest floor Water absorbs light; as a result, in aquatic environments most photosynthesis occurs near the surface In deserts, high light levels increase temperature and can stress plants and animals

Figure 52.19 Figure 52.19 Alpine tree line in Banff National Park

Rocks and Soil Many characteristics of soil limit the distribution of plants and thus the animals that feed on them Physical structure pH Mineral composition

Data from the Field Experiment Figure 52.UN03a Data from the Field Experiment Average Biomass (g/100 cm2) Spartina patens Typha angustifolia Salt Marshes Freshwater Marshes Salt Marshes Freshwater Marshes With neighbors 8 3 18 Figure 52.UN03a Skills exercise: making a bar graph and a line graph to interpret data (part 1) Without neighbors 10 20 33

Data from the Greenhouse Experiment Figure 52.UN03b Data from the Greenhouse Experiment Salinity (parts per thousand 20 40 60 80 100 % maximum biomass (Spartina patens) 77 40 29 17 9 % maximum biomass (Typha angustifolia) 80 20 10 Figure 52.UN03b Skills exercise: making a bar graph and a line graph to interpret data (part 2)

Spartina patens Figure 52.UN03c Figure 52.UN03c Skills exercise: making a bar graph and a line graph to interpret data (part 3) Spartina patens

Typha angustifolia Figure 52.UN03d Figure 52.UN03d Skills exercise: making a bar graph and a line graph to interpret data (part 4) Typha angustifolia

Area inaccessible or insufficient time Figure 52.UN04 Yes Area inaccessible or insufficient time Does dispersal limit its distribution? No Yes Does behavior limit its distribution? Habitat selection No Do biotic factors (other species) limit its distribution? Yes Predation, parasitism, competition, disease No Figure 52.UN04 Summary of key concepts: limiting factors of distribution Chemical factors: Water, oxygen, salinity, pH, soil nutrients, etc. Do abiotic factors limit its distribution? Physical factors: Temperature, light, soil structure, fire, moisture, etc.

Figure 52.UN05 Figure 52.UN05 Test your understanding, question 10 (kelp abundance)

Altitude (m) Mean height (cm) Figure 52.UN06 75 50 25 Altitude (m) Mean height (cm) 3,000 2,000 Figure 52.UN06 Test your understanding, question 12 (plant height and elevation) Sierra Nevada 1,000 Great Basin Plateau Seed collection sites

Figure 52.UN07 Figure 52.UN07 Test your understanding, question 14 (diverse habitats)