Chapter 5 Biodiversity, Species Interactions, and Population Control

Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction? Habitat Hunted: early 1900s Partial recovery Why care about sea otters? Ethics Tourism dollars Keystone species

Southern Sea Otter Figure 5.1: An endangered southern sea otter in Monterey Bay, California (USA), uses a stone to crack the shell of a clam (left). It lives in a giant kelp bed (right). Scientific studies indicate that the otters act as a keystone species in a kelp forest system by helping to control the populations of sea urchins and other kelp-eating species. Fig. 5-1a, p. 104

5-1 How Do Species Interact? Concept 5-1 Five types of species interactions—competition, predation, parasitism, mutualism, and commensalism—affect the resource use and population sizes of the species in an ecosystem.

Species Interact in Five Major Ways Interspecific Competition Predation Parasitism Mutualism Commensalism

Most Species Compete with One Another for Certain Resources For limited resources Ecological niche for exploiting resources Some niches overlap

Some Species Evolve Ways to Share Resources Resource partitioning Using only parts of resource Using at different times Using in different ways

Resource Partitioning Among Warblers Figure 5.2: Sharing the wealth: This diagram illustrates resource partitioning among five species of insect-eating warblers in the spruce forests of the U.S. state of Maine. Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion (yellow highlighted areas) of the spruce trees, and by consuming somewhat different insect species. (After R. H. MacArthur, “Population Ecology of Some Warblers in Northeastern Coniferous Forests,” Ecology 36 (1958): 533–536.) Fig. 5-2, p. 106

Black-throated Green Warbler Yellow-rumped Warbler Blackburnian Warbler Black-throated Green Warbler Cape May Warbler Bay-breasted Warbler Yellow-rumped Warbler Figure 5.2: Sharing the wealth: This diagram illustrates resource partitioning among five species of insect-eating warblers in the spruce forests of the U.S. state of Maine. Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion (yellow highlighted areas) of the spruce trees, and by consuming somewhat different insect species. (After R. H. MacArthur, “Population Ecology of Some Warblers in Northeastern Coniferous Forests,” Ecology 36 (1958): 533–536.) Fig. 5-2, p. 106

Black-throated Green Warbler Cape May Warbler Bay-breasted Warbler Blackburnian Warbler Black-throated Green Warbler Cape May Warbler Bay-breasted Warbler Yellow-rumped Warbler Stepped Art Fig. 5-2, p. 106

Specialist Species of Honeycreepers Figure 5.3: Specialist species of honeycreepers: Through natural selection, different species of honeycreepers developed specialized ecological niches that reduced competition between these species. Each species has evolved a specialized beak to take advantage of certain types of food resources. Fig. 5-3, p. 107

Insect and nectar eaters Fruit and seed eaters Insect and nectar eaters Greater Koa-finch Kuai Akialaoa Amakihi Kona Grosbeak Crested Honeycreeper Akiapolaau Figure 5.3: Specialist species of honeycreepers: Through natural selection, different species of honeycreepers developed specialized ecological niches that reduced competition between these species. Each species has evolved a specialized beak to take advantage of certain types of food resources. Maui Parrotbill Apapane Unknown finch ancestor Fig. 5-3, p. 107

Most Consumer Species Feed on Live Organisms of Other Species (1) Predators may capture prey by Walking Swimming Flying Pursuit and ambush Camouflage Chemical warfare

Predator-Prey Relationships Figure 5.4: Predator-prey relationship: This brown bear (the predator) in the U.S. state of Alaska has captured and will feed on this salmon (the prey). Fig. 5-4, p. 107

Most Consumer Species Feed on Live Organisms of Other Species (2) Prey may avoid capture by Run, swim, fly Protection: shells, bark, thorns Camouflage Chemical warfare Warning coloration Mimicry Deceptive looks Deceptive behavior

Some Ways Prey Species Avoid Their Predators Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. Fig. 5-5, p. 109

Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (a) Span worm Fig. 5-5a, p. 109

(b) Wandering leaf insect Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (b) Wandering leaf insect Fig. 5-5b, p. 109

Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (c) Bombardier beetle Fig. 5-5c, p. 109

(d) Foul-tasting monarch butterfly Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (d) Foul-tasting monarch butterfly Fig. 5-5d, p. 109

Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (e) Poison dart frog Fig. 5-5e, p. 109

(f) Viceroy butterfly mimics monarch butterfly Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (f) Viceroy butterfly mimics monarch butterfly Fig. 5-5f, p. 109

(g) Hind wings of Io moth resemble eyes of a much larger animal. Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (g) Hind wings of Io moth resemble eyes of a much larger animal. Fig. 5-5g, p. 109

Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior. (h) When touched, snake caterpillar changes shape to look like head of snake. Fig. 5-5h, p. 109

(b) Wandering leaf insect (a) Span worm (b) Wandering leaf insect (c) Bombardier beetle (d) Foul-tasting monarch butterfly (e) Poison dart frog (f) Viceroy butterfly mimics monarch butterfly (g) Hind wings of Io moth resemble eyes of a much larger animal. (h) When touched, snake caterpillar changes shape to look like head of snake. Stepped Art Fig. 5-5, p. 109

Science Focus: Threats to Kelp Forests Kelp forests: biologically diverse marine habitat Major threats to kelp forests Sea urchins Pollution from water run-off Global warming

Purple Sea Urchin Figure 5.A: This purple sea urchin inhabits the coastal waters of the U.S. state of California. Fig. 5-A, p. 108

Predator and Prey Interactions Can Drive Each Other’s Evolution Intense natural selection pressures between predator and prey populations Coevolution Interact over a long period of time Bats and moths: echolocation of bats and sensitive hearing of moths

Coevolution: A Langohrfledermaus Bat Hunting a Moth Fig. 5-6, p. 110

Some Species Feed off Other Species by Living on or in Them Parasitism Parasite is usually much smaller than the host Parasite rarely kills the host Parasite-host interaction may lead to coevolution

Parasitism: Trout with Blood-Sucking Sea Lamprey Fig. 5-7, p. 110

In Some Interactions, Both Species Benefit Mutualism Nutrition and protection relationship Gut inhabitant mutualism Not cooperation: it’s mutual exploitation

Mutualism: Hummingbird and Flower Figure 5.8: Mutualism: This hummingbird benefits by feeding on nectar in this flower, and it benefits the flower by pollinating it. Fig. 5-8, p. 110

Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish Fig. 5-9, p. 111

(a) Oxpeckers and black rhinoceros Figure 5.9: Examples of mutualism: (a) Oxpeckers (or tickbirds) feed on parasitic ticks that infest large, thick-skinned animals such as the endangered black rhinoceros. (b) A clownfish gains protection and food by living among deadly, stinging sea anemones and helps to protect the anemones from some of their predators. (a) Oxpeckers and black rhinoceros Fig. 5-9a, p. 111

(b) Clownfish and sea anemone Figure 5.9: Examples of mutualism: (a) Oxpeckers (or tickbirds) feed on parasitic ticks that infest large, thick-skinned animals such as the endangered black rhinoceros. (b) A clownfish gains protection and food by living among deadly, stinging sea anemones and helps to protect the anemones from some of their predators. (b) Clownfish and sea anemone Fig. 5-9b, p. 111

In Some Interactions, One Species Benefits and the Other Is Not Harmed Commensalism Epiphytes Birds nesting in trees

Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree Figure 5.10: In an example of commensalism, this bromeliad—an epiphyte, or air plant—in Brazil’s Atlantic tropical rain forest roots on the trunk of a tree, rather than in soil, without penetrating or harming the tree. In this interaction, the epiphyte gains access to sunlight, water, and nutrients from the tree’s debris; the tree apparently remains unharmed and gains no benefit. Fig. 5-10, p. 111