LING 123 Albany College of Pharmacy Mating Signals of Anurans & Passerines HW 1000 words essay TopicCompare and contrast the mating signals of two very dif

LING 123 Albany College of Pharmacy Mating Signals of Anurans & Passerines HW 1000 words essay TopicCompare and contrast the mating signals of two very different vertebrate orders: anurans (frogs and toads) and passerines (songbirds). What features do the anuran and passerine mating vocalizations share in common? What features are different? Discuss the mating signals themselves (acoustic structure, including elements and complexity), as well as how (anatomy and physiology) and why (sociology) those particular vocalizations are produced (by speaker) and preferred (by listener). This discussion should include comparison of the physical and social environments in which f Ling 123: Frog
Advertisement Calls
Today’s Objectives
 Biological mechanisms
underlying production and
perception of frog ad calls
 How advertisement calls impact
on frog’s chances of survival
and reproduction (issues of
adaptation)
 How female’s sensory bias plays
a role in evolution of male’s call
(an issue of phylogeny)
Anura (Frogs & Toads)
Kingdom: Animalia → Phylum: Chordata → Subphylum:
Vertebrata → Class: Amphibia → Order: Anura → Family →
Genus → Species (5000+)
N. American bullfrog
(Rana catesbeiana)
Puerto Rican coqui
(Eleutherodactylus coqui)
Tungara frog
(Physalaemus pustulosus)
http://animaldiversity.ummz.umich.edu/site/topics/frogCalls.html
http://www.fs.usda.gov
http://www.lsuhsc.edu/news/Singing%20in%20the%20Rain%20.htm
Advertisement calls functions for
male and female frogs
 During the mating season, male frogs produce advertisement calls in order
to:
 Attract potential mates
 Notify male competitors
 Male calls need to be heard
 Males need to appeal to females with their genetic qualities
 Females need to differentiate conspecific calls from heterospecific calls
 Females assess males’ genetic quality
 Females need to localize the sound source
Frog Call Production:
Mechanism
 Male frogs vocalize by squeezing their lungs with their nostrils and mouth shut
 Air flow causes vocal fold to vibrate, which generates sound (fundamental and
harmonics)
 Air flows over vocal folds and into vocal sacs, blowing them up like a balloon
 The role of the air sac is to amplify the sound
 Sexual dimorphism:
 Only male frogs have vocal sacs
 Only males make advertisement calls
 The male’s larynx is larger and heavier than the female’s larynx
(http://allaboutfrogs.org/weird/general/songs.html)
Frog’s Ear: Mechanism
 Frogs have a tympanum (ear drum) behind each eye on the
surface of the head
 They don’t have an external pinna (outer ear) like many
mammals do
Frog’s Hearing: Mechanism
 The tympanum (ear drum) vibrates in response to sound
 A rod (stapes) that connects the tympanum and inner ear vibrates
 The fluid within inner ear is sloshed back and forth
 The sloshing bends hairs on hair cells on two papillae (amphibian & basilar)
 This sends electrical pulses to brain, which interprets the sound
http://www.wonderquest.com/FrogHearing.htm
Frog’s Hearing: Mechanism
 The sloshing bends the hairs on the hair cells on two papillae
 Amphibian papilla
 Responds to low frequencies (100-1400Hz)
 Same for males & females, all sizes
 Basilar papilla
 Responds to species-specific high frequency of 1-4 kHz
 Varies with sex and size within species
 (Phylogeny)
http://www.wonderquest.com/FrogHearing.htm
Sound Localization:
Mechanism
 Ears and lungs together provide highly refined
mechanism for sound localization
 The sound can be localized by inter-aural time difference
 i.e. Delay between hitting left ear/lung vs. right ear/lung
 Frogs’ hearing mechanism has adaptive consequences
 Females can locate males (potential mates)
 Males can locate males (competitors)
Bullfrog Stuttering:
Adaptation
 Bullfrog calls sometimes contain “stutters”
 Patterns of stuttering:
 All calls begin with a croak that contains no stutters
 Number of stutters may increase up to four
 Stuttering is associated with mating (toward females)
 Non-stuttering with aggression (toward males)
Puerto Rican Coqui:
Adaptation
 Coqui frogs are native to Puerto Rico and Virgin Islands
 Male coqui produces a two-note advertisement call, the
“coqui”
 Advertisement call can reach 100 dB*
 “Co” note is used for male-male competition, higherfrequency “qui” note for attracting females
* equivalent to subway platform!
Tungara Frog Call:
Adaptation
 Characteristics of Tungara frog advertisement calls
 Males of all family species produce an advertisement call
“whine” with frequency down sweep & harmonics
 Tungara males add a broad-band “chuck” to the whine
 Call with a chuck is more attractive to females
Tungara Frog Call:
Pros & Cons (Adaptation)
 A call with a chuck is both adaptive and
counteradaptive — How so?
 A call with a chuck is more attractive to females, but
also useful to bats for prey localization
 An example of natural selection and sexual
selection providing opposing pressures on trait
expressions
http://allamericanoutdoorsman.com/facts-about-bats/
Lek Mating System (Zelick et al., 1999)
(Adaptation)
 A lek is a communal display ground/arena where
males gather for competitive display to attract female
mate
 Four characteristics of leks
 Females are attracted to the arena (lek)
 Females choose males at the lek
 Female mate choice is based solely on the male’s genetic quality
(males do not control any resources of interest to the female)
 Females obtain no resources or parental care of the young;
males’ sole contribution is to provide gametes
Signaling in Presence of Noise
 Most frogs live in rain forests, which are noisy!
 Home to numerous other signaling animals
 A male frog’s signal needs to be easily distinguishable from
those of other individuals and species
 Frogs use various strategies for signaling in an acoustically
complex environment:
 Spectrum sharing
 Time sharing
 Call alternation
Spectrum Sharing
 In radio, each station broadcasts its radio signal at a particular
frequency
 Similarly, frog species adopt different frequency ranges, giving
each species a “private” channel for its call
 Frequency range for eight species of Puerto Rican frogs:
“Frog communication”—Narins, 1995
Norins Lab, UCLA
Time Sharing/Call
Alternation
 Time sharing
 Male frogs resort to time sharing in order to ensure their calls
are heard – maximizing detectability
 Some species restrict their calls to particular times of day
 In Puerto Rico, the coqui calls from sunset to midnight.
 Bigger coquis call every four seconds; smaller coquis every two
seconds
 Call alternation
 To avoid overlap, frogs also time their calls to fit in the brief
moments when their neighbors are taking a break
Issue of male-male spacing in
a chorus
 Males need to produce advertisement calls, but also be aware of
competition around them.
 Balance is needed in being aggressive and participating in a chorus
 This is particularly true if the chorus density and vocal activity is
high.
 In such a scenario, the males will only alternate with the nearest
neighbors and ignore the farthest ones, while tolerance for
aggressive behavior increases.
Female Frog’s Sensory Biases:
Phylogeny
 Females tend to prefer lower-pitched croaks
 Females may even prefer non-existing features
 Experiments:
 Ryan & Rand compared Tungara frogs to P. coloradorum, a species
with non-overlapping geographic range
 Tungara males add a broadband chuck to the whine, while P.
coloradorum males do not
 P. coloradorum males sometimes produce double or triple calls,
while Tungara males do not
(Ryan & Rand 1998)
Female Frog’s Sensory Biases:
Phylogeny
 Experiment 1
 Tungara males add a broad-band chuck to the whine, while P.
coloradorum males do not
 Females of both species preferred a call with chucks to a call
without chucks (P. coloradorum females preferred the whine-chuck
call over their conspecific call)
Female Frog’s Sensory Biases:
Phylogeny
 Experiment 2
 P. coloradorum males sometimes produce double or triple
calls, while Tungara males do not
 Females of both species preferred a double-whine call to a singlewhine call (Tungara females preferred the double-whine call to
their conspecific single call)
Female Frog’s Sensory Biases:
Phylogeny
 Females in both species exhibit preferences for traits that
do not (yet) exist, suggesting that males have the opportunity
to evolve calls that more directly tap into those sensory biases
Hypothesized phylogeny
of different
advertisement calls
Ryan & Rand 1993
Sensory bias to trait evolution
 Sensory biases may lead to an evolution in male traits – but
how?
 Example:
 Frogs live in an environment where predators produce lowfrequency signals
 Selection will favor females who are more sensitive to these
signals and can avoid predators
 Sensitivity to low-frequency signals will cause females to also be
more sensitive to male frogs who produce such signals
Summary
 Male frogs produce species-specific advertisement calls in order
to attract potential mates and notify male competitors within a noisy
environment
 Males resort to spectrum sharing, time sharing, and call
alternation to be better heard
 Some advertisement calls contain elements (e.g., chucks, stutters) that
are directed exclusively towards females or towards other males
 Female frogs exhibit sensory biases towards particular call
features (e.g., low pitch sounds, complex signals)
 There is potential for the evolution of traits within male
advertisement calls influenced by sensory biases
LING 123 / Chatterjee
Essay 1: Frogs and Birds
20 Points (Worth 10% of Final Grade)
Essay 1: Frogs and Birds
TOPIC
Compare and contrast the mating signals of two very different vertebrate orders: anurans (frogs
and toads) and passerines (songbirds). What features do the anuran and passerine mating
vocalizations share in common? What features are different? Discuss the mating signals
themselves (acoustic structure, including elements and complexity), as well as how (anatomy and
physiology) and why (sociology) those particular vocalizations are produced (by speaker) and
preferred (by listener). This discussion should include comparison of the physical and social
environments in which frogs and songbirds live and what kinds of socio-ecological problems
each is required to solve. Your analysis should address at least two of Tinbergen’s four
perspectives on animal behavior: adaptation, mechanism, ontogeny, and phylogeny.
GUIDELINES
Essays are assessed not only for content, but also for grammar, clarity, conciseness, and
coherence. Strive to make your essays accurate, relevant, and organized, and use academic
English. Your writing should demonstrate an understanding of key scientific terms related to
sound and communication, with accurate use of technical terms such as amplitude, spectrum,
conspecific, heterospecific, etc. You might think of this as writing a short article directed towards
an educated layperson, and it should read as a prose essay, not a lab report outlining
observations. The purpose is to assess your writing skills in addition to your understanding of the
material presented in class.
For source material, you may draw on a mix of course lectures, videos and assigned
readings, but to earn full credit, you must include material from (and cite) at least two
articles from the relevant course readings. No further outside sources are required, though you
are certainly welcome to draw on other research materials if you like. There is no need to provide
citations for material you draw from lectures, unless the material originated from one of the
readings or videos. Properly cite these and any other data drawn from course readings and
videos. (You may use the formal citation style of your choice – APA or MLA, so long as you are
consistent and the source and page number of the material is made clear. If you do use additional
sources, be sure to cite them and provide full bibliographical entries.) Otherwise, as with any
academic writing, your work must be your own and in your own words.
FORMATTING AND SUBMISSION
⎯ Provide your own original, descriptive title for your essay. (Do not simply copy and paste
“Frogs and Birds”.)
⎯ Your essay must be a minimum of 1000 words long, but no longer than 1200 words. Include
the word count in your document.
⎯ Document formatting should use a 12-point font, double-spaced, have 1-inch margins on all
sides, and be saved in either doc/.docx or .pdf format only. Documents in shared drives will
not be accepted.
⎯ Your document should include your surname, first name, course name and section at the top
of the document.
⎯ The essay must be uploaded to Turnitin via Canvas before the due date/time. The essay will
be considered late if it is not submitted before the deadline.
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Objectives
 Difference between birds’ calls and
songs
 Difference between innate and
learned songs
 Explore elements of songs
 Biological mechanisms underlying
production of bird songs
 Adaptive functions of bird songs
 Hypotheses on the evolution of
repertoire size (an issue of
phylogeny)
Order: Passeriformes
Kingdom: Animalia →Phylum: Chordata → Subphylum: Vertebrata → Class: Aves
→ Order: Passeriformes → Family → Genus → Species

One of most successful vertebrate orders, 5000+ species

More than half of all bird species belong to this order

Members are called passerines or perching birds


Characteristic behaviors of passerines:


passerines 5 song types
 Some can have many more
 Brown thrashers can have 2000+
Repertoire Learning
 Species also vary in when they can learn songs
 Some have a short period (few months) after hatching (closed-ended
learners)
 White-crowned sparrows
 Some can learn & add new songs throughout life (open-ended
learners), usually seasonal
 European starlings, canaries
 Who sings depends on who competes to mate
 In many species only males sing
 In others, males & females sing equally in duets
Repertoire Size Hypotheses
(Wada 2010; Catchpole & Slater 2008)
What favors large and small repertoire size?
 Sensory bias hypothesis (Ryan & Rand 1993): Males adapt to females
preference
 Female birds habituate to certain stimulus
 Males’ song change over time to take advantage of female preference
 Repertoire hypothesis (C&S 2008): Females prefer males with larger
repertoire
 In many species, females prefer males that have a large repertoire
 The males with larger repertoire tend to have a higher reproductive
success
 The males with la…
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