Chapter 8Behavioral Ecology

Ecology 2001 鄭先祐 生態主張者 Ayo 工作室

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Behavioral Ecology

Genetic and Environmental components of Behavior Innate Behavior Learning Genetic and environmental factors

Mechanisms of Behavioral Interaction Communication Aggression Territoriality

Social systems Environmental application

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Behavioral ecology ( 行為生態學 )

Behavioral ecology, the study of behavior in an ecological context.

such as communication, aggression, territoriality, mating systems and cooperation.

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Genetic and environmental components of behavior

Innate behavior, the behaviors appear in response to a certain stimulus and from the first are performed in their typical stereotypical fashion. The specific behavior is referred to as a fixed action

pattern (FAP). A magnified sign stimulus that provokes an

exaggerated response is called a superstimulus. Learning

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The modern study of behavior has taken two distinct routes in this century -- one European, one American.

Ethology and comparative psychology

Fig 24.1 Two of the bounders of modern ethology

(a) Konrad Lorenz

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The European approach was called ethology. Its goal was to understand behavior by study its cause, development, evolution, and function through the observation of animals in the wild, or under somewhat natural conditions.

Fig 24.1 Two of the bounders of modern ethology

(b) Niko Tinbergen

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The American approach was called comparative psychology.

Its goal was to understand behavior by studying animals in the laboratory under carefully controlled conditions.

Its focus was learning, and its primary animal was the Norway rat.

American approach

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The definition of Instincts ( 本能 )

The perception of something in the environment (a releaser) triggers a reaction in a center in the central nervous system(the innate releasing mechanism) that then cause the performance of the instinctive act, sometimes composed of very stereotyped movements (fixed action patterns).

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Fig. 24.2

A male European robin in breeding condition will attack a tuft of red feathers ( 一叢紅色羽毛 ) placed in his territory.

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Fig. 24.4 Simplified diagram of how a fixed action pattern can be triggered. The releaser is perceived by some sort of receptor, which triggers the IRM to activate certain muscles, thereby producing an instinctive movement that usually involves fixed action patterns.

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Fig. 24.3 The scratching movements of dogs, as well as many other vertebrates, are considered fixed action patterns.

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Learning ( 學習 ) Learning is a change in behavior,

based on experience.Fig. 24.5 Chimpanzees are highly social creatures that live in a complex, variable, and changing world. Intelligence is important under such circumstances.

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Habituation ( 習慣 )

Habituation is , in a sense, learning not to respond to a stimulus.

The first time an animal encounters a stimulus, it may respond vigorously.

But if the stimulus is presented over and over without consequence, the response to it gradually lessens and may finally disappear altogether. (Fig. 24.6)

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Fig. 24.6 As animals become accustomed to a stimulus, habituation may occur.

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Essay 24.1

Why haven't been selected for so that by now we can all, more or less, perform such feats?

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A mnemoist

A mnemoist (a Russian profession) would sometimes memorize lines of 50 words.

Once, in just a few moments, he memorized the nonsense formula Nd2(853/vx)(2762/n2v)(86x/273)(n2b)(rd) = sv

(1625/322)(r2s5) Fifteen years later, upon request, he repeated

the entire formula without a single mistake.

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The interaction of genetic and environmental factors

The development of virtually any behavioral trait we can imagine has both environmental and genetic components.

譬如： Chap.2 Belding’s ground squirrel 的kin selection. Holmes and Sherman (1982)

The behavioral interactions among individuals in this species exemplify the interaction between genes and the environment.

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範例： Belding’s ground squirrel

Holmes and Sherman (1982) At birth, some pups were switched to different

females in combinations that created four groups of offspring: sibs reared apart, sibs reared together, nonsibs reared apart, and nonsibs reared together.

Whether they were sibs or not, individuals reared together demonstrated less aggressive behavior toward each other than individuals reared apart.

The pups apparently learn to treat the individuals with whom they grow up as kin.

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Difference between males and females Female sibs reared apart showed

lower rated of aggression toward each other than did male sibs reared apart.

Males were aggressive toward any individual with whom they did not share a nest as a juvenile.

Some innate mechanism allows females to recognize their female kin and behave less aggressively toward them.

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範例： White-crowned sparrow

Marler and Tamura (1964) showed that males of this species have song dialects characteristic of the region were they were raised (Fig. 8.1)

A series of elegant experiments by Konishi (1965) elucidated the interplay between genetics and learning in the development of the male song. (Fig. 8.2)

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Ecology 200122 Fig. 8.1 Song dialects in white-crowned sparrows

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Fig. (a) The essential events in the development of song in male white-crowned sparrows.

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Fig. 8.2 Two experimental manipulation of song learning in male white-crowned sparrows.

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Three groups (male white-crowned sparrows)

1. Chicks maintained in soundproof chambers in which they were not permitted to hear songs of any kind.(Fig. 8.2b)

2. Chicks allowed to hear songs of their species until they were five months old, at which point they were surgically deafened.(Fig. 8.2c)

3. A control groups of chicks.(Fig. 8.2a)

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Mechanisms of behavioral interaction

Communication ( 溝通 ) Aggression ( 攻擊 ) Territoriality ( 領域 )

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Communication

Any action on the part of one organism that alters the probability of a behavior in another individual.

The fitness of both individuals increases as a result.

The sending, the receiving, and the elicited behavior are all components of the communication system.

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Ecology 200129 四種溝通的管道

化學 聲音 視覺 接觸

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Chemical signals

For example, some insects use pheromones ( 費洛蒙 ) as a sex attractants and as warning signals (alarm pheromones).

Sex pheromones tend to be high-molecular-weight compounds because these molecules have the potential variability, and hence the potential specificity.

Alarm pheromones tend to be volatile, low-molecular-weight compounds which can travel far and fast to warn conspecifics..

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Discrete and graded signals

Communication signals can be divided into two basic types: discrete signals and graded signals.

Discrete signals provide simple, digital– yes or no, on or off – kinds of information. Graded signals fall along a continuum of

intensity or complexity, and their variability allows the signaler to provide richer, analog information.

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範例：螢火蟲 (Fig. 3)

Produce discrete signals. Each species has a characteristic flashing

pattern that is relatively invariant(Fig. 8.4). The flashing patterns of both males and females

are highly stereotyped. Males fly across the habitat and flash. The female communicates her receptivity and

location by responding with her own flashing.

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Fig. 8.4 Discrete signals in the sexual communication of fireflies.When a female on the ground observes the pattern of her own species, she flashes in response, attracting the male to her.

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範例：the waggle dance of the 蜜蜂 A series of graded communication signals. When a honeybee locates a new food source,

she returns to the hive and communicates the direction, distance, and quantity of food to her nest mates.

In performing the waggle dance, depicted in Fig. 8.5, the worker bee repeatedly moves in a figure-eight, she performs a so-called straight run, a straight-line movement during which she vibrates(waggles) her abdomen.

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Fig. 8.5 The waggle dance of the honeybee, which is performed both (a) outside the hive and (b) inside the hive on a vertical surface.

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Fig. 8.5 The waggle dance of the honeybee, which is performed both (a) outside the hive and (b) inside the hive on a vertical surface.

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There is a significant positive relationship between the complexity of the social system and the size of the alarm call repertoire.

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Aggression

Aggression, as an act by which one individual achieves dominance over another by physical violence or the threat of it.

Such behavior is typically considered an aspect of predation, defense against predators, or competition.

不戰而屈人之兵，謂之上策。 Fighting is more ceremonial than lethal.

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儀式化的攻擊 Ritualized pattern evolved because the

fitness of the species depends on protecting important members from lethal combat that would deprive them of the opportunity to pass on their genes.

或許可以用 Group selection argument. 但是 the advantage for the group is

different from what is advantageous for the individual.

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增進個人的 fitness

It is more likely that the adaptive basis for ritualization of such behavior involves individual fitness.

It may be to both antagonists’ advantage to recognize quickly, and with minimum trauma.

The younger or smaller individual often loses such an encounter, but given time, that individual may well become large enough to dominate others.

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範例： the great tit ( 大山雀 ) 和紅翅黑鳥 (red-winged blackbirds)

大山雀可以發出多達八種宣告領域的叫聲，這會讓沒有領域者誤以為有許多佔有領域者在這個地區，而離開該地區。

相似的結果也發生在紅翅黑鳥，運用錄音播放多隻有領域者的叫聲，入侵此地區者就會較少。若是只有單隻的叫聲，入侵者就會較多。

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範例： the spotted hyenas ( 土狼 )

One of the most violently aggressive mammals. Intense competition and aggression occur over

kills that the pack has made. In response to selective pressure, females are

larger and more aggressive than males, presumably to ensure access to kills for themselves and their offspring.

Females also are anatomically masculinized( 雄性化 ), which was achieved via increased androgen levels.

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範例： infanticide ( 殺嬰 )

It appears that in the males of the white-footed mouse, infanticide is associated with confidence of paternity just as it it in lions.

In females, infanticide appears to be related to crowding.

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Territoriality ( 領域現象 )

Home range (Fig. 8.8) Territory ( 領域 ) ： Territorial behavior

evolves to ensure access to crucial resources.

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3D 的 Home Range

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Classification of territories

Type A ： Large defended area; courtship, mating, nesting, and food gathering.

Type B ： Large defended area; all breeding but not foraging.

Type C ： Small defended area around nest. Type D ： Mating territories; for courtship

activities only. Type E ： Roosting or shelter positions.

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The size of a territory

領域雖然愈大可能愈好，但是要維持愈大的領域，所要花費的投資將會愈大。

擁有領域者，受到被掠食的風險也加大。 Type A 的物種，其 size 受到 food supply

的量影響。食物供應愈缺乏，松鼠的領域通常會愈大。 (Tamiasciurus squirrels)

Energy budget of territorial African golden-winged sunbirds (Table 8.3)

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休息與覓食，兩者能量的耗用相差 600K/ 小時。

If the production rate of a defended territory is twice that of an undefended site, the bird gains 2,400K per day by maintaining the territory .

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Territory size increases as a function of body mass.The slope is greater for carnivores.

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Social systems

Three fundamental components: 1. Group size and structure 2. The mating system 3. Cooperation and helping

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Group size and structure

An aggregation is a group of conspecifics that includes more than one family unit and is localized in a particular area.

A colony is a group of conspecifics that form a society of highly integrated individuals.

Group. This term has two meanings. 一個是泛稱。另一個是指介乎在 aggregation 和colony 之間。

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The evolutionary “decision”

The evolutionary “decision” about whether to join a group is based on the relative advantages of solitary living and group living.

An example of the balance that must be struck in the evolution of group living – the optimization of group size – is shown in Figure 8.10.

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The optimal group size is found at the intersection of those two functions.

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“A” might be defense against predators.小團體，個體少不足以防衛。過大的團體，招惹掠食者的攻擊。“ B” might represent group foraging.

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Mating system

The relationships among males and females during breeding as the mating system.

Three components: 1. The number of mates an individual takes. 2. Whether the male and female form a pair

bond. 3. The duration of the pair bond.

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Polygyny

Males mate with more than one female. This implies that not all males mate, there is

variance in male reproductive success. If resources, leading to intense competition

among the males. Because females choose males who control resources, there is a high variance in reproductive success among males, and the potential for polygyny arises. (Emlen and Oring’s model)

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Synchrony in sexual receptivity

As the degree of synchrony in sexual receptivity of females decreases, the opportunity for multiple matings increases.

If all females are receptive at the same time, it will be difficult for a male to service more than one.

At high levels of asynchrony, the cost of maintaining exclusive use of a resource exceeds the potential reproductive benefits. 因此polygyny decreases again. (Fig. 8.12)

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Polygyny 的產生，受到兩項因素的影響：1. Asynchrony 的程度 2. 資源 clumped 的程度。

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Female defense polygyny

When females associate with each other in groups.

Most often the selective pressure for female associations is predation.

例如： In gorillas, females travel in groups to avoid leopard predation; males defend such groups from other males.

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Resource defense polygyny Resource is clumped, and males defend the

resource. Females are attracted to the territory for its

resource, and males gain access to multiple females in this way.

例如： the orange-rumped honeyguid, a bird of Africa and the Indian subcontinent, feeds entirely on beeswax. Males defend bee colonies from other males. Females are attracted to the colonies and copulate with the male. Extreme polygyny results.

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Lek systems

In lek systems, the males defend only a tiny portion of a communal display area.

Females approach the display area and choose among the males that are displaying there.

例如： sage grouse leks in prairie and sage habitats, as many as 400 males may display over an area of more than a hectare. Fewer than 10% of the males achieve 75% of the matings.

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Monogamy

The frequency of monogamy is far higher in birds than in mammals; approximately 90% of all bird species are monogamous. In contrast, fewer than 5% of mammals are monogamous.

雄性多次 matings 的 fitness advantage 非常的大。因此必要有狀況的限制，才能避免其polygyny 。

鳥類與哺乳類的 monogamy 發生率的差異，顯現出限制狀況的差異。

鳥類因為 the timing of resource availability 的限制，雌性傾向於生殖 synchrony 。

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Polyandry

Polyandry, in which females mate with more than one male, is the rarest of the mating systems.

In some cases of polyandry, the sex roles are reversed, and males provide most of the parental care.

譬如： The American jacana(Jacana spinosa), a wading bird, exhibits an extreme form of polyandry. Females defend large “super- territories” that contain multiple nests attended by different males.

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The spotted sandpiper (Actitis macularia)

Females compete for mating territories, into which two or three males settle.

Each male defends a single nest in a portion of the female’s territory, providing parental care for the young, while the female defends her territory and attempts to attract still other mates.

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Cooperation and helping

Altruism ( 利他行為 ) Genetically based cooperation

Kin relationships. Coefficient of relationship

Habitat saturation and food supply A number of example of cooperative breeding

have evolved among the birds. One of the most thoroughly studies is the

acorn woodpecker.

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The acorn woodpecker

The social unit of this species is a territorial group of up to a dozen members(both males and females) that gather and store acorns in thousands of holes drilled in a tree called a granary.

This cache provides the major source of food over the winter.

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Three unusual features(Fig. 8.14)

1. Division of labor and helpers 2. Mate sharing 3. Infanticide. Females kill the first eggs

laid by other females. Whenever birds enter a group to fill a vacancy, they kill all the young.

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圖 8.14 The structure of the acorn woodpecker group is strongly influenced by the quantity of mast the group can store in the fall.

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Why?

1. The habitat is saturated; all good territories are occupied. Consequently, opportunities for young to disperse are extremely limited.

2. Mate sharing results because it provides advantages to the individual breeder.

3. The infanticide is apparently adaptive because it provides a genetic advantage over other members of the group.

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Eusocial system

1. Extensive cooperation 2. Division of labor 3. The presence of a queen.

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Fig. 8.17 Relationships between (a) reproductive costs and (b) reproductive benefits of breeders in relation to the amount of parental care.

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Environmental Application

Behavioral Ecology and captive breeding

運用 captive breeding 繁殖，以增長滅絕中的生物族群。

運用過此方法的有：California condor, black-footed ferret and the golden lion tamarin of the Brazilian rain forests.

成功的條件：了解其行為和相關社會因素。

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例如： Wolf packs and lion prides

The groups of both species are similar in size and composition.

Wolves are basically monogamous, and only the alpha male and alpha female mate. Other adults participate in rearing the offspring but do not breed.

Lion prides contain several breeding females. The males are usually related to each other.

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