Transcript The Evolution of Animal signals

Part 3 From individual
behaviour to social
systems
鄭先祐
靜宜大學 生態學系
Part 3 Social systems
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Chap. 7 The evolution of animal signals
Chap. 8 Sexual selection and mate choice
Chap. 9 Sociality and kin selection in insects
Chap.10 Predicting family dynamics in social
vertebrates
Chap. 11 The ecology of relatonships
Chap. 12 The social gene
evolution of animal signals
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The Evolution of
Animal signals
鄭先祐
靜宜大學 生態學系
The evolution of animal
signals
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7.1 Introduction
7.2 The signaller’s (發出信息者) perspective
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7.2.1 Getting the message across
7.2.2 The influence of the physical environment
7.2.3 The influence of the audience
7.2.4 The influence of other signallers
7.3 The receiver’s (接收者) perspective
7.4 conclusions and prospects
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7.2 The signaller’s perspective
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It serves to influence the receiver’s behaviour
in a way that benefits the signaller.
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但有些情況，亦可能是對接收者有利。
Signaller, 發出訊息，是有風險和能量的成本。
演化會傾向 Greater effectiveness and lower
fitness cost.
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7.2.1 getting the message
across
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訊息要能傳達，特別於長距離，吵雜的環境。
譬如：male anoles’ head-bobbing display.
1. the display begins with a series of head
movements that are of high acceleration,
velocity and amplitude compared with the rest
of the display.
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2. the anoles’ assertion display is repetitive.
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This movements are conspicuous. (Fig. 7.1)
確實辨識。
3. the anoles’ signal is stereotyped.
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Fig. 7.1 A schematic diagram of how the assertion
display of A. auratus is created, together with two
typical examples of the display.
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Fig. 7.1 the assertion display of A. auratus.
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7.2.2 The influence of the
physical environment
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Marchetti (1993), the plumage patterns of
eight species of warblers of the genus
Phylloscopus, which breed in the forests of
Kashmir, India.
All of the species are small and greenish in
colour, but they possess varying numbers of
pale colour patches on their wings, crown,
rump and tail.
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物理環境影響訊息的展現
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Experimental manipulation of male coloration
in P. inornatus directly affected territory size,
with males that were tendered more
conspicuous obtaining larger territories than
control individuals.
Species with more patches tended to occupy
dark, dense habitats, while those with fewer
patches tended to breed in open area.
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Wiley (1991) male territorial songs of
eastern North American oscine birds
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This study considered 120 species of oscines.
Three of properties concerned the temporal
structure of the song, and were indicative of
rapid modulation: the minimal period of
repeated elements, the presence or absence
of one or more buzzes and the presence or
absence of ‘side-bands’ on a song
spectrogram.
棲地區分為六種，三種是樹林型，另三種是
open habitats.
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Short repetition periods, buzzes and sidebands less common among birds of forested
habitats.
這三種特質，於樹林內都較容易被干擾。
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7.2.3 The influence of the
audience
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Endler (1992), the coloration of male guppies
provide evidence for the matching of display
design to receiver sensory capacities.
Wild populations of puppies have complex
and polymorphic colour patterns, comprising
patches of eight major types: red-orange,
yellow, bronze-green, cream-white, blue,
silver, brown, black and body colour.
Those colours, restricted to adult males, play
a role in mate choice.
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Female preferences vary among populations,
but typically favour males with more
carotenoid (red-orange and yellow) patches,
more structural colour (blue, green and silver)
patches, and patterns that contrast in colour
or patch size with the visual background.
Conspicuous and highly colourful fish suffer
greater risk of predation.
Selection had favored those colour patterns
that were most conspicuous to guppies while
being least conspicuous to predator.
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Proctor (1991) water mite
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運用 female’s pre-existing sensory properties.
(原本就存在的感應能力), which evolved for
reasons unrelated to communication.
Mite 是 ambush predators. 於水上感應獵物活
動時的水波。
雄 mite 運用其腳製造水的波動，讓雌mite 誤
以為是獵物。
愈飢餓的雌mite， 愈會受到吸引。
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7.2.4 The influence of other
signallers
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於許多訊息傳送的過程，訊息的傳達需要能獨
特出色。
Loftus-Hills & Littlejohn (1992), two species of
narrow-mouthed toad, widely distributed in
the southern US.
Males rely on an advertisement call to attract
females.
sympatric or allopatric 分布情況，可有四種。
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Sympatric 傾向可以區分開。
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Greenfield and Roizen (1993) chorusing in
the neotropical katydid (美洲大螽斯)
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An isolated male will usually maintain a regular chirp
rhythm for several minutes.
倘若兩隻male 相距10公尺內，會有 synchronization
的現象。
這種synchronization 是透過 an inhibitory resetting 的
機制。
聽到聲音，會抑制發聲，而在下一個預期出聲時，再
發聲。搶先發聲。
Females show a preference for the leading call in a
closely synchronized sequence.
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7.3 The receiver’s perspective
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7.3.1 cooperation and conflict (合作與衝突) in
signal evolution
7.3.2 physical constraints on deceit (欺騙)
7.3.3 strategic constraints on deceit
7.3.4 The possibility of rare deception
7.3.5 strategic explanations for signal
diversity
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cooperation and conflict in
signal evolution
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One of the best-known instances of
cooperative signalling is the use of a dance
‘language’ by honey bees.
Many kinds of communication involve a
conflict of interest between signaller and
receiver.
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Males are typically under stronger selection to
acquire many mates.
Females would benefit from an accurate
assessment of male mate quality.
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Threat displays
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遇到predator出現，發出警告的訊息。
倘若有 a deceitful’ mutant 出現，它將會獲利。
族群會朝向欺騙的方向演化。
什麼機制可以維持 ‘honesty’ ？
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7.3.2 physical constraints on deceit
7.3.3 strategic constraints on deceit
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7.3.2 physical constraints on
deceit
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維持雄性優越訊息的honesty，有些可以用
physical constraint。
譬如：動物通常無法自體合成 carotenoid
colour ，需要從食物獲取。
雄性展現 carotenoid colour ，必要有充分食物
作為基礎。
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7.3.3 Strategic constraints on
deceit
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有許多訊息無法靠physical constraint，需要有
strategic constraint 維護 honesty
Handicap principle (Zahavi, 1977)，sexual
display 信息的產生需要很高的cost。
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倘若身體不夠好，勉強的付出高cost 的sexual
display，會下降其生存的維護。
但是相關這方面，欠缺驗證。
最好的例子是 tail ornaments of male barn
swallows (Moller, 1994)
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7.3.4 The possibility of rare
deception
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Redondo (1993), begging by magpie and great
spotted cuckoo chicks.
The chicks that begged most intensely were found
to be those that had received smaller quantities of
food from parents, indicating that the begging
display provides reliable information about hunger.
The above reliable system of parent-offspring
communication, however, is exploited by the chicks
of great spotted cuckoos, obligate brood parasites
that are raised alongside host chicks, and severely
depress the breeding success of magpies.
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7.3.5 Strategic explanations of
signal diversity
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動物通常有可靠的資訊顯現出發出訊息者的狀態，
而且有些可有避免欺騙的機制 (Handicap
principle)。
但是鮮少研究驗證是否有 reliability 的天擇？
Zahavi (1987) 認為產出訊息的代價，可以維持
honesty，假若是對依靠訊息產出者的本身狀態
而產出的信息。
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但對發出逃走的訊息，则要靠掠食者掠食的壓力。
但是這方面的驗證，仍未有研究。
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Briskie et al. (1994) 11 spp. Of
passerine birds
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這些鳥有不同程度的混合育幼的現象。
倘若是親緣關係相差較大，幼鳥的beg 叫聲和
動作會較誇大。
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如：cuckoo chick begs more loudly than a host
chick because it has nothing to lose by depriving
its nestmates of food)
Revealed that the loudness of nestling
begging calls among the sample species was
positively correlated with the percentage of
extrapair young, illustrated in Fig. 7.3.
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Fig. 7.3 a phylogeny of the bird species (Briskie et al., 1994)
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Fig. 7.3b. A paired comparison of begging loudness between
species with high (open circles) and low (filled circles) levels of
relatedness within a brood.
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7.4 conclusions and prospects
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兩種不同天擇的力量：有效率 vs. 可靠性
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站在訊息產出者的立場：訊息的產出，需要有效率，
低成本，高獲利。
站在接受者的立場：維持訊息的真實性(honesty)，
訊息的產出需要提高成本。
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7.4.1 unanswered questions
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Multiple signals
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Why are animal displays so complex?
Models of signalling have typically assumed that
only a single form of display is abailable to
signallers.
It is only recently that they have begun to address
the possibility of multicomponent displays
(Johnstone, 1996)
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Multiple signallers
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The influence of competition among
signallers on information transfer during
communication.
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Receivers can acquire reliable information about
signallers by focusing on costly displays that only
superior or more needy individuals can afford to
use. (7.3)
However, where several signallers vie for
attention, competition has the potential to interfere
with receiver assessment of signaller condition.
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